[RFC][PATCH 6/6] x86_64: GENERIC_TIME based vsyscall code

From: john stultz
Date: Tue Aug 08 2006 - 22:16:38 EST

Re-enable vsyscall gettimeofday using the generic clocksource
infrastructure.

Signed-off-by: John Stultz <johnstul@xxxxxxxxxx>

arch/x86_64/Kconfig | 4 +
arch/x86_64/kernel/time.c | 23 +++++--
arch/x86_64/kernel/vmlinux.lds.S | 24 +-------
arch/x86_64/kernel/vsyscall.c | 116 ++++++++++++++++++++++++++-------------
include/asm-x86_64/proto.h | 2
include/asm-x86_64/timex.h | 2
include/asm-x86_64/vsyscall.h | 38 +-----------
7 files changed, 105 insertions(+), 104 deletions(-)

linux-2.6.18-rc4_timeofday-arch-x86-64-part5_C5.patch
============================================
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index fabb174..6167ce2 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -28,6 +28,10 @@ config GENERIC_TIME
bool
default y

+config GENERIC_TIME_VSYSCALL
+ bool
+ default y
+
config LOCKDEP_SUPPORT
bool
default y
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 546abc7..3501871 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -68,16 +68,9 @@ unsigned long hpet_address;
static unsigned long hpet_period; /* fsecs / HPET clock */
unsigned long hpet_tick; /* HPET clocks / interrupt */
int hpet_use_timer; /* Use counter of hpet for time keeping, otherwise PIT */
-unsigned long vxtime_hz = PIT_TICK_RATE;
int report_lost_ticks; /* command line option */
-unsigned long long monotonic_base;

-struct vxtime_data __vxtime __section_vxtime; /* for vsyscalls */
-
-volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
-unsigned long __wall_jiffies __section_wall_jiffies = INITIAL_JIFFIES;
-struct timespec __xtime __section_xtime;
-struct timezone __sys_tz __section_sys_tz;
+volatile unsigned long jiffies = INITIAL_JIFFIES;

unsigned long profile_pc(struct pt_regs *regs)
{
@@ -1021,6 +1014,13 @@ static cycle_t read_tsc(void)
return ret;
}

+static cycle_t __vsyscall_fn vread_tsc(void)
+{
+ cycle_t ret;
+ rdtscll(ret);
+ return ret;
+}
+
static struct clocksource clocksource_tsc = {
.name = "tsc",
.rating = 300,
@@ -1030,6 +1030,7 @@ static struct clocksource clocksource_ts
.shift = 22,
.update_callback = tsc_update_callback,
.is_continuous = 1,
+ .vread = vread_tsc,
};

static int tsc_update_callback(void)
@@ -1080,6 +1081,11 @@ static cycle_t read_hpet(void)
return (cycle_t)readl(hpet_ptr);
}

+static cycle_t __vsyscall_fn vread_hpet(void)
+{
+ return (cycle_t)readl((void *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
+}
+
struct clocksource clocksource_hpet = {
.name = "hpet",
.rating = 250,
@@ -1088,6 +1094,7 @@ struct clocksource clocksource_hpet = {
.mult = 0, /* set below */
.shift = HPET_SHIFT,
.is_continuous = 1,
+ .vread = vread_hpet,
};

static int __init init_hpet_clocksource(void)
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index 7c4de31..9e7c048 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -93,27 +93,11 @@ SECTIONS
__vsyscall_0 = VSYSCALL_VIRT_ADDR;

. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
- .xtime_lock : AT(VLOAD(.xtime_lock)) { *(.xtime_lock) }
- xtime_lock = VVIRT(.xtime_lock);
-
- .vxtime : AT(VLOAD(.vxtime)) { *(.vxtime) }
- vxtime = VVIRT(.vxtime);
-
- .wall_jiffies : AT(VLOAD(.wall_jiffies)) { *(.wall_jiffies) }
- wall_jiffies = VVIRT(.wall_jiffies);
-
- .sys_tz : AT(VLOAD(.sys_tz)) { *(.sys_tz) }
- sys_tz = VVIRT(.sys_tz);
-
- .sysctl_vsyscall : AT(VLOAD(.sysctl_vsyscall)) { *(.sysctl_vsyscall) }
- sysctl_vsyscall = VVIRT(.sysctl_vsyscall);
-
- .xtime : AT(VLOAD(.xtime)) { *(.xtime) }
- xtime = VVIRT(.xtime);
-
+ .vsyscall_fn : AT(VLOAD(.vsyscall_fn)) { *(.vsyscall_fn) }
. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
- .jiffies : AT(VLOAD(.jiffies)) { *(.jiffies) }
- jiffies = VVIRT(.jiffies);
+ .vsyscall_gtod_data : AT(VLOAD(.vsyscall_gtod_data)) { *(.vsyscall_gtod_data) }
+ vsyscall_gtod_data = VVIRT(.vsyscall_gtod_data);
+

.vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1)) { *(.vsyscall_1) }
.vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2)) { *(.vsyscall_2) }
diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c
index f603037..cdd8448 100644
--- a/arch/x86_64/kernel/vsyscall.c
+++ b/arch/x86_64/kernel/vsyscall.c
@@ -26,65 +26,105 @@
#include <linux/seqlock.h>
#include <linux/jiffies.h>
#include <linux/sysctl.h>
+#include <linux/clocksource.h>

#include <asm/vsyscall.h>
#include <asm/pgtable.h>
#include <asm/page.h>
+#include <asm/unistd.h>
#include <asm/fixmap.h>
#include <asm/errno.h>
#include <asm/io.h>

#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))

-int __sysctl_vsyscall __section_sysctl_vsyscall = 1;
-seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED;
+struct vsyscall_gtod_data_t {
+ seqlock_t lock;
+ int sysctl_enabled;
+ struct timeval wall_time_tv;
+ struct timezone sys_tz;
+ cycle_t offset_base;
+ struct clocksource clock;
+};
+
+struct vsyscall_gtod_data_t __vsyscall_gtod_data __section_vsyscall_gtod_data = {
+ .lock = SEQLOCK_UNLOCKED,
+ .sysctl_enabled = 1,
+};
+extern struct vsyscall_gtod_data_t vsyscall_gtod_data;

-#include <asm/unistd.h>

-static __always_inline void timeval_normalize(struct timeval * tv)
+void update_vsyscall(struct timespec* wall_time, struct clocksource* clock)
{
- time_t __sec;
+ unsigned long flags;

- __sec = tv->tv_usec / 1000000;
- if (__sec) {
- tv->tv_usec %= 1000000;
- tv->tv_sec += __sec;
- }
+ write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
+ /* copy vsyscall data */
+ vsyscall_gtod_data.clock = *clock;
+ vsyscall_gtod_data.wall_time_tv.tv_sec = wall_time->tv_sec;
+ vsyscall_gtod_data.wall_time_tv.tv_usec = wall_time->tv_nsec/1000;
+ vsyscall_gtod_data.sys_tz = sys_tz;
+
+ write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
+}
+
+/*
+ * XXX - this is ugly. gettimeofday() has a label in it so we can't
+ * call it twice.
+ */
+static __always_inline int syscall_gtod(struct timeval *tv, struct timezone *tz)
+{
+ int ret;
+
+ asm volatile("syscall"
+ : "=a" (ret)
+ : "0" (__NR_gettimeofday),"D" (tv),"S" (tz)
+ : __syscall_clobber);
+
+ return ret;
}

+
static __always_inline void do_vgettimeofday(struct timeval * tv)
{
- long sequence, t;
- unsigned long sec, usec;
+ cycle_t now, base, mask, cycle_delta;
+ unsigned long seq, mult, shift, nsec_delta;

do {
- sequence = read_seqbegin(&__xtime_lock);
-
- sec = __xtime.tv_sec;
- usec = (__xtime.tv_nsec / 1000) +
- (__jiffies - __wall_jiffies) * (1000000 / HZ);
-
- if (__vxtime.mode != VXTIME_HPET) {
- t = get_cycles_sync();
- if (t < __vxtime.last_tsc)
- t = __vxtime.last_tsc;
- usec += ((t - __vxtime.last_tsc) *
- __vxtime.tsc_quot) >> 32;
- /* See comment in x86_64 do_gettimeofday. */
- } else {
- usec += ((readl((void *)fix_to_virt(VSYSCALL_HPET) + 0xf0) -
- __vxtime.last) * __vxtime.quot) >> 32;
+ seq = read_seqbegin(&__vsyscall_gtod_data.lock);
+ if (!__vsyscall_gtod_data.clock.vread) {
+ syscall_gtod(tv, NULL);
+ return;
}
- } while (read_seqretry(&__xtime_lock, sequence));

- tv->tv_sec = sec + usec / 1000000;
- tv->tv_usec = usec % 1000000;
+ now = __vsyscall_gtod_data.clock.vread();
+
+ base = __vsyscall_gtod_data.clock.cycle_last;
+ mask = __vsyscall_gtod_data.clock.mask;
+ mult = __vsyscall_gtod_data.clock.mult;
+ shift = __vsyscall_gtod_data.clock.shift;
+
+ *tv = __vsyscall_gtod_data.wall_time_tv;
+
+ } while (read_seqretry(&__vsyscall_gtod_data.lock, seq));
+
+ /* calculate interval: */
+ cycle_delta = (now - base) & mask;
+ /* convert to nsecs: */
+ nsec_delta = (cycle_delta * mult) >> shift;
+
+ /* convert to usecs and add to timespec: */
+ tv->tv_usec += nsec_delta / NSEC_PER_USEC;
+ while (tv->tv_usec > USEC_PER_SEC) {
+ tv->tv_sec += 1;
+ tv->tv_usec -= USEC_PER_SEC;
+ }
}

