While using a plain (constant) address works, its use needlessly invokes
a SIB addressing mode, making every call site one byte larger than
necessary. Instead of using an "i" constraint with address-of operator
and a 'c' operand modifier, simply use an ordinary "m" constraint, which
the 64-bit compiler will translate to %rip-relative addressing. This way
we also tell the compiler the truth about operand usage - the memory
location gets actually read, after all.
32-bit code generation is unaffected by the change.
Signed-off-by: Jan Beulich <redacted>
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -278,7 +278,7 @@ extern void (*paravirt_iret)(void);
#define paravirt_type(op) \
[paravirt_typenum] "i" (PARAVIRT_PATCH(op)), \
- [paravirt_opptr] "i" (&(pv_ops.op))
+ [paravirt_opptr] "m" (pv_ops.op)
#define paravirt_clobber(clobber) \
[paravirt_clobber] "i" (clobber)
@@ -315,7 +315,7 @@ int paravirt_disable_iospace(void);
*/
#define PARAVIRT_CALL \
ANNOTATE_RETPOLINE_SAFE \
- "call *%c[paravirt_opptr];"
+ "call *%[paravirt_opptr];"
/*
* These macros are intended to wrap calls through one of the paravirt
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