diff options
| 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/process.c | |
| parent | 4b2e762e2e53c721458a83d547b222178bb72a34 (diff) | |
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/process.c')
| -rw-r--r-- | arch/x86/kernel/process.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index ce8b10351e28..83480373a642 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -130,6 +130,7 @@ void flush_thread(void) flush_ptrace_hw_breakpoint(tsk); memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); + drop_init_fpu(tsk); /* * Free the FPU state for non xsave platforms. They get reallocated @@ -137,6 +138,12 @@ void flush_thread(void) */ if (!use_eager_fpu()) free_thread_xstate(tsk); + else if (!used_math()) { + /* kthread execs. TODO: cleanup this horror. */ + if (WARN_ON(init_fpu(current))) + force_sig(SIGKILL, current); + math_state_restore(); + } } static void hard_disable_TSC(void) |