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x86: fix broken math-emu with lazy allocation of fpu area 

Fix the math emulation that got broken with the recent lazy allocation of FPU
area. init_fpu() need to be added for the math-emulation path aswell
for the FPU area allocation.

math emulation enabled kernel booted fine with this, in the presence
of "no387 nofxsr" boot param.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: hpa@zytor.com
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Suresh Siddha 2008-05-23 16:26:37 -07:00 committed by Thomas Gleixner
parent 5c1ea08215
commit e8a496ac8c
3 changed files with 39 additions and 20 deletions
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44
arch/x86/kernel/i387.c
View File

@ -56,6 +56,11 @@ void __cpuinit mxcsr_feature_mask_init(void)
void __init init_thread_xstate(void)
{
if (!HAVE_HWFP) {
xstate_size = sizeof(struct i387_soft_struct);
return;
}
if (cpu_has_fxsr)
xstate_size = sizeof(struct i387_fxsave_struct);
#ifdef CONFIG_X86_32
@ -94,7 +99,7 @@ void __cpuinit fpu_init(void)
int init_fpu(struct task_struct *tsk)
{
if (tsk_used_math(tsk)) {
if (tsk == current)
if (HAVE_HWFP && tsk == current)
unlazy_fpu(tsk);
return 0;
}
@ -109,6 +114,15 @@ int init_fpu(struct task_struct *tsk)
return -ENOMEM;
}
#ifdef CONFIG_X86_32
if (!HAVE_HWFP) {
memset(tsk->thread.xstate, 0, xstate_size);
finit();
set_stopped_child_used_math(tsk);
return 0;
}
#endif
if (cpu_has_fxsr) {
struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
@ -330,13 +344,13 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env;
int ret;
if (!HAVE_HWFP)
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
ret = init_fpu(target);
if (ret)
return ret;
if (!HAVE_HWFP)
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
if (!cpu_has_fxsr) {
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->fsave, 0,
@ -360,15 +374,15 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env;
int ret;
if (!HAVE_HWFP)
return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
ret = init_fpu(target);
if (ret)
return ret;
set_stopped_child_used_math(target);
if (!HAVE_HWFP)
return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
if (!cpu_has_fxsr) {
return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.xstate->fsave, 0, -1);
@ -474,18 +488,18 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
int restore_i387_ia32(struct _fpstate_ia32 __user *buf)
{
int err;
struct task_struct *tsk = current;
if (HAVE_HWFP) {
struct task_struct *tsk = current;
if (HAVE_HWFP)
clear_fpu(tsk);
if (!used_math()) {
err = init_fpu(tsk);
if (err)
return err;
}
if (!used_math()) {
err = init_fpu(tsk);
if (err)
return err;
}
if (HAVE_HWFP) {
if (cpu_has_fxsr)
err = restore_i387_fxsave(buf);
else

13
arch/x86/math-emu/fpu_entry.c
View File

@ -30,6 +30,7 @@
#include <asm/uaccess.h>
#include <asm/desc.h>
#include <asm/user.h>
#include <asm/i387.h>
#include "fpu_system.h"
#include "fpu_emu.h"
@ -146,6 +147,13 @@ asmlinkage void math_emulate(long arg)
unsigned long code_limit = 0; /* Initialized to stop compiler warnings */
struct desc_struct code_descriptor;
if (!used_math()) {
if (init_fpu(current)) {
do_group_exit(SIGKILL);
return;
}
}
#ifdef RE_ENTRANT_CHECKING
if (emulating) {
printk("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
@ -153,11 +161,6 @@ asmlinkage void math_emulate(long arg)
RE_ENTRANT_CHECK_ON;
#endif /* RE_ENTRANT_CHECKING */
if (!used_math()) {
finit();
set_used_math();
}
SETUP_DATA_AREA(arg);
FPU_ORIG_EIP = FPU_EIP;

2
include/asm-x86/i387.h
View File

@ -193,6 +193,8 @@ static inline int restore_i387(struct _fpstate __user *buf)
#else /* CONFIG_X86_32 */
extern void finit(void);
static inline void tolerant_fwait(void)
{
asm volatile("fnclex ; fwait");