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Message-ID: <77n2puylk3pox4s2du6agjiaj3joh2bxtvpjsenf72mentb7bj@siyjjbwxrasv>
Date: Sun, 7 Dec 2025 06:52:44 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>, Borislav Petkov <bp@...en8.de>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 7/8] x86/asm: Remove newlines in alternatives
On Sat, Dec 06, 2025 at 01:41:14PM -0800, Josh Poimboeuf wrote:
> In preparation for converting the alternative implementation to
> assembler macros, remove all newlines from alternative instructions.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
x86-32 fixes:
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 334c6058a1ec..2313f3fe19d0 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -441,18 +441,18 @@ static inline void call_depth_return_thunk(void) {}
* -mindirect-branch-cs-prefix.
*/
#define __CS_PREFIX(reg) \
- ".irp rs,r8,r9,r10,r11,r12,r13,r14,r15\n" \
- ".ifc \\rs," reg "\n" \
- ".byte 0x2e\n" \
- ".endif\n" \
- ".endr\n"
+ ".irp rs,r8,r9,r10,r11,r12,r13,r14,r15; " \
+ ".ifc \\rs," reg "; " \
+ ".byte 0x2e; " \
+ ".endif; " \
+ ".endr; "
/*
* Inline asm uses the %V modifier which is only in newer GCC
* which is ensured when CONFIG_MITIGATION_RETPOLINE is defined.
*/
#define CALL_NOSPEC __CS_PREFIX("%V[thunk_target]") \
- "call __x86_indirect_thunk_%V[thunk_target]\n"
+ "call __x86_indirect_thunk_%V[thunk_target]"
# define THUNK_TARGET(addr) [thunk_target] "r" (addr)
@@ -464,30 +464,30 @@ static inline void call_depth_return_thunk(void) {}
*/
# define CALL_NOSPEC \
ALTERNATIVE_2( \
- ANNOTATE_RETPOLINE_SAFE "\n" \
- "call *%[thunk_target]\n", \
- " jmp 904f;\n" \
- " .align 16\n" \
- "901: call 903f;\n" \
- "902: pause;\n" \
- " lfence;\n" \
- " jmp 902b;\n" \
- " .align 16\n" \
- "903: lea 4(%%esp), %%esp;\n" \
- " pushl %[thunk_target];\n" \
- " ret;\n" \
- " .align 16\n" \
- "904: call 901b;\n", \
+ ANNOTATE_RETPOLINE_SAFE "; " \
+ "call *%[thunk_target]; ", \
+ " jmp 904f; " \
+ " .align 16; " \
+ "901: call 903f; " \
+ "902: pause; " \
+ " lfence; " \
+ " jmp 902b; " \
+ " .align 16; " \
+ "903: lea 4(%%esp), %%esp; " \
+ " pushl %[thunk_target]; " \
+ " ret; " \
+ " .align 16; " \
+ "904: call 901b; ", \
X86_FEATURE_RETPOLINE, \
- "lfence;\n" \
- ANNOTATE_RETPOLINE_SAFE "\n" \
- "call *%[thunk_target]\n", \
+ "lfence; " \
+ ANNOTATE_RETPOLINE_SAFE "; " \
+ "call *%[thunk_target]; ", \
X86_FEATURE_RETPOLINE_LFENCE)
# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
#endif
#else /* No retpoline for C / inline asm */
-# define CALL_NOSPEC "call *%[thunk_target]\n"
+# define CALL_NOSPEC "call *%[thunk_target]; "
# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
#endif
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index c7a5d2960d57..9c5bb666bd55 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -53,7 +53,7 @@ DEFINE_PER_CPU_CACHE_HOT(struct irq_stack *, softirq_stack_ptr);
static void call_on_stack(void *func, void *stack)
{
- asm volatile("xchgl %[sp], %%esp\n"
+ asm volatile("xchgl %[sp], %%esp; "
CALL_NOSPEC
"movl %[sp], %%esp"
: [sp] "+b" (stack)
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