Commit 5d38902c authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc: Add irqtrace support for 32-bit powerpc 



Based on initial work from: Dale Farnsworth <dale@farnsworth.org>

Add the low level irq tracing hooks for 32-bit powerpc needed
to enable full lockdep functionality.

The approach taken to deal with the code in entry_32.S is that
we don't trace all the transitions of MSR:EE when we just turn
it off to peek at TI_FLAGS without races. Only when we are
calling into C code or returning from exceptions with a state
that have changed from what lockdep thinks.

There's a little bugger though: If we take an exception that
keeps interrupts enabled (such as an alignment exception) while
interrupts are enabled, we will call trace_hardirqs_on() on the
way back spurriously. Not a big deal, but to get rid of it would
require remembering in pt_regs that the exception was one of the
type that kept interrupts enabled which we don't know at this
stage. (Well, we could test all cases for regs->trap but that
sucks too much).

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: default avatarKumar Gala <galak@kernel.crashing.org>
parent 04a85d12

arch/powerpc/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -62,7 +62,6 @@ config HAVE_LATENCYTOP_SUPPORT 


config TRACE_IRQFLAGS_SUPPORT

	bool

	depends on PPC64

	default y



config LOCKDEP_SUPPORT

arch/powerpc/include/asm/hw_irq.h

+10 −10
Original line number Diff line number Diff line
@@ -68,13 +68,13 @@ static inline int irqs_disabled_flags(unsigned long flags) 


#if defined(CONFIG_BOOKE)

#define SET_MSR_EE(x)	mtmsr(x)

#define local_irq_restore(flags)	__asm__ __volatile__("wrtee %0" : : "r" (flags) : "memory")

#define raw_local_irq_restore(flags)	__asm__ __volatile__("wrtee %0" : : "r" (flags) : "memory")

#else

#define SET_MSR_EE(x)	mtmsr(x)

#define local_irq_restore(flags)	mtmsr(flags)

#define raw_local_irq_restore(flags)	mtmsr(flags)

#endif



static inline void local_irq_disable(void)

static inline void raw_local_irq_disable(void)

{

#ifdef CONFIG_BOOKE

	__asm__ __volatile__("wrteei 0": : :"memory");
@@ -86,7 +86,7 @@ static inline void local_irq_disable(void) 
#endif

}



static inline void local_irq_enable(void)

static inline void raw_local_irq_enable(void)

{

#ifdef CONFIG_BOOKE

	__asm__ __volatile__("wrteei 1": : :"memory");
@@ -98,7 +98,7 @@ static inline void local_irq_enable(void) 
#endif

}



static inline void local_irq_save_ptr(unsigned long *flags)

static inline void raw_local_irq_save_ptr(unsigned long *flags)

{

	unsigned long msr;

	msr = mfmsr();
@@ -110,12 +110,12 @@ static inline void local_irq_save_ptr(unsigned long *flags) 
#endif

}



#define local_save_flags(flags)	((flags) = mfmsr())

#define local_irq_save(flags)	local_irq_save_ptr(&flags)

#define irqs_disabled()		((mfmsr() & MSR_EE) == 0)

#define raw_local_save_flags(flags)	((flags) = mfmsr())

#define raw_local_irq_save(flags)	raw_local_irq_save_ptr(&flags)

#define raw_irqs_disabled()		((mfmsr() & MSR_EE) == 0)

#define raw_irqs_disabled_flags(flags)	(((flags) & MSR_EE) == 0)



#define hard_irq_enable()	local_irq_enable()

#define hard_irq_disable()	local_irq_disable()

#define hard_irq_disable()		raw_local_irq_disable()



static inline int irqs_disabled_flags(unsigned long flags)

{

arch/powerpc/kernel/entry_32.S

+123 −4
Original line number Diff line number Diff line
@@ -191,11 +191,49 @@ transfer_to_handler_cont: 
	mflr	r9

	lwz	r11,0(r9)		/* virtual address of handler */

	lwz	r9,4(r9)		/* where to go when done */

#ifdef CONFIG_TRACE_IRQFLAGS

	lis	r12,reenable_mmu@h

	ori	r12,r12,reenable_mmu@l

	mtspr	SPRN_SRR0,r12

	mtspr	SPRN_SRR1,r10

	SYNC

	RFI

reenable_mmu:				/* re-enable mmu so we can */

	mfmsr	r10

	lwz	r12,_MSR(r1)

