Commit e8a496ac authored by Suresh Siddha's avatar Suresh Siddha Committed by Thomas Gleixner
Browse files

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: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Cc: hpa@zytor.com
Cc: mingo@elte.hu
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5c1ea082

arch/x86/kernel/i387.c

+29 −15
Original line number Diff line number Diff line
@@ -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);
@@ -474,10 +488,9 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf) 
int restore_i387_ia32(struct _fpstate_ia32 __user *buf)

{

	int err;



	if (HAVE_HWFP) {

	struct task_struct *tsk = current;



	if (HAVE_HWFP)

		clear_fpu(tsk);



	if (!used_math()) {
@@ -486,6 +499,7 @@ int restore_i387_ia32(struct _fpstate_ia32 __user *buf) 
			return err;

	}



	if (HAVE_HWFP) {

		if (cpu_has_fxsr)

			err = restore_i387_fxsave(buf);

		else

arch/x86/math-emu/fpu_entry.c

+8 −5
Original line number Diff line number Diff line
@@ -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;

include/asm-x86/i387.h

+2 −0
Original line number Diff line number Diff line
@@ -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");

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