[PATCH v12 06/11] riscv: enable NMI-safe lockdep irqflags tracking

[Zhanpeng Zhang]

An SSE handler runs with interrupts masked, but can interrupt code whose
lockdep hardirq state is enabled. Bare nmi_enter()/nmi_exit() do not
update that state. Consequently, lockdep_assert_irqs_disabled() in the
perf overflow path can report a warning despite interrupts being masked.

Select TRACE_IRQFLAGS_NMI_SUPPORT so lockdep can update its hardirq state
inside an NMI. Pair this with irqentry_nmi_enter()/irqentry_nmi_exit() in
the SSE wrapper: these helpers save the previous tracked state, mark
interrupts disabled on entry and restore the tracked state on exit.
Selecting the configuration option alone does not perform those updates.
This follows the entry helpers used by the other RISC-V NMI-like traps.

Signed-off-by: Zhanpeng Zhang <zhangzhanpeng.jasper at bytedance.com>
---
 arch/riscv/Kconfig          | 1 +
 arch/riscv/kernel/sbi_sse.c | 7 ++++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 467a877445a..dea30784fc7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -228,6 +228,7 @@ config RISCV
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
 	select TRACE_IRQFLAGS_SUPPORT
+	select TRACE_IRQFLAGS_NMI_SUPPORT
 	select UACCESS_MEMCPY if !MMU
 	select VDSO_DATASTORE if MMU
 	select VDSO_GETRANDOM if MMU && 64BIT
diff --git a/arch/riscv/kernel/sbi_sse.c b/arch/riscv/kernel/sbi_sse.c
index 032fcc07abc..59e47a39589 100644
--- a/arch/riscv/kernel/sbi_sse.c
+++ b/arch/riscv/kernel/sbi_sse.c
@@ -2,7 +2,7 @@
 /*
  * Copyright (C) 2025 Rivos Inc.
  */
-#include <linux/nmi.h>
+#include <linux/entry-common.h>
 #include <linux/sched.h>
 #include <linux/scs.h>
 #include <linux/bitfield.h>
@@ -36,9 +36,10 @@ void noinstr do_sse(struct sse_event_arch_data *arch_evt,
 {
 	struct riscv_sse_interrupted_context context = { regs, hstatus };
 	struct riscv_sse_interrupted_context *previous;
+	irqentry_state_t state;
 	struct sbiret sret;
 
-	nmi_enter();
+	state = irqentry_nmi_enter(regs);
 	instrumentation_begin();
 
 	/* Retrieve missing GPRs from SBI */
@@ -84,7 +85,7 @@ void noinstr do_sse(struct sse_event_arch_data *arch_evt,
 
 out:
 	instrumentation_end();
-	nmi_exit();
+	irqentry_nmi_exit(regs, state);
 }
 
 static void *alloc_to_stack_pointer(void *alloc)
-- 
2.50.1 (Apple Git-155)