Use NMI instead of IPI for backtrace if RISC-V SSE NMI is supported.

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
---
 arch/riscv/kernel/smp.c                | 12 +++++++++++-
 drivers/firmware/riscv/riscv_sse_nmi.c |  2 ++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index bca95ec0b0f74..6d9a67c2c2a6e 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -342,9 +342,19 @@ static void riscv_backtrace_ipi(cpumask_t *mask)
 	send_ipi_mask(mask, IPI_CPU_BACKTRACE);
 }
 
+static void riscv_backtrace_nmi(cpumask_t *mask)
+{
+	send_nmi_mask(mask, LOCAL_NMI_BACKTRACE);
+}
+
 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
 {
-	nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi);
+	if (!nmi_support())
+		nmi_trigger_cpumask_backtrace(mask, exclude_cpu,
+					      riscv_backtrace_ipi);
+	else
+		nmi_trigger_cpumask_backtrace(mask, exclude_cpu,
+					      riscv_backtrace_nmi);
 }
 
 #ifdef CONFIG_KGDB
diff --git a/drivers/firmware/riscv/riscv_sse_nmi.c b/drivers/firmware/riscv/riscv_sse_nmi.c
index 02e2de2bb70f7..a138d6bdbc0d1 100644
--- a/drivers/firmware/riscv/riscv_sse_nmi.c
+++ b/drivers/firmware/riscv/riscv_sse_nmi.c
@@ -3,6 +3,7 @@
 #define pr_fmt(fmt) "SSE NMI: " fmt
 
 #include <linux/atomic.h>
+#include <linux/nmi.h>
 #include <linux/riscv_sbi_sse.h>
 #include <linux/riscv_sse_nmi.h>
 
@@ -59,6 +60,7 @@ static int local_nmi_handler(u32 evt, void *arg, struct pt_regs *regs)
 
 	NMI_HANDLE(LOCAL_NMI_CRASH, cpu_crash_stop, cpu, regs);
 	NMI_HANDLE(LOCAL_NMI_STOP, cpu_stop);
+	NMI_HANDLE(LOCAL_NMI_BACKTRACE, nmi_cpu_backtrace, regs);
 
 	atomic_andnot(type, this_cpu_ptr(&local_nmi));
 
-- 
2.39.5