diff options
| author | Ingo Molnar <mingo@kernel.org> | 2015-05-05 10:54:04 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-05-19 15:47:46 +0200 |
| commit | 71eb3c6d155c54fb74d2f95166162296a8f9af12 (patch) | |
| tree | a3d6eb6726c0b91297cfaf134b1eafe9875df42a | |
| parent | 0bf23f3d6cadb2f0961d0ea370371cf35480bcb5 (diff) | |
x86/fpu: Make check_fpu() init ordering independent
check_fpu() currently relies on being called early in the init sequence,
when CR0::TS has not been set up yet.
Save/restore CR0::TS across this function, to make it invariant to
init ordering. This way we'll be able to move the generic FPU setup
routines earlier in the init sequence.
Cc: Andy Lutomirski <luto@amacapital.net>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/kernel/fpu/bugs.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/bugs.c b/arch/x86/kernel/fpu/bugs.c index 400a3d713fb2..449b5f3f4925 100644 --- a/arch/x86/kernel/fpu/bugs.c +++ b/arch/x86/kernel/fpu/bugs.c @@ -23,8 +23,13 @@ static double __initdata y = 3145727.0; */ static void __init check_fpu(void) { + u32 cr0_saved; s32 fdiv_bug; + /* We might have CR0::TS set already, clear it: */ + cr0_saved = read_cr0(); + write_cr0(cr0_saved & ~X86_CR0_TS); + kernel_fpu_begin(); /* @@ -47,6 +52,8 @@ static void __init check_fpu(void) kernel_fpu_end(); + write_cr0(cr0_saved); + if (fdiv_bug) { set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV); pr_warn("Hmm, FPU with FDIV bug\n"); |