| Age | Commit message (Collapse) | Author |
|---|
|
[ Upstream commit 4f41d30cd6dc865c3cbc1a852372321eba6d4e4c ]
When appending "[defcmd]" to 'kdb_prompt_str', the size of the string
already in the buffer should be taken into account.
An option could be to switch from strncat() to strlcat() which does the
correct test to avoid such an overflow.
However, this actually looks as dead code, because 'defcmd_in_progress'
can't be true here.
See a more detailed explanation at [1].
[1]: https://lore.kernel.org/all/CAD=FV=WSh7wKN7Yp-3wWiDgX4E3isQ8uh0LCzTmd1v9Cg9j+nQ@mail.gmail.com/
Fixes: 5d5314d6795f ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 22c7fa171a02d310e3a3f6ed46a698ca8a0060ed ]
For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off
for validation. However, variable offset ptr alu is not prohibited
for this ptr kind. So the variable offset is not checked.
The following prog is accepted:
func#0 @0
0: R1=ctx() R10=fp0
0: (bf) r6 = r1 ; R1=ctx() R6_w=ctx()
1: (79) r7 = *(u64 *)(r6 +144) ; R6_w=ctx() R7_w=flow_keys()
2: (b7) r8 = 1024 ; R8_w=1024
3: (37) r8 /= 1 ; R8_w=scalar()
4: (57) r8 &= 1024 ; R8_w=scalar(smin=smin32=0,
smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400))
5: (0f) r7 += r8
mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1
mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024
mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1
mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024
6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off
=(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024,
var_off=(0x0; 0x400))
6: (79) r0 = *(u64 *)(r7 +0) ; R0_w=scalar()
7: (95) exit
This prog loads flow_keys to r7, and adds the variable offset r8
to r7, and finally causes out-of-bounds access:
BUG: unable to handle page fault for address: ffffc90014c80038
[...]
Call Trace:
<TASK>
bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline]
__bpf_prog_run include/linux/filter.h:651 [inline]
bpf_prog_run include/linux/filter.h:658 [inline]
bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline]
bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991
bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359
bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline]
__sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475
__do_sys_bpf kernel/bpf/syscall.c:5561 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5559 [inline]
__x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b
Fix this by rejecting ptr alu with variable offset on flow_keys.
Applying the patch rejects the program with "R7 pointer arithmetic
on flow_keys prohibited".
Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook")
Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240115082028.9992-1-sunhao.th@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
commit 715d82ba636cb3629a6e18a33bb9dbe53f9936ee upstream.
The following case can cause a crash due to missing attach_btf:
1) load rawtp program
2) load fentry program with rawtp as target_fd
3) create tracing link for fentry program with target_fd = 0
4) repeat 3
In the end we have:
- prog->aux->dst_trampoline == NULL
- tgt_prog == NULL (because we did not provide target_fd to link_create)
- prog->aux->attach_btf == NULL (the program was loaded with attach_prog_fd=X)
- the program was loaded for tgt_prog but we have no way to find out which one
BUG: kernel NULL pointer dereference, address: 0000000000000058
Call Trace:
<TASK>
? __die+0x20/0x70
? page_fault_oops+0x15b/0x430
? fixup_exception+0x22/0x330
? exc_page_fault+0x6f/0x170
? asm_exc_page_fault+0x22/0x30
? bpf_tracing_prog_attach+0x279/0x560
? btf_obj_id+0x5/0x10
bpf_tracing_prog_attach+0x439/0x560
__sys_bpf+0x1cf4/0x2de0
__x64_sys_bpf+0x1c/0x30
do_syscall_64+0x41/0xf0
entry_SYSCALL_64_after_hwframe+0x6e/0x76
Return -EINVAL in this situation.
Fixes: f3a95075549e0 ("bpf: Allow trampoline re-attach for tracing and lsm programs")
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-4-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 71fee48fb772ac4f6cfa63dbebc5629de8b4cc09 upstream.
When offlining and onlining CPUs the overall reported idle and iowait
times as reported by /proc/stat jump backward and forward:
cpu 132 0 176 225249 47 6 6 21 0 0
cpu0 80 0 115 112575 33 3 4 18 0 0
cpu1 52 0 60 112673 13 3 1 2 0 0
cpu 133 0 177 226681 47 6 6 21 0 0
cpu0 80 0 116 113387 33 3 4 18 0 0
cpu 133 0 178 114431 33 6 6 21 0 0 <---- jump backward
cpu0 80 0 116 114247 33 3 4 18 0 0
cpu1 52 0 61 183 0 3 1 2 0 0 <---- idle + iowait start with 0
cpu 133 0 178 228956 47 6 6 21 0 0 <---- jump forward
cpu0 81 0 117 114929 33 3 4 18 0 0
Reason for this is that get_idle_time() in fs/proc/stat.c has different
sources for both values depending on if a CPU is online or offline:
- if a CPU is online the values may be taken from its per cpu
tick_cpu_sched structure
- if a CPU is offline the values are taken from its per cpu cpustat
structure
The problem is that the per cpu tick_cpu_sched structure is set to zero on
CPU offline. See tick_cancel_sched_timer() in kernel/time/tick-sched.c.
Therefore when a CPU is brought offline and online afterwards both its idle
and iowait sleeptime will be zero, causing a jump backward in total system
idle and iowait sleeptime. In a similar way if a CPU is then brought
offline again the total idle and iowait sleeptimes will jump forward.
It looks like this behavior was introduced with commit 4b0c0f294f60
("tick: Cleanup NOHZ per cpu data on cpu down").
This was only noticed now on s390, since we switched to generic idle time
reporting with commit be76ea614460 ("s390/idle: remove arch_cpu_idle_time()
and corresponding code").
Fix this by preserving the values of idle_sleeptime and iowait_sleeptime
members of the per-cpu tick_sched structure on CPU hotplug.
Fixes: 4b0c0f294f60 ("tick: Cleanup NOHZ per cpu data on cpu down")
Reported-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240115163555.1004144-1-hca@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
[ Upstream commit b07bc2347672cc8c7293c64499f1488278c5ca3d ]
Reproduced with below sequence:
dma_declare_coherent_memory()->dma_release_coherent_memory()
->dma_declare_coherent_memory()->"return -EBUSY" error
It will return -EBUSY from the dma_assign_coherent_memory()
in dma_declare_coherent_memory(), the reason is that dev->dma_mem
pointer has not been set to NULL after it's freed.
Fixes: cf65a0f6f6ff ("dma-mapping: move all DMA mapping code to kernel/dma")
Signed-off-by: Joakim Zhang <joakim.zhang@cixtech.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit a833a17aeac73b33f79433d7cee68d5cafd71e4f ]
This patch fixes a bug around the verification of possibly-zero-sized
stack accesses. When the access was done through a var-offset stack
pointer, check_stack_access_within_bounds was incorrectly computing the
maximum-offset of a zero-sized read to be the same as the register's min
offset. Instead, we have to take in account the register's maximum
possible value. The patch also simplifies how the max offset is checked;
the check is now simpler than for min offset.
