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Commit 87b26406 authored by Brian Gerst's avatar Brian Gerst Committed by Tejun Heo
Browse files

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: default avatarBrian Gerst <brgerst@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent c2558e0e

arch/x86/include/asm/percpu.h

+13 −13
Original line number Diff line number Diff line
@@ -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__;								\

})

arch/x86/include/asm/system.h

+1 −1
Original line number Diff line number Diff line
@@ -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" 					  \