Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1355528
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: Got FPU related warning on Intel Quark during boot |
| Date | 2016-03-11 02:50 +0100 |
| Message-ID | <rbknf-79u-7@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <rb6Nk-6gw-5@gated-at.bofh.it> <rb8cq-74T-17@gated-at.bofh.it> <rb8m6-78l-5@gated-at.bofh.it> <rb8YO-7CH-19@gated-at.bofh.it> <rbanU-es-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Mar 10, 2016 at 6:59 AM, Borislav Petkov <bp@alien8.de> wrote:
> On Thu, Mar 10, 2016 at 03:31:43PM +0200, Andy Shevchenko wrote:
>> Looks like it lacks that one.
>>
>> # grep -i fxsr /proc/cpuinfo; echo $?
>> 1
>
> Ok, so looking at where the warning comes from:
>
> [ 14.714533] WARNING: CPU: 0 PID: 823 at arch/x86/include/asm/fpu/internal.h:163 fpu__clear+0x8c/0x160
>
> static inline void copy_kernel_to_fxregs(struct fxregs_state *fx)
> {
> int err;
>
> if (config_enabled(CONFIG_X86_32)) {
> err = check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
> ^^^^^^^^^^^^^^^^^
> } else {
>
> ...
>
> /* Copying from a kernel buffer to FPU registers should never fail: */
> WARN_ON_FPU(err);
>
>
> and the stacktrace is pretty clear:
>
> flush_thread
> |-> fpu__clear(&tsk->thread.fpu);
> |-> we are eager by default here:
>
> if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) {
> /* FPU state will be reallocated lazily at the first use. */
> fpu__drop(fpu);
> } else {
>
> --> we're in that branch.
>
> copy_init_fpstate_to_fpregs();
> |-> copy_kernel_to_fxregs()
>
>
> I think we should use FRSTOR on quark, i.e., copy_kernel_to_fregs().
>
> Does this untested wild guess even work?
>
> ---
> diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
> index dea8e76d60c6..bbafe5e8a1a6 100644
> --- a/arch/x86/kernel/fpu/core.c
> +++ b/arch/x86/kernel/fpu/core.c
> @@ -474,8 +474,11 @@ static inline void copy_init_fpstate_to_fpregs(void)
> {
> if (use_xsave())
> copy_kernel_to_xregs(&init_fpstate.xsave, -1);
> - else
> + else if (static_cpu_has(X86_FEATURE_FXSR))
> copy_kernel_to_fxregs(&init_fpstate.fxsave);
> + else
> + copy_kernel_to_fregs(&init_fpstate.fsave);
> +
> }
>
This looks wrong, too:
/*
* Once per bootup FPU initialization sequences that will run on most x86 CPUs:
*/
static void __init fpu__init_system_generic(void)
{
/*
* Set up the legacy init FPU context. (xstate init might overwrite this
* with a more modern format, if the CPU supports it.)
*/
fpstate_init_fxstate(&init_fpstate.fxsave); <-- wrong format on
pre-FXSR CPUs
fpu__init_system_mxcsr();
}
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Got FPU related warning on Intel Quark during boot Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-10 11:50 +0100
Re: Got FPU related warning on Intel Quark during boot Ingo Molnar <mingo@kernel.org> - 2016-03-10 12:20 +0100
Re: Got FPU related warning on Intel Quark during boot Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-10 13:50 +0100
Re: Got FPU related warning on Intel Quark during boot Borislav Petkov <bp@alien8.de> - 2016-03-10 14:00 +0100
Re: Got FPU related warning on Intel Quark during boot Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-10 14:40 +0100
Re: Got FPU related warning on Intel Quark during boot Borislav Petkov <bp@alien8.de> - 2016-03-10 16:10 +0100
Re: Got FPU related warning on Intel Quark during boot Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-10 16:30 +0100
Re: Got FPU related warning on Intel Quark during boot Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2016-03-10 16:50 +0100
Re: Got FPU related warning on Intel Quark during boot Borislav Petkov <bp@alien8.de> - 2016-03-10 17:50 +0100
Re: Got FPU related warning on Intel Quark during boot Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2016-03-10 18:20 +0100
Re: Got FPU related warning on Intel Quark during boot Borislav Petkov <bp@alien8.de> - 2016-03-10 20:10 +0100
Re: Got FPU related warning on Intel Quark during boot Andy Lutomirski <luto@amacapital.net> - 2016-03-11 02:40 +0100
Re: Got FPU related warning on Intel Quark during boot Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2016-03-11 12:00 +0100
Re: Got FPU related warning on Intel Quark during boot Andy Lutomirski <luto@amacapital.net> - 2016-03-11 02:50 +0100
Re: Got FPU related warning on Intel Quark during boot Ingo Molnar <mingo@kernel.org> - 2016-03-11 10:10 +0100
Re: Got FPU related warning on Intel Quark during boot Borislav Petkov <bp@alien8.de> - 2016-03-11 10:50 +0100
Re: Got FPU related warning on Intel Quark during boot Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2016-03-11 12:10 +0100
Re: Got FPU related warning on Intel Quark during boot Borislav Petkov <bp@alien8.de> - 2016-03-11 12:30 +0100
[PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Borislav Petkov <bp@alien8.de> - 2016-03-11 12:40 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-11 19:40 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Dave Hansen <dave.hansen@linux.intel.com> - 2016-03-11 23:10 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Borislav Petkov <bp@alien8.de> - 2016-03-11 23:30 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Andy Lutomirski <luto@amacapital.net> - 2016-03-12 18:30 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Borislav Petkov <bp@alien8.de> - 2016-03-12 18:50 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Borislav Petkov <bp@alien8.de> - 2016-03-11 23:10 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2016-03-12 13:10 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Borislav Petkov <bp@alien8.de> - 2016-03-12 13:30 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Ingo Molnar <mingo@kernel.org> - 2016-03-12 16:20 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Ingo Molnar <mingo@kernel.org> - 2016-03-12 16:10 +0100
Re: [PATCH] x86/FPU: Fix FPU handling on legacy FPU machines Ingo Molnar <mingo@kernel.org> - 2016-03-12 16:20 +0100
[tip:x86/urgent] x86/fpu: Fix eager-FPU handling on legacy FPU machines tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-03-12 16:20 +0100
csiph-web