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Subject[PATCH 1/5] MIPS: Introduce irq_stack
Date
Allocate a per-cpu irq stack for use within interrupt handlers.

Also add a utility function on_irq_stack to determine if a given stack
pointer is within the irq stack for that cpu.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>

---

arch/mips/include/asm/irq.h | 12 ++++++++++++
arch/mips/kernel/asm-offsets.c | 1 +
arch/mips/kernel/irq.c | 11 +++++++++++
3 files changed, 24 insertions(+)

diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h
index 6bf10e796553..956db6e201d1 100644
--- a/arch/mips/include/asm/irq.h
+++ b/arch/mips/include/asm/irq.h
@@ -17,6 +17,18 @@

#include <irq.h>

+#define IRQ_STACK_SIZE THREAD_SIZE
+
+extern void *irq_stack[NR_CPUS];
+
+static inline bool on_irq_stack(int cpu, unsigned long sp)
+{
+ unsigned long low = (unsigned long)irq_stack[cpu];
+ unsigned long high = low + IRQ_STACK_SIZE;
+
+ return (low <= sp && sp <= high);
+}
+
#ifdef CONFIG_I8259
static inline int irq_canonicalize(int irq)
{
diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c
index fae2f9447792..4be2763f835d 100644
--- a/arch/mips/kernel/asm-offsets.c
+++ b/arch/mips/kernel/asm-offsets.c
@@ -102,6 +102,7 @@ void output_thread_info_defines(void)
OFFSET(TI_REGS, thread_info, regs);
DEFINE(_THREAD_SIZE, THREAD_SIZE);
DEFINE(_THREAD_MASK, THREAD_MASK);
+ DEFINE(_IRQ_STACK_SIZE, IRQ_STACK_SIZE);
BLANK();
}

diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
index f25f7eab7307..2b0a371b42af 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -25,6 +25,8 @@
#include <linux/atomic.h>
#include <asm/uaccess.h>

+void *irq_stack[NR_CPUS];
+
/*
* 'what should we do if we get a hw irq event on an illegal vector'.
* each architecture has to answer this themselves.
@@ -58,6 +60,15 @@ void __init init_IRQ(void)
clear_c0_status(ST0_IM);

arch_init_irq();
+
+ for_each_possible_cpu(i) {
+ int irq_pages = IRQ_STACK_SIZE / PAGE_SIZE;
+ void *s = (void *)__get_free_pages(GFP_KERNEL, irq_pages);
+
+ irq_stack[i] = s;
+ pr_debug("CPU%d IRQ stack at 0x%p - 0x%p\n", i,
+ irq_stack[i], irq_stack[i] + IRQ_STACK_SIZE);
+ }
}

#ifdef CONFIG_DEBUG_STACKOVERFLOW
--
2.7.4
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