On Sat, 10 Mar 2007 01:32:48 +0900 (JST), Atsushi Nemoto <anemo@xxxxxxxxxxxxx> wrote:
> Currently preempt_disable/preempt_enable are scattered in FPU
> ownership management code. This patch makes own_fpu() and lost_fpu()
> can save/restore FPU context in itself and make these functions (and
> init_fpu() too) preempt-proof. This makes the FPU management codes
> much readable. Also this patch introduce raw_cpu_has_fpu macro which
> is to be used if the caller did not need atomic context.
Sorry, I had broken this patch when updating. Here is a correct one.
Subject: [PATCH] Cleanup FPU ownership management
Currently preempt_disable/preempt_enable are scattered in FPU
ownership management code. This patch makes own_fpu() and lose_fpu()
can save/restore FPU context in itself and make these functions (and
init_fpu() too) preempt-proof. This makes the FPU management codes
much readable. Also this patch introduce raw_cpu_has_fpu macro which
is to be used if the caller did not need atomic context.
Signed-off-by: Atsushi Nemoto <anemo@xxxxxxxxxxxxx>
---
arch/mips/kernel/signal.c | 17 +++--------------
arch/mips/kernel/signal32.c | 17 +++--------------
arch/mips/kernel/traps.c | 33 ++++++++-------------------------
include/asm-mips/cpu-features.h | 3 +++
include/asm-mips/cpu-info.h | 1 +
include/asm-mips/fpu.h | 30 +++++++++++++++++++++++-------
6 files changed, 41 insertions(+), 60 deletions(-)
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index c4ef270..5b50569 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -111,14 +111,7 @@ int setup_sigcontext(struct pt_regs *reg
* Save FPU state to signal context. Signal handler
* will "inherit" current FPU state.
*/
- preempt_disable();
-
- if (!is_fpu_owner()) {
- own_fpu();
- restore_fp(current);
- }
-
- preempt_enable();
+ own_fpu(1);
enable_fp_in_kernel();
err |= save_fp_context(sc);
disable_fp_in_kernel();
@@ -190,20 +183,16 @@ int restore_sigcontext(struct pt_regs *r
err |= __get_user(used_math, &sc->sc_used_math);
conditional_used_math(used_math);
- preempt_disable();
-
if (used_math()) {
/* restore fpu context if we have used it before */
- own_fpu();
- preempt_enable();
+ 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();
- preempt_enable();
+ lose_fpu(0);
}
return err;
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c
index cf5bbe0..c90c8cf 100644
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -207,14 +207,7 @@ static int setup_sigcontext32(struct pt_
* Save FPU state to signal context. Signal handler
* will "inherit" current FPU state.
*/
- preempt_disable();
-
- if (!is_fpu_owner()) {
- own_fpu();
- restore_fp(current);
- }
-
- preempt_enable();
+ own_fpu(1);
enable_fp_in_kernel();
err |= save_fp_context32(sc);
disable_fp_in_kernel();
@@ -264,20 +257,16 @@ static int restore_sigcontext32(struct p
err |= __get_user(used_math, &sc->sc_used_math);
conditional_used_math(used_math);
- preempt_disable();
-
if (used_math()) {
/* restore fpu context if we have used it before */
- own_fpu();
- preempt_enable();
+ 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();
- preempt_enable();
+ lose_fpu(0);
}
return err;
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 2aaf76b..31c897b 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -620,15 +620,8 @@ asmlinkage void do_fpe(struct pt_regs *r
* register operands before invoking the emulator, which seems
* a bit extreme for what should be an infrequent event.
*/
- preempt_disable();
-
- /* We might have lost fpu before disabling preempt... */
- if (is_fpu_owner())
- 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, ¤t->thread.fpu, 1);
@@ -639,13 +632,8 @@ asmlinkage void do_fpe(struct pt_regs *r
*/
current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X;
- preempt_disable();
-
- own_fpu(); /* Using the FPU again. */
/* Restore the hardware register state */
- restore_fp(current);
-
- preempt_enable();
+ own_fpu(1); /* Using the FPU again. */
/* If something went wrong, signal */
if (sig)
@@ -787,18 +775,14 @@ asmlinkage void do_cpu(struct pt_regs *r
if (!test_thread_flag(TIF_ALLOW_FP_IN_KERNEL))
die_if_kernel("do_cpu invoked from kernel context!",
regs);
- preempt_disable();
-
- own_fpu();
- if (used_math()) { /* Using the FPU again. */
- restore_fp(current);
- } else { /* First time FPU user. */
+ 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)
@@ -812,7 +796,6 @@ asmlinkage void do_cpu(struct pt_regs *r
}
} else {
int sig;
- preempt_enable();
sig = fpu_emulator_cop1Handler(regs,
¤t->thread.fpu, 0);
if (sig)
@@ -1278,14 +1261,14 @@ extern asmlinkage int fpu_emulator_resto
#ifdef CONFIG_SMP
static int smp_save_fp_context(struct sigcontext *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)
{
- return cpu_has_fpu
+ return raw_cpu_has_fpu
? _restore_fp_context(sc)
: fpu_emulator_restore_context(sc);
}
diff --git a/include/asm-mips/cpu-features.h b/include/asm-mips/cpu-features.h
index eadca26..5e4bed1 100644
--- a/include/asm-mips/cpu-features.h
+++ b/include/asm-mips/cpu-features.h
@@ -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)
diff --git a/include/asm-mips/cpu-info.h b/include/asm-mips/cpu-info.h
index 610d0cd..22fe845 100644
--- a/include/asm-mips/cpu-info.h
+++ b/include/asm-mips/cpu-info.h
@@ -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);
diff --git a/include/asm-mips/fpu.h b/include/asm-mips/fpu.h
index 40536a2..dfecb7b 100644
--- a/include/asm-mips/fpu.h
+++ b/include/asm-mips/fpu.h
@@ -95,31 +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 own_fpu(int restore)
+{
+ preempt_disable();
+ if (cpu_has_fpu && !__is_fpu_owner()) {
+ __own_fpu();
+ if (restore)
+ _restore_fp(current);
}
+ preempt_enable();
}
-static inline void lose_fpu(void)
+static inline void lose_fpu(int save)
{
- if (cpu_has_fpu) {
+ 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)
