linux-kernel - [PATCH v1 10/14] x86/alternative: Convert ALTERNATIVE

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Message-ID: <20240607111701.8366-11-bp@kernel.org>
Date: Fri,  7 Jun 2024 13:16:57 +0200
From: Borislav Petkov <bp@...nel.org>
To: X86 ML <x86@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
	"Borislav Petkov (AMD)" <bp@...en8.de>
Subject: [PATCH v1 10/14] x86/alternative: Convert ALTERNATIVE_3()

From: "Borislav Petkov (AMD)" <bp@...en8.de>

Zap the hack of using an ALTERNATIVE_3() internal label, as suggested by
bgerst:

  https://lore.kernel.org/r/CAMzpN2i4oJ-Dv0qO46Fd-DxNv5z9=x%2BvO%2B8g=47NiiAf8QEJYA@mail.gmail.com

in favor of a label local to this macro only, as it should be done.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 arch/x86/include/asm/alternative.h | 24 ++++--------------------
 arch/x86/kernel/fpu/xstate.h       | 14 +++++---------
 2 files changed, 9 insertions(+), 29 deletions(-)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 007baab32c14..fba12ad237e2 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -277,26 +277,10 @@ static inline int alternatives_text_reserved(void *start, void *end)
 	N_ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS,	\
 		      newinstr_yes, ft_flags)
 
-#define ALTERNATIVE_3(oldinsn, newinsn1, ft_flags1, newinsn2, ft_flags2, \
-			newinsn3, ft_flags3)				\
-	OLDINSTR_3(oldinsn, 1, 2, 3)					\
-	".pushsection .altinstructions,\"a\"\n"				\
-	ALTINSTR_ENTRY(ft_flags1, 1)					\
-	ALTINSTR_ENTRY(ft_flags2, 2)					\
-	ALTINSTR_ENTRY(ft_flags3, 3)					\
-	".popsection\n"							\
-	".pushsection .altinstr_replacement, \"ax\"\n"			\
-	ALTINSTR_REPLACEMENT(newinsn1, 1)				\
-	ALTINSTR_REPLACEMENT(newinsn2, 2)				\
-	ALTINSTR_REPLACEMENT(newinsn3, 3)				\
-	".popsection\n"
-
-
-#define N_ALTERNATIVE_3(oldinst, newinst1, flag1, newinst2, flag2,	\
-		      newinst3, flag3)					\
-	N_ALTERNATIVE(N_ALTERNATIVE_2(oldinst, newinst1, flag1, newinst2, flag2), \
-		      newinst3, flag3)
-
+#define ALTERNATIVE_3(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, \
+			newinstr3, ft_flags3)				\
+	N_ALTERNATIVE(N_ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2), \
+		      newinstr3, ft_flags3)
 /*
  * Alternative instructions for different CPU types or capabilities.
  *
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 05df04f39628..2ee0b9c53dcc 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -106,21 +106,17 @@ static inline u64 xfeatures_mask_independent(void)
  * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT
  * supports modified optimization which is not supported by XSAVE.
  *
- * We use XSAVE as a fallback.
- *
- * The 661 label is defined in the ALTERNATIVE* macros as the address of the
- * original instruction which gets replaced. We need to use it here as the
- * address of the instruction where we might get an exception at.
+ * Use XSAVE as a fallback.
  */
 #define XSTATE_XSAVE(st, lmask, hmask, err)				\
-	asm volatile(ALTERNATIVE_3(XSAVE,				\
+	asm volatile("1: " ALTERNATIVE_3(XSAVE,				\
 				   XSAVEOPT, X86_FEATURE_XSAVEOPT,	\
 				   XSAVEC,   X86_FEATURE_XSAVEC,	\
 				   XSAVES,   X86_FEATURE_XSAVES)	\
 		     "\n"						\
 		     "xor %[err], %[err]\n"				\
 		     "3:\n"						\
-		     _ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \
+		     _ASM_EXTABLE_TYPE_REG(1b, 3b, EX_TYPE_EFAULT_REG, %[err]) \
 		     : [err] "=r" (err)					\
 		     : "D" (st), "m" (*st), "a" (lmask), "d" (hmask)	\
 		     : "memory")
@@ -130,11 +126,11 @@ static inline u64 xfeatures_mask_independent(void)
  * XSAVE area format.
  */
 #define XSTATE_XRESTORE(st, lmask, hmask)				\
-	asm volatile(ALTERNATIVE(XRSTOR,				\
+	asm volatile("1: " ALTERNATIVE(XRSTOR,				\
 				 XRSTORS, X86_FEATURE_XSAVES)		\
 		     "\n"						\
 		     "3:\n"						\
-		     _ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE)	\
+		     _ASM_EXTABLE_TYPE(1b, 3b, EX_TYPE_FPU_RESTORE)	\
 		     :							\
 		     : "D" (st), "m" (*st), "a" (lmask), "d" (hmask)	\
 		     : "memory")
-- 
2.43.0