From a546498f3bf9aac311c66f965186373aee2ca0b0 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 7 Mar 2012 16:48:45 +1100 Subject: [PATCH] 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/include/asm/hw_irq.h | 10 +++++ arch/powerpc/kernel/exceptions-64e.S | 5 +-- arch/powerpc/kernel/exceptions-64s.S | 59 ++++++++-------------------- arch/powerpc/kernel/head_32.S | 4 +- arch/powerpc/kernel/head_40x.S | 4 +- arch/powerpc/kernel/head_8xx.S | 4 +- arch/powerpc/kernel/head_booke.h | 4 +- arch/powerpc/kernel/head_fsl_booke.S | 2 +- arch/powerpc/mm/fault.c | 11 ++++++ 9 files changed, 49 insertions(+), 54 deletions(-) diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h index bb712c9488b..531ba00fcba 100644 --- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -79,6 +79,11 @@ static inline bool arch_irqs_disabled(void) get_paca()->hard_enabled = 0; \ } while(0) +static inline bool arch_irq_disabled_regs(struct pt_regs *regs) +{ + return !regs->softe; +} + #else /* CONFIG_PPC64 */ #define SET_MSR_EE(x) mtmsr(x) @@ -139,6 +144,11 @@ static inline bool arch_irqs_disabled(void) #define hard_irq_disable() arch_local_irq_disable() +static inline bool arch_irq_disabled_regs(struct pt_regs *regs) +{ + return !(regs->msr & MSR_EE); +} + #endif /* CONFIG_PPC64 */ #define ARCH_IRQ_INIT_FLAGS IRQ_NOREQUEST diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S index 429983c06f9..573613d747a 100644 --- a/arch/powerpc/kernel/exceptions-64e.S +++ b/arch/powerpc/kernel/exceptions-64e.S @@ -313,7 +313,7 @@ interrupt_end_book3e: NORMAL_EXCEPTION_PROLOG(0x300, PROLOG_ADDITION_2REGS) mfspr r14,SPRN_DEAR mfspr r15,SPRN_ESR - EXCEPTION_COMMON(0x300, PACA_EXGEN, INTS_KEEP) + EXCEPTION_COMMON(0x300, PACA_EXGEN, INTS_DISABLE_ALL) b storage_fault_common /* Instruction Storage Interrupt */ @@ -321,7 +321,7 @@ interrupt_end_book3e: NORMAL_EXCEPTION_PROLOG(0x400, PROLOG_ADDITION_2REGS) li r15,0 mr r14,r10 - EXCEPTION_COMMON(0x400, PACA_EXGEN, INTS_KEEP) + EXCEPTION_COMMON(0x400, PACA_EXGEN, INTS_DISABLE_ALL) b storage_fault_common /* External Input Interrupt */ @@ -591,7 +591,6 @@ storage_fault_common: mr r5,r15 ld r14,PACA_EXGEN+EX_R14(r13) ld r15,PACA_EXGEN+EX_R15(r13) - INTS_RESTORE_HARD bl .do_page_fault cmpdi r3,0 bne- 1f 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) diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S index 0654dba2c1f..dc0488b6f6e 100644 --- a/arch/powerpc/kernel/head_32.S +++ b/arch/powerpc/kernel/head_32.S @@ -395,7 +395,7 @@ DataAccess: bl hash_page 1: lwz r5,_DSISR(r11) /* get DSISR value */ mfspr r4,SPRN_DAR - EXC_XFER_EE_LITE(0x300, handle_page_fault) + EXC_XFER_LITE(0x300, handle_page_fault) /* Instruction access exception. */ @@ -410,7 +410,7 @@ InstructionAccess: bl hash_page 1: mr r4,r12 mr r5,r9 - EXC_XFER_EE_LITE(0x400, handle_page_fault) + EXC_XFER_LITE(0x400, handle_page_fault) /* External interrupt */ EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S index 872a6af83ba..4989661b710 100644 --- a/arch/powerpc/kernel/head_40x.S +++ b/arch/powerpc/kernel/head_40x.S @@ -394,7 +394,7 @@ label: NORMAL_EXCEPTION_PROLOG mr r4,r12 /* Pass SRR0 as arg2 */ li r5,0 /* Pass zero as arg3 */ - EXC_XFER_EE_LITE(0x400, handle_page_fault) + EXC_XFER_LITE(0x400, handle_page_fault) /* 0x0500 - External Interrupt Exception */ EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) @@ -747,7 +747,7 @@ DataAccess: mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */ stw r5,_ESR(r11) mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */ - EXC_XFER_EE_LITE(0x300, handle_page_fault) + EXC_XFER_LITE(0x300, handle_page_fault) /* Other PowerPC processors, namely those derived from the 6xx-series * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved. diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index b68cb173ba2..b2a5860accf 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -220,7 +220,7 @@ DataAccess: mfspr r4,SPRN_DAR li r10,0x00f0 mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */ - EXC_XFER_EE_LITE(0x300, handle_page_fault) + EXC_XFER_LITE(0x300, handle_page_fault) /* Instruction access exception. * This is "never generated" by the MPC8xx. We jump to it for other @@ -231,7 +231,7 @@ InstructionAccess: EXCEPTION_PROLOG mr r4,r12 mr r5,r9 - EXC_XFER_EE_LITE(0x400, handle_page_fault) + EXC_XFER_LITE(0x400, handle_page_fault) /* External interrupt */ EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h index fc921bf62e1..0e4175388f4 100644 --- a/arch/powerpc/kernel/head_booke.h +++ b/arch/powerpc/kernel/head_booke.h @@ -359,7 +359,7 @@ label: mfspr r5,SPRN_ESR; /* Grab the ESR and save it */ \ stw r5,_ESR(r11); \ mfspr r4,SPRN_DEAR; /* Grab the DEAR */ \ - EXC_XFER_EE_LITE(0x0300, handle_page_fault) + EXC_XFER_LITE(0x0300, handle_page_fault) #define INSTRUCTION_STORAGE_EXCEPTION \ START_EXCEPTION(InstructionStorage) \ @@ -368,7 +368,7 @@ label: stw r5,_ESR(r11); \ mr r4,r12; /* Pass SRR0 as arg2 */ \ li r5,0; /* Pass zero as arg3 */ \ - EXC_XFER_EE_LITE(0x0400, handle_page_fault) + EXC_XFER_LITE(0x0400, handle_page_fault) #define ALIGNMENT_EXCEPTION \ START_EXCEPTION(Alignment) \ diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S index d5d78c4ceef..28e62598d0e 100644 --- a/arch/powerpc/kernel/head_fsl_booke.S +++ b/arch/powerpc/kernel/head_fsl_booke.S @@ -319,7 +319,7 @@ interrupt_base: mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */ andis. r10,r5,(ESR_ILK|ESR_DLK)@h bne 1f - EXC_XFER_EE_LITE(0x0300, handle_page_fault) + EXC_XFER_LITE(0x0300, handle_page_fault) 1: addi r3,r1,STACK_FRAME_OVERHEAD EXC_XFER_EE_LITE(0x0300, CacheLockingException) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 2f0d1b032a8..7e890065cf3 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -179,6 +179,10 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address, } #endif + /* We restore the interrupt state now */ + if (!arch_irq_disabled_regs(regs)) + local_irq_enable(); + if (in_atomic() || mm == NULL) { if (!user_mode(regs)) return SIGSEGV; @@ -213,6 +217,13 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address, goto bad_area_nosemaphore; down_read(&mm->mmap_sem); + } else { + /* + * The above down_read_trylock() might have succeeded in + * which case we'll have missed the might_sleep() from + * down_read(): + */ + might_sleep(); } vma = find_vma(mm, address); -- 2.39.2