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authorAndy Lutomirski <luto@MIT.EDU>2011-05-23 09:31:24 -0400
committerThomas Gleixner <tglx@linutronix.de>2011-05-24 14:51:28 +0200
commit8c49d9a74bac5ea3f18480307057241b808fcc0c (patch)
treea9d2d8160ca37e9292e605cf3cdd85b29646c4b7 /arch/x86/kernel/vsyscall_64.c
parentd762f4383100c2a87b1a3f2d678cd3b5425655b4 (diff)
x86-64: Clean up vdso/kernel shared variables
Variables that are shared between the vdso and the kernel are currently a bit of a mess. They are each defined with their own magic, they are accessed differently in the kernel, the vsyscall page, and the vdso, and one of them (vsyscall_clock) doesn't even really exist. This changes them all to use a common mechanism. All of them are delcared in vvar.h with a fixed address (validated by the linker script). In the kernel (as before), they look like ordinary read-write variables. In the vsyscall page and the vdso, they are accessed through a new macro VVAR, which gives read-only access. The vdso is now loaded verbatim into memory without any fixups. As a side bonus, access from the vdso is faster because a level of indirection is removed. While we're at it, pack jiffies and vgetcpu_mode into the same cacheline. Signed-off-by: Andy Lutomirski <luto@mit.edu> Cc: Andi Kleen <andi@firstfloor.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Borislav Petkov <bp@amd64.org> Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/vsyscall_64.c')
-rw-r--r--arch/x86/kernel/vsyscall_64.c46
1 files changed, 20 insertions, 26 deletions
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index dcbb28c4b694..5f6ad032575a 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -49,15 +49,8 @@
__attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace
#define __syscall_clobber "r11","cx","memory"
-/*
- * vsyscall_gtod_data contains data that is :
- * - readonly from vsyscalls
- * - written by timer interrupt or systcl (/proc/sys/kernel/vsyscall64)
- * Try to keep this structure as small as possible to avoid cache line ping pongs
- */
-int __vgetcpu_mode __section_vgetcpu_mode;
-
-struct vsyscall_gtod_data __vsyscall_gtod_data __section_vsyscall_gtod_data =
+DEFINE_VVAR(int, vgetcpu_mode);
+DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
{
.lock = SEQLOCK_UNLOCKED,
.sysctl_enabled = 1,
@@ -97,7 +90,7 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
*/
static __always_inline void do_get_tz(struct timezone * tz)
{
- *tz = __vsyscall_gtod_data.sys_tz;
+ *tz = VVAR(vsyscall_gtod_data).sys_tz;
}
static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
@@ -126,23 +119,24 @@ static __always_inline void do_vgettimeofday(struct timeval * tv)
unsigned long mult, shift, nsec;
cycle_t (*vread)(void);
do {
- seq = read_seqbegin(&__vsyscall_gtod_data.lock);
+ seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
- vread = __vsyscall_gtod_data.clock.vread;
- if (unlikely(!__vsyscall_gtod_data.sysctl_enabled || !vread)) {
+ vread = VVAR(vsyscall_gtod_data).clock.vread;
+ if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled ||
+ !vread)) {
gettimeofday(tv,NULL);
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;
+ base = VVAR(vsyscall_gtod_data).clock.cycle_last;
+ mask = VVAR(vsyscall_gtod_data).clock.mask;
+ mult = VVAR(vsyscall_gtod_data).clock.mult;
+ shift = VVAR(vsyscall_gtod_data).clock.shift;
- tv->tv_sec = __vsyscall_gtod_data.wall_time_sec;
- nsec = __vsyscall_gtod_data.wall_time_nsec;
- } while (read_seqretry(&__vsyscall_gtod_data.lock, seq));
+ tv->tv_sec = VVAR(vsyscall_gtod_data).wall_time_sec;
+ nsec = VVAR(vsyscall_gtod_data).wall_time_nsec;
+ } while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
/* calculate interval: */
cycle_delta = (now - base) & mask;
@@ -171,15 +165,15 @@ time_t __vsyscall(1) vtime(time_t *t)
{
unsigned seq;
time_t result;
- if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
+ if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
return time_syscall(t);
do {
- seq = read_seqbegin(&__vsyscall_gtod_data.lock);
+ seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
- result = __vsyscall_gtod_data.wall_time_sec;
+ result = VVAR(vsyscall_gtod_data).wall_time_sec;
- } while (read_seqretry(&__vsyscall_gtod_data.lock, seq));
+ } while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
if (t)
*t = result;
@@ -208,9 +202,9 @@ vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
We do this here because otherwise user space would do it on
its own in a likely inferior way (no access to jiffies).
If you don't like it pass NULL. */
- if (tcache && tcache->blob[0] == (j = __jiffies)) {
+ if (tcache && tcache->blob[0] == (j = VVAR(jiffies))) {
p = tcache->blob[1];
- } else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
+ } else if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
native_read_tscp(&p);
} else {