From 69ea03b56ed2c7189ccd0b5910ad39f3cad1df21 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 19 Feb 2020 09:46:47 +0100 Subject: hardirq/nmi: Allow nested nmi_enter() Since there are already a number of sites (ARM64, PowerPC) that effectively nest nmi_enter(), make the primitive support this before adding even more. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Acked-by: Marc Zyngier Acked-by: Will Deacon Cc: Michael Ellerman Link: https://lkml.kernel.org/r/20200505134100.864179229@linutronix.de --- include/linux/hardirq.h | 5 ++++- include/linux/preempt.h | 4 ++-- 2 files changed, 6 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 7c8b82f69288..a043ad826c67 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -65,13 +65,16 @@ extern void irq_exit(void); #define arch_nmi_exit() do { } while (0) #endif +/* + * nmi_enter() can nest up to 15 times; see NMI_BITS. + */ #define nmi_enter() \ do { \ arch_nmi_enter(); \ printk_nmi_enter(); \ lockdep_off(); \ ftrace_nmi_enter(); \ - BUG_ON(in_nmi()); \ + BUG_ON(in_nmi() == NMI_MASK); \ preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \ rcu_nmi_enter(); \ lockdep_hardirq_enter(); \ diff --git a/include/linux/preempt.h b/include/linux/preempt.h index bc3f1aecaa19..7d9c1c0e149c 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -26,13 +26,13 @@ * PREEMPT_MASK: 0x000000ff * SOFTIRQ_MASK: 0x0000ff00 * HARDIRQ_MASK: 0x000f0000 - * NMI_MASK: 0x00100000 + * NMI_MASK: 0x00f00000 * PREEMPT_NEED_RESCHED: 0x80000000 */ #define PREEMPT_BITS 8 #define SOFTIRQ_BITS 8 #define HARDIRQ_BITS 4 -#define NMI_BITS 1 +#define NMI_BITS 4 #define PREEMPT_SHIFT 0 #define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS) -- cgit v1.2.3