[PATCH 5/5][time][x86_64] Re-enable vsyscall support for x86_64

john stultz
2006-12-20T01:21:52Z

Cleanup and re-enable vsyscall gettimeofday using the generic
clocksource infrastructure.

Signed-off-by: John Stultz <johnstul@us.ibm.com>

arch/x86_64/Kconfig | 4 +
arch/x86_64/kernel/hpet.c | 6 +
arch/x86_64/kernel/time.c | 6 -
arch/x86_64/kernel/tsc.c | 7 ++
arch/x86_64/kernel/vmlinux.lds.S | 28 +++------
arch/x86_64/kernel/vsyscall.c | 121 +++++++++++++++++++++++----------------
include/asm-x86_64/proto.h | 2
include/asm-x86_64/timex.h | 1
include/asm-x86_64/vsyscall.h | 33 +---------
9 files changed, 105 insertions(+), 103 deletions(-)

linux-2.6.20-rc1_timeofday-arch-x86-64-vsyscall-reenablement_C7.patch
============================================
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index e1d044c..98b11c6 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 ZONE_DMA32
bool
default y
diff --git a/arch/x86_64/kernel/hpet.c b/arch/x86_64/kernel/hpet.c
index 74d95d0..cd834cc 100644
--- a/arch/x86_64/kernel/hpet.c
+++ b/arch/x86_64/kernel/hpet.c
@@ -442,6 +442,11 @@ 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,
@@ -450,6 +455,7 @@ 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/time.c b/arch/x86_64/kernel/time.c
index 4bc737c..17bb7de 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -53,13 +53,7 @@ DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
DEFINE_SPINLOCK(i8253_lock);

-unsigned long vxtime_hz = PIT_TICK_RATE;
-
-struct vxtime_data __vxtime __section_vxtime; /* for vsyscalls */
-
volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
-struct timespec __xtime __section_xtime;
-struct timezone __sys_tz __section_sys_tz;

unsigned long profile_pc(struct pt_regs *regs)
{
diff --git a/arch/x86_64/kernel/tsc.c b/arch/x86_64/kernel/tsc.c
index 958ec0a..f16733e 100644
--- a/arch/x86_64/kernel/tsc.c
+++ b/arch/x86_64/kernel/tsc.c
@@ -185,6 +185,12 @@ static cycle_t read_tsc(void)
return ret;
}

+static cycle_t __vsyscall_fn vread_tsc(void)
+{
+ cycle_t ret = (cycle_t)get_cycles_sync();
+ return ret;
+}
+
static struct clocksource clocksource_tsc = {
.name = "tsc",
.rating = 300,
@@ -194,6 +200,7 @@ static struct clocksource clocksource_ts
.shift = 22,
.update_callback = tsc_update_callback,
.is_continuous = 1,
+ .vread = vread_tsc,
};

static int tsc_update_callback(void)
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index 1e54ddf..adb4263 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -88,31 +88,25 @@ #define VVIRT(x) (ADDR(x) - VVIRT_OFFSET
__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);
+ .vsyscall_fn : AT(VLOAD(.vsyscall_fn)) { *(.vsyscall_fn) }
+ . = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
+ .vsyscall_gtod_data : AT(VLOAD(.vsyscall_gtod_data))
+ { *(.vsyscall_gtod_data) }
+ vsyscall_gtod_data = VVIRT(.vsyscall_gtod_data);

.vgetcpu_mode : AT(VLOAD(.vgetcpu_mode)) { *(.vgetcpu_mode) }
vgetcpu_mode = VVIRT(.vgetcpu_mode);

- .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);
-
. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
.jiffies : AT(VLOAD(.jiffies)) { *(.jiffies) }
jiffies = VVIRT(.jiffies);

- .vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1)) { *(.vsyscall_1) }
- .vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2)) { *(.vsyscall_2) }
- .vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3)) { *(.vsyscall_3) }
+ .vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1))
+ { *(.vsyscall_1) }
+ .vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2))
+ { *(.vsyscall_2) }
+ .vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3))
+ { *(.vsyscall_3) }

. = VSYSCALL_VIRT_ADDR + 4096;

diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c
index 2433d6f..9814bf8 100644
--- a/arch/x86_64/kernel/vsyscall.c
+++ b/arch/x86_64/kernel/vsyscall.c
@@ -26,6 +26,7 @@ #include <linux/timer.h>
#include <linux/seqlock.h>
#include <linux/jiffies.h>
#include <linux/sysctl.h>
+#include <linux/clocksource.h>
#include <linux/getcpu.h>
#include <linux/cpu.h>
#include <linux/smp.h>
@@ -34,6 +35,7 @@ #include <linux/notifier.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>
@@ -44,56 +46,41 @@ #include <asm/topology.h>
#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
#define __syscall_clobber "r11","rcx","memory"

-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;
+};
int __vgetcpu_mode __section_vgetcpu_mode;

-#include <asm/unistd.h>
-
-static __always_inline void timeval_normalize(struct timeval * tv)
+struct vsyscall_gtod_data_t __vsyscall_gtod_data __section_vsyscall_gtod_data =
{
- time_t __sec;
-
- __sec = tv->tv_usec / 1000000;
- if (__sec) {
- tv->tv_usec %= 1000000;
- tv->tv_sec += __sec;
- }
-}
+ .lock = SEQLOCK_UNLOCKED,
+ .sysctl_enabled = 1,
+};

