diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-08-14 13:44:30 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-08-16 09:39:16 +0200 |
| commit | 095b8303f3835c68ac4a8b6d754ca1c3b6230711 (patch) | |
| tree | cb7fa68badd16e2ae51f0c8d30037894b25dc853 /arch | |
| parent | objtool/x86: Fix SRSO mess (diff) | |
| download | linux-095b8303f3835c68ac4a8b6d754ca1c3b6230711.tar.xz linux-095b8303f3835c68ac4a8b6d754ca1c3b6230711.zip | |
x86/alternative: Make custom return thunk unconditional
There is infrastructure to rewrite return thunks to point to any
random thunk one desires, unwrap that from CALL_THUNKS, which up to
now was the sole user of that.
[ bp: Make the thunks visible on 32-bit and add ifdeffery for the
32-bit builds. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.775293785@infradead.org
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 9 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 2 |
3 files changed, 7 insertions, 8 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index e50db53a4cb9..b3625cceb2f0 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -341,17 +341,18 @@ extern retpoline_thunk_t __x86_indirect_thunk_array[]; extern retpoline_thunk_t __x86_indirect_call_thunk_array[]; extern retpoline_thunk_t __x86_indirect_jump_thunk_array[]; +#ifdef CONFIG_RETHUNK extern void __x86_return_thunk(void); +#else +static inline void __x86_return_thunk(void) {} +#endif + extern void zen_untrain_ret(void); extern void srso_untrain_ret(void); extern void srso_untrain_ret_alias(void); extern void entry_ibpb(void); -#ifdef CONFIG_CALL_THUNKS extern void (*x86_return_thunk)(void); -#else -#define x86_return_thunk (&__x86_return_thunk) -#endif #ifdef CONFIG_CALL_DEPTH_TRACKING extern void __x86_return_skl(void); diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 2dcf3a06af09..099d58d02a26 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -687,10 +687,6 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end) #ifdef CONFIG_RETHUNK -#ifdef CONFIG_CALL_THUNKS -void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk; -#endif - /* * Rewrite the compiler generated return thunk tail-calls. * diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 6c04aef4b63b..3bc0d149eacd 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -63,6 +63,8 @@ EXPORT_SYMBOL_GPL(x86_pred_cmd); static DEFINE_MUTEX(spec_ctrl_mutex); +void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk; + /* Update SPEC_CTRL MSR and its cached copy unconditionally */ static void update_spec_ctrl(u64 val) { |