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x86, fpu: split FPU state from task struct - v5

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Split the FPU save area from the task struct. This allows easy migration
of FPU context, and it's generally cleaner. It also allows the following
two optimizations:

1) only allocate when the application actually uses FPU, so in the first
lazy FPU trap. This could save memory for non-fpu using apps. Next patch
does this lazy allocation.

2) allocate the right size for the actual cpu rather than 512 bytes always.
Patches enabling xsave/xrstor support (coming shortly) will take advantage
of this.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Suresh Siddha
2008-03-10 15:28:04 -07:00
committed by Ingo Molnar
parent fa5c463941
commit 61c4628b53
16 changed files with 161 additions and 90 deletions
Download Patch File Download Diff File Expand all files Collapse all files

80
arch/x86/kernel/i387.c
View File

@@ -8,6 +8,7 @@
#include <linux/module.h>
#include <linux/regset.h>
#include <linux/sched.h>
#include <linux/bootmem.h>
#include <asm/sigcontext.h>
#include <asm/processor.h>
@@ -35,17 +36,18 @@
#endif
static unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
unsigned int xstate_size;
static struct i387_fxsave_struct fx_scratch __cpuinitdata;
void mxcsr_feature_mask_init(void)
void __cpuinit mxcsr_feature_mask_init(void)
{
unsigned long mask = 0;
clts();
if (cpu_has_fxsr) {
memset(&current->thread.i387.fxsave, 0,
sizeof(struct i387_fxsave_struct));
asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
mask = current->thread.i387.fxsave.mxcsr_mask;
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;
}
@@ -53,6 +55,17 @@ void mxcsr_feature_mask_init(void)
stts();
}
void __init init_thread_xstate(void)
{
if (cpu_has_fxsr)
xstate_size = sizeof(struct i387_fxsave_struct);
#ifdef CONFIG_X86_32
else
xstate_size = sizeof(struct i387_fsave_struct);
#endif
init_task.thread.xstate = alloc_bootmem(xstate_size);
}
#ifdef CONFIG_X86_64
/*
* Called at bootup to set up the initial FPU state that is later cloned
@@ -61,10 +74,6 @@ void mxcsr_feature_mask_init(void)
void __cpuinit fpu_init(void)
{
unsigned long oldcr0 = read_cr0();
extern void __bad_fxsave_alignment(void);
if (offsetof(struct task_struct, thread.i387.fxsave) & 15)
__bad_fxsave_alignment();
set_in_cr4(X86_CR4_OSFXSR);
set_in_cr4(X86_CR4_OSXMMEXCPT);
@@ -93,18 +102,19 @@ void init_fpu(struct task_struct *tsk)
}
if (cpu_has_fxsr) {
memset(&tsk->thread.i387.fxsave, 0,
sizeof(struct i387_fxsave_struct));
tsk->thread.i387.fxsave.cwd = 0x37f;
struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
memset(fx, 0, xstate_size);
fx->cwd = 0x37f;
if (cpu_has_xmm)
tsk->thread.i387.fxsave.mxcsr = MXCSR_DEFAULT;
fx->mxcsr = MXCSR_DEFAULT;
} else {
memset(&tsk->thread.i387.fsave, 0,
sizeof(struct i387_fsave_struct));
tsk->thread.i387.fsave.cwd = 0xffff037fu;
tsk->thread.i387.fsave.swd = 0xffff0000u;
tsk->thread.i387.fsave.twd = 0xffffffffu;
tsk->thread.i387.fsave.fos = 0xffff0000u;
struct i387_fsave_struct *fp = &tsk->thread.xstate->fsave;
memset(fp, 0, xstate_size);
fp->cwd = 0xffff037fu;
fp->swd = 0xffff0000u;
fp->twd = 0xffffffffu;
fp->fos = 0xffff0000u;
}
/*
* Only the device not available exception or ptrace can call init_fpu.
@@ -132,7 +142,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
init_fpu(target);
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.i387.fxsave, 0, -1);
&target->thread.xstate->fxsave, 0, -1);
}
int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
@@ -148,12 +158,12 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
set_stopped_child_used_math(target);
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.i387.fxsave, 0, -1);
&target->thread.xstate->fxsave, 0, -1);
/*
* mxcsr reserved bits must be masked to zero for security reasons.
*/
target->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
target->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
return ret;
}
@@ -233,7 +243,7 @@ static inline u32 twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
static void
convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
{
struct i387_fxsave_struct *fxsave = &tsk->thread.i387.fxsave;
struct i387_fxsave_struct *fxsave = &tsk->thread.xstate->fxsave;
struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
int i;
@@ -273,7 +283,7 @@ static void convert_to_fxsr(struct task_struct *tsk,
const struct user_i387_ia32_struct *env)
{
struct i387_fxsave_struct *fxsave = &tsk->thread.i387.fxsave;
struct i387_fxsave_struct *fxsave = &tsk->thread.xstate->fxsave;
struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
int i;
@@ -310,7 +320,8 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr) {
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.i387.fsave, 0, -1);
&target->thread.xstate->fsave, 0,
-1);
}
if (kbuf && pos == 0 && count == sizeof(env)) {
@@ -338,7 +349,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr) {
return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.i387.fsave, 0, -1);
&target->thread.xstate->fsave, 0, -1);
}
if (pos > 0 || count < sizeof(env))
@@ -358,11 +369,11 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf)
{
struct task_struct *tsk = current;
struct i387_fsave_struct *fp = &tsk->thread.xstate->fsave;
unlazy_fpu(tsk);
tsk->thread.i387.fsave.status = tsk->thread.i387.fsave.swd;
if (__copy_to_user(buf, &tsk->thread.i387.fsave,
sizeof(struct i387_fsave_struct)))
fp->status = fp->swd;
if (__copy_to_user(buf, fp, sizeof(struct i387_fsave_struct)))
return -1;
return 1;
}
@@ -370,6 +381,7 @@ static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf)
static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
{
struct task_struct *tsk = current;
struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
struct user_i387_ia32_struct env;
int err = 0;
@@ -379,12 +391,12 @@ static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
if (__copy_to_user(buf, &env, sizeof(env)))
return -1;
err |= __put_user(tsk->thread.i387.fxsave.swd, &buf->status);
err |= __put_user(fx->swd, &buf->status);
err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
if (err)
return -1;
if (__copy_to_user(&buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
if (__copy_to_user(&buf->_fxsr_env[0], fx,
sizeof(struct i387_fxsave_struct)))
return -1;
return 1;
@@ -417,7 +429,7 @@ static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf)
struct task_struct *tsk = current;
clear_fpu(tsk);
return __copy_from_user(&tsk->thread.i387.fsave, buf,
return __copy_from_user(&tsk->thread.xstate->fsave, buf,
sizeof(struct i387_fsave_struct));
}
@@ -428,10 +440,10 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
int err;
clear_fpu(tsk);
err = __copy_from_user(&tsk->thread.i387.fxsave, &buf->_fxsr_env[0],
err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],
sizeof(struct i387_fxsave_struct));
/* mxcsr reserved bits must be masked to zero for security reasons */
tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
tsk->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
if (err || __copy_from_user(&env, buf, sizeof(env)))
return 1;
convert_to_fxsr(tsk, &env);