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authorPetr Mladek <pmladek@suse.com>2020-02-24 13:13:31 +0100
committerThomas Gleixner <tglx@linutronix.de>2020-05-19 15:51:16 +0200
commit8c4e93c362ff114def211d4629b120af86eb1275 (patch)
treee2568aa0d2327ceb10846e0273740820f6d6c4ac /kernel/printk
parent1ed0948eea079a4c802d08cdb2e8db1eee0860f1 (diff)
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 <pmladek@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134100.681374113@linutronix.de
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/internal.h8
-rw-r--r--kernel/printk/printk_safe.c4
2 files changed, 7 insertions, 5 deletions
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index b2b0f526f249..660f9a6bf73a 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 d9a659a686f3..e8791f206417 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);
}
/*