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Commit 53dc8028 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
Browse files

[MIPS] FPU ownership management & preemption fixes 



Signed-off-by: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent c6a2f467

arch/mips/kernel/r2300_switch.S

+6 −4
Original line number Diff line number Diff line
@@ -49,8 +49,7 @@ LEAF(resume) 
#ifndef CONFIG_CPU_HAS_LLSC

	sw      zero, ll_bit

#endif

	mfc0	t1, CP0_STATUS

	sw	t1, THREAD_STATUS(a0)

	mfc0	t2, CP0_STATUS

	cpu_save_nonscratch a0

	sw	ra, THREAD_REG31(a0)
@@ -60,8 +59,8 @@ LEAF(resume) 
	lw	t3, TASK_THREAD_INFO(a0)

	lw	t0, TI_FLAGS(t3)

	li	t1, _TIF_USEDFPU

	and	t2, t0, t1

	beqz	t2, 1f

	and	t1, t0

	beqz	t1, 1f

	nor	t1, zero, t1



	and	t0, t0, t1
@@ -74,10 +73,13 @@ LEAF(resume) 
	li	t1, ~ST0_CU1

	and	t0, t0, t1

	sw	t0, ST_OFF(t3)

	/* clear thread_struct CU1 bit */

	and	t2, t1



	fpu_save_single a0, t0			# clobbers t0



1:

	sw	t2, THREAD_STATUS(a0)

	/*

	 * The order of restoring the registers takes care of the race

	 * updating $28, $29 and kernelsp without disabling ints.

arch/mips/kernel/r4k_switch.S

+6 −4
Original line number Diff line number Diff line
@@ -48,8 +48,7 @@ 
#ifndef CONFIG_CPU_HAS_LLSC

	sw	zero, ll_bit

#endif

	mfc0	t1, CP0_STATUS

	LONG_S	t1, THREAD_STATUS(a0)

	mfc0	t2, CP0_STATUS

	cpu_save_nonscratch a0

	LONG_S	ra, THREAD_REG31(a0)
@@ -59,8 +58,8 @@ 
	PTR_L	t3, TASK_THREAD_INFO(a0)

	LONG_L	t0, TI_FLAGS(t3)

	li	t1, _TIF_USEDFPU

	and	t2, t0, t1

	beqz	t2, 1f

	and	t1, t0

	beqz	t1, 1f

	nor	t1, zero, t1



	and	t0, t0, t1
@@ -73,10 +72,13 @@ 
	li	t1, ~ST0_CU1

	and	t0, t0, t1

	LONG_S	t0, ST_OFF(t3)

	/* clear thread_struct CU1 bit */

	and	t2, t1



	fpu_save_double a0 t0 t1		# c0_status passed in t0

						# clobbers t1

1:

	LONG_S	t2, THREAD_STATUS(a0)



	/*

	 * The order of restoring the registers takes care of the race

arch/mips/kernel/signal.c

+12 −17
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 
{

	int err = 0;

	int i;

	unsigned int used_math;



	err |= __put_user(regs->cp0_epc, &sc->sc_pc);
@@ -104,22 +105,18 @@ int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 
		err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);

	}



	err |= __put_user(!!used_math(), &sc->sc_used_math);

	used_math = !!used_math();

	err |= __put_user(used_math, &sc->sc_used_math);



	if (used_math()) {

	if (used_math) {

		/*

		 * Save FPU state to signal context. Signal handler

		 * will "inherit" current FPU state.

		 */

		preempt_disable();



		if (!is_fpu_owner()) {

			own_fpu();

			restore_fp(current);

		}

		own_fpu(1);

		enable_fp_in_kernel();

		err |= save_fp_context(sc);



		preempt_enable();

		disable_fp_in_kernel();

	}

	return err;

}
@@ -188,20 +185,18 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 
	err |= __get_user(used_math, &sc->sc_used_math);

	conditional_used_math(used_math);



	preempt_disable();



	if (used_math()) {

	if (used_math) {

		/* restore fpu context if we have used it before */

		own_fpu();

		own_fpu(0);

		enable_fp_in_kernel();

		if (!err)

			err = check_and_restore_fp_context(sc);

		disable_fp_in_kernel();

