diff options
author | Andi Kleen <ak@suse.de> | 2008-01-30 15:32:39 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-01-30 15:32:39 +0300 |
commit | 6d63de8dbcda98511206897562ecfcdacf18f523 (patch) | |
tree | f845f109636c3cc7eddad455b89ffb986a1188d0 /include | |
parent | f06e4ec1c15691b0cfd2397ae32214fa36c90d71 (diff) | |
download | linux-6d63de8dbcda98511206897562ecfcdacf18f523.tar.xz |
x86: remove get_cycles_sync
rdtsc is now speculation-safe, so no need for the sync variants of
the APIs.
[ mingo@elte.hu: removed the nsec_barrier() complication. ]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include')
-rw-r--r-- | include/asm-x86/tsc.h | 60 |
1 files changed, 8 insertions, 52 deletions
diff --git a/include/asm-x86/tsc.h b/include/asm-x86/tsc.h index 401303724130..f51a50da35aa 100644 --- a/include/asm-x86/tsc.h +++ b/include/asm-x86/tsc.h @@ -36,62 +36,18 @@ static inline cycles_t get_cycles(void) return ret; } -/* Like get_cycles, but make sure the CPU is synchronized. */ -static __always_inline cycles_t __get_cycles_sync(void) +static inline cycles_t vget_cycles(void) { - unsigned long long ret; - unsigned eax, edx; - /* - * Use RDTSCP if possible; it is guaranteed to be synchronous - * and doesn't cause a VMEXIT on Hypervisors + * We only do VDSOs on TSC capable CPUs, so this shouldnt + * access boot_cpu_data (which is not VDSO-safe): */ - alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP, - ASM_OUTPUT2("=a" (eax), "=d" (edx)), - "a" (0U), "d" (0U) : "ecx", "memory"); - ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax); - if (ret) - return ret; - - /* - * Don't do an additional sync on CPUs where we know - * RDTSC is already synchronous: - */ - alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC, - "=a" (eax), "0" (1) : "ebx","ecx","edx","memory"); - - return 0; -} - -static __always_inline cycles_t get_cycles_sync(void) -{ - unsigned long long ret; - ret = __get_cycles_sync(); - if (!ret) - rdtscll(ret); - return ret; -} - -#ifdef CONFIG_PARAVIRT -/* - * For paravirt guests, some functionalities are executed through function - * pointers in the various pvops structures. - * These function pointers exist inside the kernel and can not - * be accessed by user space. To avoid this, we make a copy of the - * get_cycles_sync (called in kernel) but force the use of native_read_tsc. - * Ideally, the guest should set up it's own clock and vread - */ -static __always_inline long long vget_cycles_sync(void) -{ - unsigned long long ret; - ret = __get_cycles_sync(); - if (!ret) - ret = native_read_tsc(); - return ret; -} -#else -# define vget_cycles_sync() get_cycles_sync() +#ifndef CONFIG_X86_TSC + if (!cpu_has_tsc) + return 0; #endif + return (cycles_t) native_read_tsc(); +} extern void tsc_init(void); extern void mark_tsc_unstable(char *reason); |