The bug was allowing accesses to erroneously pass the
check_stack_access_within_bounds() checks, only to later crash in
check_stack_range_initialized() when all the possibly-affected stack
slots are iterated (this time with a correct max offset).
check_stack_range_initialized() is relying on
check_stack_access_within_bounds() for its accesses to the
stack-tracking vector to be within bounds; in the case of zero-sized
accesses, we were essentially only verifying that the lowest possible
slot was within bounds. We would crash when the max-offset of the stack
pointer was >= 0 (which shouldn't pass verification, and hopefully is
not something anyone's code attempts to do in practice).
Thanks Hao for reporting!
Fixes: 01f810ace9ed3 ("bpf: Allow variable-offset stack access")
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231207041150.229139-2-andreimatei1@gmail.com
Closes: https://lore.kernel.org/bpf/CACkBjsZGEUaRCHsmaX=h-efVogsRfK1FPxmkgb0Os_frnHiNdw@mail.gmail.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae ]
When register is spilled onto a stack as a 1/2/4-byte register, we set
slot_type[BPF_REG_SIZE - 1] (plus potentially few more below it,
depending on actual spill size). So to check if some stack slot has
spilled register we need to consult slot_type[7], not slot_type[0].
To avoid the need to remember and double-check this in the future, just
use is_spilled_reg() helper.
Fixes: 27113c59b6d0 ("bpf: Check the other end of slot_type for STACK_SPILL")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 876673364161da50eed6b472d746ef88242b2368 ]
When updating or deleting an inner map in map array or map htab, the map
may still be accessed by non-sleepable program or sleepable program.
However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map
directly through bpf_map_put(), if the ref-counter is the last one
(which is true for most cases), the inner map will be freed by
ops->map_free() in a kworker. But for now, most .map_free() callbacks
don't use synchronize_rcu() or its variants to wait for the elapse of a
RCU grace period, so after the invocation of ops->map_free completes,
the bpf program which is accessing the inner map may incur
use-after-free problem.
Fix the free of inner map by invoking bpf_map_free_deferred() after both
one RCU grace period and one tasks trace RCU grace period if the inner
map has been removed from the outer map before. The deferment is
accomplished by using call_rcu() or call_rcu_tasks_trace() when
releasing the last ref-counter of bpf map. The newly-added rcu_head
field in bpf_map shares the same storage space with work field to
reduce the size of bpf_map.
Fixes: bba1dc0b55ac ("bpf: Remove redundant synchronize_rcu.")
Fixes: 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in sleepable programs")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231204140425.1480317-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 20c20bd11a0702ce4dc9300c3da58acf551d9725 ]
map is the pointer of outer map, and need_defer needs some explanation.
need_defer tells the implementation to defer the reference release of
the passed element and ensure that the element is still alive before
the bpf program, which may manipulate it, exits.
The following three cases will invoke map_fd_put_ptr() and different
need_defer values will be passed to these callers:
1) release the reference of the old element in the map during map update
or map deletion. The release must be deferred, otherwise the bpf
program may incur use-after-free problem, so need_defer needs to be
true.
2) release the reference of the to-be-added element in the error path of
map update. The to-be-added element is not visible to any bpf
program, so it is OK to pass false for need_defer parameter.
3) release the references of all elements in the map during map release.
Any bpf program which has access to the map must have been exited and
released, so need_defer=false will be OK.
These two parameters will be used by the following patches to fix the
potential use-after-free problem for map-in-map.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231204140425.1480317-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 876673364161 ("bpf: Defer the free of inner map when necessary")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit e6c86c513f440bec5f1046539c7e3c6c653842da ]
As an accident of implementation, an RCU Tasks Trace grace period also
acts as an RCU grace period. However, this could change at any time.
This commit therefore creates an rcu_trace_implies_rcu_gp() that currently
returns true to codify this accident. Code relying on this accident
must call this function to verify that this accident is still happening.
Reported-by: Hou Tao <houtao@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Link: https://lore.kernel.org/r/20221014113946.965131-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 876673364161 ("bpf: Defer the free of inner map when necessary")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 0acd03a5bd188b0c501d285d938439618bd855c4 ]
Given verifier checks actual value, r0 has to be precise, so we need to
propagate precision properly. r0 also has to be marked as read,
otherwise subsequent state comparisons will ignore such register as
unimportant and precision won't really help here.
Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit b8e3a87a627b575896e448021e5c2f8a3bc19931 ]
Currently get_perf_callchain only supports user stack walking for
the current task. Passing the correct *crosstask* param will return
0 frames if the task passed to __bpf_get_stack isn't the current
one instead of a single incorrect frame/address. This change
passes the correct *crosstask* param but also does a preemptive
check in __bpf_get_stack if the task is current and returns
-EOPNOTSUPP if it is not.
This issue was found using bpf_get_task_stack inside a BPF
iterator ("iter/task"), which iterates over all tasks.
bpf_get_task_stack works fine for fetching kernel stacks
but because get_perf_callchain relies on the caller to know
if the requested *task* is the current one (via *crosstask*)
it was failing in a confusing way.
It might be possible to get user stacks for all tasks utilizing
something like access_process_vm but that requires the bpf
program calling bpf_get_task_stack to be sleepable and would
therefore be a breaking change.
Fixes: fa28dcb82a38 ("bpf: Introduce helper bpf_get_task_stack()")
Signed-off-by: Jordan Rome <jordalgo@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 9b75dbeb36fcd9fc7ed51d370310d0518a387769 ]
When looking up an element in LPM trie, the condition 'matchlen ==
trie->max_prefixlen' will never return true, if key->prefixlen is larger
than trie->max_prefixlen. Consequently all elements in the LPM trie will
be visited and no element is returned in the end.
To resolve this, check key->prefixlen first before walking the LPM trie.
Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation")
Signed-off-by: Florian Lehner <dev@der-flo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231105085801.3742-1-dev@der-flo.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 712292308af2265cd9b126aedfa987f10f452a33 ]
As the ring buffer recording requires cmpxchg() to work, if the
architecture does not support cmpxchg in NMI, then do not do any recording
within an NMI.
Link: https://lore.kernel.org/linux-trace-kernel/20231213175403.6fc18540@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 1cc111b9cddc71ce161cd388f11f0e9048edffdb ]
KASAN report following issue. The root cause is when opening 'hist'
file of an instance and accessing 'trace_event_file' in hist_show(),
but 'trace_event_file' has been freed due to the instance being removed.
'hist_debug' file has the same problem. To fix it, call
tracing_{open,release}_file_tr() in file_operations callback to have
the ref count and avoid 'trace_event_file' being freed.
BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278
Read of size 8 at addr ffff242541e336b8 by task head/190
CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c #133
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x98/0xf8
show_stack+0x1c/0x30
dump_stack_lvl+0x44/0x58
print_report+0xf0/0x5a0
kasan_report+0x80/0xc0
__asan_report_load8_noabort+0x1c/0x28
hist_show+0x11e0/0x1278
seq_read_iter+0x344/0xd78
seq_read+0x128/0x1c0
vfs_read+0x198/0x6c8
ksys_read+0xf4/0x1e0
__arm64_sys_read+0x70/0xa8
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Allocated by task 188:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_alloc_info+0x20/0x30
__kasan_slab_alloc+0x6c/0x80
kmem_cache_alloc+0x15c/0x4a8
trace_create_new_event+0x84/0x348
__trace_add_new_event+0x18/0x88
event_trace_add_tracer+0xc4/0x1a0
trace_array_create_dir+0x6c/0x100
trace_array_create+0x2e8/0x568
instance_mkdir+0x48/0x80
tracefs_syscall_mkdir+0x90/0xe8
vfs_mkdir+0x3c4/0x610
do_mkdirat+0x144/0x200
__arm64_sys_mkdirat+0x8c/0xc0
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Freed by task 191:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_free_info+0x34/0x58
__kasan_slab_free+0xe4/0x158
kmem_cache_free+0x19c/0x508
event_file_put+0xa0/0x120
remove_event_file_dir+0x180/0x320
event_trace_del_tracer+0xb0/0x180
__remove_instance+0x224/0x508
instance_rmdir+0x44/0x78
tracefs_syscall_rmdir+0xbc/0x140
vfs_rmdir+0x1cc/0x4c8
do_rmdir+0x220/0x2b8
__arm64_sys_unlinkat+0xc0/0x100
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 60be76eeabb3d83858cc6577fc65c7d0f36ffd42 ]
If for some reason the trace_marker write does not have a nul byte for the
string, it will overflow the print:
trace_seq_printf(s, ": %s", field->buf);
The field->buf could be missing the nul byte. To prevent overflow, add the
max size that the buf can be by using the event size and the field
location.
int max = iter->ent_size - offsetof(struct print_entry, buf);
trace_seq_printf(s, ": %*.s", max, field->buf);
Link: https://lore.kernel.org/linux-trace-kernel/20231212084444.4619b8ce@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit b55b0a0d7c4aa2dac3579aa7e6802d1f57445096 ]
If a large event was added to the ring buffer that is larger than what the
trace_seq can handle, it just drops the output:
~# cat /sys/kernel/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<...>-859 [001] ..... 141.118951: tracing_mark_write <...>-859 [001] ..... 141.148201: tracing_mark_write: 78901234
Instead, catch this case and add some context:
~# cat /sys/kernel/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<...>-852 [001] ..... 121.550551: tracing_mark_write[LINE TOO BIG]
<...>-852 [001] ..... 121.550581: tracing_mark_write: 78901234
This now emulates the same output as trace_pipe.
Link: https://lore.kernel.org/linux-trace-kernel/20231209171058.78c1a026@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
commit dfce9cb3140592b886838e06f3e0c25fea2a9cae upstream.
Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8b9
("bpf: Support new 32bit offset jmp instruction") added support for new
32bit offset jmp instruction. Unfortunately, in function
bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset
(plus/minor a small delta) compares to 16-bit offset bound
[S16_MIN, S16_MAX], which caused the following verification failure:
$ ./test_progs-cpuv4 -t verif_scale_pyperf180
...
insn 10 cannot be patched due to 16-bit range
...
libbpf: failed to load object 'pyperf180.bpf.o'
scale_test:FAIL:expect_success unexpected error: -12 (errno 12)
#405 verif_scale_pyperf180:FAIL
Note that due to recent llvm18 development, the patch [2] (already applied
in bpf-next) needs to be applied to bpf tree for testing purpose.
The fix is rather simple. For 32bit offset branch insn, the adjusted
offset compares to [S32_MIN, S32_MAX] and then verification succeeded.
[1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@linux.dev
[2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev
Fixes: 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231201024640.3417057-1-yonghong.song@linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
[ Upstream commit dec890089bf79a4954b61482715ee2d084364856 ]
The following race can cause rb_time_read() to observe a corrupted time
stamp:
rb_time_cmpxchg()
[...]
if (!rb_time_read_cmpxchg(&t->msb, msb, msb2))
return false;
if (!rb_time_read_cmpxchg(&t->top, top, top2))
return false;
<interrupted before updating bottom>
__rb_time_read()
[...]
do {
c = local_read(&t->cnt);
top = local_read(&t->top);
bottom = local_read(&t->bottom);
msb = local_read(&t->msb);
} while (c != local_read(&t->cnt));
*cnt = rb_time_cnt(top);
/* If top and msb counts don't match, this interrupted a write */
if (*cnt != rb_time_cnt(msb))
return false;
^ this check fails to catch that "bottom" is still not updated.
So the old "bottom" value is returned, which is wrong.
Fix this by checking that all three of msb, top, and bottom 2-bit cnt
values match.
The reason to favor checking all three fields over requiring a specific
update order for both rb_time_set() and rb_time_cmpxchg() is because
checking all three fields is more robust to handle partial failures of
rb_time_cmpxchg() when interrupted by nested rb_time_set().
Link: https://lore.kernel.org/lkml/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212193049.680122-1-mathieu.desnoyers@efficios.com
Fixes: f458a1453424e ("ring-buffer: Test last update in 32bit version of __rb_time_read()")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit f7b3ea8cf72f3d6060fe08e461805181e7450a13 ]
group_cpus_evenly() has become a generic function which can be used for
other subsystems than the interrupt subsystem, so move it into lib/.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20221227022905.352674-6-ming.lei@redhat.com
Stable-dep-of: 0263f92fadbb ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 523f1ea76aad9025f9bd5258d77f4406fa9dbe5d ]
Map irq vector into group, which allows to abstract the algorithm for
a generic use case outside of the interrupt core.
Rename irq_build_affinity_masks as group_cpus_evenly, so the API can be
reused for blk-mq to make default queue mapping even though irq vectors
aren't involved.
No functional change, just rename vector as group.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20221227022905.352674-5-ming.lei@redhat.com
Stable-dep-of: 0263f92fadbb ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit e7bdd7f0cbd1c001bb9b4d3313edc5ee094bc3f8 ]
Prepare for abstracting irq_build_affinity_masks() into a public function
for assigning all CPUs evenly into several groups.
Don't pass irq_affinity_desc array to irq_build_affinity_masks, instead
return a cpumask array by storing each assigned group into one element of
the array.
This allows to provide a generic interface for grouping all CPUs evenly
from a NUMA and CPU locality viewpoint, and the cost is one extra allocation
in irq_build_affinity_masks(), which should be fine since it is done via
GFP_KERNEL and irq_build_affinity_masks() is a slow path anyway.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20221227022905.352674-4-ming.lei@redhat.com
Stable-dep-of: 0263f92fadbb ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 1f962d91a15af54301c63febb8ac2ba07aa3654f ]
Pass affinity managed mask array to irq_build_affinity_masks() so that the
index of the first affinity managed vector is always zero.
