[GIT PULL] x86/fpu for v2.6.37

From: Ingo Molnar
Date: Thu Oct 21 2010 - 09:46:16 EST

Linus,

Please pull the latest x86-fpu-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-fpu-for-linus

Thanks,

Ingo

------------------>
Brian Gerst (12):
x86: Use correct type for %cr4
x86, fpu: Merge fpu_init()
x86, fpu: Merge tolerant_fwait()
x86, fpu: Merge __save_init_fpu()
x86-64, fpu: Disable preemption when using TS_USEDFPU
x86-64, fpu: Fix %cs value in convert_from_fxsr()
x86-64, fpu: Simplify constraints for fxsave/fxtstor
x86-32, fpu: Remove math_emulate stub
x86, fpu: Remove unnecessary ifdefs from i387 code.
x86, fpu: Remove PSHUFB_XMM5_* macros
x86-32, fpu: Rewrite fpu_save_init()
x86, fpu: Merge fpu_save_init()

Robert Richter (1):
x86, xsave: Disable xsave in i387 emulation mode


arch/x86/include/asm/i387.h | 195 ++++++++++---------------------------
arch/x86/include/asm/processor.h | 4 +-
arch/x86/kernel/cpu/common.c | 7 --
arch/x86/kernel/i387.c | 58 ++++++------
arch/x86/kernel/process_64.c | 2 +-
arch/x86/kernel/traps.c | 35 +------
6 files changed, 90 insertions(+), 211 deletions(-)

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index a73a8d5..70626ed 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -55,6 +55,12 @@ extern int save_i387_xstate_ia32(void __user *buf);
extern int restore_i387_xstate_ia32(void __user *buf);
#endif

+#ifdef CONFIG_MATH_EMULATION
+extern void finit_soft_fpu(struct i387_soft_struct *soft);
+#else
+static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}
+#endif
+
#define X87_FSW_ES (1 << 7) /* Exception Summary */

static __always_inline __pure bool use_xsaveopt(void)
@@ -67,6 +73,11 @@ static __always_inline __pure bool use_xsave(void)
return static_cpu_has(X86_FEATURE_XSAVE);
}

+static __always_inline __pure bool use_fxsr(void)
+{
+ return static_cpu_has(X86_FEATURE_FXSR);
+}
+
extern void __sanitize_i387_state(struct task_struct *);

static inline void sanitize_i387_state(struct task_struct *tsk)
@@ -77,19 +88,11 @@ static inline void sanitize_i387_state(struct task_struct *tsk)
}

#ifdef CONFIG_X86_64
-
-/* Ignore delayed exceptions from user space */
-static inline void tolerant_fwait(void)
-{
- asm volatile("1: fwait\n"
- "2:\n"
- _ASM_EXTABLE(1b, 2b));
-}
-
static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
{
int err;

+ /* See comment in fxsave() below. */
asm volatile("1: rex64/fxrstor (%[fx])\n\t"
"2:\n"
".section .fixup,\"ax\"\n"
@@ -98,44 +101,10 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
".previous\n"
_ASM_EXTABLE(1b, 3b)
: [err] "=r" (err)
-#if 0 /* See comment in fxsave() below. */
- : [fx] "r" (fx), "m" (*fx), "0" (0));
-#else
- : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
-#endif
+ : [fx] "R" (fx), "m" (*fx), "0" (0));
return err;
}

-/* AMD CPUs don't save/restore FDP/FIP/FOP unless an exception
- is pending. Clear the x87 state here by setting it to fixed
- values. The kernel data segment can be sometimes 0 and sometimes
- new user value. Both should be ok.
- Use the PDA as safe address because it should be already in L1. */
-static inline void fpu_clear(struct fpu *fpu)
-{
- struct xsave_struct *xstate = &fpu->state->xsave;
- struct i387_fxsave_struct *fx = &fpu->state->fxsave;
-
- /*
- * xsave header may indicate the init state of the FP.
- */
- if (use_xsave() &&
- !(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
- return;
-
- if (unlikely(fx->swd & X87_FSW_ES))
- asm volatile("fnclex");
- alternative_input(ASM_NOP8 ASM_NOP2,
- " emms\n" /* clear stack tags */
- " fildl %%gs:0", /* load to clear state */
- X86_FEATURE_FXSAVE_LEAK);
-}
-
-static inline void clear_fpu_state(struct task_struct *tsk)
-{
- fpu_clear(&tsk->thread.fpu);
-}
-
static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
{
int err;
@@ -149,6 +118,7 @@ static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
if (unlikely(err))
return -EFAULT;

