4 files changed, 42 insertions, 4 deletions

diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug
index bc989e522a04..08a332f6ee87 100644
--- a/arch/parisc/Kconfig.debug
+++ b/arch/parisc/Kconfig.debug
@@ -13,3 +13,14 @@ config DEBUG_RODATA
          If in doubt, say "N".
 
 endmenu
+
+config DEBUG_STACKOVERFLOW
+        bool "Check for stack overflows"
+        default y
+        depends on DEBUG_KERNEL
+        ---help---
+          Say Y here if you want to check the overflows of kernel, IRQ
+          and exception stacks. This option will cause messages of the
+          stacks in detail when free stack space drops below a certain
+          limit.
+          If in doubt, say "N".
diff --git a/arch/parisc/include/asm/thread_info.h b/arch/parisc/include/asm/thread_info.h
index 6182832e5b6c..540c88fa8f86 100644
--- a/arch/parisc/include/asm/thread_info.h
+++ b/arch/parisc/include/asm/thread_info.h
@@ -40,7 +40,7 @@ struct thread_info {
 
 /* thread information allocation */
 
-#define THREAD_SIZE_ORDER            2
+#define THREAD_SIZE_ORDER       2 /* PA-RISC requires at least 16k stack */
 /* Be sure to hunt all references to this down when you change the size of
  * the kernel stack */
 #define THREAD_SIZE             (PAGE_SIZE << THREAD_SIZE_ORDER)
diff --git a/arch/parisc/kernel/irq.c b/arch/parisc/kernel/irq.c
index 8094d3ed3b64..61e51ac85659 100644
--- a/arch/parisc/kernel/irq.c
+++ b/arch/parisc/kernel/irq.c
@@ -330,6 +330,34 @@ static inline int eirr_to_irq(unsigned long eirr)
         return (BITS_PER_LONG - bit) + TIMER_IRQ;
 }
 
+int sysctl_panic_on_stackoverflow = 1;
+
+static inline void stack_overflow_check(struct pt_regs *regs)
+{
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+        #define STACK_MARGIN    (256*6)
+
+        /* Our stack starts directly behind the thread_info struct. */
+        unsigned long stack_start = (unsigned long) current_thread_info();
+        unsigned long sp = regs->gr[30];
+
+        /* if sr7 != 0, we interrupted a userspace process which we do not want
+         * to check for stack overflow. We will only check the kernel stack. */
+        if (regs->sr[7])
+                return;
+
+        if (likely((sp - stack_start) < (THREAD_SIZE - STACK_MARGIN)))
+                return;
+
+        pr_emerg("stackcheck: %s will most likely overflow kernel stack "
+                 "(sp:%lx, stk bottom-top:%lx-%lx)\n",
+                current->comm, sp, stack_start, stack_start + THREAD_SIZE);
+
+        if (sysctl_panic_on_stackoverflow)
+                panic("low stack detected by irq handler - check messages\n");
+#endif
+}
+
 /* ONLY called from entry.S:intr_extint() */
 void do_cpu_irq_mask(struct pt_regs *regs)
 {
@@ -364,6 +392,7 @@ void do_cpu_irq_mask(struct pt_regs *regs)
                 goto set_out;
         }
 #endif
+        stack_overflow_check(regs);
         generic_handle_irq(irq);
 
  out:
@@ -420,6 +449,4 @@ void __init init_IRQ(void)
         cpu_eiem = EIEM_MASK(TIMER_IRQ);
 #endif
         set_eiem(cpu_eiem);     /* EIEM : enable all external intr */
-
 }
-
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index 64a999882e4f..4bb095a2f6fc 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -95,7 +95,7 @@ SECTIONS
         NOTES
 
         /* Data */
-        RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
+        RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, PAGE_SIZE)
 
         /* PA-RISC locks requires 16-byte alignment */
         . = ALIGN(16);