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Subject[PATCH 12/17] x86-64: Use absolute displacements for per-cpu accesses.
Date
Accessing memory through %gs should not use rip-relative addressing.
Adding a P prefix for the argument tells gcc to not add (%rip) to
the memory references.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
arch/x86/include/asm/percpu.h | 26 +++++++++++++-------------
arch/x86/include/asm/system.h | 2 +-
2 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 03aa4b0..165d527 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -39,10 +39,10 @@
#include <linux/stringify.h>

#ifdef CONFIG_SMP
-#define __percpu_seg_str "%%"__stringify(__percpu_seg)":"
+#define __percpu_arg(x) "%%"__stringify(__percpu_seg)":%P" #x
#define __my_cpu_offset percpu_read(this_cpu_off)
#else
-#define __percpu_seg_str
+#define __percpu_arg(x) "%" #x
#endif

/* For arch-specific code, we can use direct single-insn ops (they
@@ -58,22 +58,22 @@ do { \
} \
switch (sizeof(var)) { \
case 1: \
- asm(op "b %1,"__percpu_seg_str"%0" \
+ asm(op "b %1,"__percpu_arg(0) \
: "+m" (var) \
: "ri" ((T__)val)); \
break; \
case 2: \
- asm(op "w %1,"__percpu_seg_str"%0" \
+ asm(op "w %1,"__percpu_arg(0) \
: "+m" (var) \
: "ri" ((T__)val)); \
break; \
case 4: \
- asm(op "l %1,"__percpu_seg_str"%0" \
+ asm(op "l %1,"__percpu_arg(0) \
: "+m" (var) \
: "ri" ((T__)val)); \
break; \
case 8: \
- asm(op "q %1,"__percpu_seg_str"%0" \
+ asm(op "q %1,"__percpu_arg(0) \
: "+m" (var) \
: "r" ((T__)val)); \
break; \
@@ -86,22 +86,22 @@ do { \
typeof(var) ret__; \
switch (sizeof(var)) { \
case 1: \
- asm(op "b "__percpu_seg_str"%1,%0" \
+ asm(op "b "__percpu_arg(1)",%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
case 2: \
- asm(op "w "__percpu_seg_str"%1,%0" \
+ asm(op "w "__percpu_arg(1)",%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
case 4: \
- asm(op "l "__percpu_seg_str"%1,%0" \
+ asm(op "l "__percpu_arg(1)",%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
case 8: \
- asm(op "q "__percpu_seg_str"%1,%0" \
+ asm(op "q "__percpu_arg(1)",%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
@@ -122,9 +122,9 @@ do { \
#define x86_test_and_clear_bit_percpu(bit, var) \
({ \
int old__; \
- asm volatile("btr %1,"__percpu_seg_str"%c2\n\tsbbl %0,%0" \
- : "=r" (old__) \
- : "dIr" (bit), "i" (&per_cpu__##var) : "memory"); \
+ asm volatile("btr %2,"__percpu_arg(1)"\n\tsbbl %0,%0" \
+ : "=r" (old__), "+m" (per_cpu__##var) \
+ : "dIr" (bit)); \
old__; \
})

diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index 4399aac..d1dc27d 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -94,7 +94,7 @@ do { \
"call __switch_to\n\t" \
".globl thread_return\n" \
"thread_return:\n\t" \
- "movq "__percpu_seg_str"%P[current_task],%%rsi\n\t" \
+ "movq "__percpu_arg([current_task])",%%rsi\n\t" \
"movq %P[thread_info](%%rsi),%%r8\n\t" \
LOCK_PREFIX "btr %[tif_fork],%P[ti_flags](%%r8)\n\t" \
"movq %%rax,%%rdi\n\t" \
--
1.6.1.rc1


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