[tip: x86/asm] x86/irq/32: Add ASM_CALL_CONSTRAINT to inline asm using CALL_NOSPEC

[tip-bot2 for Uros Bizjak]

The following commit has been merged into the x86/asm branch of tip:

Commit-ID:     94770fe8648b80ee7ec4484e43b2381a25b62746
Gitweb:        https://git.kernel.org/tip/94770fe8648b80ee7ec4484e43b2381a25b62746
Author:        Uros Bizjak <ubizjak@xxxxxxxxx>
AuthorDate:    Mon, 03 Mar 2025 16:54:23 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 04 Mar 2025 10:53:51 +01:00

x86/irq/32: Add ASM_CALL_CONSTRAINT to inline asm using CALL_NOSPEC

This constraint should be used for any inline asm which has a CALL
instruction, otherwise the compiler may schedule the asm before the
frame pointer gets set up by the containing function, causing objtool
to print a "call without frame pointer save/setup" warning.

Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250303155446.112769-3-ubizjak@xxxxxxxxx
---
 arch/x86/kernel/irq_32.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index eab4580..f351fa1 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -59,6 +59,7 @@ static void call_on_stack(void *func, void *stack)
 		     "movl %[sp], %%esp"
 		     : [sp] "+b" (stack)
 		     : [thunk_target] "D" (func)
+		       COMMA(ASM_CALL_CONSTRAINT)
 		     : "memory", "cc", "edx", "ecx", "eax");
 }
 
@@ -98,6 +99,7 @@ static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc)
 		     "movl %[sp], %%esp"
 		     : "+a" (desc), [sp] "+b" (isp)
 		     : [thunk_target] "D" (desc->handle_irq)
+		       COMMA(ASM_CALL_CONSTRAINT)
 		     : "memory", "cc", "edx", "ecx");
 	return 1;
 }