[PATCH v5 18/21] powerpc: move NMI entry/exit code into wrapper
Christophe Leroy
christophe.leroy at csgroup.eu
Thu Jan 14 02:13:37 AEDT 2021
Le 13/01/2021 à 08:32, Nicholas Piggin a écrit :
> This moves the common NMI entry and exit code into the interrupt handler
> wrappers.
>
> This changes the behaviour of soft-NMI (watchdog) and HMI interrupts, and
> also MCE interrupts on 64e, by adding missing parts of the NMI entry to
> them.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
> arch/powerpc/include/asm/interrupt.h | 24 ++++++++++++++++
> arch/powerpc/kernel/mce.c | 11 --------
> arch/powerpc/kernel/traps.c | 42 +++++-----------------------
> arch/powerpc/kernel/watchdog.c | 10 +++----
> 4 files changed, 35 insertions(+), 52 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
> index e278dffe7657..01192e213f9a 100644
> --- a/arch/powerpc/include/asm/interrupt.h
> +++ b/arch/powerpc/include/asm/interrupt.h
> @@ -95,14 +95,38 @@ static inline void interrupt_async_exit_prepare(struct pt_regs *regs, struct int
> }
>
> struct interrupt_nmi_state {
> +#ifdef CONFIG_PPC64
> + u8 ftrace_enabled;
> +#endif
> };
>
> static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct interrupt_nmi_state *state)
> {
> +#ifdef CONFIG_PPC64
> + state->ftrace_enabled = this_cpu_get_ftrace_enabled();
> + this_cpu_set_ftrace_enabled(0);
> +#endif
> +
> + /*
> + * Do not use nmi_enter() for pseries hash guest taking a real-mode
> + * NMI because not everything it touches is within the RMA limit.
> + */
> + if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
> + !firmware_has_feature(FW_FEATURE_LPAR) ||
> + radix_enabled() || (mfmsr() & MSR_DR))
> + nmi_enter();
> }
>
> static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct interrupt_nmi_state *state)
> {
> + if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
> + !firmware_has_feature(FW_FEATURE_LPAR) ||
> + radix_enabled() || (mfmsr() & MSR_DR))
> + nmi_exit();
> +
> +#ifdef CONFIG_PPC64
> + this_cpu_set_ftrace_enabled(state->ftrace_enabled);
> +#endif
> }
>
> /**
> diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
> index 54269947113d..51456217ec40 100644
> --- a/arch/powerpc/kernel/mce.c
> +++ b/arch/powerpc/kernel/mce.c
> @@ -592,12 +592,6 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
> DEFINE_INTERRUPT_HANDLER_NMI(machine_check_early)
> {
> long handled = 0;
> - u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
> -
> - this_cpu_set_ftrace_enabled(0);
> - /* Do not use nmi_enter/exit for pseries hpte guest */
> - if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
> - nmi_enter();
>
> hv_nmi_check_nonrecoverable(regs);
>
> @@ -607,11 +601,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_early)
> if (ppc_md.machine_check_early)
> handled = ppc_md.machine_check_early(regs);
>
> - if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
> - nmi_exit();
> -
> - this_cpu_set_ftrace_enabled(ftrace_enabled);
> -
> return handled;
> }
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index b4f23e871a68..43d23232ef5c 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -435,11 +435,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
> {
> unsigned long hsrr0, hsrr1;
> bool saved_hsrrs = false;
> - u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
> -
> - this_cpu_set_ftrace_enabled(0);
> -
> - nmi_enter();
>
> /*
> * System reset can interrupt code where HSRRs are live and MSR[RI]=1.
