diff options
| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2019-12-21 08:32:28 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-01-26 22:15:09 +1100 |
| commit | 63289e7d3a645a4291ec43c1d526dd4a811da1a0 (patch) | |
| tree | 0fca41eaaab4e435a4bb9b66910ad367133e72af /arch/powerpc/include/asm/thread_info.h | |
| parent | 028474876f472c3b6eee633aed528a1206609657 (diff) | |
| download | linux-63289e7d3a645a4291ec43c1d526dd4a811da1a0.tar.bz2 | |
powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK
In order to ease stack overflow detection, align
stack to 2 * THREAD_SIZE when using VMAP_STACK.
This allows overflow detection using a single bit check.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/60e9ae86b7d2cdcf21468787076d345663648f46.1576916812.git.christophe.leroy@c-s.fr
Diffstat (limited to 'arch/powerpc/include/asm/thread_info.h')
| -rw-r--r-- | arch/powerpc/include/asm/thread_info.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index 488d5c4670ff..a2270749b282 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h @@ -22,6 +22,19 @@ #define THREAD_SIZE (1 << THREAD_SHIFT) +/* + * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by + * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry + * assembly. + */ +#ifdef CONFIG_VMAP_STACK +#define THREAD_ALIGN_SHIFT (THREAD_SHIFT + 1) +#else +#define THREAD_ALIGN_SHIFT THREAD_SHIFT +#endif + +#define THREAD_ALIGN (1 << THREAD_ALIGN_SHIFT) + #ifndef __ASSEMBLY__ #include <linux/cache.h> #include <asm/processor.h> |