diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2022-10-28 00:54:41 +0300 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2022-12-15 21:37:26 +0300 |
| commit | 97e3d26b5e5f371b3ee223d94dd123e6c442ba80 (patch) | |
| tree | 80ee0994078b5307c6edd071d36574313c995243 /arch/x86/include/asm/pgtable_areas.h | |
| parent | 3f148f3318140035e87decc1214795ff0755757b (diff) | |
| download | linux-97e3d26b5e5f371b3ee223d94dd123e6c442ba80.tar.xz | |
x86/mm: Randomize per-cpu entry area
Seth found that the CPU-entry-area; the piece of per-cpu data that is
mapped into the userspace page-tables for kPTI is not subject to any
randomization -- irrespective of kASLR settings.
On x86_64 a whole P4D (512 GB) of virtual address space is reserved for
this structure, which is plenty large enough to randomize things a
little.
As such, use a straight forward randomization scheme that avoids
duplicates to spread the existing CPUs over the available space.
[ bp: Fix le build. ]
Reported-by: Seth Jenkins <sethjenkins@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'arch/x86/include/asm/pgtable_areas.h')
| -rw-r--r-- | arch/x86/include/asm/pgtable_areas.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/include/asm/pgtable_areas.h b/arch/x86/include/asm/pgtable_areas.h index d34cce1b995c..4f056fb88174 100644 --- a/arch/x86/include/asm/pgtable_areas.h +++ b/arch/x86/include/asm/pgtable_areas.h @@ -11,6 +11,12 @@ #define CPU_ENTRY_AREA_RO_IDT_VADDR ((void *)CPU_ENTRY_AREA_RO_IDT) -#define CPU_ENTRY_AREA_MAP_SIZE (CPU_ENTRY_AREA_PER_CPU + CPU_ENTRY_AREA_ARRAY_SIZE - CPU_ENTRY_AREA_BASE) +#ifdef CONFIG_X86_32 +#define CPU_ENTRY_AREA_MAP_SIZE (CPU_ENTRY_AREA_PER_CPU + \ + (CPU_ENTRY_AREA_SIZE * NR_CPUS) - \ + CPU_ENTRY_AREA_BASE) +#else +#define CPU_ENTRY_AREA_MAP_SIZE P4D_SIZE +#endif #endif /* _ASM_X86_PGTABLE_AREAS_H */ |