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percpu: Omit segment prefix in the UP case for cmpxchg_double
Omit the segment prefix in the UP case. GS is not used then and we will generate segfaults if cmpxchg16b is used otherwise. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -45,7 +45,7 @@
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#include <linux/stringify.h>
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#ifdef CONFIG_SMP
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#define __percpu_arg(x) "%%"__stringify(__percpu_seg)":%P" #x
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#define __percpu_prefix "%%"__stringify(__percpu_seg)":"
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#define __my_cpu_offset percpu_read(this_cpu_off)
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/*
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@ -62,9 +62,11 @@
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(typeof(*(ptr)) __kernel __force *)tcp_ptr__; \
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})
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#else
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#define __percpu_arg(x) "%P" #x
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#define __percpu_prefix ""
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#endif
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#define __percpu_arg(x) __percpu_prefix "%P" #x
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/*
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* Initialized pointers to per-cpu variables needed for the boot
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* processor need to use these macros to get the proper address
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@ -516,11 +518,11 @@ do { \
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typeof(o2) __n2 = n2; \
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typeof(o2) __dummy; \
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alternative_io("call this_cpu_cmpxchg16b_emu\n\t" P6_NOP4, \
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"cmpxchg16b %%gs:(%%rsi)\n\tsetz %0\n\t", \
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"cmpxchg16b " __percpu_prefix "(%%rsi)\n\tsetz %0\n\t", \
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X86_FEATURE_CX16, \
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ASM_OUTPUT2("=a"(__ret), "=d"(__dummy)), \
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"S" (&pcp1), "b"(__n1), "c"(__n2), \
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"a"(__o1), "d"(__o2)); \
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"a"(__o1), "d"(__o2) : "memory"); \
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__ret; \
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})
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@ -10,6 +10,12 @@
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#include <asm/frame.h>
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#include <asm/dwarf2.h>
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#ifdef CONFIG_SMP
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#define SEG_PREFIX %gs:
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#else
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#define SEG_PREFIX
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#endif
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.text
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/*
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@ -37,13 +43,13 @@ this_cpu_cmpxchg16b_emu:
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pushf
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cli
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cmpq %gs:(%rsi), %rax
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cmpq SEG_PREFIX(%rsi), %rax
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jne not_same
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cmpq %gs:8(%rsi), %rdx
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cmpq SEG_PREFIX 8(%rsi), %rdx
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jne not_same
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movq %rbx, %gs:(%rsi)
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movq %rcx, %gs:8(%rsi)
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movq %rbx, SEG_PREFIX(%rsi)
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movq %rcx, SEG_PREFIX 8(%rsi)
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popf
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mov $1, %al
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