From 411f790cd7e91fac0db80d3cf789cb6deeac298e Mon Sep 17 00:00:00 2001 From: Stefani Seibold Date: Mon, 17 Mar 2014 23:22:03 +0100 Subject: [PATCH] x86, vdso: Revamp vclock_gettime.c This intermediate patch revamps the vclock_gettime.c by moving some functions around. It is only for spliting purpose, to make whole the 32 bit vdso timer patch easier to review. Reviewed-by: Andy Lutomirski Signed-off-by: Stefani Seibold Link: http://lkml.kernel.org/r/1395094933-14252-4-git-send-email-stefani@seibold.net Signed-off-by: H. Peter Anvin --- arch/x86/vdso/vclock_gettime.c | 85 +++++++++++++++++----------------- 1 file changed, 42 insertions(+), 43 deletions(-) diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c index eb5d7a56f8d4..bbc80657050f 100644 --- a/arch/x86/vdso/vclock_gettime.c +++ b/arch/x86/vdso/vclock_gettime.c @@ -26,41 +26,26 @@ #define gtod (&VVAR(vsyscall_gtod_data)) -notrace static cycle_t vread_tsc(void) +static notrace cycle_t vread_hpet(void) { - cycle_t ret; - u64 last; - - /* - * Empirically, a fence (of type that depends on the CPU) - * before rdtsc is enough to ensure that rdtsc is ordered - * with respect to loads. The various CPU manuals are unclear - * as to whether rdtsc can be reordered with later loads, - * but no one has ever seen it happen. - */ - rdtsc_barrier(); - ret = (cycle_t)vget_cycles(); - - last = VVAR(vsyscall_gtod_data).clock.cycle_last; - - if (likely(ret >= last)) - return ret; + return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + HPET_COUNTER); +} - /* - * GCC likes to generate cmov here, but this branch is extremely - * predictable (it's just a funciton of time and the likely is - * very likely) and there's a data dependence, so force GCC - * to generate a branch instead. I don't barrier() because - * we don't actually need a barrier, and if this function - * ever gets inlined it will generate worse code. - */ - asm volatile (""); - return last; +notrace static long vdso_fallback_gettime(long clock, struct timespec *ts) +{ + long ret; + asm("syscall" : "=a" (ret) : + "0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory"); + return ret; } -static notrace cycle_t vread_hpet(void) +notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz) { - return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + HPET_COUNTER); + long ret; + + asm("syscall" : "=a" (ret) : + "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory"); + return ret; } #ifdef CONFIG_PARAVIRT_CLOCK @@ -133,23 +118,37 @@ static notrace cycle_t vread_pvclock(int *mode) } #endif -notrace static long vdso_fallback_gettime(long clock, struct timespec *ts) +notrace static cycle_t vread_tsc(void) { - long ret; - asm("syscall" : "=a" (ret) : - "0" (__NR_clock_gettime),"D" (clock), "S" (ts) : "memory"); - return ret; -} + cycle_t ret; + u64 last; -notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz) -{ - long ret; + /* + * Empirically, a fence (of type that depends on the CPU) + * before rdtsc is enough to ensure that rdtsc is ordered + * with respect to loads. The various CPU manuals are unclear + * as to whether rdtsc can be reordered with later loads, + * but no one has ever seen it happen. + */ + rdtsc_barrier(); + ret = (cycle_t)vget_cycles(); - asm("syscall" : "=a" (ret) : - "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory"); - return ret; -} + last = VVAR(vsyscall_gtod_data).clock.cycle_last; + if (likely(ret >= last)) + return ret; + + /* + * GCC likes to generate cmov here, but this branch is extremely + * predictable (it's just a funciton of time and the likely is + * very likely) and there's a data dependence, so force GCC + * to generate a branch instead. I don't barrier() because + * we don't actually need a barrier, and if this function + * ever gets inlined it will generate worse code. + */ + asm volatile (""); + return last; +} notrace static inline u64 vgetsns(int *mode) { -- 2.34.1