linux-kernel - [PATCH] x86/speculation: Remove the extra ifdef around CALL

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Message-ID: <20250320-call-nospec-extra-ifdef-v1-1-d9b084d24820@linux.intel.com>
Date: Thu, 20 Mar 2025 11:13:15 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org, Josh Poimboeuf <jpoimboe@...nel.org>,
	Andrew Cooper <andrew.cooper3@...rix.com>
Subject: [PATCH] x86/speculation: Remove the extra ifdef around CALL_NOSPEC

Commit 010c4a461c1d ("x86/speculation: Simplify and make CALL_NOSPEC
consistent") added an ifdef CONFIG_MITIGATION_RETPOLINE around the
CALL_NOSPEC definition. This is not required as this code is already under
a larger ifdef.

Remove the extra ifdef, no functional change.

vmlinux size remains same before and after this change.

CONFIG_MITIGATION_RETPOLINE=y:
    text	   data	    bss	    dec		hex	filename
25434752	7342290	2301212	35078254	217406e	vmlinux.before
25434752	7342290	2301212	35078254	217406e	vmlinux.after

 # CONFIG_MITIGATION_RETPOLINE is not set:
    text	   data	    bss	    dec		hex	filename
22943094	6214994	1550152	30708240	1d49210	vmlinux.before
22943094	6214994	1550152	30708240	1d49210	vmlinux.after

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
---
 arch/x86/include/asm/nospec-branch.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index aee26bb8230f861dda7a4a568159d4cf77df45f6..c4816719150dce9f5ecc676cdcf38356fc96d166 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -434,12 +434,8 @@ static inline void call_depth_return_thunk(void) {}
  * Inline asm uses the %V modifier which is only in newer GCC
  * which is ensured when CONFIG_MITIGATION_RETPOLINE is defined.
  */
-#ifdef CONFIG_MITIGATION_RETPOLINE
 #define CALL_NOSPEC	__CS_PREFIX("%V[thunk_target]")	\
 			"call __x86_indirect_thunk_%V[thunk_target]\n"
-#else
-#define CALL_NOSPEC	"call *%[thunk_target]\n"
-#endif
 
 # define THUNK_TARGET(addr) [thunk_target] "r" (addr)
 

---
base-commit: 4701f33a10702d5fc577c32434eb62adde0a1ae1
change-id: 20250320-call-nospec-extra-ifdef-64b4942e7597

Best regards,
-- 
Thanks,
Pawan