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| author | Gerald Schaefer <gerald.schaefer@de.ibm.com> | 2019-11-19 14:30:53 +0300 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2019-11-30 12:52:45 +0300 |
| commit | a9f2f6865d784477e1c7b59269d3a384abafd9ca (patch) | |
| tree | 2c79590ce114bb6436fab466d58303ad974094e5 /arch/s390/boot/startup.c | |
| parent | e76e69611e944ecc38aaf8fe3a7bebdc3c5daf84 (diff) | |
| download | linux-a9f2f6865d784477e1c7b59269d3a384abafd9ca.tar.xz | |
s390/kaslr: store KASLR offset for early dumps
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>
Diffstat (limited to 'arch/s390/boot/startup.c')
| -rw-r--r-- | arch/s390/boot/startup.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index fbd341ea03b8..3b3a11f95269 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); |