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| author | Ingo Molnar <mingo@kernel.org> | 2015-05-27 12:22:29 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-05-27 14:11:25 +0200 |
| commit | 9ba6b79102a594293c79f30319cabf476c5e300e (patch) | |
| tree | 7e8c24ce19756a1a10680f7adbc03475fb690e6b /arch/x86/kernel | |
| parent | x86/fpu: Split out the fpu__activate_fpstate_read() method (diff) | |
| download | linux-9ba6b79102a594293c79f30319cabf476c5e300e.tar.xz linux-9ba6b79102a594293c79f30319cabf476c5e300e.zip | |
x86/fpu: Optimize fpu__activate_fpstate_read()
fpu__activate_fpstate_read() is used before FPU registers are
read from the fpstate by ptrace and core dumping.
It's not necessary to unlazy non-current child tasks in this case,
since the reading of registers is non-destructive.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 174add372bb8..06cb7e3e9886 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -312,10 +312,7 @@ void fpu__activate_fpstate_read(struct fpu *fpu) if (fpu->fpregs_active) { fpu__save(fpu); } else { - if (fpu->fpstate_active) { - /* Invalidate any lazy state: */ - fpu->last_cpu = -1; - } else { + if (!fpu->fpstate_active) { fpstate_init(&fpu->state); /* Safe to do for current and for stopped child tasks: */ |