[PATCH] Generic BUG for x86-64

This makes x86-64 use the generic BUG machinery.

The main advantage in using the generic BUG machinery for x86-64 is that
the inlined overhead of BUG is just the ud2a instruction; the file+line
information are no longer inlined into the instruction stream.  This
reduces cache pollution.

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>

4 files changed, 23 insertions, 25 deletions

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index bfbb9bcae123..3254a616c69e 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -96,6 +96,11 @@ config AUDIT_ARCH
         bool
         default y
 
+config GENERIC_BUG
+        bool
+        default y
+        depends on BUG
+
 source "init/Kconfig"
 
 
diff --git a/arch/x86_64/kernel/module.c b/arch/x86_64/kernel/module.c
index 9d0958ff547f..a888e67f5874 100644
--- a/arch/x86_64/kernel/module.c
+++ b/arch/x86_64/kernel/module.c
@@ -23,6 +23,7 @@
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/bug.h>
 
 #include <asm/system.h>
 #include <asm/page.h>
@@ -173,10 +174,12 @@ int module_finalize(const Elf_Ehdr *hdr,
                                             lseg, lseg + locks->sh_size,
                                             tseg, tseg + text->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/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index a1641ffdffcf..b54ccc07f379 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -31,6 +31,7 @@
 #include <linux/kexec.h>
 #include <linux/unwind.h>
 #include <linux/uaccess.h>
+#include <linux/bug.h>
 
 #include <asm/system.h>
 #include <asm/io.h>
@@ -524,30 +525,15 @@ bad:
         printk("\n");
 }       
 
-void handle_BUG(struct pt_regs *regs)
-{ 
-        struct bug_frame f;
-        long len;
-        const char *prefix = "";
+int is_valid_bugaddr(unsigned long rip)
+{
+        unsigned short ud2;
 
-        if (user_mode(regs))
-                return; 
-        if (__copy_from_user(&f, (const void __user *) regs->rip,
-                             sizeof(struct bug_frame)))
-                return; 
-        if (f.filename >= 0 ||
-            f.ud2[0] != 0x0f || f.ud2[1] != 0x0b) 
-                return;
-        len = __strnlen_user((char *)(long)f.filename, PATH_MAX) - 1;
-        if (len < 0 || len >= PATH_MAX)
-                f.filename = (int)(long)"unmapped filename";
-        else if (len > 50) {
-                f.filename += len - 50;
-                prefix = "...";
-        }
-        printk("----------- [cut here ] --------- [please bite here ] ---------\n");
-        printk(KERN_ALERT "Kernel BUG at %s%.50s:%d\n", prefix, (char *)(long)f.filename, f.line);
-} 
+        if (__copy_from_user(&ud2, (const void __user *) rip, sizeof(ud2)))
+                return 0;
+
+        return ud2 == 0x0b0f;
+}
 
 #ifdef CONFIG_BUG
 void out_of_line_bug(void)
@@ -627,7 +613,9 @@ void die(const char * str, struct pt_regs * regs, long err)
 {
         unsigned long flags = oops_begin();
 
-        handle_BUG(regs);
+        if (!user_mode(regs))
+                report_bug(regs->rip);
+
         __die(str, regs, err);
         oops_end(flags);
         do_exit(SIGSEGV); 
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index 6a1f8f491e5d..6c417788c54b 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -51,6 +51,8 @@ SECTIONS
 
   RODATA
 
+  BUG_TABLE
+
   . = ALIGN(PAGE_SIZE);        /* Align data segment to page size boundary */
                                 /* Data */
   .data : AT(ADDR(.data) - LOAD_OFFSET) {