-static __always_inline void do_vgettimeofday(struct timeval * tv)
+void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
{
- long sequence, t;
- unsigned long sec, usec;
-
- do {
- sequence = read_seqbegin(&__xtime_lock);
-
- sec = __xtime.tv_sec;
- usec = __xtime.tv_nsec / 1000;
-
- 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 __iomem *)
- fix_to_virt(VSYSCALL_HPET) + 0xf0) -
- __vxtime.last) * __vxtime.quot) >> 32;
- }
- } while (read_seqretry(&__xtime_lock, sequence));
-
- tv->tv_sec = sec + usec / 1000000;
- tv->tv_usec = usec % 1000000;
+ unsigned long flags;
+
+ 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);
}

-/* RED-PEN may want to readd seq locking, but then the variable should be write-once. */
+/* 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)
@@ -101,7 +88,8 @@ static __always_inline int gettimeofday(
int ret;
asm volatile("vsysc2: syscall"
: "=a" (ret)
- : "0" (__NR_gettimeofday),"D" (tv),"S" (tz) : __syscall_clobber );
+ : "0" (__NR_gettimeofday),"D" (tv),"S" (tz)
+ : __syscall_clobber );
return ret;
}

@@ -114,10 +102,44 @@ static __always_inline long time_syscall
return secs;
}

+static __always_inline void do_vgettimeofday(struct timeval * tv)
+{
+ cycle_t now, base, mask, cycle_delta;
+ unsigned long seq, mult, shift, nsec_delta;
+ cycle_t (*vread)(void);
+ do {
+ seq = read_seqbegin(&__vsyscall_gtod_data.lock);
+
+ vread = __vsyscall_gtod_data.clock.vread;
+ if (unlikely(!__vsyscall_gtod_data.sysctl_enabled || !vread)) {
+ gettimeofday(tv,0);
+ return;
+ }
+ now = 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;
+ }
+}
+
int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
{
- if (!__sysctl_vsyscall)
- return gettimeofday(tv,tz);
if (tv)
do_vgettimeofday(tv);
if (tz)
@@ -129,11 +151,11 @@ 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;
}

/* Fast way to get current CPU and node.
@@ -210,7 +232,7 @@ static int vsyscall_sysctl_change(ctl_ta
ret = -ENOMEM;
goto out;
}
- if (!sysctl_vsyscall) {
+ if (!vsyscall_gtod_data.sysctl_enabled) {
writew(SYSCALL, map1);
writew(SYSCALL, map2);
} else {
@@ -232,7 +254,8 @@ 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 914b5f6..25d5415 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -45,9 +45,7 @@ extern u32 pmtmr_ioport;
#else
#define pmtmr_ioport 0
#endif
-extern int sysctl_vsyscall;
extern int nohpet;
-extern unsigned long vxtime_hz;

extern void early_printk(const char *fmt, ...) __attribute__((format(printf,1,2)));

diff --git a/include/asm-x86_64/timex.h b/include/asm-x86_64/timex.h
index a4d0066..a73d535 100644
--- a/include/asm-x86_64/timex.h
+++ b/include/asm-x86_64/timex.h
@@ -51,7 +51,6 @@ #define FSEC_PER_TICK (FSEC_PER_SEC / HZ
#define NS_SCALE 10 /* 2^10, carefully chosen */
#define US_SCALE 32 /* 2^32, arbitralrily chosen */

-extern struct vxtime_data vxtime;
extern void mark_tsc_unstable(void);
extern void set_cyc2ns_scale(unsigned long khz);
#endif
diff --git a/include/asm-x86_64/vsyscall.h b/include/asm-x86_64/vsyscall.h
index 05cb8dd..1899a8d 100644
--- a/include/asm-x86_64/vsyscall.h
+++ b/include/asm-x86_64/vsyscall.h
@@ -16,51 +16,28 @@ #define VSYSCALL_ADDR(vsyscall_nr) (VSYS
#ifdef __KERNEL__
#include <linux/seqlock.h>

-#define __section_vxtime __attribute__ ((unused, __section__ (".vxtime"), aligned(16)))
#define __section_vgetcpu_mode __attribute__ ((unused, __section__ (".vgetcpu_mode"), 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
+/* 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 VGETCPU_RDTSCP 1
#define VGETCPU_LSL 2

-struct vxtime_data {
- long hpet_address; /* HPET base address */
- int last;
- unsigned long last_tsc;
- long quot;
- long tsc_quot;
- int mode;
-};
-
#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 int __vgetcpu_mode;
-extern struct timespec __xtime;
extern volatile unsigned long __jiffies;
-extern struct timezone __sys_tz;
-extern seqlock_t __xtime_lock;

/* kernel space (writeable) */
-extern struct vxtime_data vxtime;
extern int vgetcpu_mode;
extern struct timezone sys_tz;
-extern int sysctl_vsyscall;
extern seqlock_t xtime_lock;
-
-extern int sysctl_vsyscall;
-
-#define ARCH_HAVE_XTIME_LOCK 1
+extern struct vsyscall_gtod_data_t vsyscall_gtod_data;

#endif /* __KERNEL__ */