RISC-V: self-contained IPI handling routine

Currently, the IPI handling routine riscv_software_interrupt() does
not take any argument and also does not perform irq_enter()/irq_exit().

This patch makes IPI handling routine more self-contained by:
1. Passing "pt_regs *" argument
2. Explicitly doing irq_enter()/irq_exit()
3. Explicitly save/restore "pt_regs *" using set_irq_regs()

With above changes, IPI handling routine does not depend on caller
function to perform irq_enter()/irq_exit() and save/restore of
"pt_regs *" hence its more self-contained. This also enables us
to call IPI handling routine from IRQCHIP drivers.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 6e1b0e0325eb92a26bba60f7c08c7c32a37a45d0..0183e15ace66260122dd12c451ac45b3bd4895b8 100644 (file)
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -13,7 +13,6 @@
 #define NR_IRQS         0
 
 void riscv_timer_interrupt(void);
-void riscv_software_interrupt(void);
 
 #include <asm-generic/irq.h>
 

diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index f4c7cfda6b7fb4ddd663c098714a0e0aa7c59880..40bb1c15a731f3b66d23e3189bd8ee2a05c71a57 100644 (file)
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -28,6 +28,9 @@ void show_ipi_stats(struct seq_file *p, int prec);
 /* SMP initialization hook for setup_arch */
 void __init setup_smp(void);
 
+/* Called from C code, this handles an IPI. */
+void handle_IPI(struct pt_regs *regs);
+
 /* Hook for the generic smp_call_function_many() routine. */
 void arch_send_call_function_ipi_mask(struct cpumask *mask);
 

diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 345c4f2eba13f41a58cdf2f2193f08371863a68f..bb0bfcd537e7f3200b5b2a56699d93e36969b7dd 100644 (file)
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -19,12 +19,15 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 
 asmlinkage __visible void __irq_entry do_IRQ(struct pt_regs *regs)
 {
-       struct pt_regs *old_regs = set_irq_regs(regs);
+       struct pt_regs *old_regs;
 
-       irq_enter();
        switch (regs->cause & ~CAUSE_IRQ_FLAG) {
        case RV_IRQ_TIMER:
+               old_regs = set_irq_regs(regs);
+               irq_enter();
                riscv_timer_interrupt();
+               irq_exit();
+               set_irq_regs(old_regs);
                break;
 #ifdef CONFIG_SMP
        case RV_IRQ_SOFT:
@@ -32,19 +35,20 @@ asmlinkage __visible void __irq_entry do_IRQ(struct pt_regs *regs)
                 * We only use software interrupts to pass IPIs, so if a non-SMP
                 * system gets one, then we don't know what to do.
                 */
-               riscv_software_interrupt();
+               handle_IPI(regs);
                break;
 #endif
        case RV_IRQ_EXT:
+               old_regs = set_irq_regs(regs);
+               irq_enter();
                handle_arch_irq(regs);
+               irq_exit();
+               set_irq_regs(old_regs);
                break;
        default:
                pr_alert("unexpected interrupt cause 0x%lx", regs->cause);
                BUG();
        }
-       irq_exit();
-
-       set_irq_regs(old_regs);
 }
 
 void __init init_IRQ(void)

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index a65a8fa0c22d690f600afd5404bd519d48034808..b1d4f452f8436cd03b4c6ef0164d1fb1eb40a722 100644 (file)
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -123,11 +123,14 @@ static inline void clear_ipi(void)
                clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
 }
 
-void riscv_software_interrupt(void)
+void handle_IPI(struct pt_regs *regs)
 {
+       struct pt_regs *old_regs = set_irq_regs(regs);
        unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
        unsigned long *stats = ipi_data[smp_processor_id()].stats;
 
+       irq_enter();
+
        clear_ipi();
 
        while (true) {
@@ -138,7 +141,7 @@ void riscv_software_interrupt(void)
 
                ops = xchg(pending_ipis, 0);
                if (ops == 0)
-                       return;
+                       goto done;
 
                if (ops & (1 << IPI_RESCHEDULE)) {
                        stats[IPI_RESCHEDULE]++;
@@ -160,6 +163,10 @@ void riscv_software_interrupt(void)
                /* Order data access and bit testing. */
                mb();
        }
+
+done:
+       irq_exit();
+       set_irq_regs(old_regs);
 }
 
 static const char * const ipi_names[] = {