[PATCH] Generic BUG for i386

This makes i386 use the generic BUG machinery.  There are no functional
changes from the old i386 implementation.

The main advantage in using the generic BUG machinery for i386 is that the
inlined overhead of BUG is just the ud2a instruction; the file+line(+function)
information are no longer inlined into the instruction stream.  This reduces
cache pollution, and makes disassembly work properly.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Hugh Dickens <hugh@veritas.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 42 insertions, 40 deletions

diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index ea70359..c2362c7 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -49,6 +49,11 @@ config GENERIC_IOMAP
 	bool
 	default y
 
+config GENERIC_BUG
+	bool
+	default y
+	depends on BUG
+
 config GENERIC_HWEIGHT
 	bool
 	default y
diff --git a/arch/i386/kernel/module.c b/arch/i386/kernel/module.c
index d7d9c8b2..3db0a544 100644
--- a/arch/i386/kernel/module.c
+++ b/arch/i386/kernel/module.c
@@ -21,6 +21,7 @@
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/bug.h>
 
 #if 0
 #define DEBUGP printk
@@ -141,10 +142,11 @@ int module_finalize(const Elf_Ehdr *hdr,
 		apply_paravirt(pseg, pseg + para->sh_size);
 	}
 
-	return 0;
+	return module_bug_finalize(hdr, sechdrs, me);
 }
 
 void module_arch_cleanup(struct module *mod)
 {
 	alternatives_smp_module_del(mod);
+	module_bug_cleanup(mod);
 }
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 68de48e..2b30dbf 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -30,6 +30,7 @@
 #include <linux/unwind.h>
 #include <linux/uaccess.h>
 #include <linux/nmi.h>
+#include <linux/bug.h>
 
 #ifdef CONFIG_EISA
 #include <linux/ioport.h>
@@ -420,43 +421,22 @@ void show_registers(struct pt_regs *regs)
 	printk("\n");
 }	
 
-static void handle_BUG(struct pt_regs *regs)
+int is_valid_bugaddr(unsigned long eip)
 {
-	unsigned long eip = regs->eip;
 	unsigned short ud2;
 
 	if (eip < PAGE_OFFSET)
-		return;
+		return 0;
 	if (probe_kernel_address((unsigned short *)eip, ud2))
-		return;
-	if (ud2 != 0x0b0f)
-		return;
-
-	printk(KERN_EMERG "------------[ cut here ]------------\n");
-
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-	do {
-		unsigned short line;
-		char *file;
-		char c;
-
-		if (probe_kernel_address((unsigned short *)(eip + 2), line))
-			break;
-		if (probe_kernel_address((char **)(eip + 4), file) ||
-		    (unsigned long)file < PAGE_OFFSET ||
-			probe_kernel_address(file, c))
-			file = "<bad filename>";
+		return 0;
 
-		printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
-		return;
-	} while (0);
-#endif
-	printk(KERN_EMERG "Kernel BUG at [verbose debug info unavailable]\n");
+	return ud2 == 0x0b0f;
 }
 
-/* This is gone through when something in the kernel
- * has done something bad and is about to be terminated.
-*/
+/*
+ * This is gone through when something in the kernel has done something bad and
+ * is about to be terminated.
+ */
 void die(const char * str, struct pt_regs * regs, long err)
 {
 	static struct {
@@ -488,7 +468,8 @@ void die(const char * str, struct pt_regs * regs, long err)
 		unsigned long esp;
 		unsigned short ss;
 
-		handle_BUG(regs);
+		report_bug(regs->eip);
+
 		printk(KERN_EMERG "%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
 #ifdef CONFIG_PREEMPT
 		printk(KERN_EMERG "PREEMPT ");
diff --git a/arch/i386/kernel/vmlinux.lds.S b/arch/i386/kernel/vmlinux.lds.S
index 56e6ad5c..16d3c71 100644
--- a/arch/i386/kernel/vmlinux.lds.S
+++ b/arch/i386/kernel/vmlinux.lds.S
@@ -57,6 +57,8 @@ SECTIONS
 
   RODATA
 
+  BUG_TABLE
+
   . = ALIGN(4);
   .tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {
   	__tracedata_start = .;
diff --git a/include/asm-i386/bug.h b/include/asm-i386/bug.h
index 8062cdb..b0fd78c 100644
--- a/include/asm-i386/bug.h
+++ b/include/asm-i386/bug.h
@@ -4,20 +4,32 @@
 
 /*
  * Tell the user there is some problem.
- * The offending file and line are encoded after the "officially
- * undefined" opcode for parsing in the trap handler.
+ * The offending file and line are encoded encoded in the __bug_table section.
  */
 
 #ifdef CONFIG_BUG
 #define HAVE_ARCH_BUG
+
 #ifdef CONFIG_DEBUG_BUGVERBOSE
-#define BUG()				\
- __asm__ __volatile__(	"ud2\n"		\
-			"\t.word %c0\n"	\
-			"\t.long %c1\n"	\
-			 : : "i" (__LINE__), "i" (__FILE__))
+#define BUG()								\
+	do {								\
+		asm volatile("1:\tud2\n"				\
+			     ".pushsection __bug_table,\"a\"\n"		\
+			     "2:\t.long 1b, %c0\n"			\
+			     "\t.word %c1, 0\n"				\
+			     "\t.org 2b+%c2\n"				\
+			     ".popsection"				\
+			     : : "i" (__FILE__), "i" (__LINE__),	\
+			     "i" (sizeof(struct bug_entry)));		\
+		for(;;) ;						\
+	} while(0)
+
 #else
-#define BUG() __asm__ __volatile__("ud2\n")
+#define BUG()								\
+	do {								\
+		asm volatile("ud2");					\
+		for(;;) ;						\
+	} while(0)
 #endif
 #endif
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ee46fb3..2c133c0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -285,7 +285,7 @@ config DEBUG_HIGHMEM
 config DEBUG_BUGVERBOSE
 	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 	depends on BUG
-	depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV || SUPERH || GENERIC_BUG
+	depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG
 	default !EMBEDDED
 	help
 	  Say Y here to make BUG() panics output the file name and line number