MIPS: Introduce irq_stack

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>
Acked-by: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14740/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 24 insertions, 0 deletions

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 6080582a26d1..a7277698d328 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 f8f5836eb3c1..ba150c755fcc 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -25,6 +25,8 @@
 #include <linux/atomic.h>
 #include <linux/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