From a546498f3bf9aac311c66f965186373aee2ca0b0 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 7 Mar 2012 16:48:45 +1100 Subject: powerpc: Call do_page_fault() with interrupts off We currently turn interrupts back to their previous state before calling do_page_fault(). This can be annoying when debugging as a bad fault will potentially have lost some processor state before getting into the debugger. We also end up calling some generic code with interrupts enabled such as notify_page_fault() with interrupts enabled, which could be unexpected. This changes our code to behave more like other architectures, and make the assembly entry code call into do_page_faults() with interrupts disabled. They are conditionally re-enabled from within do_page_fault() in the same spot x86 does it. While there, add the might_sleep() test in the case of a successful trylock of the mmap semaphore, again like x86. Also fix a bug in the existing assembly where r12 (_MSR) could get clobbered by C calls (the DTL accounting in the exception common macro and DISABLE_INTS) in some cases. Signed-off-by: Benjamin Herrenschmidt --- v2. Add the r12 clobber fix --- arch/powerpc/kernel/exceptions-64s.S | 59 +++++++++++------------------------- 1 file changed, 17 insertions(+), 42 deletions(-) (limited to 'arch/powerpc/kernel/exceptions-64s.S') diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 3af80e82830..d8ff6d37fc4 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -559,6 +559,8 @@ data_access_common: mfspr r10,SPRN_DSISR stw r10,PACA_EXGEN+EX_DSISR(r13) EXCEPTION_PROLOG_COMMON(0x300, PACA_EXGEN) + DISABLE_INTS + ld r12,_MSR(r1) ld r3,PACA_EXGEN+EX_DAR(r13) lwz r4,PACA_EXGEN+EX_DSISR(r13) li r5,0x300 @@ -573,6 +575,7 @@ h_data_storage_common: stw r10,PACA_EXGEN+EX_DSISR(r13) EXCEPTION_PROLOG_COMMON(0xe00, PACA_EXGEN) bl .save_nvgprs + DISABLE_INTS addi r3,r1,STACK_FRAME_OVERHEAD bl .unknown_exception b .ret_from_except @@ -581,6 +584,8 @@ h_data_storage_common: .globl instruction_access_common instruction_access_common: EXCEPTION_PROLOG_COMMON(0x400, PACA_EXGEN) + DISABLE_INTS + ld r12,_MSR(r1) ld r3,_NIP(r1) andis. r4,r12,0x5820 li r5,0x400 @@ -884,24 +889,6 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_SLB) lwz r0,TI_PREEMPT(r11) /* If we're in an "NMI" */ andis. r0,r0,NMI_MASK@h /* (i.e. an irq when soft-disabled) */ bne 77f /* then don't call hash_page now */ - - /* We run with interrupts both soft and hard disabled */ - DISABLE_INTS - - /* - * Currently, trace_hardirqs_off() will be called by DISABLE_INTS - * and will clobber volatile registers when irq tracing is enabled - * so we need to reload them. It may be possible to be smarter here - * and move the irq tracing elsewhere but let's keep it simple for - * now - */ -#ifdef CONFIG_TRACE_IRQFLAGS - ld r3,_DAR(r1) - ld r4,_DSISR(r1) - ld r5,_TRAP(r1) - ld r12,_MSR(r1) - clrrdi r5,r5,4 -#endif /* CONFIG_TRACE_IRQFLAGS */ /* * We need to set the _PAGE_USER bit if MSR_PR is set or if we are * accessing a userspace segment (even from the kernel). We assume @@ -931,36 +918,16 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_SLB) beq fast_exc_return_irq /* Return from exception on success */ /* For a hash failure, we don't bother re-enabling interrupts */ - ble- 12f - - /* - * hash_page couldn't handle it, set soft interrupt enable back - * to what it was before the trap. Note that .arch_local_irq_restore - * handles any interrupts pending at this point. - */ - ld r3,SOFTE(r1) - TRACE_AND_RESTORE_IRQ_PARTIAL(r3, 11f) - bl .arch_local_irq_restore - b 11f - -/* We have a data breakpoint exception - handle it */ -handle_dabr_fault: - bl .save_nvgprs - ld r4,_DAR(r1) - ld r5,_DSISR(r1) - addi r3,r1,STACK_FRAME_OVERHEAD - bl .do_dabr - b .ret_from_except_lite + ble- 13f /* Here we have a page fault that hash_page can't handle. */ handle_page_fault: - ENABLE_INTS 11: ld r4,_DAR(r1) ld r5,_DSISR(r1) addi r3,r1,STACK_FRAME_OVERHEAD bl .do_page_fault cmpdi r3,0 - beq+ 13f + beq+ 12f bl .save_nvgprs mr r5,r3 addi r3,r1,STACK_FRAME_OVERHEAD @@ -968,12 +935,20 @@ handle_page_fault: bl .bad_page_fault b .ret_from_except -13: b .ret_from_except_lite +/* We have a data breakpoint exception - handle it */ +handle_dabr_fault: + bl .save_nvgprs + ld r4,_DAR(r1) + ld r5,_DSISR(r1) + addi r3,r1,STACK_FRAME_OVERHEAD + bl .do_dabr +12: b .ret_from_except_lite + /* We have a page fault that hash_page could handle but HV refused * the PTE insertion */ -12: bl .save_nvgprs +13: bl .save_nvgprs mr r5,r3 addi r3,r1,STACK_FRAME_OVERHEAD ld r4,_DAR(r1) -- cgit v1.2.3-18-g5258