From: Peter Zijlstra peterz@infradead.org
stable inclusion from stable-v5.10.192 commit bd3d12e6fda0a7911a0f56f223924bb075b92d1e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7RQ67
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 095b8303f3835c68ac4a8b6d754ca1c3b6230711 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- arch/x86/include/asm/nospec-branch.h | 5 +++++ arch/x86/kernel/cpu/bugs.c | 2 ++ 2 files changed, 7 insertions(+)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index a010ae7fe6fd..fc4006fc86c2 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -195,7 +195,12 @@ _ASM_PTR " 999b\n\t" \ ".popsection\n\t"
+#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); diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 55c1917e3f32..baec1be43135 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -61,6 +61,8 @@ 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) {