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 <npig...@gmail.com>
---
 arch/powerpc/include/asm/interrupt.h | 26 +++++++++++++++++++
 arch/powerpc/kernel/mce.c            | 12 ---------
 arch/powerpc/kernel/traps.c          | 38 +++++-----------------------
 arch/powerpc/kernel/watchdog.c       | 10 +++-----
 4 files changed, 37 insertions(+), 49 deletions(-)

diff --git a/arch/powerpc/include/asm/interrupt.h 
b/arch/powerpc/include/asm/interrupt.h
index 83fe1d64cf23..69eb8a432984 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -31,6 +31,27 @@ static inline void interrupt_enter_prepare(struct pt_regs 
*regs)
 }
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
+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)
+{
+       this_cpu_set_ftrace_enabled(0);
+
+       nmi_enter();
+}
+
+static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct 
interrupt_nmi_state *state)
+{
+       nmi_exit();
+
+       this_cpu_set_ftrace_enabled(state->ftrace_enabled);
+}
+
+
 /**
  * DECLARE_INTERRUPT_HANDLER_RAW - Declare raw interrupt handler function
  * @func:      Function name of the entry point
@@ -177,10 +198,15 @@ static __always_inline long ___##func(struct pt_regs 
*regs);              \
                                                                        \
 __visible noinstr long func(struct pt_regs *regs)                      \
 {                                                                      \
+       struct interrupt_nmi_state state;                               \
        long ret;                                                       \
                                                                        \
+       interrupt_nmi_enter_prepare(regs, &state);                      \
+                                                                       \
        ret = ___##func (regs);                                         \
                                                                        \
+       interrupt_nmi_exit_prepare(regs, &state);                       \
+                                                                       \
        return ret;                                                     \
 }                                                                      \
                                                                        \
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index d0bbcc4fe13c..9f39deed4fca 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -592,13 +592,6 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
 DEFINE_INTERRUPT_HANDLER_NMI(machine_check_early)
 {
        long handled = 0;
-       bool nested = in_nmi();
-       u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
-
-       this_cpu_set_ftrace_enabled(0);
-
-       if (!nested)
-               nmi_enter();
 
        hv_nmi_check_nonrecoverable(regs);
 
@@ -608,11 +601,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_early)
        if (ppc_md.machine_check_early)
                handled = ppc_md.machine_check_early(regs);
 
-       if (!nested)
-               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 3784578db630..01ddbe5ed5a4 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -443,11 +443,6 @@ 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.
@@ -519,10 +514,6 @@ 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;
@@ -828,6 +819,12 @@ 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
@@ -836,20 +833,6 @@ 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);
@@ -874,24 +857,17 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
        if (check_io_access(regs))
                goto bail;
 
-       if (nmi) nmi_exit();
-
        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
 }
 
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;
 }
 
-- 
2.23.0

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