+ /* See comment in fxsave() below. */
asm volatile("1: rex64/fxsave (%[fx])\n\t"
"2:\n"
".section .fixup,\"ax\"\n"
@@ -157,11 +127,7 @@ static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
".previous\n"
_ASM_EXTABLE(1b, 3b)
: [err] "=r" (err), "=m" (*fx)
-#if 0 /* See comment in fxsave() below. */
- : [fx] "r" (fx), "0" (0));
-#else
- : [fx] "cdaSDb" (fx), "0" (0));
-#endif
+ : [fx] "R" (fx), "0" (0));
if (unlikely(err) &&
__clear_user(fx, sizeof(struct i387_fxsave_struct)))
err = -EFAULT;
@@ -174,57 +140,26 @@ static inline void fpu_fxsave(struct fpu *fpu)
/* Using "rex64; fxsave %0" is broken because, if the memory operand
uses any extended registers for addressing, a second REX prefix
will be generated (to the assembler, rex64 followed by semicolon
- is a separate instruction), and hence the 64-bitness is lost. */
-#if 0
- /* Using "fxsaveq %0" would be the ideal choice, but is only supported
- starting with gas 2.16. */
- __asm__ __volatile__("fxsaveq %0"
- : "=m" (fpu->state->fxsave));
-#elif 0
- /* Using, as a workaround, the properly prefixed form below isn't
+ is a separate instruction), and hence the 64-bitness is lost.
+ Using "fxsaveq %0" would be the ideal choice, but is only supported
+ starting with gas 2.16.
+ asm volatile("fxsaveq %0"
+ : "=m" (fpu->state->fxsave));
+ Using, as a workaround, the properly prefixed form below isn't
accepted by any binutils version so far released, complaining that
the same type of prefix is used twice if an extended register is
- needed for addressing (fix submitted to mainline 2005-11-21). */
- __asm__ __volatile__("rex64/fxsave %0"
- : "=m" (fpu->state->fxsave));
-#else
- /* This, however, we can work around by forcing the compiler to select
+ needed for addressing (fix submitted to mainline 2005-11-21).
+ asm volatile("rex64/fxsave %0"
+ : "=m" (fpu->state->fxsave));
+ This, however, we can work around by forcing the compiler to select
an addressing mode that doesn't require extended registers. */
- __asm__ __volatile__("rex64/fxsave (%1)"
- : "=m" (fpu->state->fxsave)
- : "cdaSDb" (&fpu->state->fxsave));
-#endif
-}
-
-static inline void fpu_save_init(struct fpu *fpu)
-{
- if (use_xsave())
- fpu_xsave(fpu);
- else
- fpu_fxsave(fpu);
-
- fpu_clear(fpu);
-}
-
-static inline void __save_init_fpu(struct task_struct *tsk)
-{
- fpu_save_init(&tsk->thread.fpu);
- task_thread_info(tsk)->status &= ~TS_USEDFPU;
+ asm volatile("rex64/fxsave (%[fx])"
+ : "=m" (fpu->state->fxsave)
+ : [fx] "R" (&fpu->state->fxsave));
}

#else /* CONFIG_X86_32 */

-#ifdef CONFIG_MATH_EMULATION
-extern void finit_soft_fpu(struct i387_soft_struct *soft);
-#else
-static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}
-#endif
-
-static inline void tolerant_fwait(void)
-{
- asm volatile("fnclex ; fwait");
-}
-
/* perform fxrstor iff the processor has extended states, otherwise frstor */
static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
{
@@ -241,6 +176,14 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
return 0;
}

+static inline void fpu_fxsave(struct fpu *fpu)
+{
+ asm volatile("fxsave %[fx]"
+ : [fx] "=m" (fpu->state->fxsave));
+}
+
+#endif /* CONFIG_X86_64 */
+
/* We need a safe address that is cheap to find and that is already
in L1 during context switch. The best choices are unfortunately
different for UP and SMP */
@@ -256,47 +199,33 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
static inline void fpu_save_init(struct fpu *fpu)
{
if (use_xsave()) {
- struct xsave_struct *xstate = &fpu->state->xsave;
- struct i387_fxsave_struct *fx = &fpu->state->fxsave;
-
fpu_xsave(fpu);

/*
* xsave header may indicate the init state of the FP.
*/
- if (!(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
- goto end;
-
- if (unlikely(fx->swd & X87_FSW_ES))
- asm volatile("fnclex");
-
- /*
- * we can do a simple return here or be paranoid :)
- */
- goto clear_state;
+ if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP))
+ return;
+ } else if (use_fxsr()) {
+ fpu_fxsave(fpu);
+ } else {
+ asm volatile("fsave %[fx]; fwait"
+ : [fx] "=m" (fpu->state->fsave));
+ return;
}

