On Mon, Dec 05, 2016 at 05:01:14PM -0800, Andy Lutomirski wrote:
> The old code didn't work at all because it adjusted the current caps
> instead of the forced caps. Anything it did would be undone later
> during cpu identification. Fix that and, while we're at it, improve
> the logging and don't bother running it if CPUID is available.
>
> Signed-off-by: Andy Lutomirski <[email protected]>
> ---
> arch/x86/kernel/fpu/init.c | 28 ++++++++++++++++------------
> 1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
> index 60dece392b3a..75e1bf3b0319 100644
> --- a/arch/x86/kernel/fpu/init.c
> +++ b/arch/x86/kernel/fpu/init.c
> @@ -50,29 +50,33 @@ void fpu__init_cpu(void)
>
> /*
> * The earliest FPU detection code.
> - *
> - * Set the X86_FEATURE_FPU CPU-capability bit based on
> - * trying to execute an actual sequence of FPU instructions:
> */
> static void fpu__init_system_early_generic(struct cpuinfo_x86 *c)
> {
> - unsigned long cr0;
> - u16 fsw, fcw;
> + if (!boot_cpu_has(X86_FEATURE_CPUID) &&
> + !test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
Flip test and save an indentation level.
> + /*
> + * Set the X86_FEATURE_FPU CPU-capability bit based on
> + * trying to execute an actual sequence of FPU instructions:
> + */
>
> - fsw = fcw = 0xffff;
> + unsigned long cr0;
> + u16 fsw, fcw;
>
> - cr0 = read_cr0();
> - cr0 &= ~(X86_CR0_TS | X86_CR0_EM);
> - write_cr0(cr0);
> + fsw = fcw = 0xffff;
> +
> + cr0 = read_cr0();
> + cr0 &= ~(X86_CR0_TS | X86_CR0_EM);
> + write_cr0(cr0);
>
> - if (!test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
> asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
> : "+m" (fsw), "+m" (fcw));
> + pr_info("x86/fpu: FSW=0x%04hx FCW=0x%04hx\n", fsw, fcw);
Why do we want those in dmesg? Maybe KERN_DEBUG?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
