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Both radix and hash on book3s requires to detect if kfence
early init is enabled or not. Hash needs to disable kfence
if early init is not enabled because with kfence the linear map is
mapped using PAGE_SIZE rather than 16M mapping.
We don't support multiple page sizes for slb entry used for kernel
linear map in book3s64.
This patch refactors out the common functions required to detect kfence
early init is enabled or not.
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/f4a787224fbe5bb787158ace579780c0257f6602.1729271995.git.ritesh.list@gmail.com
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Now that linear map functionality of debug_pagealloc is made generic,
enable kfence to use this generic infrastructure.
1. Define kfence related linear map variables.
- u8 *linear_map_kf_hash_slots;
- unsigned long linear_map_kf_hash_count;
- DEFINE_RAW_SPINLOCK(linear_map_kf_hash_lock);
2. The linear map size allocated in RMA region is quite small
(KFENCE_POOL_SIZE >> PAGE_SHIFT) which is 512 bytes by default.
3. kfence pool memory is reserved using memblock_phys_alloc() which has
can come from anywhere.
(default 255 objects => ((1+255) * 2) << PAGE_SHIFT = 32MB)
4. The hash slot information for kfence memory gets added in linear map
in hash_linear_map_add_slot() (which also adds for debug_pagealloc).
Reported-by: Pavithra Prakash <pavrampu@linux.vnet.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/5c2b61941b344077a2b8654dab46efa0322af3af.1729271995.git.ritesh.list@gmail.com
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Kfence on book3s Hash on pseries is anyways broken. It fails to boot
due to RMA size limitation. That is because, kfence with Hash uses
debug_pagealloc infrastructure. debug_pagealloc allocates linear map
for entire dram size instead of just kfence relevant objects.
This means for 16TB of DRAM it will require (16TB >> PAGE_SHIFT)
which is 256MB which is half of RMA region on P8.
crash kernel reserves 256MB and we also need 2048 * 16KB * 3 for
emergency stack and some more for paca allocations.
That means there is not enough memory for reserving the full linear map
in the RMA region, if the DRAM size is too big (>=16TB)
(The issue is seen above 8TB with crash kernel 256 MB reservation).
Now Kfence does not require linear memory map for entire DRAM.
It only needs for kfence objects. So this patch temporarily removes the
kfence functionality since debug_pagealloc code needs some refactoring.
We will bring in kfence on Hash support in later patches.
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/1761bc39674473c8878dedca15e0d9a0d3a1b528.1729271995.git.ritesh.list@gmail.com
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When KFENCE is enabled, total system memory is mapped at page level
granularity. But in radix MMU mode, ~3GB additional memory is needed
to map 100GB of system memory at page level granularity when compared
to using 2MB direct mapping.This is not desired considering KFENCE is
designed to be enabled in production kernels [1].
Mapping only the memory allocated for KFENCE pool at page granularity is
sufficient to enable KFENCE support. So, allocate __kfence_pool during
bootup and map it at page granularity instead of mapping all system
memory at page granularity.
Without patch:
# cat /proc/meminfo
MemTotal: 101201920 kB
With patch:
# cat /proc/meminfo
MemTotal: 104483904 kB
Note that enabling KFENCE at runtime is disabled for radix MMU for now,
as it depends on the ability to split page table mappings and such APIs
are not currently implemented for radix MMU.
All kfence_test.c testcases passed with this patch.
[1] https://lore.kernel.org/all/20201103175841.3495947-2-elver@google.com/
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240701130021.578240-1-hbathini@linux.ibm.com
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Making virt_to_pfn() a static inline taking a strongly typed
(const void *) makes the contract of a passing a pointer of that
type to the function explicit and exposes any misuse of the
macro virt_to_pfn() acting polymorphic and accepting many types
such as (void *), (unitptr_t) or (unsigned long) as arguments
without warnings.
Move the virt_to_pfn() and related functions below the
declaration of __pa() so it compiles.
For symmetry do the same with pfn_to_kaddr().
As the file is included right into the linker file, we need
to surround the functions with ifndef __ASSEMBLY__ so we
don't cause compilation errors.
The conversion moreover exposes the fact that pmd_page_vaddr()
was returning an unsigned long rather than a const void * as
could be expected, so all the sites defining pmd_page_vaddr()
had to be augmented as well.
Finally the KVM code in book3s_64_mmu_hv.c was passing an
unsigned int to virt_to_phys() so fix that up with a cast so the
result compiles.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[mpe: Fixup kfence.h, simplify pfn_to_kaddr() & pmd_page_vaddr()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230809-virt-to-phys-powerpc-v1-1-12e912a7d439@linaro.org
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KFENCE support was added for ppc32 in commit 90cbac0e995d
("powerpc: Enable KFENCE for PPC32").
Enable KFENCE on ppc64 architecture with hash and radix MMUs.
It uses the same mechanism as debug pagealloc to
protect/unprotect pages. All KFENCE kunit tests pass on both
MMUs.
KFENCE memory is initially allocated using memblock but is
later marked as SLAB allocated. This necessitates the change
to __pud_free to ensure that the KFENCE pages are freed
appropriately.
Based on previous work by Christophe Leroy and Jordan Niethe.
Signed-off-by: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926075726.2846-4-nicholas@linux.ibm.com
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Add architecture specific implementation details for KFENCE and enable
KFENCE for the ppc32 architecture. In particular, this implements the
required interface in <asm/kfence.h>.
KFENCE requires that attributes for pages from its memory pool can
individually be set. Therefore, force the Read/Write linear map to be
mapped at page granularity.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8dfe1bd2abde26337c1d8c1ad0acfcc82185e0d5.1614868445.git.christophe.leroy@csgroup.eu
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