- /* Use more nops than strictly needed in case the compiler
- varies code */
- alternative_input(
- "fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
- "fxsave %[fx]\n"
- "bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
- X86_FEATURE_FXSR,
- [fx] "m" (fpu->state->fxsave),
- [fsw] "m" (fpu->state->fxsave.swd) : "memory");
-clear_state:
+ if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES))
+ asm volatile("fnclex");
+
/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
is pending. Clear the x87 state here by setting it to fixed
values. safe_address is a random variable that should be in L1 */
alternative_input(
- GENERIC_NOP8 GENERIC_NOP2,
+ ASM_NOP8 ASM_NOP2,
"emms\n\t" /* clear stack tags */
- "fildl %[addr]", /* set F?P to defined value */
+ "fildl %P[addr]", /* set F?P to defined value */
X86_FEATURE_FXSAVE_LEAK,
[addr] "m" (safe_address));
-end:
- ;
}

static inline void __save_init_fpu(struct task_struct *tsk)
@@ -305,9 +234,6 @@ static inline void __save_init_fpu(struct task_struct *tsk)
task_thread_info(tsk)->status &= ~TS_USEDFPU;
}

-
-#endif /* CONFIG_X86_64 */
-
static inline int fpu_fxrstor_checking(struct fpu *fpu)
{
return fxrstor_checking(&fpu->state->fxsave);
@@ -344,7 +270,10 @@ static inline void __unlazy_fpu(struct task_struct *tsk)
static inline void __clear_fpu(struct task_struct *tsk)
{
if (task_thread_info(tsk)->status & TS_USEDFPU) {
- tolerant_fwait();
+ /* Ignore delayed exceptions from user space */
+ asm volatile("1: fwait\n"
+ "2:\n"
+ _ASM_EXTABLE(1b, 2b));
task_thread_info(tsk)->status &= ~TS_USEDFPU;
stts();
}
@@ -405,19 +334,6 @@ static inline void irq_ts_restore(int TS_state)
stts();
}

-#ifdef CONFIG_X86_64
-
-static inline void save_init_fpu(struct task_struct *tsk)
-{
- __save_init_fpu(tsk);
- stts();
-}
-
-#define unlazy_fpu __unlazy_fpu
-#define clear_fpu __clear_fpu
-
-#else /* CONFIG_X86_32 */
-
/*
* These disable preemption on their own and are safe
*/
@@ -443,8 +359,6 @@ static inline void clear_fpu(struct task_struct *tsk)
preempt_enable();
}

-#endif /* CONFIG_X86_64 */
-
/*
* i387 state interaction
*/
@@ -508,7 +422,4 @@ extern void fpu_finit(struct fpu *fpu);

#endif /* __ASSEMBLY__ */

-#define PSHUFB_XMM5_XMM0 .byte 0x66, 0x0f, 0x38, 0x00, 0xc5
-#define PSHUFB_XMM5_XMM6 .byte 0x66, 0x0f, 0x38, 0x00, 0xf5
-
#endif /* _ASM_X86_I387_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 325b7bd..396b80f 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -602,7 +602,7 @@ extern unsigned long mmu_cr4_features;

static inline void set_in_cr4(unsigned long mask)
{
- unsigned cr4;
+ unsigned long cr4;

mmu_cr4_features |= mask;
cr4 = read_cr4();
@@ -612,7 +612,7 @@ static inline void set_in_cr4(unsigned long mask)

static inline void clear_in_cr4(unsigned long mask)
{
- unsigned cr4;
+ unsigned long cr4;

mmu_cr4_features &= ~mask;
cr4 = read_cr4();
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 490dac6..f9e23e8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1264,13 +1264,6 @@ void __cpuinit cpu_init(void)
clear_all_debug_regs();
dbg_restore_debug_regs();

- /*
- * Force FPU initialization:
- */
- current_thread_info()->status = 0;
- clear_used_math();
- mxcsr_feature_mask_init();
-
fpu_init();
xsave_init();
}
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 1f11f5c..e795e36 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -67,19 +67,22 @@ static void __cpuinit init_thread_xstate(void)
*/

if (!HAVE_HWFP) {
+ /*
+ * 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);
-#ifdef CONFIG_X86_32
else
xstate_size = sizeof(struct i387_fsave_struct);
-#endif
}

-#ifdef CONFIG_X86_64
/*
* Called at bootup to set up the initial FPU state that is later cloned
* into all processes.
@@ -87,12 +90,21 @@ static void __cpuinit init_thread_xstate(void)

void __cpuinit fpu_init(void)
{
- unsigned long oldcr0 = read_cr0();
-
- set_in_cr4(X86_CR4_OSFXSR);
- set_in_cr4(X86_CR4_OSXMMEXCPT);
+ unsigned long cr0;
+ unsigned long cr4_mask = 0;