	} else {

		/* signal handler may have used FPU.  Give it up. */

		lose_fpu();

		lose_fpu(0);

	}



	preempt_enable();



	return err;

}

arch/mips/kernel/signal32.c

+12 −17
Original line number Diff line number Diff line
@@ -181,6 +181,7 @@ static int setup_sigcontext32(struct pt_regs *regs, 
{

	int err = 0;

	int i;

	u32 used_math;



	err |= __put_user(regs->cp0_epc, &sc->sc_pc);
@@ -200,22 +201,18 @@ static int setup_sigcontext32(struct pt_regs *regs, 
		err |= __put_user(mflo3(), &sc->sc_lo3);

	}



	err |= __put_user(!!used_math(), &sc->sc_used_math);

	used_math = !!used_math();

	err |= __put_user(used_math, &sc->sc_used_math);



	if (used_math()) {

	if (used_math) {

		/*

		 * Save FPU state to signal context.  Signal handler

		 * will "inherit" current FPU state.

		 */

		preempt_disable();



		if (!is_fpu_owner()) {

			own_fpu();

			restore_fp(current);

		}

		own_fpu(1);

		enable_fp_in_kernel();

		err |= save_fp_context32(sc);



		preempt_enable();

		disable_fp_in_kernel();

	}

	return err;

}
@@ -262,20 +259,18 @@ static int restore_sigcontext32(struct pt_regs *regs, 
	err |= __get_user(used_math, &sc->sc_used_math);

	conditional_used_math(used_math);



	preempt_disable();



	if (used_math()) {

	if (used_math) {

		/* restore fpu context if we have used it before */

		own_fpu();

		own_fpu(0);

		enable_fp_in_kernel();

		if (!err)

			err = check_and_restore_fp_context32(sc);

		disable_fp_in_kernel();

	} else {

		/* signal handler may have used FPU.  Give it up. */

		lose_fpu();

		lose_fpu(0);

	}



	preempt_enable();



	return err;

}

arch/mips/kernel/traps.c

+37 −47
Original line number Diff line number Diff line
@@ -610,16 +610,6 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 
	if (fcr31 & FPU_CSR_UNI_X) {

		int sig;



		preempt_disable();



#ifdef CONFIG_PREEMPT

		if (!is_fpu_owner()) {

			/* We might lose fpu before disabling preempt... */

			own_fpu();

			BUG_ON(!used_math());

			restore_fp(current);

		}

#endif

		/*

		 * Unimplemented operation exception.  If we've got the full

		 * software emulator on-board, let's use it...
@@ -630,18 +620,12 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 
		 * register operands before invoking the emulator, which seems

		 * a bit extreme for what should be an infrequent event.

		 */

		save_fp(current);

		/* Ensure 'resume' not overwrite saved fp context again. */

		lose_fpu();



		preempt_enable();

		lose_fpu(1);



		/* Run the emulator */

		sig = fpu_emulator_cop1Handler (regs, &current->thread.fpu, 1);



		preempt_disable();



		own_fpu();	/* Using the FPU again.  */

		/*

		 * We can't allow the emulated instruction to leave any of

		 * the cause bit set in $fcr31.
@@ -649,9 +633,7 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 
		current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X;



		/* Restore the hardware register state */

		restore_fp(current);



		preempt_enable();

		own_fpu(1);	/* Using the FPU again.  */



		/* If something went wrong, signal */

		if (sig)
@@ -775,12 +757,11 @@ asmlinkage void do_cpu(struct pt_regs *regs) 
{

	unsigned int cpid;



	die_if_kernel("do_cpu invoked from kernel context!", regs);



	cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;



	switch (cpid) {

	case 0:

		die_if_kernel("do_cpu invoked from kernel context!", regs);

		if (!cpu_has_llsc)

			if (!simulate_llsc(regs))

				return;
@@ -791,21 +772,30 @@ asmlinkage void do_cpu(struct pt_regs *regs) 
		break;



	case 1:

		preempt_disable();



		own_fpu();

		if (used_math()) {	/* Using the FPU again.  */

			restore_fp(current);

