From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756748Ab1E0RjX (ORCPT ); Fri, 27 May 2011 13:39:23 -0400 Received: from DMZ-MAILSEC-SCANNER-5.MIT.EDU ([18.7.68.34]:50920 "EHLO dmz-mailsec-scanner-5.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755906Ab1E0RjJ (ORCPT ); Fri, 27 May 2011 13:39:09 -0400 X-AuditID: 12074422-b7b0eae000007f48-03-4ddfe1bec312 From: Andy Lutomirski To: Thomas Gleixner , Ingo Molnar , x86@kernel.org Cc: linux-kernel@vger.kernel.org, Andy Lutomirski Subject: [PATCH 3/5] x86-64: Remove kernel.vsyscall64 sysctl Date: Fri, 27 May 2011 13:38:40 -0400 Message-Id: <4f7ce93b87e24b2bc1ea9de4052ab0a497a2a6a3.1306517576.git.luto@mit.edu> X-Mailer: git-send-email 1.7.5.1 In-Reply-To: References: In-Reply-To: References: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrIIsWRmVeSWpSXmKPExsUixG6norvv4X1fg4s/hS36rhxlt7i8aw6b xZZLzawWmzdNZbb4seExqwOrx622P8weO2fdZffYtKqTzePduXPsHp83yQWwRnHZpKTmZJal FunbJXBlzNm8hrVgv0FF59np7A2Mr9W7GDk5JARMJFb//ssGYYtJXLi3Hsjm4hAS2Mcocelj OyuEs4FR4tqRKywgVUICz5gk7h0qArHZBFQkOpY+YAKxRQTiJBpm/2YFsZkFHCRuPz7CCGIL C9hIrDn/nR3EZhFQlZhx5T9YnFcgSGLioVZ2iM0KEleuzAObzylgIHH97w52iF36Et8vrmPD JT6BUWABI8MqRtmU3Crd3MTMnOLUZN3i5MS8vNQiXVO93MwSvdSU0k2M4NB0UdrB+POg0iFG AQ5GJR5e9YP3fYVYE8uKK3MPMUpyMCmJ8vo9AArxJeWnVGYkFmfEF5XmpBYfYpTgYFYS4TXZ D5TjTUmsrEotyodJSXOwKInzzpFU9xUSSE8sSc1OTS1ILYLJynBwKEnwCgBjUEiwKDU9tSIt M6cEIc3EwQkynAdouCdIDW9xQWJucWY6RP4Uoy5H49odBxmFWPLy81KlxHmNQIoEQIoySvPg 5sBSyitGcaC3hHntQKp4gOkIbtIroCVMQEt0ft8FWVKSiJCSamAUmLDrS+sfhqj1JTNP/187 t4Jbqbb05aoJl2I6FLqV5ugKsBS/0+GNLy1/eNd4+2eD8jrTAsZPYWu3bDdT6JV0vPlnHev2 Q/OrRUufxeYvXdV/dPtbkadFd+49uunqM3OlQvrtjzMPyx1d2+5laHP7IcvrmY93Xf/3y+nm zuK1H00cuthFhQ3mKrEUZyQaajEXFScCAEL6mNYEAwAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's unnecessary overhead in code that's supposed to be highly optimized. Removing it allows us to remove one of the two syscall instructions in the vsyscall page. The only sensible use for it is for UML users, and it doesn't fully address inconsistent vsyscall results on UML. The real fix for UML is to stop using vsyscalls entirely. Signed-off-by: Andy Lutomirski --- arch/x86/include/asm/vgtod.h | 1 - arch/x86/kernel/vsyscall_64.c | 34 +------------------------ arch/x86/vdso/vclock_gettime.c | 55 +++++++++++++++------------------------ 3 files changed, 22 insertions(+), 68 deletions(-) diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h index 646b4c1..aa5add8 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -11,7 +11,6 @@ struct vsyscall_gtod_data { time_t wall_time_sec; u32 wall_time_nsec; - int sysctl_enabled; struct timezone sys_tz; struct { /* extract of a clocksource struct */ cycle_t (*vread)(void); diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c index ee22180..3e8dac7 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -53,7 +53,6 @@ DEFINE_VVAR(int, vgetcpu_mode); DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) = { .lock = SEQLOCK_UNLOCKED, - .sysctl_enabled = 1, }; void update_vsyscall_tz(void) @@ -103,15 +102,6 @@ static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz) return ret; } -static __always_inline long time_syscall(long *t) -{ - long secs; - asm volatile("syscall" - : "=a" (secs) - : "0" (__NR_time),"D" (t) : __syscall_clobber); - return secs; -} - static __always_inline void do_vgettimeofday(struct timeval * tv) { cycle_t now, base, mask, cycle_delta; @@ -122,8 +112,7 @@ static __always_inline void do_vgettimeofday(struct timeval * tv) seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock); vread = VVAR(vsyscall_gtod_data).clock.vread; - if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled || - !vread)) { + if (unlikely(!vread)) { gettimeofday(tv,NULL); return; } @@ -165,8 +154,6 @@ time_t __vsyscall(1) vtime(time_t *t) { unsigned seq; time_t result; - if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled)) - return time_syscall(t); do { seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock); @@ -227,22 +214,6 @@ static long __vsyscall(3) venosys_1(void) return -ENOSYS; } -#ifdef CONFIG_SYSCTL -static ctl_table kernel_table2[] = { - { .procname = "vsyscall64", - .data = &vsyscall_gtod_data.sysctl_enabled, .