| Date | Tue, 05 May 2020 15:16:33 +0200 | From | Thomas Gleixner <> | Subject | [patch V4 part 1 31/36] printk: Disallow instrumenting print_nmi_enter() |
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From: Peter Zijlstra <peterz@infradead.org>
It happens early in nmi_enter(), no tracing, probing or other funnies allowed. Specifically as nmi_enter() will be used in do_debug(), which would cause recursive exceptions when kprobed.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/printk/printk_safe.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -10,6 +10,7 @@ #include <linux/cpumask.h> #include <linux/irq_work.h> #include <linux/printk.h> +#include <linux/kprobes.h> #include "internal.h" @@ -293,12 +294,12 @@ static __printf(1, 0) int vprintk_nmi(co return printk_safe_log_store(s, fmt, args); } -void notrace printk_nmi_enter(void) +void noinstr printk_nmi_enter(void) { this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET); } -void notrace printk_nmi_exit(void) +void noinstr printk_nmi_exit(void) { this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET); }
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