diff options
| author | Brian Gerst <brgerst@gmail.com> | 2025-01-23 14:07:39 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-02-18 10:15:09 +0100 |
| commit | 80d47defddc000271502057ebd7efa4fd6481542 (patch) | |
| tree | 8b352a713b9f87567eb3d3a4ac1bcc55bc9311ed /arch/x86/kernel/cpu | |
| parent | 78c4374ef8b842c6abf195d6f963853c7ec464d2 (diff) | |
| download | linux-next-80d47defddc000271502057ebd7efa4fd6481542.tar.gz linux-next-80d47defddc000271502057ebd7efa4fd6481542.zip | |
x86/stackprotector/64: Convert to normal per-CPU variable
Older versions of GCC fixed the location of the stack protector canary
at %gs:40. This constraint forced the percpu section to be linked at
absolute address 0 so that the canary could be the first data object in
the percpu section. Supporting the zero-based percpu section requires
additional code to handle relocations for RIP-relative references to
percpu data, extra complexity to kallsyms, and workarounds for linker
bugs due to the use of absolute symbols.
GCC 8.1 supports redefining where the canary is located, allowing it to
become a normal percpu variable instead of at a fixed location. This
removes the constraint that the percpu section must be zero-based.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250123190747.745588-8-brgerst@gmail.com
Diffstat (limited to 'arch/x86/kernel/cpu')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 7cce91b19fb2..b71178f0ed6c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2089,8 +2089,7 @@ void syscall_init(void) if (!cpu_feature_enabled(X86_FEATURE_FRED)) idt_syscall_init(); } - -#else /* CONFIG_X86_64 */ +#endif /* CONFIG_X86_64 */ #ifdef CONFIG_STACKPROTECTOR DEFINE_PER_CPU(unsigned long, __stack_chk_guard); @@ -2099,8 +2098,6 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); #endif #endif -#endif /* CONFIG_X86_64 */ - /* * Clear all 6 debug registers: */ |