This allows to simplify the implementation a bit.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20221227022905.352674-3-ming.lei@redhat.com
Stable-dep-of: 0263f92fadbb ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit cdf07f0ea48a3b52f924714d477366ac510ee870 ]
The 'firstvec' parameter is always same with the parameter of
'startvec', so use 'startvec' directly inside irq_build_affinity_masks().
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20221227022905.352674-2-ming.lei@redhat.com
Stable-dep-of: 0263f92fadbb ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 4bb7ea946a370707315ab774432963ce47291946 ]
Fix an edge case in __mark_chain_precision() which prematurely stops
backtracking instructions in a state if it happens that state's first
and last instruction indexes are the same. This situations doesn't
necessarily mean that there were no instructions simulated in a state,
but rather that we starting from the instruction, jumped around a bit,
and then ended up at the same instruction before checkpointing or
marking precision.
To distinguish between these two possible situations, we need to consult
jump history. If it's empty or contain a single record "bridging" parent
state and first instruction of processed state, then we indeed
backtracked all instructions in this state. But if history is not empty,
we are definitely not done yet.
Move this logic inside get_prev_insn_idx() to contain it more nicely.
Use -ENOENT return code to denote "we are out of instructions"
situation.
This bug was exposed by verifier_loop1.c's bounded_recursion subtest, once
the next fix in this patch set is applied.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231110002638.4168352-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 3feb263bb516ee7e1da0acd22b15afbb9a7daa19 ]
ldimm64 instructions are 16-byte long, and so have to be handled
appropriately in check_cfg(), just like the rest of BPF verifier does.
This has implications in three places:
- when determining next instruction for non-jump instructions;
- when determining next instruction for callback address ldimm64
instructions (in visit_func_call_insn());
- when checking for unreachable instructions, where second half of
ldimm64 is expected to be unreachable;
We take this also as an opportunity to report jump into the middle of
ldimm64. And adjust few test_verifier tests accordingly.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reported-by: Hao Sun <sunhao.th@gmail.com>
Fixes: 475fb78fbf48 ("bpf: verifier (add branch/goto checks)")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231110002638.4168352-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 4cd58e9af8b9d9fff6b7145e742abbfcda0af4af ]
Add interpreter/jit/verifier support for 32bit offset jmp instruction.
If a conditional jmp instruction needs more than 16bit offset,
it can be simulated with a conditional jmp + a 32bit jmp insn.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011231.3716103-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 3feb263bb516 ("bpf: handle ldimm64 properly in check_cfg()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 653ae3a874aca6764a4c1f5a8bf1b072ade0d6f4 ]
Instead of referencing processed instruction repeatedly as insns[t]
throughout entire visit_insn() function, take a local insn pointer and
work with it in a cleaner way.
It makes enhancing this function further a bit easier as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230302235015.2044271-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 3feb263bb516 ("bpf: handle ldimm64 properly in check_cfg()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit dcb2288b1fd9a8cdf2f3b8c0c7b3763346ef515f ]
Number of total instructions in BPF program (including subprogs) can and
is accessed from env->prog->len. visit_func_call_insn() doesn't do any
checks against insn_cnt anymore, relying on push_insn() to do this check
internally. So remove unnecessary insn_cnt input argument from
visit_func_call_insn() and visit_insn() functions.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221207195534.2866030-1-andrii@kernel.org
Stable-dep-of: 3feb263bb516 ("bpf: handle ldimm64 properly in check_cfg()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 618945fbed501b6e5865042068a51edfb2dda948 ]
Don't mark some instructions as jump points when there are actually no
jumps and instructions are just processed sequentially. Such case is
handled naturally by precision backtracking logic without the need to
update jump history. See get_prev_insn_idx(). It goes back linearly by
one instruction, unless current top of jmp_history is pointing to
current instruction. In such case we use `st->jmp_history[cnt - 1].prev_idx`
to find instruction from which we jumped to the current instruction
non-linearly.
Also remove both jump and prune point marking for instruction right
after unconditional jumps, as program flow can get to the instruction
right after unconditional jump instruction only if there is a jump to
that instruction from somewhere else in the program. In such case we'll
mark such instruction as prune/jump point because it's a destination of
a jump.
This change has no changes in terms of number of instructions or states
processes across Cilium and selftests programs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20221206233345.438540-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 3feb263bb516 ("bpf: handle ldimm64 properly in check_cfg()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit bffdeaa8a5af7200b0e74c9d5a41167f86626a36 ]
BPF verifier marks some instructions as prune points. Currently these
prune points serve two purposes.
It's a point where verifier tries to find previously verified state and
check current state's equivalence to short circuit verification for
current code path.
But also currently it's a point where jump history, used for precision
backtracking, is updated. This is done so that non-linear flow of
execution could be properly backtracked.
Such coupling is coincidental and unnecessary. Some prune points are not
part of some non-linear jump path, so don't need update of jump history.
On the other hand, not all instructions which have to be recorded in
jump history necessarily are good prune points.
This patch splits prune and jump points into independent flags.
Currently all prune points are marked as jump points to minimize amount
of changes in this patch, but next patch will perform some optimization
of prune vs jmp point placement.
No functional changes are intended.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221206233345.438540-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 3feb263bb516 ("bpf: handle ldimm64 properly in check_cfg()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 2b5dcb31a19a2e0acd869b12c9db9b2d696ef544 ]
From commit ebf7d1f508a73871 ("bpf, x64: rework pro/epilogue and tailcall
handling in JIT"), the tailcall on x64 works better than before.
From commit e411901c0b775a3a ("bpf: allow for tailcalls in BPF subprograms
for x64 JIT"), tailcall is able to run in BPF subprograms on x64.
From commit 5b92a28aae4dd0f8 ("bpf: Support attaching tracing BPF program
to other BPF programs"), BPF program is able to trace other BPF programs.
How about combining them all together?
1. FENTRY/FEXIT on a BPF subprogram.
2. A tailcall runs in the BPF subprogram.
3. The tailcall calls the subprogram's caller.
As a result, a tailcall infinite loop comes up. And the loop would halt
the machine.
As we know, in tail call context, the tail_call_cnt propagates by stack
and rax register between BPF subprograms. So do in trampolines.
Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT")
Fixes: e411901c0b77 ("bpf: allow for tailcalls in BPF subprograms for x64 JIT")
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20230912150442.2009-3-hffilwlqm@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 4a8e65b0c348e42107c64381e692e282900be361 ]
SRCU callbacks acceleration might fail if the preceding callbacks
advance also fails. This can happen when the following steps are met:
1) The RCU_WAIT_TAIL segment has callbacks (say for gp_num 8) and the
RCU_NEXT_READY_TAIL also has callbacks (say for gp_num 12).
2) The grace period for RCU_WAIT_TAIL is observed as started but not yet
completed so rcu_seq_current() returns 4 + SRCU_STATE_SCAN1 = 5.
