diff options
author | Andy Lutomirski <luto@MIT.EDU> | 2011-05-23 09:31:24 -0400 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2011-05-24 14:51:28 +0200 |
commit | 8c49d9a74bac5ea3f18480307057241b808fcc0c (patch) | |
tree | a9d2d8160ca37e9292e605cf3cdd85b29646c4b7 /arch/x86/kernel | |
parent | d762f4383100c2a87b1a3f2d678cd3b5425655b4 (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')
-rw-r--r-- | arch/x86/kernel/time.c | 2 | ||||
-rw-r--r-- | arch/x86/kernel/tsc.c | 4 | ||||
-rw-r--r-- | arch/x86/kernel/vmlinux.lds.S | 34 | ||||
-rw-r--r-- | arch/x86/kernel/vsyscall_64.c | 46 |
4 files changed, 34 insertions, 52 deletions
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c index 25a28a245937..00cbb272627f 100644 --- a/arch/x86/kernel/time.c +++ b/arch/x86/kernel/time.c @@ -23,7 +23,7 @@ #include <asm/time.h> #ifdef CONFIG_X86_64 -volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES; +DEFINE_VVAR(volatile unsigned long, jiffies) = INITIAL_JIFFIES; #endif unsigned long profile_pc(struct pt_regs *regs) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 9335bf7dd2e7..db697b81b8b1 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -777,8 +777,8 @@ static cycle_t __vsyscall_fn vread_tsc(void) ret = (cycle_t)vget_cycles(); rdtsc_barrier(); - return ret >= __vsyscall_gtod_data.clock.cycle_last ? - ret : __vsyscall_gtod_data.clock.cycle_last; + return ret >= VVAR(vsyscall_gtod_data).clock.cycle_last ? + ret : VVAR(vsyscall_gtod_data).clock.cycle_last; } #endif diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 49927a863cc1..74b5ad450c7e 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -161,6 +161,12 @@ SECTIONS #define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0) #define VVIRT(x) (ADDR(x) - VVIRT_OFFSET) +#define EMIT_VVAR(x, offset) .vsyscall_var_ ## x \ + ADDR(.vsyscall_0) + offset \ + : AT(VLOAD(.vsyscall_var_ ## x)) { \ + *(.vsyscall_var_ ## x) \ + } \ + x = VVIRT(.vsyscall_var_ ## x); . = ALIGN(4096); __vsyscall_0 = .; @@ -175,18 +181,6 @@ SECTIONS *(.vsyscall_fn) } - . = ALIGN(L1_CACHE_BYTES); - .vsyscall_gtod_data : AT(VLOAD(.vsyscall_gtod_data)) { - *(.vsyscall_gtod_data) - } - - vsyscall_gtod_data = VVIRT(.vsyscall_gtod_data); - .vsyscall_clock : AT(VLOAD(.vsyscall_clock)) { - *(.vsyscall_clock) - } - vsyscall_clock = VVIRT(.vsyscall_clock); - - .vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1)) { *(.vsyscall_1) } @@ -194,21 +188,14 @@ SECTIONS *(.vsyscall_2) } - .vgetcpu_mode : AT(VLOAD(.vgetcpu_mode)) { - *(.vgetcpu_mode) - } - vgetcpu_mode = VVIRT(.vgetcpu_mode); - - . = ALIGN(L1_CACHE_BYTES); - .jiffies : AT(VLOAD(.jiffies)) { - *(.jiffies) - } - jiffies = VVIRT(.jiffies); - .vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3)) { *(.vsyscall_3) } +#define __VVAR_KERNEL_LDS +#include <asm/vvar.h> +#undef __VVAR_KERNEL_LDS + . = __vsyscall_0 + PAGE_SIZE; #undef VSYSCALL_ADDR @@ -216,6 +203,7 @@ SECTIONS #undef VLOAD #undef VVIRT_OFFSET #undef VVIRT +#undef EMIT_VVAR #endif /* CONFIG_X86_64 */ 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 { |