[PATCH 6.12.y 2/4] panic: Add vpanic()

[Sasha Levin <sashal@kernel.org>]

From: Nam Cao <namcao@linutronix.de>

[ Upstream commit 3f045de7f557850ca6b3632c6d45c2cdaf948694 ]

vpanic() is useful for implementing runtime verification reactors. Add it.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Stable-dep-of: ed9e4c1ff15d ("panic: restore variable arguments to nmi_panic()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/panic.h |  3 +++
 kernel/panic.c        | 16 ++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/linux/panic.h b/include/linux/panic.h
index f0b779d2915e6..baf7de33aa0e6 100644
--- a/include/linux/panic.h
+++ b/include/linux/panic.h
@@ -3,6 +3,7 @@
 #define _LINUX_PANIC_H
 
 #include <linux/compiler_attributes.h>
+#include <linux/stdarg.h>
 #include <linux/types.h>
 
 struct pt_regs;
@@ -10,6 +11,8 @@ struct pt_regs;
 extern long (*panic_blink)(int state);
 __printf(1, 2)
 void panic(const char *fmt, ...) __noreturn __cold;
+__printf(1, 0)
+void vpanic(const char *fmt, va_list args) __noreturn __cold;
 void nmi_panic(struct pt_regs *regs, const char *msg);
 void check_panic_on_warn(const char *origin);
 extern void oops_enter(void);
diff --git a/kernel/panic.c b/kernel/panic.c
index d5307a8e89283..dce6197233161 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -327,13 +327,13 @@ static void panic_other_cpus_shutdown(bool crash_kexec)
 /**
  * panic - halt the system
  * @fmt: The text string to print
+ * @args: Arguments for the format string
  *
  * Display a message, then perform cleanups. This function never returns.
  */
-void panic(const char *fmt, ...)
+void vpanic(const char *fmt, va_list args)
 {
 	static char buf[1024];
-	va_list args;
 	long i, i_next = 0, len;
 	int state = 0;
 	int old_cpu, this_cpu;
@@ -384,9 +384,7 @@ void panic(const char *fmt, ...)
 
 	console_verbose();
 	bust_spinlocks(1);
-	va_start(args, fmt);
 	len = vscnprintf(buf, sizeof(buf), fmt, args);
-	va_end(args);
 
 	if (len && buf[len - 1] == '\n')
 		buf[len - 1] = '\0';
@@ -523,7 +521,17 @@ void panic(const char *fmt, ...)
 		mdelay(PANIC_TIMER_STEP);
 	}
 }
+EXPORT_SYMBOL(vpanic);
 
+/* Identical to vpanic(), except it takes variadic arguments instead of va_list */
+void panic(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vpanic(fmt, args);
+	va_end(args);
+}
 EXPORT_SYMBOL(panic);
 
 #define TAINT_FLAG(taint, _c_true, _c_false, _module)			\
-- 
2.53.0