- write_cr0(oldcr0 & ~(X86_CR0_TS|X86_CR0_EM)); /* clear TS and EM */
+ if (cpu_has_fxsr)
+ cr4_mask |= X86_CR4_OSFXSR;
+ if (cpu_has_xmm)
+ cr4_mask |= X86_CR4_OSXMMEXCPT;
+ if (cr4_mask)
+ set_in_cr4(cr4_mask);
+
+ cr0 = read_cr0();
+ cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
+ if (!HAVE_HWFP)
+ cr0 |= X86_CR0_EM;
+ write_cr0(cr0);

if (!smp_processor_id())
init_thread_xstate();
@@ -103,24 +115,12 @@ void __cpuinit fpu_init(void)
clear_used_math();
}

-#else /* CONFIG_X86_64 */
-
-void __cpuinit fpu_init(void)
-{
- if (!smp_processor_id())
- init_thread_xstate();
-}
-
-#endif /* CONFIG_X86_32 */
-
void fpu_finit(struct fpu *fpu)
{
-#ifdef CONFIG_X86_32
if (!HAVE_HWFP) {
finit_soft_fpu(&fpu->state->soft);
return;
}
-#endif

if (cpu_has_fxsr) {
struct i387_fxsave_struct *fx = &fpu->state->fxsave;
@@ -385,19 +385,17 @@ convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
#ifdef CONFIG_X86_64
env->fip = fxsave->rip;
env->foo = fxsave->rdp;
+ /*
+ * should be actually ds/cs at fpu exception time, but
+ * that information is not available in 64bit mode.
+ */
+ env->fcs = task_pt_regs(tsk)->cs;
if (tsk == current) {
- /*
- * should be actually ds/cs at fpu exception time, but
- * that information is not available in 64bit mode.
- */
- asm("mov %%ds, %[fos]" : [fos] "=r" (env->fos));
- asm("mov %%cs, %[fcs]" : [fcs] "=r" (env->fcs));
+ savesegment(ds, env->fos);
} else {
- struct pt_regs *regs = task_pt_regs(tsk);
-
- env->fos = 0xffff0000 | tsk->thread.ds;
- env->fcs = regs->cs;
+ env->fos = tsk->thread.ds;
}
+ env->fos |= 0xffff0000;
#else
env->fip = fxsave->fip;
env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3d9ea53..b3d7a3a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -424,7 +424,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
load_TLS(next, cpu);

/* Must be after DS reload */
- unlazy_fpu(prev_p);
+ __unlazy_fpu(prev_p);

/* Make sure cpu is ready for new context */
if (preload_fpu)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 60788de..d439685 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -776,21 +776,10 @@ asmlinkage void math_state_restore(void)
}
EXPORT_SYMBOL_GPL(math_state_restore);

-#ifndef CONFIG_MATH_EMULATION
-void math_emulate(struct math_emu_info *info)
-{
- printk(KERN_EMERG
- "math-emulation not enabled and no coprocessor found.\n");
- printk(KERN_EMERG "killing %s.\n", current->comm);
- force_sig(SIGFPE, current);
- schedule();
-}
-#endif /* CONFIG_MATH_EMULATION */
-
dotraplinkage void __kprobes
do_device_not_available(struct pt_regs *regs, long error_code)
{
-#ifdef CONFIG_X86_32
+#ifdef CONFIG_MATH_EMULATION
if (read_cr0() & X86_CR0_EM) {
struct math_emu_info info = { };

@@ -798,12 +787,12 @@ do_device_not_available(struct pt_regs *regs, long error_code)

info.regs = regs;
math_emulate(&info);
- } else {
- math_state_restore(); /* interrupts still off */
- conditional_sti(regs);
+ return;
}
-#else
- math_state_restore();
+#endif
+ math_state_restore(); /* interrupts still off */
+#ifdef CONFIG_X86_32
+ conditional_sti(regs);
#endif
}

@@ -881,18 +870,6 @@ void __init trap_init(void)
#endif

#ifdef CONFIG_X86_32
- if (cpu_has_fxsr) {
- printk(KERN_INFO "Enabling fast FPU save and restore... ");
- set_in_cr4(X86_CR4_OSFXSR);
- printk("done.\n");
- }
- if (cpu_has_xmm) {
- printk(KERN_INFO
- "Enabling unmasked SIMD FPU exception support... ");
- set_in_cr4(X86_CR4_OSXMMEXCPT);
- printk("done.\n");
- }
-
set_system_trap_gate(SYSCALL_VECTOR, &system_call);
set_bit(SYSCALL_VECTOR, used_vectors);
#endif
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