[PATCH 6.1 113/195] Revert "x86/alternative: Make custom return thunk unconditional"

Greg Kroah-Hartman
2024-02-27T14:17:30Z

From: "Borislav Petkov (AMD)" <bp@alien8.de>

This reverts commit 53ebbe1c8c02aa7b7f072dd2f96bca4faa1daa59.

Revert the backport of upstream commit:

095b8303f383 ("x86/alternative: Make custom return thunk unconditional")

in order to backport the full version now that

770ae1b70952 ("x86/returnthunk: Allow different return thunks")

has been backported.

Revert it here so that the build breakage is kept at minimum.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/nospec-branch.h | 4 ----
arch/x86/kernel/cpu/bugs.c | 2 --
2 files changed, 6 deletions(-)

--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -205,11 +205,7 @@
typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];
extern retpoline_thunk_t __x86_indirect_thunk_array[];

-#ifdef CONFIG_RETHUNK
extern void __x86_return_thunk(void);
-#else
-static inline void __x86_return_thunk(void) {}
-#endif

extern void retbleed_return_thunk(void);
extern void srso_return_thunk(void);
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -62,8 +62,6 @@ 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)
{