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Subject[PATCH v5 1/6] RISC-V: self-contained IPI handling routine
Date
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>
---
arch/riscv/include/asm/irq.h | 1 -
arch/riscv/include/asm/smp.h | 3 +++
arch/riscv/kernel/irq.c | 16 ++++++++++------
arch/riscv/kernel/smp.c | 11 +++++++++--
4 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 6e1b0e0325eb..0183e15ace66 100644
--- 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 f4c7cfda6b7f..40bb1c15a731 100644
--- 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 345c4f2eba13..bb0bfcd537e7 100644
--- 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 a65a8fa0c22d..b1d4f452f843 100644
--- 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[] = {
--
2.25.1
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