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| author |   Andy Lutomirski <luto@amacapital.net> | 2014-10-24 15:58:13 -0700 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-02-04 12:10:49 +0100 |
| commit | a66734297f78707ce39d756b656bfae861d53f62 (patch) | |
| tree | c58ac7f3a43522fd5f40527ee69eb0057cce41b0 /arch/x86/include/asm/mmu_context.h | |
| parent | perf/x86: Only allow rdpmc if a perf_event is mapped (diff) | |
| download | linux-dev-a66734297f78707ce39d756b656bfae861d53f62.tar.xz linux-dev-a66734297f78707ce39d756b656bfae861d53f62.zip | |
perf/x86: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks
While perfmon2 is a sufficiently evil library (it pokes MSRs
directly) that breaking it is fair game, it's still useful, so we
might as well try to support it. This allows users to write 2 to
/sys/devices/cpu/rdpmc to disable all rdpmc protection so that hack
like perfmon2 can continue to work.
At some point, if perf_event becomes fast enough to replace
perfmon2, then this can go.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vince Weaver <vince@deater.net>
Cc: "hillf.zj" <hillf.zj@alibaba-inc.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/caac3c1c707dcca48ecbc35f4def21495856f479.1414190806.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/mmu_context.h')
| -rw-r--r-- | arch/x86/include/asm/mmu_context.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 89c1fece224e..883f6b933fa4 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -19,9 +19,12 @@ static inline void paravirt_activate_mm(struct mm_struct *prev, #endif /* !CONFIG_PARAVIRT */ #ifdef CONFIG_PERF_EVENTS +extern struct static_key rdpmc_always_available; + static inline void load_mm_cr4(struct mm_struct *mm) { - if (atomic_read(&mm->context.perf_rdpmc_allowed)) + if (static_key_true(&rdpmc_always_available) || + atomic_read(&mm->context.perf_rdpmc_allowed)) cr4_set_bits(X86_CR4_PCE); else cr4_clear_bits(X86_CR4_PCE); |