From 5b13d863573e746739ccfc24ac1a9473cfee8df1 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 7 Apr 2008 20:58:08 +0200 Subject: revert "x86: tsc prevent time going backwards" revert: | commit 47001d603375f857a7fab0e9c095d964a1ea0039 | Author: Thomas Gleixner | Date: Tue Apr 1 19:45:18 2008 +0200 | | x86: tsc prevent time going backwards it has been identified to cause suspend regression - and the commit fixes a longstanding bug that existed before 2.6.25 was opened - so it can wait some more until the effects are better understood. Signed-off-by: Ingo Molnar --- arch/x86/kernel/tsc_32.c | 15 +-------------- arch/x86/kernel/tsc_64.c | 23 +++-------------------- 2 files changed, 4 insertions(+), 34 deletions(-) diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index d7498b34c8e..f14cfd9d1f9 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -287,27 +287,14 @@ core_initcall(cpufreq_tsc); /* clock source code */ static unsigned long current_tsc_khz = 0; -static struct clocksource clocksource_tsc; -/* - * We compare the TSC to the cycle_last value in the clocksource - * structure to avoid a nasty time-warp issue. This can be observed in - * a very small window right after one CPU updated cycle_last under - * xtime lock and the other CPU reads a TSC value which is smaller - * than the cycle_last reference value due to a TSC which is slighty - * behind. This delta is nowhere else observable, but in that case it - * results in a forward time jump in the range of hours due to the - * unsigned delta calculation of the time keeping core code, which is - * necessary to support wrapping clocksources like pm timer. - */ static cycle_t read_tsc(void) { cycle_t ret; rdtscll(ret); - return ret >= clocksource_tsc.cycle_last ? - ret : clocksource_tsc.cycle_last; + return ret; } static struct clocksource clocksource_tsc = { diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c index 01fc9f0c39e..947554ddabb 100644 --- a/arch/x86/kernel/tsc_64.c +++ b/arch/x86/kernel/tsc_64.c @@ -11,7 +11,6 @@ #include #include #include -#include static int notsc __initdata = 0; @@ -291,34 +290,18 @@ int __init notsc_setup(char *s) __setup("notsc", notsc_setup); -static struct clocksource clocksource_tsc; -/* - * We compare the TSC to the cycle_last value in the clocksource - * structure to avoid a nasty time-warp. This can be observed in a - * very small window right after one CPU updated cycle_last under - * xtime/vsyscall_gtod lock and the other CPU reads a TSC value which - * is smaller than the cycle_last reference value due to a TSC which - * is slighty behind. This delta is nowhere else observable, but in - * that case it results in a forward time jump in the range of hours - * due to the unsigned delta calculation of the time keeping core - * code, which is necessary to support wrapping clocksources like pm - * timer. - */ +/* clock source code: */ static cycle_t read_tsc(void) { cycle_t ret = (cycle_t)get_cycles(); - - return ret >= clocksource_tsc.cycle_last ? - ret : clocksource_tsc.cycle_last; + return ret; } static cycle_t __vsyscall_fn vread_tsc(void) { cycle_t ret = (cycle_t)vget_cycles(); - - return ret >= __vsyscall_gtod_data.clock.cycle_last ? - ret : __vsyscall_gtod_data.clock.cycle_last; + return ret; } static struct clocksource clocksource_tsc = { -- cgit v1.2.3-70-g09d2 From 4f41c94d5c24e3b3453e9df03c0a80ca1acf00d2 Mon Sep 17 00:00:00 2001 From: Karsten Wiese Date: Mon, 7 Apr 2008 12:14:45 +0200 Subject: x86: fix call to set_cyc2ns_scale() from time_cpufreq_notifier() In time_cpufreq_notifier() the cpu id to act upon is held in freq->cpu. Use it instead of smp_processor_id() in the call to set_cyc2ns_scale(). This makes the preempt_*able() unnecessary and lets set_cyc2ns_scale() update the intended cpu's cyc2ns. Related mail/thread: http://lkml.org/lkml/2007/12/7/130 Signed-off-by: Karsten Wiese Signed-off-by: Ingo Molnar --- arch/x86/kernel/tsc_32.c | 4 +--- arch/x86/kernel/tsc_64.c | 4 +--- 2 files changed, 2 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index f14cfd9d1f9..c2241e04ea5 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -256,9 +256,7 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data) ref_freq, freq->new); if (!