		} else {			/* First time FPU user.  */

		if (!test_thread_flag(TIF_ALLOW_FP_IN_KERNEL))

			die_if_kernel("do_cpu invoked from kernel context!",

				      regs);

		if (used_math())	/* Using the FPU again.  */

			own_fpu(1);

		else {			/* First time FPU user.  */

			init_fpu();

			set_used_math();

		}



		if (cpu_has_fpu) {

			preempt_enable();

		if (raw_cpu_has_fpu) {

			if (test_thread_flag(TIF_ALLOW_FP_IN_KERNEL)) {

				local_irq_disable();

				if (cpu_has_fpu)

					regs->cp0_status |= ST0_CU1;

				/*

				 * We must return without enabling

				 * interrupts to ensure keep FPU

				 * ownership until resume.

				 */

				return;

			}

		} else {

			int sig;

			preempt_enable();

			sig = fpu_emulator_cop1Handler(regs,

						&current->thread.fpu, 0);

			if (sig)
@@ -1259,26 +1249,26 @@ static inline void mips_srs_init(void) 
/*

 * This is used by native signal handling

 */

asmlinkage int (*save_fp_context)(struct sigcontext *sc);

asmlinkage int (*restore_fp_context)(struct sigcontext *sc);

asmlinkage int (*save_fp_context)(struct sigcontext __user *sc);

asmlinkage int (*restore_fp_context)(struct sigcontext __user *sc);



extern asmlinkage int _save_fp_context(struct sigcontext *sc);

extern asmlinkage int _restore_fp_context(struct sigcontext *sc);

extern asmlinkage int _save_fp_context(struct sigcontext __user *sc);

extern asmlinkage int _restore_fp_context(struct sigcontext __user *sc);



extern asmlinkage int fpu_emulator_save_context(struct sigcontext *sc);

extern asmlinkage int fpu_emulator_restore_context(struct sigcontext *sc);

extern asmlinkage int fpu_emulator_save_context(struct sigcontext __user *sc);

extern asmlinkage int fpu_emulator_restore_context(struct sigcontext __user *sc);



#ifdef CONFIG_SMP

static int smp_save_fp_context(struct sigcontext *sc)

static int smp_save_fp_context(struct sigcontext __user *sc)

{

	return cpu_has_fpu

	return raw_cpu_has_fpu

	       ? _save_fp_context(sc)

	       : fpu_emulator_save_context(sc);

}



static int smp_restore_fp_context(struct sigcontext *sc)

static int smp_restore_fp_context(struct sigcontext __user *sc)

{

	return cpu_has_fpu

	return raw_cpu_has_fpu

	       ? _restore_fp_context(sc)

	       : fpu_emulator_restore_context(sc);

}
@@ -1306,14 +1296,14 @@ static inline void signal_init(void) 
/*

 * This is used by 32-bit signal stuff on the 64-bit kernel

 */

asmlinkage int (*save_fp_context32)(struct sigcontext32 *sc);

asmlinkage int (*restore_fp_context32)(struct sigcontext32 *sc);

asmlinkage int (*save_fp_context32)(struct sigcontext32 __user *sc);

asmlinkage int (*restore_fp_context32)(struct sigcontext32 __user *sc);



extern asmlinkage int _save_fp_context32(struct sigcontext32 *sc);

extern asmlinkage int _restore_fp_context32(struct sigcontext32 *sc);

extern asmlinkage int _save_fp_context32(struct sigcontext32 __user *sc);

extern asmlinkage int _restore_fp_context32(struct sigcontext32 __user *sc);



extern asmlinkage int fpu_emulator_save_context32(struct sigcontext32 *sc);

extern asmlinkage int fpu_emulator_restore_context32(struct sigcontext32 *sc);

extern asmlinkage int fpu_emulator_save_context32(struct sigcontext32 __user *sc);

extern asmlinkage int fpu_emulator_restore_context32(struct sigcontext32 __user *sc);



static inline void signal32_init(void)

{