> @@ -511,10 +506,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
> mtspr(SPRN_HSRR1, hsrr1);
> }
>
> - nmi_exit();
> -
> - this_cpu_set_ftrace_enabled(ftrace_enabled);
> -
> /* What should we do here? We could issue a shutdown or hard reset. */
>
> return 0;
> @@ -792,6 +783,12 @@ int machine_check_generic(struct pt_regs *regs)
> #endif /* everything else */
>
>
> +/*
> + * BOOK3S_64 does not call this handler as a non-maskable interrupt
> + * (it uses its own early real-mode handler to handle the MCE proper
> + * and then raises irq_work to call this handler when interrupts are
> + * enabled).
> + */
> #ifdef CONFIG_PPC_BOOK3S_64
> DEFINE_INTERRUPT_HANDLER_ASYNC(machine_check_exception)
> #else
> @@ -800,20 +797,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
> {
> int recover = 0;
>
> - /*
> - * BOOK3S_64 does not call this handler as a non-maskable interrupt
> - * (it uses its own early real-mode handler to handle the MCE proper
> - * and then raises irq_work to call this handler when interrupts are
> - * enabled).
> - *
> - * This is silly. The BOOK3S_64 should just call a different function
> - * rather than expecting semantics to magically change. Something
> - * like 'non_nmi_machine_check_exception()', perhaps?
> - */
> - const bool nmi = !IS_ENABLED(CONFIG_PPC_BOOK3S_64);
> -
> - if (nmi) nmi_enter();
> -
> __this_cpu_inc(irq_stat.mce_exceptions);
>
> add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
> @@ -838,24 +821,17 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
> if (check_io_access(regs))
> goto bail;
>
> - if (nmi) nmi_exit();
> -
IIRC, not doing the nmi_exit() before the die() is problematic.
See
https://github.com/linuxppc/linux/commit/daf00ae71dad8aa05965713c62558aeebf2df48e#diff-70077148c383252ca949063eaf1b0250620e4607b43f4ef3fd2d8f448a83ab0a
> die("Machine check", regs, SIGBUS);
>
> /* Must die if the interrupt is not recoverable */
> if (!(regs->msr & MSR_RI))
> die("Unrecoverable Machine check", regs, SIGBUS);
>
> -#ifdef CONFIG_PPC_BOOK3S_64
> bail:
> +#ifdef CONFIG_PPC_BOOK3S_64
> return;
> #else
> return 0;
> -
> -bail:
> - if (nmi) nmi_exit();
> -
> - return 0;
> #endif
> }
> NOKPROBE_SYMBOL(machine_check_exception);
> @@ -1873,14 +1849,10 @@ DEFINE_INTERRUPT_HANDLER(vsx_unavailable_tm)
> #ifdef CONFIG_PPC64
> DEFINE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi)
> {
> - nmi_enter();
> -
> __this_cpu_inc(irq_stat.pmu_irqs);
>
> perf_irq(regs);
>
> - nmi_exit();
> -
> return 0;
> }
> #endif
> diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
> index 824b9376ac35..dc39534836a3 100644
> --- a/arch/powerpc/kernel/watchdog.c
> +++ b/arch/powerpc/kernel/watchdog.c
> @@ -254,11 +254,12 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
> int cpu = raw_smp_processor_id();
> u64 tb;
>
> + /* should only arrive from kernel, with irqs disabled */
> + WARN_ON_ONCE(!arch_irq_disabled_regs(regs));
> +
> if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
> return 0;
>
> - nmi_enter();
> -
> __this_cpu_inc(irq_stat.soft_nmi_irqs);
>
> tb = get_tb();
> @@ -266,7 +267,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
> wd_smp_lock(&flags);
> if (cpumask_test_cpu(cpu, &wd_smp_cpus_stuck)) {
> wd_smp_unlock(&flags);
> - goto out;
> + return 0;
> }
> set_cpu_stuck(cpu, tb);
>
> @@ -290,9 +291,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
> if (wd_panic_timeout_tb < 0x7fffffff)
> mtspr(SPRN_DEC, wd_panic_timeout_tb);
>
> -out:
> - nmi_exit();
> -
> return 0;
> }
>
>
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