3) This value is passed to rcu_segcblist_advance() which can't move
any segment forward and fails.
4) srcu_gp_start_if_needed() still proceeds with callback acceleration.
But then the call to rcu_seq_snap() observes the grace period for the
RCU_WAIT_TAIL segment (gp_num 8) as completed and the subsequent one
for the RCU_NEXT_READY_TAIL segment as started
(ie: 8 + SRCU_STATE_SCAN1 = 9) so it returns a snapshot of the
next grace period, which is 16.
5) The value of 16 is passed to rcu_segcblist_accelerate() but the
freshly enqueued callback in RCU_NEXT_TAIL can't move to
RCU_NEXT_READY_TAIL which already has callbacks for a previous grace
period (gp_num = 12). So acceleration fails.
6) Note in all these steps, srcu_invoke_callbacks() hadn't had a chance
to run srcu_invoke_callbacks().
Then some very bad outcome may happen if the following happens:
7) Some other CPU races and starts the grace period number 16 before the
CPU handling previous steps had a chance. Therefore srcu_gp_start()
isn't called on the latter sdp to fix the acceleration leak from
previous steps with a new pair of call to advance/accelerate.
8) The grace period 16 completes and srcu_invoke_callbacks() is finally
called. All the callbacks from previous grace periods (8 and 12) are
correctly advanced and executed but callbacks in RCU_NEXT_READY_TAIL
still remain. Then rcu_segcblist_accelerate() is called with a
snaphot of 20.
9) Since nothing started the grace period number 20, callbacks stay
unhandled.
This has been reported in real load:
[3144162.608392] INFO: task kworker/136:12:252684 blocked for more
than 122 seconds.
[3144162.615986] Tainted: G O K 5.4.203-1-tlinux4-0011.1 #1
[3144162.623053] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[3144162.631162] kworker/136:12 D 0 252684 2 0x90004000
[3144162.631189] Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
[3144162.631192] Call Trace:
[3144162.631202] __schedule+0x2ee/0x660
[3144162.631206] schedule+0x33/0xa0
[3144162.631209] schedule_timeout+0x1c4/0x340
[3144162.631214] ? update_load_avg+0x82/0x660
[3144162.631217] ? raw_spin_rq_lock_nested+0x1f/0x30
[3144162.631218] wait_for_completion+0x119/0x180
[3144162.631220] ? wake_up_q+0x80/0x80
[3144162.631224] __synchronize_srcu.part.19+0x81/0xb0
[3144162.631226] ? __bpf_trace_rcu_utilization+0x10/0x10
[3144162.631227] synchronize_srcu+0x5f/0xc0
[3144162.631236] irqfd_shutdown+0x3c/0xb0 [kvm]
[3144162.631239] ? __schedule+0x2f6/0x660
[3144162.631243] process_one_work+0x19a/0x3a0
[3144162.631244] worker_thread+0x37/0x3a0
[3144162.631247] kthread+0x117/0x140
[3144162.631247] ? process_one_work+0x3a0/0x3a0
[3144162.631248] ? __kthread_cancel_work+0x40/0x40
[3144162.631250] ret_from_fork+0x1f/0x30
Fix this with taking the snapshot for acceleration _before_ the read
of the current grace period number.
The only side effect of this solution is that callbacks advancing happen
then _after_ the full barrier in rcu_seq_snap(). This is not a problem
because that barrier only cares about:
1) Ordering accesses of the update side before call_srcu() so they don't
bleed.
2) See all the accesses prior to the grace period of the current gp_num
The only things callbacks advancing need to be ordered against are
carried by snp locking.
Reported-by: Yong He <alexyonghe@tencent.com>
Co-developed-by:: Yong He <alexyonghe@tencent.com>
Signed-off-by: Yong He <alexyonghe@tencent.com>
Co-developed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Co-developed-by: Neeraj upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Neeraj upadhyay <Neeraj.Upadhyay@amd.com>
Link: http://lore.kernel.org/CANZk6aR+CqZaqmMWrC2eRRPY12qAZnDZLwLnHZbNi=xXMB401g@mail.gmail.com
Fixes: da915ad5cf25 ("srcu: Parallelize callback handling")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit d91bdd96b55cc3ce98d883a60f133713821b80a6 ]
The SMT control mechanism got added as speculation attack vector
mitigation. The implemented logic relies on the primary thread mask to
be set up properly.
This turns out to be an issue with XEN/PV guests because their CPU hotplug
mechanics do not enumerate APICs and therefore the mask is never correctly
populated.
This went unnoticed so far because by chance XEN/PV ends up with
smp_num_siblings == 2. So smt_hotplug_control stays at its default value
CPU_SMT_ENABLED and the primary thread mask is never evaluated in the
context of CPU hotplug.
This stopped "working" with the upcoming overhaul of the topology
evaluation which legitimately provides a fake topology for XEN/PV. That
sets smp_num_siblings to 1, which causes the core CPU hot-plug core to
refuse to bring up the APs.
This happens because smt_hotplug_control is set to CPU_SMT_NOT_SUPPORTED
which causes cpu_smt_allowed() to evaluate the unpopulated primary thread
mask with the conclusion that all non-boot CPUs are not valid to be
plugged.
Make cpu_smt_allowed() more robust and take CPU_SMT_NOT_SUPPORTED and
CPU_SMT_NOT_IMPLEMENTED into account. Rename it to cpu_bootable() while at
it as that makes it more clear what the function is about.
The primary mask issue on x86 XEN/PV needs to be addressed separately as
there are users outside of the CPU hotplug code too.
Fixes: 05736e4ac13c ("cpu/hotplug: Provide knobs to control SMT")
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.149440843@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 38253464bc821d6de6bba81bb1412ebb36f6cbd1 ]
Some architectures allows partial SMT states, i.e. when not all SMT threads
are brought online.
To support that, add an architecture helper which checks whether a given
CPU is allowed to be brought online depending on how many SMT threads are
currently enabled. Since this is only applicable to architecture supporting
partial SMT, only these architectures should select the new configuration
variable CONFIG_SMT_NUM_THREADS_DYNAMIC. For the other architectures, not
supporting the partial SMT states, there is no need to define
topology_cpu_smt_allowed(), the generic code assumed that all the threads
are allowed or only the primary ones.
Call the helper from cpu_smt_enable(), and cpu_smt_allowed() when SMT is
enabled, to check if the particular thread should be onlined. Notably,
also call it from cpu_smt_disable() if CPU_SMT_ENABLED, to allow
offlining some threads to move from a higher to lower number of threads
online.
[ ldufour: Slightly reword the commit's description ]
[ ldufour: Introduce CONFIG_SMT_NUM_THREADS_DYNAMIC ]
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-7-ldufour@linux.ibm.com
Stable-dep-of: d91bdd96b55c ("cpu/SMT: Make SMT control more robust against enumeration failures")
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
commit 926fe783c8a64b33997fec405cf1af3e61aed441 upstream.
