diff options
| author | Gerald Schaefer <gerald.schaefer@de.ibm.com> | 2019-11-19 12:30:53 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-17 19:56:51 +0100 |
| commit | c5407f8859fb56ed8508ac1ac03ee5d3abbad0f9 (patch) | |
| tree | 020b7d18ce2ab9f98cd1718d5667af1a9bb57f50 | |
| parent | a7c1c595334351bc798703aa02f94f260349df26 (diff) | |
s390/kaslr: store KASLR offset for early dumps
commit a9f2f6865d784477e1c7b59269d3a384abafd9ca upstream.
The KASLR offset is added to vmcoreinfo in arch_crash_save_vmcoreinfo(),
so that it can be found by crash when processing kernel dumps.
However, arch_crash_save_vmcoreinfo() is called during a subsys_initcall,
so if the kernel crashes before that, we have no vmcoreinfo and no KASLR
offset.
Fix this by storing the KASLR offset in the lowcore, where the vmcore_info
pointer will be stored, and where it can be found by crash. In order to
make it distinguishable from a real vmcore_info pointer, mark it as uneven
(KASLR offset itself is aligned to THREAD_SIZE).
When arch_crash_save_vmcoreinfo() stores the real vmcore_info pointer in
the lowcore, it overwrites the KASLR offset. At that point, the KASLR
offset is not yet added to vmcoreinfo, so we also need to move the
mem_assign_absolute() behind the vmcoreinfo_append_str().
Fixes: b2d24b97b2a9 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/s390/boot/startup.c | 5 | ||||
| -rw-r--r-- | arch/s390/kernel/machine_kexec.c | 2 |
2 files changed, 6 insertions, 1 deletions
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index 5367950510f6..fa0150285d38 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -170,6 +170,11 @@ void startup_kernel(void) handle_relocs(__kaslr_offset); if (__kaslr_offset) { + /* + * Save KASLR offset for early dumps, before vmcore_info is set. + * Mark as uneven to distinguish from real vmcore_info pointer. + */ + S390_lowcore.vmcore_info = __kaslr_offset | 0x1UL; /* Clear non-relocated kernel */ if (IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) memset(img, 0, vmlinux.image_size); diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c index 444a19125a81..d402ced7f7c3 100644 --- a/arch/s390/kernel/machine_kexec.c +++ b/arch/s390/kernel/machine_kexec.c @@ -254,10 +254,10 @@ void arch_crash_save_vmcoreinfo(void) VMCOREINFO_SYMBOL(lowcore_ptr); VMCOREINFO_SYMBOL(high_memory); VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS); - mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note()); vmcoreinfo_append_str("SDMA=%lx\n", __sdma); vmcoreinfo_append_str("EDMA=%lx\n", __edma); vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset()); + mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note()); } void machine_shutdown(void) |