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Message-ID: <20230814121148.775293785@infradead.org>
Date: Mon, 14 Aug 2023 13:44:30 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org,
David.Kaplan@....com, Andrew.Cooper3@...rix.com,
jpoimboe@...nel.org, gregkh@...uxfoundation.org,
nik.borisov@...e.com
Subject: [PATCH v2 04/11] 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.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
arch/x86/include/asm/nospec-branch.h | 4 ----
arch/x86/kernel/alternative.c | 2 --
2 files changed, 6 deletions(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -347,11 +347,7 @@ 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);
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -687,9 +687,7 @@ void __init_or_module noinline apply_ret
#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.
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