Recent changes to count number of matching symbols when creating
a kprobe event failed to take into account kernel modules. As such, it
breaks kprobes on kernel module symbols, by assuming there is no match.
Fix this my calling module_kallsyms_on_each_symbol() in addition to
kallsyms_on_each_match_symbol() to perform a proper counting.
Link: https://lore.kernel.org/all/20231027233126.2073148-1-andrii@kernel.org/
Cc: Francis Laniel <flaniel@linux.microsoft.com>
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Fixes: b022f0c7e404 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Hao Wei Tee <angelsl@in04.sg>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 73feb8d5fa3b755bb51077c0aabfb6aa556fd498 upstream.
Making module_kallsyms_on_each_symbol generally available, so it
can be used outside CONFIG_LIVEPATCH option in following changes.
Rather than adding another ifdef option let's make the function
generally available (when CONFIG_KALLSYMS and CONFIG_MODULES
options are defined).
Cc: Christoph Hellwig <hch@lst.de>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20221025134148.3300700-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit b803d7c664d55705831729d2f2e29c874bcd62ea upstream.
To synchronize the timestamps with the ring buffer reservation, there are
two timestamps that are saved in the buffer meta data.
1. before_stamp
2. write_stamp
When the two are equal, the write_stamp is considered valid, as in, it may
be used to calculate the delta of the next event as the write_stamp is the
timestamp of the previous reserved event on the buffer.
This is done by the following:
/*A*/ w = current position on the ring buffer
before = before_stamp
after = write_stamp
ts = read current timestamp
if (before != after) {
write_stamp is not valid, force adding an absolute
timestamp.
}
/*B*/ before_stamp = ts
/*C*/ write = local_add_return(event length, position on ring buffer)
if (w == write - event length) {
/* Nothing interrupted between A and C */
/*E*/ write_stamp = ts;
delta = ts - after
/*
* If nothing interrupted again,
* before_stamp == write_stamp and write_stamp
* can be used to calculate the delta for
* events that come in after this one.
*/
} else {
/*
* The slow path!
* Was interrupted between A and C.
*/
This is the place that there's a bug. We currently have:
after = write_stamp
ts = read current timestamp
/*F*/ if (write == current position on the ring buffer &&
after < ts && cmpxchg(write_stamp, after, ts)) {
delta = ts - after;
} else {
delta = 0;
}
The assumption is that if the current position on the ring buffer hasn't
moved between C and F, then it also was not interrupted, and that the last
event written has a timestamp that matches the write_stamp. That is the
write_stamp is valid.
But this may not be the case:
If a task context event was interrupted by softirq between B and C.
And the softirq wrote an event that got interrupted by a hard irq between
C and E.
and the hard irq wrote an event (does not need to be interrupted)
We have:
/*B*/ before_stamp = ts of normal context
---> interrupted by softirq
/*B*/ before_stamp = ts of softirq context
---> interrupted by hardirq
/*B*/ before_stamp = ts of hard irq context
/*E*/ write_stamp = ts of hard irq context
/* matches and write_stamp valid */
<----
/*E*/ write_stamp = ts of softirq context
/* No longer matches before_stamp, write_stamp is not valid! */
<---
w != write - length, go to slow path
// Right now the order of events in the ring buffer is:
//
// |-- softirq event --|-- hard irq event --|-- normal context event --|
//
after = write_stamp (this is the ts of softirq)
ts = read current timestamp
if (write == current position on the ring buffer [true] &&
after < ts [true] && cmpxchg(write_stamp, after, ts) [true]) {
delta = ts - after [Wrong!]
The delta is to be between the hard irq event and the normal context
event, but the above logic made the delta between the softirq event and
the normal context event, where the hard irq event is between the two. This
will shift all the remaining event timestamps on the sub-buffer
incorrectly.
The write_stamp is only valid if it matches the before_stamp. The cmpxchg
does nothing to help this.
Instead, the following logic can be done to fix this:
before = before_stamp
ts = read current timestamp
before_stamp = ts
after = write_stamp
if (write == current position on the ring buffer &&
after == before && after < ts) {
delta = ts - after
} else {
delta = 0;
}
The above will only use the write_stamp if it still matches before_stamp
and was tested to not have changed since C.
As a bonus, with this logic we do not need any 64-bit cmpxchg() at all!
This means the 32-bit rb_time_t workaround can finally be removed. But
that's for a later time.
Link: https://lore.kernel.org/linux-trace-kernel/20231218175229.58ec3daf@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231218230712.3a76b081@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: dd93942570789 ("ring-buffer: Do not try to put back write_stamp")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 083e9f65bd215582bf8f6a920db729fadf16704f upstream.
When filtering is enabled, a temporary buffer is created to place the
content of the trace event output so that the filter logic can decide
from the trace event output if the trace event should be filtered out or
not. If it is to be filtered out, the content in the temporary buffer is
simply discarded, otherwise it is written into the trace buffer.
But if an interrupt were to come in while a previous event was using that
temporary buffer, the event written by the interrupt would actually go
into the ring buffer itself to prevent corrupting the data on the
temporary buffer. If the event is to be filtered out, the event in the
ring buffer is discarded, or if it fails to discard because another event
were to have already come in, it is turned into padding.
The update to the write_stamp in the rb_try_to_discard() happens after a
fix was made to force the next event after the discard to use an absolute
timestamp by setting the before_stamp to zero so it does not match the
write_stamp (which causes an event to use the absolute timestamp).
But there's an effort in rb_try_to_discard() to put back the write_stamp
to what it was before the event was added. But this is useless and
wasteful because nothing is going to be using that write_stamp for
calculations as it still will not match the before_stamp.
Remove this useless update, and in doing so, we remove another
cmpxchg64()!
Also update the comments to reflect this change as well as remove some
extra white space in another comment.
Link: https://lore.kernel.org/linux-trace-kernel/20231215081810.1f4f38fe@rorschach.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes: b2dd797543cf ("ring-buffer: Force absolute timestamp on discard of event")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 39a7dc23a1ed0fe81141792a09449d124c5953bd upstream.
If an application blocks on the snapshot or snapshot_raw files, expecting
to be woken up when a snapshot occurs, it will not happen. Or it may
happen with an unexpected result.
That result is that the application will be reading the main buffer
instead of the snapshot buffer. That is because when the snapshot occurs,
the main and snapshot buffers are swapped. But the reader has a descriptor
still pointing to the buffer that it originally connected to.
This is fine for the main buffer readers, as they may be blocked waiting
for a watermark to be hit, and when a snapshot occurs, the data that the
main readers want is now on the snapshot buffer.
But for waiters of the snapshot buffer, they are waiting for an event to
occur that will trigger the snapshot and they can then consume it quickly
to save the snapshot before the next snapshot occurs. But to do this, they
need to read the new snapshot buffer, not the old one that is now
receiving new data.
