On Tue, Jan 12, 2016 at 04:00:49AM -0800, tip-bot for yu-cheng yu wrote:
> Commit-ID: 4f81cbafcce2c603db7865e9d0e461f7947d77d4
> Gitweb: http://git.kernel.org/tip/4f81cbafcce2c603db7865e9d0e461f7947d77d4
> Author: yu-cheng yu <yu-cheng.yu@xxxxxxxxx>
> AuthorDate: Wed, 6 Jan 2016 14:24:51 -0800
> Committer: Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Tue, 12 Jan 2016 11:51:20 +0100
>
> x86/fpu: Fix early FPU command-line parsing
>
> The function fpu__init_system() is executed before
> parse_early_param(). This causes wrong FPU configuration. This
> patch fixes this issue by parsing boot_command_line in the
> beginning of fpu__init_system().
>
> With all four patches in this series, each parameter disables
> features as the following:
>
> eagerfpu=off: eagerfpu, avx, avx2, avx512, mpx
> no387: fpu
> nofxsr: fxsr, fxsropt, xmm
> noxsave: xsave, xsaveopt, xsaves, xsavec, avx, avx2, avx512,
> mpx, xgetbv1 noxsaveopt: xsaveopt
> noxsaves: xsaves
>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
> Cc: Ravi V. Shankar <ravi.v.shankar@xxxxxxxxx>
> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: yu-cheng yu <yu-cheng.yu@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/1452119094-7252-2-git-send-email-yu-cheng.yu@xxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
> arch/x86/kernel/fpu/init.c | 109 ++++++++++++++++-----------------------------
> 1 file changed, 38 insertions(+), 71 deletions(-)
...
> + * We parse fpu parameters early because fpu__init_system() is executed
> + * before parse_early_param().
> + */
> +static void __init fpu__init_parse_early_param(void)
> +{
> + /*
> + * No need to check "eagerfpu=auto" again, since it is the
> + * initial default.
> + */
> + if (cmdline_find_option_bool(boot_command_line, "eagerfpu=off"))
> + eagerfpu = DISABLE;
> + else if (cmdline_find_option_bool(boot_command_line, "eagerfpu=on"))
> + eagerfpu = ENABLE;
> +
> + if (cmdline_find_option_bool(boot_command_line, "no387"))
> + setup_clear_cpu_cap(X86_FEATURE_FPU);
> +
> + if (cmdline_find_option_bool(boot_command_line, "nofxsr")) {
> + setup_clear_cpu_cap(X86_FEATURE_FXSR);
> + setup_clear_cpu_cap(X86_FEATURE_FXSR_OPT);
> + setup_clear_cpu_cap(X86_FEATURE_XMM);
> + }
> +
> + if (cmdline_find_option_bool(boot_command_line, "noxsave"))
> + fpu__xstate_clear_all_cpu_caps();
> +
> + if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
> + setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
> +
> + if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
> + setup_clear_cpu_cap(X86_FEATURE_XSAVES);
This could certainly be improved: we're iterating over the *whole*
command line each time for each option unconditionally instead of
iterating word by word and comparing it with all strings.
We'd need something like cmdline_for_each_word() or so, though...
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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