	xor	r10,r10,r12

	andi.	r10,r10,MSR_EE		/* Did EE change? */

	beq	1f



	/* Save handler and return address into the 2 unused words

	 * of the STACK_FRAME_OVERHEAD (sneak sneak sneak). Everything

	 * else can be recovered from the pt_regs except r3 which for

	 * normal interrupts has been set to pt_regs and for syscalls

	 * is an argument, so we temporarily use ORIG_GPR3 to save it

	 */

	stw	r9,8(r1)

	stw	r11,12(r1)

	stw	r3,ORIG_GPR3(r1)

	bl	trace_hardirqs_off

	lwz	r0,GPR0(r1)

	lwz	r3,ORIG_GPR3(r1)

	lwz	r4,GPR4(r1)

	lwz	r5,GPR5(r1)

	lwz	r6,GPR6(r1)

	lwz	r7,GPR7(r1)

	lwz	r8,GPR8(r1)

	lwz	r9,8(r1)

	lwz	r11,12(r1)

1:	mtctr	r11

	mtlr	r9

	bctr				/* jump to handler */

#else /* CONFIG_TRACE_IRQFLAGS */

	mtspr	SPRN_SRR0,r11

	mtspr	SPRN_SRR1,r10

	mtlr	r9

	SYNC

	RFI				/* jump to handler, enable MMU */

#endif /* CONFIG_TRACE_IRQFLAGS */



#if defined (CONFIG_6xx) || defined(CONFIG_E500)

4:	rlwinm	r12,r12,0,~_TLF_NAPPING
@@ -251,6 +289,31 @@ _GLOBAL(DoSyscall) 
#ifdef SHOW_SYSCALLS

	bl	do_show_syscall

#endif /* SHOW_SYSCALLS */

#ifdef CONFIG_TRACE_IRQFLAGS

	/* Return from syscalls can (and generally will) hard enable

	 * interrupts. You aren't supposed to call a syscall with

	 * interrupts disabled in the first place. However, to ensure

	 * that we get it right vs. lockdep if it happens, we force

	 * that hard enable here with appropriate tracing if we see

	 * that we have been called with interrupts off

	 */

	mfmsr	r11

	andi.	r12,r11,MSR_EE

	bne+	1f

	/* We came in with interrupts disabled, we enable them now */

	bl	trace_hardirqs_on

	mfmsr	r11

	lwz	r0,GPR0(r1)

	lwz	r3,GPR3(r1)

	lwz	r4,GPR4(r1)

	ori	r11,r11,MSR_EE

	lwz	r5,GPR5(r1)

	lwz	r6,GPR6(r1)

	lwz	r7,GPR7(r1)

	lwz	r8,GPR8(r1)

	mtmsr	r11

1:

#endif /* CONFIG_TRACE_IRQFLAGS */

	rlwinm	r10,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */

	lwz	r11,TI_FLAGS(r10)

	andi.	r11,r11,_TIF_SYSCALL_T_OR_A
@@ -275,6 +338,7 @@ ret_from_syscall: 
	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */

	/* disable interrupts so current_thread_info()->flags can't change */

	LOAD_MSR_KERNEL(r10,MSR_KERNEL)	/* doesn't include MSR_EE */

	/* Note: We don't bother telling lockdep about it */

	SYNC

	MTMSRD(r10)

	lwz	r9,TI_FLAGS(r12)
@@ -288,6 +352,19 @@ ret_from_syscall: 
	oris	r11,r11,0x1000	/* Set SO bit in CR */

	stw	r11,_CCR(r1)

syscall_exit_cont:

	lwz	r8,_MSR(r1)

#ifdef CONFIG_TRACE_IRQFLAGS

	/* If we are going to return from the syscall with interrupts

	 * off, we trace that here. It shouldn't happen though but we

	 * want to catch the bugger if it does right ?

	 */

	andi.	r10,r8,MSR_EE

	bne+	1f

	stw	r3,GPR3(r1)

	bl      trace_hardirqs_off

	lwz	r3,GPR3(r1)

1:

#endif /* CONFIG_TRACE_IRQFLAGS */

#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)

	/* If the process has its own DBCR0 value, load it up.  The internal

	   debug mode bit tells us that dbcr0 should be loaded. */
@@ -311,7 +388,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) 
	mtlr	r4

	mtcr	r5

	lwz	r7,_NIP(r1)

	lwz	r8,_MSR(r1)

	FIX_SRR1(r8, r0)

	lwz	r2,GPR2(r1)

	lwz	r1,GPR1(r1)
@@ -394,7 +470,9 @@ syscall_exit_work: 
	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)

	beq	ret_from_except



	/* Re-enable interrupts */

	/* Re-enable interrupts. There is no need to trace that with

	 * lockdep as we are supposed to have IRQs on at this point

	 */

	ori	r10,r10,MSR_EE

	SYNC

	MTMSRD(r10)
@@ -705,6 +783,7 @@ ret_from_except: 
	/* Hard-disable interrupts so that current_thread_info()->flags