Also, it does not make sense to have a watermark "buffer_percent" on the
snapshot buffer, as the snapshot buffer is static and does not receive new
data except all at once.
Link: https://lore.kernel.org/linux-trace-kernel/20231228095149.77f5b45d@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: debdd57f5145f ("tracing: Make a snapshot feature available from userspace")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 623b1f896fa8a669a277ee5a258307a16c7377a3 upstream.
The tracefs file "buffer_percent" is to allow user space to set a
water-mark on how much of the tracing ring buffer needs to be filled in
order to wake up a blocked reader.
0 - is to wait until any data is in the buffer
1 - is to wait for 1% of the sub buffers to be filled
50 - would be half of the sub buffers are filled with data
100 - is not to wake the waiter until the ring buffer is completely full
Unfortunately the test for being full was:
dirty = ring_buffer_nr_dirty_pages(buffer, cpu);
return (dirty * 100) > (full * nr_pages);
Where "full" is the value for "buffer_percent".
There is two issues with the above when full == 100.
1. dirty * 100 > 100 * nr_pages will never be true
That is, the above is basically saying that if the user sets
buffer_percent to 100, more pages need to be dirty than exist in the
ring buffer!
2. The page that the writer is on is never considered dirty, as dirty
pages are only those that are full. When the writer goes to a new
sub-buffer, it clears the contents of that sub-buffer.
That is, even if the check was ">=" it would still not be equal as the
most pages that can be considered "dirty" is nr_pages - 1.
To fix this, add one to dirty and use ">=" in the compare.
Link: https://lore.kernel.org/linux-trace-kernel/20231226125902.4a057f1d@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: 03329f9939781 ("tracing: Add tracefs file buffer_percentage")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 88b30c7f5d27e1594d70dc2bd7199b18f2b57fa9 upstream.
The synth_event_gen_test module can be built in, if someone wants to run
the tests at boot up and not have to load them.
The synth_event_gen_test_init() function creates and enables the synthetic
events and runs its tests.
The synth_event_gen_test_exit() disables the events it created and
destroys the events.
If the module is builtin, the events are never disabled. The issue is, the
events should be disable after the tests are run. This could be an issue
if the rest of the boot up tests are enabled, as they expect the events to
be in a known state before testing. That known state happens to be
disabled.
When CONFIG_SYNTH_EVENT_GEN_TEST=y and CONFIG_EVENT_TRACE_STARTUP_TEST=y
a warning will trigger:
Running tests on trace events:
Testing event create_synth_test:
Enabled event during self test!
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1 at kernel/trace/trace_events.c:4150 event_trace_self_tests+0x1c2/0x480
Modules linked in:
CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc2-test-00031-gb803d7c664d5-dirty #276
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:event_trace_self_tests+0x1c2/0x480
Code: bb e8 a2 ab 5d fc 48 8d 7b 48 e8 f9 3d 99 fc 48 8b 73 48 40 f6 c6 01 0f 84 d6 fe ff ff 48 c7 c7 20 b6 ad bb e8 7f ab 5d fc 90 <0f> 0b 90 48 89 df e8 d3 3d 99 fc 48 8b 1b 4c 39 f3 0f 85 2c ff ff
RSP: 0000:ffffc9000001fdc0 EFLAGS: 00010246
RAX: 0000000000000029 RBX: ffff88810399ca80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffb9f19478 RDI: ffff88823c734e64
RBP: ffff88810399f300 R08: 0000000000000000 R09: fffffbfff79eb32a
R10: ffffffffbcf59957 R11: 0000000000000001 R12: ffff888104068090
R13: ffffffffbc89f0a0 R14: ffffffffbc8a0f08 R15: 0000000000000078
FS: 0000000000000000(0000) GS:ffff88823c700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001f6282001 CR4: 0000000000170ef0
Call Trace:
<TASK>
? __warn+0xa5/0x200
? event_trace_self_tests+0x1c2/0x480
? report_bug+0x1f6/0x220
? handle_bug+0x6f/0x90
? exc_invalid_op+0x17/0x50
? asm_exc_invalid_op+0x1a/0x20
? tracer_preempt_on+0x78/0x1c0
? event_trace_self_tests+0x1c2/0x480
? __pfx_event_trace_self_tests_init+0x10/0x10
event_trace_self_tests_init+0x27/0xe0
do_one_initcall+0xd6/0x3c0
? __pfx_do_one_initcall+0x10/0x10
? kasan_set_track+0x25/0x30
? rcu_is_watching+0x38/0x60
kernel_init_freeable+0x324/0x450
? __pfx_kernel_init+0x10/0x10
kernel_init+0x1f/0x1e0
? _raw_spin_unlock_irq+0x33/0x50
ret_from_fork+0x34/0x60
? __pfx_kernel_init+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>
This is because the synth_event_gen_test_init() left the synthetic events
that it created enabled. By having it disable them after testing, the
other selftests will run fine.
Link: https://lore.kernel.org/linux-trace-kernel/20231220111525.2f0f49b0@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 9fe41efaca084 ("tracing: Add synth event generation test module")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Alexander Graf <graf@amazon.com>
Tested-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 4b7de801606e504e69689df71475d27e35336fb3 upstream.
Lee pointed out issue found by syscaller [0] hitting BUG in prog array
map poke update in prog_array_map_poke_run function due to error value
returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing
bpf program kallsym symbols, which is accounted for with check for
-EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump
and cause imbalance for the next tail call update check which will
fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load
bpf_check
do_misc_fixups
prog_array_map_poke_track
map_update_elem
bpf_fd_array_map_update_elem
prog_array_map_poke_run
bpf_arch_text_poke returns -EINVAL
bpf_prog_kallsyms_add
After bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next
poke update fails on expected jump instruction check in bpf_arch_text_poke
with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which
makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address
in bpf_arch_text_poke, so instead of splitting the function or adding new
'checkip' argument in previous version, it seems best to move the whole
map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT")
Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Cc: Lee Jones <lee@kernel.org>
Cc: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20231206083041.1306660-2-jolsa@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 0aa0e5289cfe984a8a9fdd79ccf46ccf080151f7 upstream.
The rb_time_cmpxchg() on 32-bit architectures requires setting three
32-bit words to represent the 64-bit timestamp, with some salt for
synchronization. Those are: msb, top, and bottom
The issue is, the rb_time_cmpxchg() did not properly salt the msb portion,
and the msb that was written was stale.
Link: https://lore.kernel.org/linux-trace-kernel/20231215084114.20899342@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: f03f2abce4f39 ("ring-buffer: Have 32 bit time stamps use all 64 bits")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit dd939425707898da992e59ab0fcfae4652546910 upstream.
If an update to an event is interrupted by another event between the time
the initial event allocated its buffer and where it wrote to the
write_stamp, the code try to reset the write stamp back to the what it had
just overwritten. It knows that it was overwritten via checking the
before_stamp, and if it didn't match what it wrote to the before_stamp
before it allocated its space, it knows it was overwritten.
