From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
Subject: Re: [PATCH v3 3/9] powerpc/64e: remove implicit soft-masking and interrupt exit restart logic
Date: Wed, 30 Jun 2021 09:56:45 +0200 [thread overview]
Message-ID: <a7eef3ac-7ea8-8bf8-f656-c88aa876f5f6@csgroup.eu> (raw)
In-Reply-To: <20210630074621.2109197-4-npiggin@gmail.com>
Le 30/06/2021 à 09:46, Nicholas Piggin a écrit :
> 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 <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 <asm/kprobes.h>
> #include <asm/runlatch.h>
>
> -#ifdef CONFIG_PPC64
> +#ifdef CONFIG_PPC_BOOK3S_64
Can we avoid that ifdef and use IS_ENABLED(CONFIG_PPC_BOOK3S_64) below ?
> 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
Allthough we are already in a PPC64 section, wouldn't it be better to use CONFIG_PPC_BOOK3S_64 ?
Can we use IS_ENABLED(CONFIG_PPC_BOOK3S_64) instead ?
> /* 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
IS_ENABLED(CONFIG_PPC_BOOK3S_64) instead ?
> 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 */
>
next prev parent reply other threads:[~2021-06-30 7:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-30 7:46 [PATCH v3 0/9] powerpc: fast interrupt exit bug and misc fixes Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 1/9] powerpc/64s: fix hash page fault interrupt handler Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 2/9] powerpc/64e: fix CONFIG_RELOCATABLE build warnings Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 3/9] powerpc/64e: remove implicit soft-masking and interrupt exit restart logic Nicholas Piggin
2021-06-30 7:56 ` Christophe Leroy [this message]
2021-07-01 1:26 ` Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 4/9] powerpc/64s: add a table of implicit soft-masked addresses Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 5/9] powerpc/64s/interrupt: preserve regs->softe for NMI interrupts Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 6/9] powerpc/64: enable MSR[EE] in irq replay pt_regs Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 7/9] powerpc/64/interrupt: add missing kprobe annotations on interrupt exit symbols Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 8/9] powerpc/64s/interrupt: clean up interrupt return labels Nicholas Piggin
2021-06-30 7:46 ` [PATCH v3 9/9] powerpc/64s: move ret_from_fork etc above __end_soft_masked Nicholas Piggin
2021-06-30 13:14 ` [PATCH v3 0/9] powerpc: fast interrupt exit bug and misc fixes Michael Ellerman
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