4 files changed, 73 insertions, 20 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3269576dbfa8..1412da8ccf05 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -215,6 +215,10 @@ config ARM_PATCH_PHYS_VIRT_16BIT
           to allow physical memory down to a theoretical minimum of 64K
           boundaries.
 
+config GENERIC_BUG
+        def_bool y
+        depends on BUG
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"
diff --git a/arch/arm/include/asm/bug.h b/arch/arm/include/asm/bug.h
index 4d88425a4169..9abe7a07d5ac 100644
--- a/arch/arm/include/asm/bug.h
+++ b/arch/arm/include/asm/bug.h
@@ -3,21 +3,58 @@
 
 
 #ifdef CONFIG_BUG
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-extern void __bug(const char *file, int line) __attribute__((noreturn));
-
-/* give file/line information */
-#define BUG()           __bug(__FILE__, __LINE__)
 
+/*
+ * Use a suitable undefined instruction to use for ARM/Thumb2 bug handling.
+ * We need to be careful not to conflict with those used by other modules and
+ * the register_undef_hook() system.
+ */
+#ifdef CONFIG_THUMB2_KERNEL
+#define BUG_INSTR_VALUE 0xde02
+#define BUG_INSTR_TYPE ".hword "
 #else
+#define BUG_INSTR_VALUE 0xe7f001f2
+#define BUG_INSTR_TYPE ".word "
+#endif
 
-/* this just causes an oops */
-#define BUG()           do { *(int *)0 = 0; } while (1)
 
-#endif
+#define BUG() _BUG(__FILE__, __LINE__, BUG_INSTR_VALUE)
+#define _BUG(file, line, value) __BUG(file, line, value)
+
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+
+/*
+ * The extra indirection is to ensure that the __FILE__ string comes through
+ * OK. Many version of gcc do not support the asm %c parameter which would be
+ * preferable to this unpleasantness. We use mergeable string sections to
+ * avoid multiple copies of the string appearing in the kernel image.
+ */
+
+#define __BUG(__file, __line, __value)                          \
+do {                                                            \
+        BUILD_BUG_ON(sizeof(struct bug_entry) != 12);           \
+        asm volatile("1:\t" BUG_INSTR_TYPE #__value "\n"        \
+                ".pushsection .rodata.str, \"aMS\", %progbits, 1\n" \
+                "2:\t.asciz " #__file "\n"                      \
+                ".popsection\n"                                 \
+                ".pushsection __bug_table,\"a\"\n"              \
+                "3:\t.word 1b, 2b\n"                            \
+                "\t.hword " #__line ", 0\n"                     \
+                ".popsection");                                 \
+        unreachable();                                          \
+} while (0)
+
+#else  /* not CONFIG_DEBUG_BUGVERBOSE */
+
+#define __BUG(__file, __line, __value)                          \
+do {                                                            \
+        asm volatile(BUG_INSTR_TYPE #__value);                  \
+        unreachable();                                          \
+} while (0)
+#endif  /* CONFIG_DEBUG_BUGVERBOSE */
 
 #define HAVE_ARCH_BUG
-#endif
+#endif  /* CONFIG_BUG */
 
 #include <asm-generic/bug.h>
 
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index bc9f9da782cb..74969248c375 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -21,6 +21,7 @@
 #include <linux/kdebug.h>
 #include <linux/module.h>
 #include <linux/kexec.h>
+#include <linux/bug.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/sched.h>
@@ -270,6 +271,8 @@ void die(const char *str, struct pt_regs *regs, int err)
         spin_lock_irq(&die_lock);
         console_verbose();
         bust_spinlocks(1);
+        if (!user_mode(regs))
+                report_bug(regs->ARM_pc, regs);
         ret = __die(str, err, thread, regs);
 
         if (regs && kexec_should_crash(thread->task))
@@ -301,6 +304,24 @@ void arm_notify_die(const char *str, struct pt_regs *regs,
         }
 }
 
+#ifdef CONFIG_GENERIC_BUG
+
+int is_valid_bugaddr(unsigned long pc)
+{
+#ifdef CONFIG_THUMB2_KERNEL
+        unsigned short bkpt;
+#else
+        unsigned long bkpt;
+#endif
+
+        if (probe_kernel_address((unsigned *)pc, bkpt))
+                return 0;
+
+        return bkpt == BUG_INSTR_VALUE;
+}
+
+#endif
+
 static LIST_HEAD(undef_hook);
 static DEFINE_SPINLOCK(undef_lock);
 
@@ -706,16 +727,6 @@ baddataabort(int code, unsigned long instr, struct pt_regs *regs)
         arm_notify_die("unknown data abort code", regs, &info, instr, 0);
 }
 
-void __attribute__((noreturn)) __bug(const char *file, int line)
-{
-        printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
-        *(int *)0 = 0;
-
-        /* Avoid "noreturn function does return" */
-        for (;;);
-}
-EXPORT_SYMBOL(__bug);
-
 void __readwrite_bug(const char *fn)
 {
         printk("%s called, but not implemented\n", fn);
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index bf977f8514f6..7b2541efd9f8 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -21,7 +21,8 @@
 #define ARM_CPU_KEEP(x)
 #endif
 
-#if defined(CONFIG_SMP_ON_UP) && !defined(CONFIG_DEBUG_SPINLOCK)
+#if (defined(CONFIG_SMP_ON_UP) && !defined(CONFIG_DEBUG_SPINLOCK)) || \
+        defined(CONFIG_GENERIC_BUG)
 #define ARM_EXIT_KEEP(x)        x
 #else
 #define ARM_EXIT_KEEP(x)