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec }, - {} -}; - -static ctl_table kernel_root_table2[] = { - { .procname = "kernel", .mode = 0555, - .child = kernel_table2 }, - {} -}; -#endif - /* Assume __initcall executes before all user space. Hopefully kmod doesn't violate that. We'll find out if it does. */ static void __cpuinit vsyscall_set_cpu(int cpu) @@ -301,9 +272,6 @@ static int __init vsyscall_init(void) BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime)); BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE))); BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu)); -#ifdef CONFIG_SYSCTL - register_sysctl_table(kernel_root_table2); -#endif on_each_cpu(cpu_vsyscall_init, NULL, 1); /* notifier priority > KVM */ hotcpu_notifier(cpu_vsyscall_notifier, 30); diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c index a724905..cf54813 100644 --- a/arch/x86/vdso/vclock_gettime.c +++ b/arch/x86/vdso/vclock_gettime.c @@ -116,21 +116,21 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts) notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts) { - if (likely(gtod->sysctl_enabled)) - switch (clock) { - case CLOCK_REALTIME: - if (likely(gtod->clock.vread)) - return do_realtime(ts); - break; - case CLOCK_MONOTONIC: - if (likely(gtod->clock.vread)) - return do_monotonic(ts); - break; - case CLOCK_REALTIME_COARSE: - return do_realtime_coarse(ts); - case CLOCK_MONOTONIC_COARSE: - return do_monotonic_coarse(ts); - } + switch (clock) { + case CLOCK_REALTIME: + if (likely(gtod->clock.vread)) + return do_realtime(ts); + break; + case CLOCK_MONOTONIC: + if (likely(gtod->clock.vread)) + return do_monotonic(ts); + break; + case CLOCK_REALTIME_COARSE: + return do_realtime_coarse(ts); + case CLOCK_MONOTONIC_COARSE: + return do_monotonic_coarse(ts); + } + return vdso_fallback_gettime(clock, ts); } int clock_gettime(clockid_t, struct timespec *) @@ -139,7 +139,7 @@ int clock_gettime(clockid_t, struct timespec *) notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz) { long ret; - if (likely(gtod->sysctl_enabled && gtod->clock.vread)) { + if (likely(gtod->clock.vread)) { if (likely(tv != NULL)) { BUILD_BUG_ON(offsetof(struct timeval, tv_usec) != offsetof(struct timespec, tv_nsec) || @@ -161,27 +161,14 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz) int gettimeofday(struct timeval *, struct timezone *) __attribute__((weak, alias("__vdso_gettimeofday"))); -/* This will break when the xtime seconds get inaccurate, but that is - * unlikely */ - -static __always_inline long time_syscall(long *t) -{ - long secs; - asm volatile("syscall" - : "=a" (secs) - : "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory"); - return secs; -} - +/* + * This will break when the xtime seconds get inaccurate, but that is + * unlikely + */ notrace time_t __vdso_time(time_t *t) { - time_t result; - - if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled)) - return time_syscall(t); - /* This is atomic on x86_64 so we don't need any locks. */ - result = ACCESS_ONCE(VVAR(vsyscall_gtod_data).wall_time_sec); + time_t result = ACCESS_ONCE(VVAR(vsyscall_gtod_data).wall_time_sec); if (t) *t = result; -- 1.7.5.1