diff options
-rw-r--r-- | arch/x86/vdso/vgetcpu.c | 19 | ||||
-rw-r--r-- | kernel/sys.c | 20 |
2 files changed, 3 insertions, 36 deletions
diff --git a/arch/x86/vdso/vgetcpu.c b/arch/x86/vdso/vgetcpu.c index 91f6e85d0fc2..3b1ae1abfba9 100644 --- a/arch/x86/vdso/vgetcpu.c +++ b/arch/x86/vdso/vgetcpu.c | |||
@@ -13,32 +13,17 @@ | |||
13 | #include <asm/vgtod.h> | 13 | #include <asm/vgtod.h> |
14 | #include "vextern.h" | 14 | #include "vextern.h" |
15 | 15 | ||
16 | long __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache) | 16 | long __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused) |
17 | { | 17 | { |
18 | unsigned int dummy, p; | 18 | unsigned int dummy, p; |
19 | unsigned long j = 0; | ||
20 | 19 | ||
21 | /* Fast cache - only recompute value once per jiffies and avoid | 20 | if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) { |
22 | relatively costly rdtscp/cpuid otherwise. | ||
23 | This works because the scheduler usually keeps the process | ||
24 | on the same CPU and this syscall doesn't guarantee its | ||
25 | results anyways. | ||
26 | We do this here because otherwise user space would do it on | ||
27 | its own in a likely inferior way (no access to jiffies). | ||
28 | If you don't like it pass NULL. */ | ||
29 | if (tcache && tcache->blob[0] == (j = *vdso_jiffies)) { | ||
30 | p = tcache->blob[1]; | ||
31 | } else if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) { | ||
32 | /* Load per CPU data from RDTSCP */ | 21 | /* Load per CPU data from RDTSCP */ |
33 | rdtscp(dummy, dummy, p); | 22 | rdtscp(dummy, dummy, p); |
34 | } else { | 23 | } else { |
35 | /* Load per CPU data from GDT */ | 24 | /* Load per CPU data from GDT */ |
36 | asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG)); | 25 | asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG)); |
37 | } | 26 | } |
38 | if (tcache) { | ||
39 | tcache->blob[0] = j; | ||
40 | tcache->blob[1] = p; | ||
41 | } | ||
42 | if (cpu) | 27 | if (cpu) |
43 | *cpu = p & 0xfff; | 28 | *cpu = p & 0xfff; |
44 | if (node) | 29 | if (node) |
diff --git a/kernel/sys.c b/kernel/sys.c index 304b5410d746..d1fe71eb4546 100644 --- a/kernel/sys.c +++ b/kernel/sys.c | |||
@@ -1750,7 +1750,7 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3, | |||
1750 | } | 1750 | } |
1751 | 1751 | ||
1752 | asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep, | 1752 | asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep, |
1753 | struct getcpu_cache __user *cache) | 1753 | struct getcpu_cache __user *unused) |
1754 | { | 1754 | { |
1755 | int err = 0; | 1755 | int err = 0; |
1756 | int cpu = raw_smp_processor_id(); | 1756 | int cpu = raw_smp_processor_id(); |
@@ -1758,24 +1758,6 @@ asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep, | |||
1758 | err |= put_user(cpu, cpup); | 1758 | err |= put_user(cpu, cpup); |
1759 | if (nodep) | 1759 | if (nodep) |
1760 | err |= put_user(cpu_to_node(cpu), nodep); | 1760 | err |= put_user(cpu_to_node(cpu), nodep); |
1761 | if (cache) { | ||
1762 | /* | ||
1763 | * The cache is not needed for this implementation, | ||
1764 | * but make sure user programs pass something | ||
1765 | * valid. vsyscall implementations can instead make | ||
1766 | * good use of the cache. Only use t0 and t1 because | ||
1767 | * these are available in both 32bit and 64bit ABI (no | ||
1768 | * need for a compat_getcpu). 32bit has enough | ||
1769 | * padding | ||
1770 | */ | ||
1771 | unsigned long t0, t1; | ||
1772 | get_user(t0, &cache->blob[0]); | ||
1773 | get_user(t1, &cache->blob[1]); | ||
1774 | t0++; | ||
1775 | t1++; | ||
1776 | put_user(t0, &cache->blob[0]); | ||
1777 | put_user(t1, &cache->blob[1]); | ||
1778 | } | ||
1779 | return err ? -EFAULT : 0; | 1761 | return err ? -EFAULT : 0; |
1780 | } | 1762 | } |
1781 | 1763 | ||