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[MIPS] FPU ownership management & preemption fixes 

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
hifive-unleashed-5.1
Atsushi Nemoto 2007-03-10 01:07:45 +09:00 committed by Ralf Baechle
parent c6a2f46793
commit 53dc80287d
10 changed files with 126 additions and 105 deletions
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10
arch/mips/kernel/r2300_switch.S
View File

@ -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.

10
arch/mips/kernel/r4k_switch.S
View File

@ -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

29
arch/mips/kernel/signal.c
View File

@ -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;
}

29
arch/mips/kernel/signal32.c
View File

@ -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;
}

84
arch/mips/kernel/traps.c
View File

@ -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)
{

8
arch/mips/math-emu/kernel_linkage.c
View File

@ -51,7 +51,7 @@ void fpu_emulator_init_fpu(void)
* with appropriate macros from uaccess.h
*/
int fpu_emulator_save_context(struct sigcontext *sc)
int fpu_emulator_save_context(struct sigcontext __user *sc)
{
int i;
int err = 0;
@ -65,7 +65,7 @@ int fpu_emulator_save_context(struct sigcontext *sc)
return err;
}
int fpu_emulator_restore_context(struct sigcontext *sc)
int fpu_emulator_restore_context(struct sigcontext __user *sc)
{
int i;
int err = 0;
@ -84,7 +84,7 @@ int fpu_emulator_restore_context(struct sigcontext *sc)
* This is the o32 version
*/
int fpu_emulator_save_context32(struct sigcontext32 *sc)
int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
{
int i;
int err = 0;
@ -98,7 +98,7 @@ int fpu_emulator_save_context32(struct sigcontext32 *sc)
return err;
}
int fpu_emulator_restore_context32(struct sigcontext32 *sc)
int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
{
int i;
int err = 0;

3
include/asm-mips/cpu-features.h
View File

@ -40,6 +40,9 @@
#endif
#ifndef cpu_has_fpu
#define cpu_has_fpu (current_cpu_data.options & MIPS_CPU_FPU)
#define raw_cpu_has_fpu (raw_current_cpu_data.options & MIPS_CPU_FPU)
#else
#define raw_cpu_has_fpu cpu_has_fpu
#endif
#ifndef cpu_has_32fpr
#define cpu_has_32fpr (cpu_data[0].options & MIPS_CPU_32FPR)

1
include/asm-mips/cpu-info.h
View File

@ -87,6 +87,7 @@ struct cpuinfo_mips {
extern struct cpuinfo_mips cpu_data[];
#define current_cpu_data cpu_data[smp_processor_id()]
#define raw_current_cpu_data cpu_data[raw_smp_processor_id()]
extern void cpu_probe(void);
extern void cpu_report(void);

56
include/asm-mips/fpu.h
View File

@ -27,11 +27,11 @@
struct sigcontext;
struct sigcontext32;
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 (*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 void fpu_emulator_init_fpu(void);
extern void _init_fpu(void);
@ -68,6 +68,8 @@ do { \
/* We don't care about the c0 hazard here */ \
} while (0)
#define __fpu_enabled() (read_c0_status() & ST0_CU1)
#define enable_fpu() \
do { \
if (cpu_has_fpu) \
@ -93,31 +95,47 @@ static inline int is_fpu_owner(void)
return cpu_has_fpu && __is_fpu_owner();
}
static inline void own_fpu(void)
static inline void __own_fpu(void)
{
if (cpu_has_fpu) {
__enable_fpu();
KSTK_STATUS(current) |= ST0_CU1;
set_thread_flag(TIF_USEDFPU);
}
__enable_fpu();
KSTK_STATUS(current) |= ST0_CU1;
set_thread_flag(TIF_USEDFPU);
}
static inline void lose_fpu(void)
static inline void own_fpu(int restore)
{
if (cpu_has_fpu) {
preempt_disable();
if (cpu_has_fpu && !__is_fpu_owner()) {
__own_fpu();
if (restore)
_restore_fp(current);
}
preempt_enable();
}
static inline void lose_fpu(int save)
{
preempt_disable();
if (is_fpu_owner()) {
if (save)
_save_fp(current);
KSTK_STATUS(current) &= ~ST0_CU1;
clear_thread_flag(TIF_USEDFPU);
__disable_fpu();
}
preempt_enable();
}
static inline void init_fpu(void)
{
preempt_disable();
if (cpu_has_fpu) {
__own_fpu();
_init_fpu();
} else {
fpu_emulator_init_fpu();
}
preempt_enable();
}
static inline void save_fp(struct task_struct *tsk)
@ -144,4 +162,18 @@ static inline fpureg_t *get_fpu_regs(struct task_struct *tsk)
return tsk->thread.fpu.fpr;
}
static inline void enable_fp_in_kernel(void)
{
set_thread_flag(TIF_ALLOW_FP_IN_KERNEL);
/* make sure CU1 and FPU ownership are consistent */
if (!__is_fpu_owner() && __fpu_enabled())
__disable_fpu();
}
static inline void disable_fp_in_kernel(void)
{
BUG_ON(!__is_fpu_owner() && __fpu_enabled());
clear_thread_flag(TIF_ALLOW_FP_IN_KERNEL);
}
#endif /* _ASM_FPU_H */

1
include/asm-mips/thread_info.h
View File

@ -119,6 +119,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 18
#define TIF_FREEZE 19
#define TIF_ALLOW_FP_IN_KERNEL 20
#define TIF_SYSCALL_TRACE 31 /* syscall trace active */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)