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authorChristoph Hellwig <hch@lst.de>2010-06-28 14:15:54 +0200
committerThomas Gleixner <tglx@linutronix.de>2010-06-29 12:12:59 +0200
commit7974891db234467eaf1fec613ec0129cb4ac2332 (patch)
tree09de403e54e39f4f25a1c15a29f5b201d4c11729 /arch
parent5904b3b81d25166e5e39b9727645bb47937618e3 (diff)
downloadop-kernel-dev-7974891db234467eaf1fec613ec0129cb4ac2332.zip
op-kernel-dev-7974891db234467eaf1fec613ec0129cb4ac2332.tar.gz
x86: Always use irq stacks
IRQ stacks provide much better safety against unexpected stack use from interrupts, at the minimal downside of slightly higher memory usage. Enable irq stacks also for the default 8k stack on 32-bit kernels to minimize the problem of stack overflows through interrupt activity. This is what the 64-bit kernel and various other architectures already do. Signed-off-by: Christoph Hellwig <hch@lst.de> LKML-Reference: <20100628121554.GA6605@lst.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig.debug3
-rw-r--r--arch/x86/include/asm/irq.h12
-rw-r--r--arch/x86/kernel/irq_32.c6
3 files changed, 6 insertions, 15 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 7508508..badda8e 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -128,8 +128,7 @@ config 4KSTACKS
If you say Y here the kernel will use a 4Kb stacksize for the
kernel stack attached to each process/thread. This facilitates
running more threads on a system and also reduces the pressure
- on the VM subsystem for higher order allocations. This option
- will also use IRQ stacks to compensate for the reduced stackspace.
+ on the VM subsystem for higher order allocations.
config DOUBLEFAULT
default y
diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index 5458380..0bf5b00 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -19,18 +19,16 @@ static inline int irq_canonicalize(int irq)
# define ARCH_HAS_NMI_WATCHDOG
#endif
-#ifdef CONFIG_4KSTACKS
- extern void irq_ctx_init(int cpu);
- extern void irq_ctx_exit(int cpu);
-# define __ARCH_HAS_DO_SOFTIRQ
+#ifdef CONFIG_X86_32
+extern void irq_ctx_init(int cpu);
+extern void irq_ctx_exit(int cpu);
#else
# define irq_ctx_init(cpu) do { } while (0)
# define irq_ctx_exit(cpu) do { } while (0)
-# ifdef CONFIG_X86_64
-# define __ARCH_HAS_DO_SOFTIRQ
-# endif
#endif
+#define __ARCH_HAS_DO_SOFTIRQ
+
#ifdef CONFIG_HOTPLUG_CPU
#include <linux/cpumask.h>
extern void fixup_irqs(void);
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 10709f2..67f5f9f 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -49,7 +49,6 @@ static inline int check_stack_overflow(void) { return 0; }
static inline void print_stack_overflow(void) { }
#endif
-#ifdef CONFIG_4KSTACKS
/*
* per-CPU IRQ handling contexts (thread information and stack)
*/
@@ -187,11 +186,6 @@ asmlinkage void do_softirq(void)
local_irq_restore(flags);
}
-#else
-static inline int
-execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) { return 0; }
-#endif
-
bool handle_irq(unsigned irq, struct pt_regs *regs)
{
struct irq_desc *desc;
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