/* RED-PEN may want to readd seq locking, but then the variable should be write-once. */
static __always_inline void do_get_tz(struct timezone * tz)
{
- *tz = __sys_tz;
+ *tz = __vsyscall_gtod_data.sys_tz;
}

static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
@@ -107,7 +147,7 @@ static __always_inline long time_syscall

int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
{
- if (!__sysctl_vsyscall)
+ if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
return gettimeofday(tv,tz);
if (tv)
do_vgettimeofday(tv);
@@ -120,11 +160,11 @@ int __vsyscall(0) vgettimeofday(struct t
* unlikely */
time_t __vsyscall(1) vtime(time_t *t)
{
- if (!__sysctl_vsyscall)
+ if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
return time_syscall(t);
else if (t)
- *t = __xtime.tv_sec;
- return __xtime.tv_sec;
+ *t = __vsyscall_gtod_data.wall_time_tv.tv_sec;
+ return __vsyscall_gtod_data.wall_time_tv.tv_sec;
}

long __vsyscall(2) venosys_0(void)
@@ -163,7 +203,7 @@ static int vsyscall_sysctl_change(ctl_ta
ret = -ENOMEM;
goto out;
}
- if (!sysctl_vsyscall) {
+ if (!vsyscall_gtod_data.sysctl_enabled) {
*map1 = SYSCALL;
*map2 = SYSCALL;
} else {
@@ -186,7 +226,7 @@ static int vsyscall_sysctl_nostrat(ctl_t

static ctl_table kernel_table2[] = {
{ .ctl_name = 99, .procname = "vsyscall64",
- .data = &sysctl_vsyscall, .maxlen = sizeof(int), .mode = 0644,
+ .data = &vsyscall_gtod_data.sysctl_enabled, .maxlen = sizeof(int), .mode = 0644,
.strategy = vsyscall_sysctl_nostrat,
.proc_handler = vsyscall_sysctl_change },
{ 0, }
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index 716ac55..33d1a19 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -47,9 +47,7 @@ extern u32 pmtmr_ioport;
#else
#define pmtmr_ioport 0
#endif
-extern int sysctl_vsyscall;
extern int nohpet;
-extern unsigned long vxtime_hz;

extern int numa_setup(char *opt);

diff --git a/include/asm-x86_64/timex.h b/include/asm-x86_64/timex.h
index 11c6820..043a774 100644
--- a/include/asm-x86_64/timex.h
+++ b/include/asm-x86_64/timex.h
@@ -47,6 +47,4 @@ extern void mark_tsc_unstable(void);
extern int read_current_timer(unsigned long *timer_value);
#define ARCH_HAS_READ_CURRENT_TIMER 1

-extern struct vxtime_data vxtime;
-
#endif
diff --git a/include/asm-x86_64/vsyscall.h b/include/asm-x86_64/vsyscall.h
index a85e16f..0b5a499 100644
--- a/include/asm-x86_64/vsyscall.h
+++ b/include/asm-x86_64/vsyscall.h
@@ -15,49 +15,19 @@ enum vsyscall_num {

#ifdef __KERNEL__

-#define __section_vxtime __attribute__ ((unused, __section__ (".vxtime"), aligned(16)))
-#define __section_wall_jiffies __attribute__ ((unused, __section__ (".wall_jiffies"), aligned(16)))
-#define __section_jiffies __attribute__ ((unused, __section__ (".jiffies"), aligned(16)))
-#define __section_sys_tz __attribute__ ((unused, __section__ (".sys_tz"), aligned(16)))
-#define __section_sysctl_vsyscall __attribute__ ((unused, __section__ (".sysctl_vsyscall"), aligned(16)))
-#define __section_xtime __attribute__ ((unused, __section__ (".xtime"), aligned(16)))
-#define __section_xtime_lock __attribute__ ((unused, __section__ (".xtime_lock"), aligned(16)))
-
-#define VXTIME_TSC 1
-#define VXTIME_HPET 2
-#define VXTIME_PMTMR 3
-
-struct vxtime_data {
- long hpet_address; /* HPET base address */
- int last;
- unsigned long last_tsc;
- long quot;
- long tsc_quot;
- int mode;
-};
+/* Definitions for CONFIG_GENERIC_TIME definitions */
+#define __section_vsyscall_gtod_data __attribute__ ((unused, __section__ (".vsyscall_gtod_data"),aligned(16)))
+#define __vsyscall_fn __attribute__ ((unused,__section__(".vsyscall_fn")))
+

#define hpet_readl(a) readl((const void __iomem *)fix_to_virt(FIX_HPET_BASE) + a)
#define hpet_writel(d,a) writel(d, (void __iomem *)fix_to_virt(FIX_HPET_BASE) + a)

-/* vsyscall space (readonly) */
-extern struct vxtime_data __vxtime;
-extern struct timespec __xtime;
-extern volatile unsigned long __jiffies;
-extern unsigned long __wall_jiffies;
-extern struct timezone __sys_tz;
-extern seqlock_t __xtime_lock;
-
/* kernel space (writeable) */
-extern struct vxtime_data vxtime;
extern unsigned long wall_jiffies;
extern struct timezone sys_tz;
-extern int sysctl_vsyscall;
extern seqlock_t xtime_lock;

-extern int sysctl_vsyscall;
-
-#define ARCH_HAVE_XTIME_LOCK 1
-
#endif /* __KERNEL__ */

#endif /* _ASM_X86_64_VSYSCALL_H_ */
-
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