[PATCH v10 11/11] x86/alternatives: Adapt assembly for PIE support

From: Thomas Garnier
Date: Wed Dec 04 2019 - 19:10:45 EST


Change the assembly options to work with pointers instead of integers.
The generated code is the same PIE just ensures input is a pointer.

Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.

Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxxxx>
---
arch/x86/include/asm/alternative.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 13adca37c99a..43a148042656 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -243,7 +243,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
/* Like alternative_io, but for replacing a direct call with another one. */
#define alternative_call(oldfunc, newfunc, feature, output, input...) \
asm_inline volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
- : output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
+ : output : [old] "X" (oldfunc), [new] "X" (newfunc), ## input)

/*
* Like alternative_call, but there are two features and respective functions.
@@ -256,8 +256,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
"call %P[new2]", feature2) \
: output, ASM_CALL_CONSTRAINT \
- : [old] "i" (oldfunc), [new1] "i" (newfunc1), \
- [new2] "i" (newfunc2), ## input)
+ : [old] "X" (oldfunc), [new1] "X" (newfunc1), \
+ [new2] "X" (newfunc2), ## input)

/*
* use this macro(s) if you need more than one output parameter
--
2.24.0.393.g34dc348eaf-goog