diff options
| -rw-r--r-- | arch/x86/include/asm/percpu.h | 48 | ||||
| -rw-r--r-- | arch/x86/lib/Makefile | 1 | ||||
| -rw-r--r-- | arch/x86/lib/cmpxchg16b_emu.S | 59 |
3 files changed, 108 insertions, 0 deletions
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index 3788f4649db..260ac7af1fd 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -451,6 +451,26 @@ do { \ #define irqsafe_cpu_cmpxchg_4(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval) #endif /* !CONFIG_M386 */ +#ifdef CONFIG_X86_CMPXCHG64 +#define percpu_cmpxchg8b_double(pcp1, o1, o2, n1, n2) \ +({ \ + char __ret; \ + typeof(o1) __o1 = o1; \ + typeof(o1) __n1 = n1; \ + typeof(o2) __o2 = o2; \ + typeof(o2) __n2 = n2; \ + typeof(o2) __dummy = n2; \ + asm volatile("cmpxchg8b "__percpu_arg(1)"\n\tsetz %0\n\t" \ + : "=a"(__ret), "=m" (pcp1), "=d"(__dummy) \ + : "b"(__n1), "c"(__n2), "a"(__o1), "d"(__o2)); \ + __ret; \ +}) + +#define __this_cpu_cmpxchg_double_4(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg8b_double(pcp1, o1, o2, n1, n2) +#define this_cpu_cmpxchg_double_4(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg8b_double(pcp1, o1, o2, n1, n2) +#define irqsafe_cpu_cmpxchg_double_4(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg8b_double(pcp1, o1, o2, n1, n2) +#endif /* CONFIG_X86_CMPXCHG64 */ + /* * Per cpu atomic 64 bit operations are only available under 64 bit. * 32 bit must fall back to generic operations. @@ -480,6 +500,34 @@ do { \ #define irqsafe_cpu_xor_8(pcp, val) percpu_to_op("xor", (pcp), val) #define irqsafe_cpu_xchg_8(pcp, nval) percpu_xchg_op(pcp, nval) #define irqsafe_cpu_cmpxchg_8(pcp, oval, nval) percpu_cmpxchg_op(pcp, oval, nval) + +/* + * Pretty complex macro to generate cmpxchg16 instruction. The instruction + * is not supported on early AMD64 processors so we must be able to emulate + * it in software. The address used in the cmpxchg16 instruction must be + * aligned to a 16 byte boundary. + */ +#define percpu_cmpxchg16b_double(pcp1, o1, o2, n1, n2) \ +({ \ + char __ret; \ + typeof(o1) __o1 = o1; \ + typeof(o1) __n1 = n1; \ + typeof(o2) __o2 = o2; \ + typeof(o2) __n2 = n2; \ + typeof(o2) __dummy; \ + alternative_io("call this_cpu_cmpxchg16b_emu\n\t" P6_NOP4, \ + "cmpxchg16b %%gs:(%%rsi)\n\tsetz %0\n\t", \ + X86_FEATURE_CX16, \ + ASM_OUTPUT2("=a"(__ret), "=d"(__dummy)), \ + "S" (&pcp1), "b"(__n1), "c"(__n2), \ + "a"(__o1), "d"(__o2)); \ + __ret; \ +}) + +#define __this_cpu_cmpxchg_double_8(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg16b_double(pcp1, o1, o2, n1, n2) +#define this_cpu_cmpxchg_double_8(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg16b_double(pcp1, o1, o2, n1, n2) +#define irqsafe_cpu_cmpxchg_double_8(pcp1, pcp2, o1, o2, n1, n2) percpu_cmpxchg16b_double(pcp1, o1, o2, n1, n2) + #endif /* This is not atomic against other CPUs -- CPU preemption needs to be off */ diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index e10cf070ede..f2479f19ddd 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -42,4 +42,5 @@ else lib-y += memmove_64.o memset_64.o lib-y += copy_user_64.o rwlock_64.o copy_user_nocache_64.o lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem_64.o + lib-y += cmpxchg16b_emu.o endif diff --git a/arch/x86/lib/cmpxchg16b_emu.S b/arch/x86/lib/cmpxchg16b_emu.S new file mode 100644 index 00000000000..3e8b08a6de2 --- /dev/null +++ b/arch/x86/lib/cmpxchg16b_emu.S @@ -0,0 +1,59 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + * + */ +#include <linux/linkage.h> +#include <asm/alternative-asm.h> +#include <asm/frame.h> +#include <asm/dwarf2.h> + +.text + +/* + * Inputs: + * %rsi : memory location to compare + * %rax : low 64 bits of old value + * %rdx : high 64 bits of old value + * %rbx : low 64 bits of new value + * %rcx : high 64 bits of new value + * %al : Operation successful + */ +ENTRY(this_cpu_cmpxchg16b_emu) +CFI_STARTPROC + +# +# Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not +# via the ZF. Caller will access %al to get result. +# +# Note that this is only useful for a cpuops operation. Meaning that we +# do *not* have a fully atomic operation but just an operation that is +# *atomic* on a single cpu (as provided by the this_cpu_xx class of +# macros). +# +this_cpu_cmpxchg16b_emu: + pushf + cli + + cmpq %gs:(%rsi), %rax + jne not_same + cmpq %gs:8(%rsi), %rdx + jne not_same + + movq %rbx, %gs:(%rsi) + movq %rcx, %gs:8(%rsi) + + popf + mov $1, %al + ret + + not_same: + popf + xor %al,%al + ret + +CFI_ENDPROC + +ENDPROC(this_cpu_cmpxchg16b_emu) |