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Date: Wed, 6 Jan 2016 14:24:51 -0800
From: yu-cheng yu <yu-cheng.yu@...el.com>
To: linux-kernel@...r.kernel.org
Cc: yu-cheng yu <yu-cheng.yu@...el.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...e.de>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
Fenghua Yu <fenghua.yu@...el.com>
Subject: [PATCH 1/4] 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@...el.com>
Cc: x86@...nel.org
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>
Cc: Ravi V. Shankar <ravi.v.shankar@...el.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
---
arch/x86/kernel/fpu/init.c | 109 ++++++++++++++++-----------------------------
1 file changed, 38 insertions(+), 71 deletions(-)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index be39b5f..057b73e 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -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
@@ -261,18 +264,6 @@ 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:
*/
@@ -307,11 +298,46 @@ static void __init fpu__init_system_ctx_switch(void)
}
/*
+ * 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);
/*
@@ -335,62 +361,3 @@ 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);
--
1.9.1
--
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