x86-64: Use absolute displacements for per-cpu accesses.

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>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 03aa4b00a1c3ff3bf31b1a9a57f49d3c31021841..165d5272ece19f97734e616a38f39c93116e298c 100644 (file)
--- 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 4399aac680e926ff5e0148258af0f5d060c0179f..d1dc27dba36da4ed20a72c3014adaa901b7ea073 100644 (file)
--- 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"                                       \