[Xen-devel] [PATCH v2 03/27] x86: Use symbol name in jump table for PIE support

[Thomas Garnier <thgarnie@xxxxxxxxxx>]

Replace the %c constraint with %P. The %c is incompatible with PIE
because it implies an immediate value whereas %P reference a symbol.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx>
---
 arch/x86/include/asm/jump_label.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h 
b/arch/x86/include/asm/jump_label.h
index 8c0de4282659..dfdcdc39604a 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -37,9 +37,9 @@ static __always_inline bool arch_static_branch(struct 
static_key *key, bool bran
                ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
                ".pushsection __jump_table,  \"aw\" \n\t"
                _ASM_ALIGN "\n\t"
-               _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
+               _ASM_PTR "1b, %l[l_yes], %P0 \n\t"
                ".popsection \n\t"
-               : :  "i" (key), "i" (branch) : : l_yes);
+               : :  "X" (&((char *)key)[branch]) : : l_yes);
 
        return false;
 l_yes:
@@ -53,9 +53,9 @@ static __always_inline bool arch_static_branch_jump(struct 
static_key *key, bool
                "2:\n\t"
                ".pushsection __jump_table,  \"aw\" \n\t"
                _ASM_ALIGN "\n\t"
-               _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
+               _ASM_PTR "1b, %l[l_yes], %P0 \n\t"
                ".popsection \n\t"
-               : :  "i" (key), "i" (branch) : : l_yes);
+               : :  "X" (&((char *)key)[branch]) : : l_yes);
 
        return false;
 l_yes:
-- 
2.16.2.660.g709887971b-goog


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