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Subject[PATCH v6 11/27] x86/paravirt: Adapt assembly for PIE support
Date
if PIE is enabled, switch the paravirt assembly constraints to be
compatible. The %c/i constrains generate smaller code so is kept by
default.

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

Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
---
arch/x86/include/asm/paravirt_types.h | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 488c59686a73..8cfcc1b463de 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -342,9 +342,17 @@ extern struct paravirt_patch_template pv_ops;
#define PARAVIRT_PATCH(x) \
(offsetof(struct paravirt_patch_template, x) / sizeof(void *))

+#ifdef CONFIG_X86_PIE
+#define paravirt_opptr_call "a"
+#define paravirt_opptr_type "p"
+#else
+#define paravirt_opptr_call "c"
+#define paravirt_opptr_type "i"
+#endif
+
#define paravirt_type(op) \
[paravirt_typenum] "i" (PARAVIRT_PATCH(op)), \
- [paravirt_opptr] "i" (&(pv_ops.op))
+ [paravirt_opptr] paravirt_opptr_type (&(pv_ops.op))
#define paravirt_clobber(clobber) \
[paravirt_clobber] "i" (clobber)

@@ -392,7 +400,7 @@ int paravirt_disable_iospace(void);
*/
#define PARAVIRT_CALL \
ANNOTATE_RETPOLINE_SAFE \
- "call *%c[paravirt_opptr];"
+ "call *%" paravirt_opptr_call "[paravirt_opptr];"

/*
* These macros are intended to wrap calls through one of the paravirt
--
2.20.1.495.gaa96b0ce6b-goog
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