(freq->flags & CPUFREQ_CONST_LOOPS)) { tsc_khz = cpu_khz; - preempt_disable(); - set_cyc2ns_scale(cpu_khz, smp_processor_id()); - preempt_enable(); + set_cyc2ns_scale(cpu_khz, freq->cpu); /* * TSC based sched_clock turns * to junk w/ cpufreq diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c index 947554ddabb..d3bebaaad84 100644 --- a/arch/x86/kernel/tsc_64.c +++ b/arch/x86/kernel/tsc_64.c @@ -148,9 +148,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, mark_tsc_unstable("cpufreq changes"); } - preempt_disable(); - set_cyc2ns_scale(tsc_khz_ref, smp_processor_id()); - preempt_enable(); + set_cyc2ns_scale(tsc_khz_ref, freq->cpu); return 0; } -- cgit v1.2.3-70-g09d2 From 871de939030c903fd5ed50a7c4c88e02998e1cbc Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Mon, 7 Apr 2008 11:56:34 -0700 Subject: x86: fix 64-bit asm NOPS for CONFIG_GENERIC_CPU ASM_NOP's for 64-bit kernel with CONFIG_GENERIC_CPU is broken with the recent x86 nops merge. They were using GENERIC_NOPS which will truncate the upper 32bits of %rsi, because of the missing 64bit rex prefix. For now, fall back ASM NOPS for generic cpu to K8 NOPS, similar to the code before the wrong x86 nop merge. This should resolve the crash seen by Ingo on a test-system: BUG: unable to handle kernel paging request at 00000000d80d8ee8 IP: [] save_i387_ia32+0x61/0xd8 PGD b8e0067 PUD 51490067 PMD 0 Oops: 0000 [1] SMP CPU 2 Modules linked in: Pid: 3871, comm: distcc Not tainted 2.6.25-rc7-sched-devel.git-x86-latest.git #359 RIP: 0010:[] [] save_i387_ia32+0x61/0xd8 RSP: 0000:ffff81003abd3cb8 EFLAGS: 00010246 RAX: ffff810082e93400 RBX: 00000000ffc37f84 RCX: ffff8100d80d8ee0 RDX: 0000000000000000 RSI: 00000000d80d8ee0 RDI: ffff810082e93400 RBP: 00000000ffc37fdc R08: 00000000ffc37f88 R09: 0000000000000008 R10: ffff81003abd2000 R11: 0000000000000000 R12: ffff810082e93400 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff81011fb12dc0(0063) knlGS:00000000f7f1a6c0 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00000000d80d8ee8 CR3: 0000000076922000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process distcc (pid: 3871, threadinfo ffff81003abd2000, task ffff8100d80d8ee0) Stack: ffff8100bb670380 ffffffff8026de50 0000000000000118 0000000000000002 0000000000000002 ffff81003abd3e68 ffff81003abd3ed8 ffff81003abd3de8 ffff81003abd3d18 ffffffff80229785 ffff8100d80d8ee0 ffff810001041280 Call Trace: [] ? __generic_file_aio_write_nolock+0x343/0x377 [] ? update_curr+0x54/0x64 [] ? ia32_setup_sigcontext+0x125/0x1d2 [] ? ia32_setup_frame+0x73/0x1a5 [] ? do_notify_resume+0x1aa/0x7db [] ? getnstimeofday+0x31/0x85 [] ? ktime_get_ts+0x17/0x48 [] ? ktime_get+0xc/0x41 [] ? hrtimer_nanosleep+0x75/0xd5 [] ? hrtimer_wakeup+0x0/0x21 [] ? int_signal+0x12/0x17 [] ? dummy_file_free_security+0x0/0x1 Code: a6 08 05 00 00 f6 40 14 01 74 34 4c 89 e7 48 0f ae 07 48 8b 86 08 05 00 00 80 78 02 00 79 02 db e2 90 8d b4 26 00 00 00 00 89 f6 <48> 8b 46 08 83 60 14 fe 0f 20 c0 48 83 c8 08 0f 22 c0 eb 07 c6 Signed-off-by: Suresh Siddha Signed-off-by: Ingo Molnar --- include/asm-x86/nops.h | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/include/asm-x86/nops.h b/include/asm-x86/nops.h index e3b2bce0aff..b3930ae539b 100644 --- a/include/asm-x86/nops.h +++ b/include/asm-x86/nops.h @@ -73,16 +73,7 @@ #define P6_NOP7 ".byte 0x0f,0x1f,0x80,0,0,0,0\n" #define P6_NOP8 ".byte 0x0f,0x1f,0x84,0x00,0,0,0,0\n" -#if defined(CONFIG_MK8) -#define ASM_NOP1 K8_NOP1 -#define ASM_NOP2 K8_NOP2 -#define ASM_NOP3 K8_NOP3 -#define ASM_NOP4 K8_NOP4 -#define ASM_NOP5 K8_NOP5 -#define ASM_NOP6 K8_NOP6 -#define ASM_NOP7 K8_NOP7 -#define ASM_NOP8 K8_NOP8 -#elif defined(CONFIG_MK7) +#if defined(CONFIG_MK7) #define ASM_NOP1 K7_NOP1 #define ASM_NOP2 K7_NOP2 #define ASM_NOP3 K7_NOP3 @@ -100,6 +91,15 @@ #define ASM_NOP6 P6_NOP6 #define ASM_NOP7 P6_NOP7 #define ASM_NOP8 P6_NOP8 +#elif defined(CONFIG_X86_64) +#define ASM_NOP1 K8_NOP1 +#define ASM_NOP2 K8_NOP2 +#define ASM_NOP3 K8_NOP3 +#define ASM_NOP4 K8_NOP4 +#define ASM_NOP5 K8_NOP5 +#define ASM_NOP6 K8_NOP6 +#define ASM_NOP7 K8_NOP7 +#define ASM_NOP8 K8_NOP8 #else #define ASM_NOP1 GENERIC_NOP1 #define ASM_NOP2 GENERIC_NOP2 -- cgit v1.2.3-70-g09d2