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authorWolfgang Wiedmeyer <wolfgit@wiedmeyer.de>2015-10-23 03:29:33 +0200
committerWolfgang Wiedmeyer <wolfgit@wiedmeyer.de>2015-10-23 03:29:33 +0200
commit15dfd0df63ce6847081d09b2bbd567cc0cc4eae1 (patch)
tree3b73f24fcef970bfcace3cbb297cfa57f3994682 /arch/x86/kernel/vread_tsc_64.c
parent328aa7a45af61bc0060c80847daa67fef7b9c0d0 (diff)
parent0149138c4142da287d23f9d5c6038f7fb5e30ac2 (diff)
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initial merge with 3.2.72
Diffstat (limited to 'arch/x86/kernel/vread_tsc_64.c')
-rw-r--r--arch/x86/kernel/vread_tsc_64.c36
1 files changed, 0 insertions, 36 deletions
diff --git a/arch/x86/kernel/vread_tsc_64.c b/arch/x86/kernel/vread_tsc_64.c
deleted file mode 100644
index a81aa9e..0000000
--- a/arch/x86/kernel/vread_tsc_64.c
+++ /dev/null
@@ -1,36 +0,0 @@
-/* This code runs in userspace. */
-
-#define DISABLE_BRANCH_PROFILING
-#include <asm/vgtod.h>
-
-notrace cycle_t __vsyscall_fn vread_tsc(void)
-{
- cycle_t ret;
- u64 last;
-
- /*
- * Empirically, a fence (of type that depends on the CPU)
- * before rdtsc is enough to ensure that rdtsc is ordered
- * with respect to loads. The various CPU manuals are unclear
- * as to whether rdtsc can be reordered with later loads,
- * but no one has ever seen it happen.
- */
- rdtsc_barrier();
- ret = (cycle_t)vget_cycles();
-
- last = VVAR(vsyscall_gtod_data).clock.cycle_last;
-
- if (likely(ret >= last))
- return ret;
-
- /*
- * GCC likes to generate cmov here, but this branch is extremely
- * predictable (it's just a funciton of time and the likely is
- * very likely) and there's a data dependence, so force GCC
- * to generate a branch instead. I don't barrier() because
- * we don't actually need a barrier, and if this function
- * ever gets inlined it will generate worse code.
- */
- asm volatile ("");
- return last;
-}