From 8c4e93c362ff114def211d4629b120af86eb1275 Mon Sep 17 00:00:00 2001 From: Petr Mladek Date: Mon, 24 Feb 2020 13:13:31 +0100 Subject: [PATCH] printk: Prepare for nested printk_nmi_enter() There is plenty of space in the printk_context variable. Reserve one byte there for the NMI context to be on the safe side. It should never overflow. The BUG_ON(in_nmi() == NMI_MASK) in nmi_enter() will trigger much earlier. Signed-off-by: Petr Mladek Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Link: https://lkml.kernel.org/r/20200505134100.681374113@linutronix.de --- kernel/printk/internal.h | 8 +++++--- kernel/printk/printk_safe.c | 4 ++-- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index b2b0f52..660f9a6 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -6,9 +6,11 @@ #ifdef CONFIG_PRINTK -#define PRINTK_SAFE_CONTEXT_MASK 0x3fffffff -#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x40000000 -#define PRINTK_NMI_CONTEXT_MASK 0x80000000 +#define PRINTK_SAFE_CONTEXT_MASK 0x007ffffff +#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x008000000 +#define PRINTK_NMI_CONTEXT_MASK 0xff0000000 + +#define PRINTK_NMI_CONTEXT_OFFSET 0x010000000 extern raw_spinlock_t logbuf_lock; diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index d9a659a..e8791f2 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -295,12 +295,12 @@ static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args) void notrace printk_nmi_enter(void) { - this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK); + this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET); } void notrace printk_nmi_exit(void) { - this_cpu_and(printk_context, ~PRINTK_NMI_CONTEXT_MASK); + this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET); } /* -- 2.7.4