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-rw-r--r--tools/objtool/Documentation/stack-validation.txt6
1 files changed, 3 insertions, 3 deletions
diff --git a/tools/objtool/Documentation/stack-validation.txt b/tools/objtool/Documentation/stack-validation.txt
index 6a1af43862df..3995735a878f 100644
--- a/tools/objtool/Documentation/stack-validation.txt
+++ b/tools/objtool/Documentation/stack-validation.txt
@@ -194,10 +194,10 @@ they mean, and suggestions for how to fix them.
If it's a GCC-compiled .c file, the error may be because the function
uses an inline asm() statement which has a "call" instruction. An
asm() statement with a call instruction must declare the use of the
- stack pointer in its output operand. For example, on x86_64:
+ stack pointer in its output operand. On x86_64, this means adding
+ the ASM_CALL_CONSTRAINT as an output constraint:
- register void *__sp asm("rsp");
- asm volatile("call func" : "+r" (__sp));
+ asm volatile("call func" : ASM_CALL_CONSTRAINT);
Otherwise the stack frame may not get created before the call.