From 9b69d48c7516a29cdaacd18d8bf5f575014a42a1 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 30 Jun 2021 17:46:15 +1000 Subject: [PATCH] powerpc/64e: remove implicit soft-masking and interrupt exit restart logic The implicit soft-masking to speed up interrupt return was going to be used by 64e as well, but it has not been extensively tested on that platform and is not considered ready. It was intended to be disabled before merge. Disable it for now. Most of the restart code is common with 64s, so with more correctness and performance testing this could be re-enabled again by adding the extra soft-mask checks to interrupt handlers and flipping exit_must_hard_disable(). Fixes: 9d1988ca87dd ("powerpc/64: treat low kernel text as irqs soft-masked") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210630074621.2109197-4-npiggin@gmail.com --- arch/powerpc/include/asm/interrupt.h | 33 ++++++++++++++++++++-------- arch/powerpc/kernel/exceptions-64e.S | 12 +--------- arch/powerpc/kernel/interrupt.c | 2 +- arch/powerpc/kernel/interrupt_64.S | 16 ++++++++++++-- 4 files changed, 40 insertions(+), 23 deletions(-) diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h index 8b4b1e84e110..f13c93b033c7 100644 --- a/arch/powerpc/include/asm/interrupt.h +++ b/arch/powerpc/include/asm/interrupt.h @@ -73,20 +73,34 @@ #include #include -#ifdef CONFIG_PPC64 +#ifdef CONFIG_PPC_BOOK3S_64 extern char __end_soft_masked[]; unsigned long search_kernel_restart_table(unsigned long addr); -#endif -#ifdef CONFIG_PPC_BOOK3S_64 DECLARE_STATIC_KEY_FALSE(interrupt_exit_not_reentrant); +static inline bool is_implicit_soft_masked(struct pt_regs *regs) +{ + if (regs->msr & MSR_PR) + return false; + + if (regs->nip >= (unsigned long)__end_soft_masked) + return false; + + return true; +} + static inline void srr_regs_clobbered(void) { local_paca->srr_valid = 0; local_paca->hsrr_valid = 0; } #else +static inline bool is_implicit_soft_masked(struct pt_regs *regs) +{ + return false; +} + static inline void srr_regs_clobbered(void) { } @@ -150,11 +164,13 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup */ if (TRAP(regs) != INTERRUPT_PROGRAM) { CT_WARN_ON(ct_state() != CONTEXT_KERNEL); - BUG_ON(regs->nip < (unsigned long)__end_soft_masked); + BUG_ON(is_implicit_soft_masked(regs)); } +#ifdef CONFIG_PPC_BOOK3S /* Move this under a debugging check */ if (arch_irq_disabled_regs(regs)) BUG_ON(search_kernel_restart_table(regs->nip)); +#endif } #endif @@ -244,10 +260,9 @@ static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct inte local_paca->irq_soft_mask = IRQS_ALL_DISABLED; local_paca->irq_happened |= PACA_IRQ_HARD_DIS; - if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !(regs->msr & MSR_PR) && - regs->nip < (unsigned long)__end_soft_masked) { - // Kernel code running below __end_soft_masked is - // implicitly soft-masked. + if (is_implicit_soft_masked(regs)) { + // Adjust regs->softe soft implicit soft-mask, so + // arch_irq_disabled_regs(regs) behaves as expected. regs->softe = IRQS_ALL_DISABLED; } @@ -282,6 +297,7 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter */ #ifdef CONFIG_PPC64 +#ifdef CONFIG_PPC_BOOK3S if (arch_irq_disabled_regs(regs)) { unsigned long rst = search_kernel_restart_table(regs->nip); if (rst) @@ -289,7 +305,6 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter } #endif -#ifdef CONFIG_PPC64 if (nmi_disables_ftrace(regs)) this_cpu_set_ftrace_enabled(state->ftrace_enabled); diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S index d634bfceed2c..1401787b0b93 100644 --- a/arch/powerpc/kernel/exceptions-64e.S +++ b/arch/powerpc/kernel/exceptions-64e.S @@ -342,17 +342,7 @@ ret_from_mc_except: #define PROLOG_ADDITION_MASKABLE_GEN(n) \ lbz r10,PACAIRQSOFTMASK(r13); /* are irqs soft-masked? */ \ andi. r10,r10,IRQS_DISABLED; /* yes -> go out of line */ \ - bne masked_interrupt_book3e_##n; \ - /* Kernel code below __end_soft_masked is implicitly masked */ \ - andi. r10,r11,MSR_PR; \ - bne 1f; /* user -> not masked */ \ - std r14,PACA_EXGEN+EX_R14(r13); \ - LOAD_REG_IMMEDIATE_SYM(r14, r10, __end_soft_masked); \ - mfspr r10,SPRN_SRR0; \ - cmpld r10,r14; \ - ld r14,PACA_EXGEN+EX_R14(r13); \ - blt masked_interrupt_book3e_##n; \ -1: + bne masked_interrupt_book3e_##n /* * Additional regs must be re-loaded from paca before EXCEPTION_COMMON* is diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index 0052702ee5ac..21bbd615ca41 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -36,7 +36,7 @@ static inline bool exit_must_hard_disable(void) #else static inline bool exit_must_hard_disable(void) { - return IS_ENABLED(CONFIG_PPC32); + return true; } #endif diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S index e7a50613a570..09b8d8846c67 100644 --- a/arch/powerpc/kernel/interrupt_64.S +++ b/arch/powerpc/kernel/interrupt_64.S @@ -231,7 +231,7 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_emulate) li r10,IRQS_ALL_DISABLED stb r10,PACAIRQSOFTMASK(r13) b system_call_vectored_common -#endif +#endif /* CONFIG_PPC_BOOK3S */ .balign IFETCH_ALIGN_BYTES .globl system_call_common_real @@ -320,10 +320,12 @@ END_BTB_FLUSH_SECTION li r5,0 /* !scv */ bl syscall_exit_prepare std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */ +#ifdef CONFIG_PPC_BOOK3S .Lsyscall_rst_start: lbz r11,PACAIRQHAPPENED(r13) andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l bne- syscall_restart +#endif li r11,IRQS_ENABLED stb r11,PACAIRQSOFTMASK(r13) li r11,0 @@ -396,6 +398,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) b .Lsyscall_restore_regs_cont .Lsyscall_rst_end: +#ifdef CONFIG_PPC_BOOK3S syscall_restart: GET_PACA(r13) ld r1,PACA_EXIT_SAVE_R1(r13) @@ -409,6 +412,7 @@ syscall_restart: b .Lsyscall_rst_start RESTART_TABLE(.Lsyscall_rst_start, .Lsyscall_rst_end, syscall_restart) +#endif #ifdef CONFIG_PPC_TRANSACTIONAL_MEM tabort_syscall: @@ -504,10 +508,12 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()) bne- .Lrestore_nvgprs_\srr .Lrestore_nvgprs_\srr\()_cont: std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */ +#ifdef CONFIG_PPC_BOOK3S .Linterrupt_return_\srr\()_user_rst_start: lbz r11,PACAIRQHAPPENED(r13) andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l bne- interrupt_return_\srr\()_user_restart +#endif li r11,IRQS_ENABLED stb r11,PACAIRQSOFTMASK(r13) li r11,0 @@ -590,6 +596,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) REST_NVGPRS(r1) b .Lrestore_nvgprs_\srr\()_cont +#ifdef CONFIG_PPC_BOOK3S interrupt_return_\srr\()_user_restart: GET_PACA(r13) ld r1,PACA_EXIT_SAVE_R1(r13) @@ -602,6 +609,7 @@ interrupt_return_\srr\()_user_restart: b .Linterrupt_return_\srr\()_user_rst_start RESTART_TABLE(.Linterrupt_return_\srr\()_user_rst_start, .Linterrupt_return_\srr\()_user_rst_end, interrupt_return_\srr\()_user_restart) +#endif .balign IFETCH_ALIGN_BYTES .Lkernel_interrupt_return_\srr\(): @@ -615,9 +623,11 @@ RESTART_TABLE(.Linterrupt_return_\srr\()_user_rst_start, .Linterrupt_return_\srr cmpwi r11,IRQS_ENABLED stb r11,PACAIRQSOFTMASK(r13) bne 1f +#ifdef CONFIG_PPC_BOOK3S lbz r11,PACAIRQHAPPENED(r13) andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l bne- interrupt_return_\srr\()_kernel_restart +#endif li r11,0 stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS 1: @@ -717,6 +727,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) b . /* prevent speculative execution */ .Linterrupt_return_\srr\()_kernel_rst_end: +#ifdef CONFIG_PPC_BOOK3S interrupt_return_\srr\()_kernel_restart: GET_PACA(r13) ld r1,PACA_EXIT_SAVE_R1(r13) @@ -729,14 +740,15 @@ interrupt_return_\srr\()_kernel_restart: b .Linterrupt_return_\srr\()_kernel_rst_start RESTART_TABLE(.Linterrupt_return_\srr\()_kernel_rst_start, .Linterrupt_return_\srr\()_kernel_rst_end, interrupt_return_\srr\()_kernel_restart) +#endif .endm interrupt_return_macro srr #ifdef CONFIG_PPC_BOOK3S interrupt_return_macro hsrr -#endif /* CONFIG_PPC_BOOK3S */ .globl __end_soft_masked __end_soft_masked: DEFINE_FIXED_SYMBOL(__end_soft_masked) +#endif /* CONFIG_PPC_BOOK3S */