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Fix sparc TIF_USEDFPU flag atomicity

PATCH In review Mathieu Desnoyers 3 participants 6 messages Mar 10, 2007 SPARC + UltraSPARC (sparc/sparc64)

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Mathieu Desnoyers

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#0 lore raw

PATCH 1/1 Fix sparc TIF_USEDFPU flag atomicity

Fix sparc TIF_USEDFPU flag atomicity

Non atomic update of TIF can be very dangerous, except at thread structure creation time. Here I standardize the TIF_USEDFPU usage of the sparc arch. This fix addresses the issue with *_ti_thread_flag().

Applies on 2.6.20.

Signed-off-by Mathieu Desnoyers <[email protected]>
arch/sparc/kernel/process.c +9 -8
@@ -348,7 +348,7 @@ void exit_thread(void)
 #ifndef CONFIG_SMP
 	if(last_task_used_math = current) {
 #else
-	if(current_thread_info()->flags & _TIF_USEDFPU) {
+	if(test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
 #endif
 		/* Keep process from leaving FPU in a bogon state. */
 		put_psr(get_psr() | PSR_EF);

@@ -357,7 +357,7 @@ void exit_thread(void)
 #ifndef CONFIG_SMP
 		last_task_used_math = NULL;
 #else
-		current_thread_info()->flags &= ~_TIF_USEDFPU;
+		clear_ti_thread_flag(current_thread_info(), TIF_USEDFPU);
 #endif
 	}
 }

@@ -371,7 +371,7 @@ void flush_thread(void)
 #ifndef CONFIG_SMP
 	if(last_task_used_math = current) {
 #else
-	if(current_thread_info()->flags & _TIF_USEDFPU) {
+	if(test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
 #endif
 		/* Clean the fpu. */
 		put_psr(get_psr() | PSR_EF);

@@ -380,7 +380,7 @@ void flush_thread(void)
 #ifndef CONFIG_SMP
 		last_task_used_math = NULL;
 #else
-		current_thread_info()->flags &= ~_TIF_USEDFPU;
+		clear_ti_thread_flag(current_thread_info(), TIF_USEDFPU);
 #endif
 	}
 

@@ -466,13 +466,13 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
 #ifndef CONFIG_SMP
 	if(last_task_used_math = current) {
 #else
-	if(current_thread_info()->flags & _TIF_USEDFPU) {
+	if(test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
 #endif
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&p->thread.float_regs[0], &p->thread.fsr,
 		       &p->thread.fpqueue[0], &p->thread.fpqdepth);
 #ifdef CONFIG_SMP
-		current_thread_info()->flags &= ~_TIF_USEDFPU;
+		clear_ti_thread_flag(current_thread_info(), TIF_USEDFPU);
 #endif
 	}
 

@@ -609,13 +609,14 @@ int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
 		return 1;
 	}
 #ifdef CONFIG_SMP
-	if (current_thread_info()->flags & _TIF_USEDFPU) {
+	if (test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
 		if (regs != NULL) {
 			regs->psr &= ~(PSR_EF);
-			current_thread_info()->flags &= ~(_TIF_USEDFPU);
+			clear_ti_thread_flag(current_thread_info(),
+				TIF_USEDFPU);
 		}
 	}
 #else
arch/sparc/kernel/traps.c +3 -3
index 6a70d21..8ec8d08 100644
@@ -259,7 +259,7 @@ void do_fpd_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 	} else {
 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
 	}
-	current_thread_info()->flags |= _TIF_USEDFPU;
+	set_ti_thread_flag(current_thread_info(), TIF_USEDFPU);
 #endif
 }
 

@@ -290,7 +290,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 #ifndef CONFIG_SMP
 	if(!fpt) {
 #else
-        if(!(task_thread_info(fpt)->flags & _TIF_USEDFPU)) {
+        if(!test_ti_thread_flag(task_thread_info(fpt), TIF_USEDFPU)) {
 #endif
 		fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth);
 		regs->psr &= ~PSR_EF;

@@ -333,7 +333,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 	/* nope, better SIGFPE the offending process... */
 	       
 #ifdef CONFIG_SMP
-	task_thread_info(fpt)->flags &= ~_TIF_USEDFPU;
+	clear_tsk_thread_flag(fpt, TIF_USEDFPU);
 #endif
 	if(psr & PSR_PS) {
 		/* The first fsr store/load we tried trapped,
Signature · 3 lines
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
#1 lore raw

Review void exit_thread(void) · line 354

Quoted 9 lines · Mathieu Desnoyers
(quoted diff) +1 -1
@@ -348,7 +348,7 @@ void exit_thread(void)
 #ifndef CONFIG_SMP
 	if(last_task_used_math = current) {
 #else
-	if(current_thread_info()->flags & _TIF_USEDFPU) {
+	if(test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
 #endif
 		/* Keep process from leaving FPU in a bogon state. */
 		put_psr(get_psr() | PSR_EF);

Oh dear. Could we bit a bit more idiomatic here? For instance, something like:

