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x86/fpu: Fix early FPU command-line parsing

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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@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: yu-cheng yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/1452119094-7252-2-git-send-email-yu-cheng.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
yu-cheng yu 2016-01-06 14:24:51 -08:00 committed by Ingo Molnar
parent b500f77bae
commit 4f81cbafcc
1 changed files with 38 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

109
arch/x86/kernel/fpu/init.c
View File

@ -3,8 +3,11 @@
*/
#include <asm/fpu/internal.h>
#include <asm/tlbflush.h>
#include <asm/setup.h>
#include <asm/cmdline.h>
#include <linux/sched.h>
#include <linux/init.h>
/*
* Initialize the TS bit in CR0 according to the style of context-switches
@ -270,18 +273,6 @@ static void __init fpu__init_system_xstate_size_legacy(void)
*/
static enum { AUTO, ENABLE, DISABLE } eagerfpu = AUTO;
static int __init eager_fpu_setup(char *s)
{
if (!strcmp(s, "on"))
eagerfpu = ENABLE;
else if (!strcmp(s, "off"))
eagerfpu = DISABLE;
else if (!strcmp(s, "auto"))
eagerfpu = AUTO;
return 1;
}
__setup("eagerfpu=", eager_fpu_setup);
/*
* Pick the FPU context switching strategy:
*/
@ -315,12 +306,47 @@ static void __init fpu__init_system_ctx_switch(void)
printk(KERN_INFO "x86/fpu: Using '%s' FPU context switches.\n", eagerfpu == ENABLE ? "eager" : "lazy");
}
/*
* 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);
}
/*
* Called on the boot CPU once per system bootup, to set up the initial
* FPU state that is later cloned into all processes:
*/
void __init fpu__init_system(struct cpuinfo_x86 *c)
{
fpu__init_parse_early_param();
fpu__init_system_early_generic(c);
/*
@ -344,62 +370,3 @@ void __init fpu__init_system(struct cpuinfo_x86 *c)
fpu__init_system_ctx_switch();
}
/*
* Boot parameter to turn off FPU support and fall back to math-emu:
*/
static int __init no_387(char *s)
{
setup_clear_cpu_cap(X86_FEATURE_FPU);
return 1;
}
__setup("no387", no_387);
/*
* Disable all xstate CPU features:
*/
static int __init x86_noxsave_setup(char *s)
{
if (strlen(s))
return 0;
fpu__xstate_clear_all_cpu_caps();
return 1;
}
__setup("noxsave", x86_noxsave_setup);
/*
* Disable the XSAVEOPT instruction specifically:
*/
static int __init x86_noxsaveopt_setup(char *s)
{
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
return 1;
}
__setup("noxsaveopt", x86_noxsaveopt_setup);
/*
* Disable the XSAVES instruction:
*/
static int __init x86_noxsaves_setup(char *s)
{
setup_clear_cpu_cap(X86_FEATURE_XSAVES);
return 1;
}
__setup("noxsaves", x86_noxsaves_setup);
/*
* Disable FX save/restore and SSE support:
*/
static int __init x86_nofxsr_setup(char *s)
{
setup_clear_cpu_cap(X86_FEATURE_FXSR);
setup_clear_cpu_cap(X86_FEATURE_FXSR_OPT);
setup_clear_cpu_cap(X86_FEATURE_XMM);
return 1;
}
__setup("nofxsr", x86_nofxsr_setup);