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| author | Oleg Nesterov <oleg@redhat.com> | 2015-01-19 19:52:12 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2015-02-23 15:50:45 +0100 |
| commit | 110d7f7513bbb916b8654da9e2973ac5bed929a9 (patch) | |
| tree | 923e255abef680d1354c3e18df2044f19d6dbcbb /arch/x86/kernel/xsave.c | |
| parent | 4b2e762e2e53c721458a83d547b222178bb72a34 (diff) | |
| download | lwn-110d7f7513bbb916b8654da9e2973ac5bed929a9.tar.gz lwn-110d7f7513bbb916b8654da9e2973ac5bed929a9.zip | |
x86/fpu: Don't abuse FPU in kernel threads if use_eager_fpu()
AFAICS, there is no reason why kernel threads should have FPU context
even if use_eager_fpu() == T. Now that interrupted_kernel_fpu_idle()
does not check __thread_has_fpu() in the use_eager_fpu() case, we
can remove the init_fpu() code from eager_fpu_init() and change
flush_thread() called by do_execve() to initialize FPU.
Note: of course, the change in flush_thread() is horrible and must be
cleanuped. We need the new helper, and flush_thread() should return the
error if init_fpu() fails.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/20150119185212.GD16427@redhat.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'arch/x86/kernel/xsave.c')
| -rw-r--r-- | arch/x86/kernel/xsave.c | 13 |
1 files changed, 1 insertions, 12 deletions
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index 0de1fae2bdf0..de9dcf89a302 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -688,7 +688,7 @@ void eager_fpu_init(void) { static __refdata void (*boot_func)(void) = eager_fpu_init_bp; - clear_used_math(); + WARN_ON(used_math()); current_thread_info()->status = 0; if (eagerfpu == ENABLE) @@ -703,17 +703,6 @@ void eager_fpu_init(void) boot_func(); boot_func = NULL; } - - /* - * This is same as math_state_restore(). But use_xsave() is - * not yet patched to use math_state_restore(). - */ - init_fpu(current); - __thread_fpu_begin(current); - if (cpu_has_xsave) - xrstor_state(init_xstate_buf, -1); - else - fxrstor_checking(&init_xstate_buf->i387); } /* |