To put back the write_stamp, it uses the before_stamp it read. The problem
here is that by writing the before_stamp to the write_stamp it makes the
two equal again, which means that the write_stamp can be considered valid
as the last timestamp written to the ring buffer. But this is not
necessarily true. The event that interrupted the event could have been
interrupted in a way that it was interrupted as well, and can end up
leaving with an invalid write_stamp. But if this happens and returns to
this context that uses the before_stamp to update the write_stamp again,
it can possibly incorrectly make it valid, causing later events to have in
correct time stamps.
As it is OK to leave this function with an invalid write_stamp (one that
doesn't match the before_stamp), there's no reason to try to make it valid
again in this case. If this race happens, then just leave with the invalid
write_stamp and the next event to come along will just add a absolute
timestamp and validate everything again.
Bonus points: This gets rid of another cmpxchg64!
Link: https://lore.kernel.org/linux-trace-kernel/20231214222921.193037a7@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit fff88fa0fbc7067ba46dde570912d63da42c59a9 upstream.
Mathieu Desnoyers pointed out an issue in the rb_time_cmpxchg() for 32 bit
architectures. That is:
static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
{
unsigned long cnt, top, bottom, msb;
unsigned long cnt2, top2, bottom2, msb2;
u64 val;
/* The cmpxchg always fails if it interrupted an update */
if (!__rb_time_read(t, &val, &cnt2))
return false;
if (val != expect)
return false;
<<<< interrupted here!
cnt = local_read(&t->cnt);
The problem is that the synchronization counter in the rb_time_t is read
*after* the value of the timestamp is read. That means if an interrupt
were to come in between the value being read and the counter being read,
it can change the value and the counter and the interrupted process would
be clueless about it!
The counter needs to be read first and then the value. That way it is easy
to tell if the value is stale or not. If the counter hasn't been updated,
then the value is still good.
Link: https://lore.kernel.org/linux-trace-kernel/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212115301.7a9c9a64@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 10464b4aa605e ("ring-buffer: Add rb_time_t 64 bit operations for speeding up 32 bit")
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit b3ae7b67b87fed771fa5bf95389df06b0433603e upstream.
The maximum ring buffer data size is the maximum size of data that can be
recorded on the ring buffer. Events must be smaller than the sub buffer
data size minus any meta data. This size is checked before trying to
allocate from the ring buffer because the allocation assumes that the size
will fit on the sub buffer.
The maximum size was calculated as the size of a sub buffer page (which is
currently PAGE_SIZE minus the sub buffer header) minus the size of the
meta data of an individual event. But it missed the possible adding of a
time stamp for events that are added long enough apart that the event meta
data can't hold the time delta.
When an event is added that is greater than the current BUF_MAX_DATA_SIZE
minus the size of a time stamp, but still less than or equal to
BUF_MAX_DATA_SIZE, the ring buffer would go into an infinite loop, looking
for a page that can hold the event. Luckily, there's a check for this loop
and after 1000 iterations and a warning is emitted and the ring buffer is
disabled. But this should never happen.
This can happen when a large event is added first, or after a long period
where an absolute timestamp is prefixed to the event, increasing its size
by 8 bytes. This passes the check and then goes into the algorithm that
causes the infinite loop.
For events that are the first event on the sub-buffer, it does not need to
add a timestamp, because the sub-buffer itself contains an absolute
timestamp, and adding one is redundant.
The fix is to check if the event is to be the first event on the
sub-buffer, and if it is, then do not add a timestamp.
This also fixes 32 bit adding a timestamp when a read of before_stamp or
write_stamp is interrupted. There's still no need to add that timestamp if
the event is going to be the first event on the sub buffer.
Also, if the buffer has "time_stamp_abs" set, then also check if the
length plus the timestamp is greater than the BUF_MAX_DATA_SIZE.
Link: https://lore.kernel.org/all/20231212104549.58863438@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231212071837.5fdd6c13@gandalf.local.home
Link: https://lore.kernel.org/linux-trace-kernel/20231212111617.39e02849@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: a4543a2fa9ef3 ("ring-buffer: Get timestamp after event is allocated")
Fixes: 58fbc3c63275c ("ring-buffer: Consolidate add_timestamp to remove some branches")
Reported-by: Kent Overstreet <kent.overstreet@linux.dev> # (on IRC)
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit b049525855fdd0024881c9b14b8fbec61c3f53d3 upstream.
For the ring buffer iterator (non-consuming read), the event needs to be
copied into the iterator buffer to make sure that a writer does not
overwrite it while the user is reading it. If a write happens during the
copy, the buffer is simply discarded.
But the temp buffer itself was not big enough. The allocation of the
buffer was only BUF_MAX_DATA_SIZE, which is the maximum data size that can
be passed into the ring buffer and saved. But the temp buffer needs to
hold the meta data as well. That would be BUF_PAGE_SIZE and not
BUF_MAX_DATA_SIZE.
Link: https://lore.kernel.org/linux-trace-kernel/20231212072558.61f76493@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 785888c544e04 ("ring-buffer: Have rb_iter_head_event() handle concurrent writer")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 9e45e39dc249c970d99d2681f6bcb55736fd725c upstream.
The ring buffer timestamps are synchronized by two timestamp placeholders.
One is the "before_stamp" and the other is the "write_stamp" (sometimes
referred to as the "after stamp" but only in the comments. These two
stamps are key to knowing how to handle nested events coming in with a
lockless system.
When moving across sub-buffers, the before stamp is updated but the write
stamp is not. There's an effort to put back the before stamp to something
that seems logical in case there's nested events. But as the current event
is about to cross sub-buffers, and so will any new nested event that happens,
updating the before stamp is useless, and could even introduce new race
conditions.
The first event on a sub-buffer simply uses the sub-buffer's timestamp
and keeps a "delta" of zero. The "before_stamp" and "write_stamp" are not
used in the algorithm in this case. There's no reason to try to fix the
before_stamp when this happens.
As a bonus, it removes a cmpxchg() when crossing sub-buffers!
Link: https://lore.kernel.org/linux-trace-kernel/20231211114420.36dde01b@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit d06aff1cb13d2a0d52b48e605462518149c98c81 upstream.
The snapshot buffer is to mimic the main buffer so that when a snapshot is
needed, the snapshot and main buffer are swapped. When the snapshot buffer
is allocated, it is set to the minimal size that the ring buffer may be at
and still functional. When it is allocated it becomes the same size as the
main ring buffer, and when the main ring buffer changes in size, it should
do.
Currently, the resize only updates the snapshot buffer if it's used by the
current tracer (ie. the preemptirqsoff tracer). But it needs to be updated
anytime it is allocated.
When changing the size of the main buffer, instead of looking to see if
the current tracer is utilizing the snapshot buffer, just check if it is
allocated to know if it should be updated or not.
Also fix typo in comment just above the code change.
Link: https://lore.kernel.org/linux-trace-kernel/20231210225447.48476a6a@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions")
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