Index: linux-2.6/arch/sparc/kernel/process.c
=================================--- linux-2.6.orig/arch/sparc/kernel/process.c 2007-03-09 23:24:12.934472032 -0800
+++ linux-2.6/arch/sparc/kernel/process.c 2007-03-09 23:29:26.592346376 -0800
@@ -348,7 +348,7 @@
#ifndef CONFIG_SMP
if(last_task_used_math = current) {
#else
- if(current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
#endif
/* Keep process from leaving FPU in a bogon state. */ put_psr(get_psr() | PSR_EF);
@@ -357,7 +357,7 @@
#ifndef CONFIG_SMP
last_task_used_math = NULL;
#else
- current_thread_info()->flags &= ~_TIF_USEDFPU;
+ clear_thread_flag(TIF_USEDFPU);
#endif
}
}
@@ -371,7 +371,7 @@
#ifndef CONFIG_SMP
if(last_task_used_math = current) {
#else
- if(current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
#endif
/* Clean the fpu. */
put_psr(get_psr() | PSR_EF);
@@ -380,7 +380,7 @@
#ifndef CONFIG_SMP
last_task_used_math = NULL;
#else
- current_thread_info()->flags &= ~_TIF_USEDFPU;
+ clear_thread_flag(TIF_USEDFPU);
#endif
}

@@ -466,13 +466,13 @@
#ifndef CONFIG_SMP
if(last_task_used_math = current) {
#else
- if(current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
#endif
put_psr(get_psr() | PSR_EF); fpsave(&p->thread.float_regs[0], &p->thread.fsr,
&p->thread.fpqueue[0], &p->thread.fpqdepth);
#ifdef CONFIG_SMP
- current_thread_info()->flags &= ~_TIF_USEDFPU;
+ clear_thread_flag(TIF_USEDFPU);
#endif
}

@@ -609,13 +609,13 @@
return 1;
}
#ifdef CONFIG_SMP
- if (current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
put_psr(get_psr() | PSR_EF); fpsave(&current->thread.float_regs[0], &current->thread.fsr,
&current->thread.fpqueue[0], &current->thread.fpqdepth);
if (regs != NULL) {
regs->psr &= ~(PSR_EF);
- current_thread_info()->flags &= ~(_TIF_USEDFPU);
+ clear_thread_flag(TIF_USEDFPU);
}
}
#else
Index: linux-2.6/arch/sparc/kernel/traps.c
=================================--- linux-2.6.orig/arch/sparc/kernel/traps.c 2007-03-09 23:40:33.994379450 -0800
+++ linux-2.6/arch/sparc/kernel/traps.c 2007-03-09 23:44:07.910569839 -0800
@@ -259,7 +259,7 @@
} else {
fpload(&current->thread.float_regs[0], &current->thread.fsr);
}
- current_thread_info()->flags |= _TIF_USEDFPU;
+ set_thread_flag(TIF_USEDFPU);
#endif
}

@@ -290,7 +290,7 @@
#ifndef CONFIG_SMP
if(!fpt) {
#else
- if(!(task_thread_info(fpt)->flags & _TIF_USEDFPU)) {
+ if (!test_tsk_thread_flag(fpt, TIF_USEDFPU)) {
#endif
fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth); regs->psr &= ~PSR_EF;
@@ -333,7 +333,7 @@
/* nope, better SIGFPE the offending process... */

#ifdef CONFIG_SMP
- task_thread_info(fpt)->flags &= ~_TIF_USEDFPU;
+ clear_tsk_thread_flag(fpt, TIF_USEDFPU);
#endif
if(psr & PSR_PS) {
/* The first fsr store/load we tried trapped,

maintainer
#2 lore raw

From: William Lee Irwin III <[email protected]>
Date: Sat, 10 Mar 2007 00:26:46 -0800

Quoted 5 lines · Mathieu Desnoyers
Quoted 4 lines
(quoted diff) +0 -0
@@ -348,7 +348,7 @@ void exit_thread(void)
 #ifndef CONFIG_SMP
 	if(last_task_used_math = current) {
 #else
Quoted 8 lines

Review void exit_thread(void) · line 354

Quoted 5 lines
(quoted diff) +1 -1
-	if(current_thread_info()->flags & _TIF_USEDFPU) {
+	if(test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
 #endif
 		/* Keep process from leaving FPU in a bogon state. */
 		put_psr(get_psr() | PSR_EF);

Oh dear. Could we bit a bit more idiomatic here? For instance, something like:

Ok I pulled the sparc32 patch back out until there is some consensus here :)

#3 lore raw
Quoted 2 lines · William Lee Irwin III
Quoted 2 lines

Oh dear. Could we bit a bit more idiomatic here? For instance, something like:

Quoted 2 lines · David Miller

Ok I pulled the sparc32 patch back out until there is some consensus here :)

It's just a minor touch-up. If Mathieu is okay with it, I'd rather leave him as the author and just send along an Acked-by: with it. I'm not terribly attached to it, either. I just choked on my soda when I saw set_ti_thread_flag(task_thread_info(fpt), TI_USEDFPU) etc. go by. (Which reminds me, I really need to figure out how to consolidate the UP and SMP cases for all this.)

-- wli

author
#4 lore raw
Quoted 16 lines · * William Lee Irwin III ([email protected]) wrote:
Quoted 2 lines · William Lee Irwin III
Quoted 2 lines

Oh dear. Could we bit a bit more idiomatic here? For instance, something like:

Quoted 2 lines · David Miller

Ok I pulled the sparc32 patch back out until there is some consensus here :)

It's just a minor touch-up. If Mathieu is okay with it, I'd rather leave him as the author and just send along an Acked-by: with it. I'm not terribly attached to it, either. I just choked on my soda when I saw set_ti_thread_flag(task_thread_info(fpt), TI_USEDFPU) etc. go by. (Which reminds me, I really need to figure out how to consolidate the UP and SMP cases for all this.)

Quoted 1 line

-- wli

Hello,

William's implementation is indeed neater than mine. So the consensus goes to his patch as far as I'm concerned.

Mathieu

Signature · 3 lines
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68