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x86/fpu: Split out the boot time FPU init code into fpu/init.c

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Move boot time FPU initialization code into init.c, to better
isolate it into its own domain.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2015-04-22 10:53:34 +02:00
parent f89e32e0a3
commit 0c86753790
3 changed files with 94 additions and 89 deletions
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2
arch/x86/kernel/fpu/Makefile
View File

@ -2,4 +2,4 @@
# Build rules for the FPU support code:
#
obj-y += core.o xsave.o
obj-y += init.o core.o xsave.o

88
arch/x86/kernel/fpu/core.c
View File

@ -139,94 +139,6 @@ void fpu__save(struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(fpu__save);
unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
unsigned int xstate_size;
EXPORT_SYMBOL_GPL(xstate_size);
static struct i387_fxsave_struct fx_scratch;
static void mxcsr_feature_mask_init(void)
{
unsigned long mask = 0;
if (cpu_has_fxsr) {
memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
asm volatile("fxsave %0" : "+m" (fx_scratch));
mask = fx_scratch.mxcsr_mask;
if (mask == 0)
mask = 0x0000ffbf;
}
mxcsr_feature_mask &= mask;
}
static void fpstate_xstate_init_size(void)
{
/*
* Note that xstate_size might be overwriten later during
* xsave_init().
*/
if (!cpu_has_fpu) {
/*
* Disable xsave as we do not support it if i387
* emulation is enabled.
*/
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
xstate_size = sizeof(struct i387_soft_struct);
return;
}
if (cpu_has_fxsr)
xstate_size = sizeof(struct i387_fxsave_struct);
else
xstate_size = sizeof(struct i387_fsave_struct);
}
/*
* Called on the boot CPU at bootup to set up the initial FPU state that
* is later cloned into all processes.
*
* Also called on secondary CPUs to set up the FPU state of their
* idle threads.
*/
void fpu__cpu_init(void)
{
unsigned long cr0;
unsigned long cr4_mask = 0;
#ifndef CONFIG_MATH_EMULATION
if (!cpu_has_fpu) {
pr_emerg("No FPU found and no math emulation present\n");
pr_emerg("Giving up\n");
for (;;)
asm volatile("hlt");
}
#endif
if (cpu_has_fxsr)
cr4_mask |= X86_CR4_OSFXSR;
if (cpu_has_xmm)
cr4_mask |= X86_CR4_OSXMMEXCPT;
if (cr4_mask)
cr4_set_bits(cr4_mask);
cr0 = read_cr0();
cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
if (!cpu_has_fpu)
cr0 |= X86_CR0_EM;
write_cr0(cr0);
/*
* fpstate_xstate_init_size() is only called once, to avoid overriding
* 'xstate_size' during (secondary CPU) bootup or during CPU hotplug.
*/
if (xstate_size == 0)
fpstate_xstate_init_size();
mxcsr_feature_mask_init();
xsave_init();
eager_fpu_init();
}
void fpstate_init(struct fpu *fpu)
{
if (!cpu_has_fpu) {

93
arch/x86/kernel/fpu/init.c Normal file
View File

@ -0,0 +1,93 @@
/*
* x86 FPU boot time init code
*/
#include <asm/fpu-internal.h>
#include <asm/tlbflush.h>
unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
unsigned int xstate_size;
EXPORT_SYMBOL_GPL(xstate_size);
static struct i387_fxsave_struct fx_scratch;
static void mxcsr_feature_mask_init(void)
{
unsigned long mask = 0;
if (cpu_has_fxsr) {
memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
asm volatile("fxsave %0" : "+m" (fx_scratch));
mask = fx_scratch.mxcsr_mask;
if (mask == 0)
mask = 0x0000ffbf;
}
mxcsr_feature_mask &= mask;
}
static void fpstate_xstate_init_size(void)
{
/*
* Note that xstate_size might be overwriten later during
* xsave_init().
*/
if (!cpu_has_fpu) {
/*
* Disable xsave as we do not support it if i387
* emulation is enabled.
*/
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
xstate_size = sizeof(struct i387_soft_struct);
return;
}
if (cpu_has_fxsr)
xstate_size = sizeof(struct i387_fxsave_struct);
else
xstate_size = sizeof(struct i387_fsave_struct);
}
/*
* Called on the boot CPU at bootup to set up the initial FPU state that
* is later cloned into all processes.
*
* Also called on secondary CPUs to set up the FPU state of their
* idle threads.
*/
void fpu__cpu_init(void)
{
unsigned long cr0;
unsigned long cr4_mask = 0;
#ifndef CONFIG_MATH_EMULATION
if (!cpu_has_fpu) {
pr_emerg("No FPU found and no math emulation present\n");
pr_emerg("Giving up\n");
for (;;)
asm volatile("hlt");
}
#endif
if (cpu_has_fxsr)
cr4_mask |= X86_CR4_OSFXSR;
if (cpu_has_xmm)
cr4_mask |= X86_CR4_OSXMMEXCPT;
if (cr4_mask)
cr4_set_bits(cr4_mask);
cr0 = read_cr0();
cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
if (!cpu_has_fpu)
cr0 |= X86_CR0_EM;
write_cr0(cr0);
/*
* fpstate_xstate_init_size() is only called once, to avoid overriding
* 'xstate_size' during (secondary CPU) bootup or during CPU hotplug.
*/
if (xstate_size == 0)
fpstate_xstate_init_size();
mxcsr_feature_mask_init();
xsave_init();
eager_fpu_init();
}