x86/boot: Remove semicolon from "rep" prefixes

Minimum version of binutils required to compile the kernel is 2.25.
This version correctly handles the "rep" prefixes, so it is possible
to remove the semicolon, which was used to support ancient versions
of GNU as.

Due to the semicolon, the compiler considers "rep; insn" (or its
alternate "rep\n\tinsn" form) as two separate instructions. Removing
the semicolon makes asm length calculations more accurate, consequently
making scheduling and inlining decisions of the compiler more accurate.

Removing the semicolon also enables assembler checks involving "rep"
prefixes. Trying to assemble e.g. "rep addl %eax, %ebx" results in:

  Error: invalid instruction `add' after `rep'

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Mares <mj@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250418071437.4144391-1-ubizjak@gmail.com

7 files changed, 15 insertions, 15 deletions

diff --git a/arch/x86/boot/bioscall.S b/arch/x86/boot/bioscall.S
index aa9b96457584..cf4a6155714e 100644
--- a/arch/x86/boot/bioscall.S
+++ b/arch/x86/boot/bioscall.S
@@ -32,7 +32,7 @@ intcall:
 	movw	%dx, %si
 	movw	%sp, %di
 	movw	$11, %cx
-	rep; movsl
+	rep movsl
 
 	/* Pop full state from the stack */
 	popal
@@ -67,7 +67,7 @@ intcall:
 	jz	4f
 	movw	%sp, %si
 	movw	$11, %cx
-	rep; movsl
+	rep movsl
 4:	addw	$44, %sp
 
 	/* Restore state and return */
diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 38f17a1e1e36..f3771a6373c7 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -155,14 +155,14 @@ static inline void wrgs32(u32 v, addr_t addr)
 static inline bool memcmp_fs(const void *s1, addr_t s2, size_t len)
 {
 	bool diff;
-	asm volatile("fs; repe; cmpsb" CC_SET(nz)
+	asm volatile("fs repe cmpsb" CC_SET(nz)
 		     : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
 	return diff;
 }
 static inline bool memcmp_gs(const void *s1, addr_t s2, size_t len)
 {
 	bool diff;
-	asm volatile("gs; repe; cmpsb" CC_SET(nz)
+	asm volatile("gs repe cmpsb" CC_SET(nz)
 		     : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
 	return diff;
 }
diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
index 81fc1eaa3229..9af19d9614cb 100644
--- a/arch/x86/boot/compressed/string.c
+++ b/arch/x86/boot/compressed/string.c
@@ -15,9 +15,9 @@ static void *____memcpy(void *dest, const void *src, size_t n)
 {
 	int d0, d1, d2;
 	asm volatile(
-		"rep ; movsl\n\t"
+		"rep movsl\n\t"
 		"movl %4,%%ecx\n\t"
-		"rep ; movsb\n\t"
+		"rep movsb"
 		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
 		: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
 		: "memory");
@@ -29,9 +29,9 @@ static void *____memcpy(void *dest, const void *src, size_t n)
 {
 	long d0, d1, d2;
 	asm volatile(
-		"rep ; movsq\n\t"
+		"rep movsq\n\t"
 		"movq %4,%%rcx\n\t"
-		"rep ; movsb\n\t"
+		"rep movsb"
 		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
 		: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
 		: "memory");
diff --git a/arch/x86/boot/copy.S b/arch/x86/boot/copy.S
index 6afd05e819d2..3973a67cd04e 100644
--- a/arch/x86/boot/copy.S
+++ b/arch/x86/boot/copy.S
@@ -22,10 +22,10 @@ SYM_FUNC_START_NOALIGN(memcpy)
 	movw	%dx, %si
 	pushw	%cx
 	shrw	$2, %cx
-	rep; movsl
+	rep movsl
 	popw	%cx
 	andw	$3, %cx
-	rep; movsb
+	rep movsb
 	popw	%di
 	popw	%si
 	retl
@@ -38,10 +38,10 @@ SYM_FUNC_START_NOALIGN(memset)
 	imull	$0x01010101,%eax
 	pushw	%cx
 	shrw	$2, %cx
-	rep; stosl
+	rep stosl
 	popw	%cx
 	andw	$3, %cx
-	rep; stosb
+	rep stosb
 	popw	%di
 	retl
 SYM_FUNC_END(memset)
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index b5c79f43359b..9cb91421b4e4 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -585,7 +585,7 @@ start_of_setup:
 	xorl	%eax, %eax
 	subw	%di, %cx
 	shrw	$2, %cx
-	rep; stosl
+	rep stosl
 
 # Jump to C code (should not return)
 	calll	main
diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
index 84f7a883ce1e..f35369bb14c5 100644
--- a/arch/x86/boot/string.c
+++ b/arch/x86/boot/string.c
@@ -32,7 +32,7 @@
 int memcmp(const void *s1, const void *s2, size_t len)
 {
 	bool diff;
-	asm("repe; cmpsb" CC_SET(nz)
+	asm("repe cmpsb" CC_SET(nz)
 	    : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
 	return diff;
 }
diff --git a/arch/x86/boot/video.c b/arch/x86/boot/video.c
index f2e96905b3fe..0641c8c46aee 100644
--- a/arch/x86/boot/video.c
+++ b/arch/x86/boot/video.c
@@ -292,7 +292,7 @@ static void restore_screen(void)
 			     "shrw %%cx ; "
 			     "jnc 1f ; "
 			     "stosw \n\t"
-			     "1: rep;stosl ; "
+			     "1: rep stosl ; "
 			     "popw %%es"
 			     : "+D" (dst), "+c" (npad)
 			     : "bdS" (video_segment),