powerpc: move NMI entry/exit code into wrapper

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@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-40-npiggin@gmail.com

diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index ca8e08b..cd819d4 100644 (file)
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -94,14 +94,42 @@ 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
+       /* Allow DEC and PMI to be traced when they are soft-NMI */
+       if (TRAP(regs) != 0x900 && TRAP(regs) != 0xf00 && TRAP(regs) != 0x260) {
+               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
+       if (TRAP(regs) != 0x900 && TRAP(regs) != 0xf00 && TRAP(regs) != 0x260)
+               this_cpu_set_ftrace_enabled(state->ftrace_enabled);
+#endif
 }
 
 /**

diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index cfe96cd..11f0cae 100644 (file)
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -587,12 +587,6 @@ 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);
 
@@ -602,11 +596,6 @@ 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 13fb93a..39c8b7e 100644 (file)
--- 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.
@@ -514,10 +509,6 @@ out:
                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;
@@ -809,6 +800,12 @@ void die_mce(const char *str, struct pt_regs *regs, long err)
 }
 NOKPROBE_SYMBOL(die_mce);
 
+/*
+ * 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
@@ -817,20 +814,6 @@ 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);
@@ -862,8 +845,6 @@ bail:
        if (!(regs->msr & MSR_RI))
                die_mce("Unrecoverable Machine check", regs, SIGBUS);
 
-       if (nmi) nmi_exit();
-
 #ifdef CONFIG_PPC_BOOK3S_64
        return;
 #else
@@ -1892,14 +1873,10 @@ DEFINE_INTERRUPT_HANDLER(vsx_unavailable_tm)
 DECLARE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi);
 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 be6b228..c9a8f47 100644 (file)
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -255,11 +255,12 @@ 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();
@@ -267,7 +268,7 @@ 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);
 
@@ -291,9 +292,6 @@ 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;
 }