	 * can't change between when we test it and when we return

	 * from the interrupt. */

	/* Note: We don't bother telling lockdep about it */

	LOAD_MSR_KERNEL(r10,MSR_KERNEL)

	SYNC			/* Some chip revs have problems here... */

	MTMSRD(r10)		/* disable interrupts */
@@ -744,11 +823,24 @@ resume_kernel: 
	beq+	restore

	andi.	r0,r3,MSR_EE	/* interrupts off? */

	beq	restore		/* don't schedule if so */

#ifdef CONFIG_TRACE_IRQFLAGS

	/* Lockdep thinks irqs are enabled, we need to call

	 * preempt_schedule_irq with IRQs off, so we inform lockdep

	 * now that we -did- turn them off already

	 */

	bl	trace_hardirqs_off

#endif

1:	bl	preempt_schedule_irq

	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)

	lwz	r3,TI_FLAGS(r9)

	andi.	r0,r3,_TIF_NEED_RESCHED

	bne-	1b

#ifdef CONFIG_TRACE_IRQFLAGS

	/* And now, to properly rebalance the above, we tell lockdep they

	 * are being turned back on, which will happen when we return

	 */

	bl	trace_hardirqs_on

#endif

#else

resume_kernel:

#endif /* CONFIG_PREEMPT */
@@ -765,6 +857,28 @@ restore: 
	stw	r6,icache_44x_need_flush@l(r4)

1:

#endif  /* CONFIG_44x */



	lwz	r9,_MSR(r1)

#ifdef CONFIG_TRACE_IRQFLAGS

	/* Lockdep doesn't know about the fact that IRQs are temporarily turned

	 * off in this assembly code while peeking at TI_FLAGS() and such. However

	 * we need to inform it if the exception turned interrupts off, and we

	 * are about to trun them back on.

	 *

	 * The problem here sadly is that we don't know whether the exceptions was

	 * one that turned interrupts off or not. So we always tell lockdep about

	 * turning them on here when we go back to wherever we came from with EE

	 * on, even if that may meen some redudant calls being tracked. Maybe later

	 * we could encode what the exception did somewhere or test the exception

	 * type in the pt_regs but that sounds overkill

	 */

	andi.	r10,r9,MSR_EE

	beq	1f

	bl	trace_hardirqs_on

	lwz	r9,_MSR(r1)

1:

#endif /* CONFIG_TRACE_IRQFLAGS */



	lwz	r0,GPR0(r1)

	lwz	r2,GPR2(r1)

	REST_4GPRS(3, r1)
@@ -782,7 +896,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) 
	stwcx.	r0,0,r1			/* to clear the reservation */



#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))

	lwz	r9,_MSR(r1)

	andi.	r10,r9,MSR_RI		/* check if this exception occurred */

	beql	nonrecoverable		/* at a bad place (MSR:RI = 0) */
@@ -805,7 +918,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) 
	MTMSRD(r10)		/* clear the RI bit */

	.globl exc_exit_restart

exc_exit_restart:

	lwz	r9,_MSR(r1)

	lwz	r12,_NIP(r1)

	FIX_SRR1(r9,r10)

	mtspr	SPRN_SRR0,r12
@@ -1035,11 +1147,18 @@ do_work: /* r10 contains MSR_KERNEL here */ 
	beq	do_user_signal



do_resched:			/* r10 contains MSR_KERNEL here */

	/* Note: We don't need to inform lockdep that we are enabling

	 * interrupts here. As far as it knows, they are already enabled

	 */

	ori	r10,r10,MSR_EE

	SYNC

	MTMSRD(r10)		/* hard-enable interrupts */

	bl	schedule

recheck:

	/* Note: And we don't tell it we are disabling them again

	 * neither. Those disable/enable cycles used to peek at

	 * TI_FLAGS aren't advertised.

	 */

	LOAD_MSR_KERNEL(r10,MSR_KERNEL)

	SYNC

	MTMSRD(r10)		/* disable interrupts */

arch/powerpc/kernel/setup_32.c

+2 −0
Original line number Diff line number Diff line
@@ -119,6 +119,8 @@ notrace unsigned long __init early_init(unsigned long dt_ptr) 
 */

notrace void __init machine_init(unsigned long dt_ptr)

{

	lockdep_init();



	/* Enable early debugging if any specified (see udbg.h) */

	udbg_early_init();

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