[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>

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index bfbb9bc..3254a61 100644 (file)
--- 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 9d0958f..a888e67 100644 (file)
--- 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 a1641ff..b54ccc0 100644 (file)
--- 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 6a1f8f4..6c41778 100644 (file)
--- 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) {

diff --git a/include/asm-x86_64/bug.h b/include/asm-x86_64/bug.h
index 80ac1fe..6826064 100644 (file)
--- a/include/asm-x86_64/bug.h
+++ b/include/asm-x86_64/bug.h
@@ -1,30 +1,30 @@
 #ifndef __ASM_X8664_BUG_H
 #define __ASM_X8664_BUG_H 1
 
-#include <linux/stringify.h>
-
-/*
- * Tell the user there is some problem.  The exception handler decodes 
- * this frame.
- */
-struct bug_frame {
-       unsigned char ud2[2];
-       unsigned char push;
-       signed int filename;
-       unsigned char ret;
-       unsigned short line;
-} __attribute__((packed));
-
 #ifdef CONFIG_BUG
 #define HAVE_ARCH_BUG
-/* We turn the bug frame into valid instructions to not confuse
-   the disassembler. Thanks to Jan Beulich & Suresh Siddha
-   for nice instruction selection.
-   The magic numbers generate mov $64bitimm,%eax ; ret $offset. */
-#define BUG()                                                          \
-       asm volatile(                                                   \
-       "ud2 ; pushq $%c1 ; ret $%c0" ::                                \
-                    "i"(__LINE__), "i" (__FILE__))
+
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+#define BUG()                                                          \
+       do {                                                            \
+               asm volatile("1:\tud2\n"                                \
+                            ".pushsection __bug_table,\"a\"\n"         \
+                            "2:\t.quad 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()                                                          \
+       do {                                                            \
+               asm volatile("ud2");                                    \
+               for(;;) ;                                               \
+       } while(0)
+#endif
+
 void out_of_line_bug(void);
 #else
 static inline void out_of_line_bug(void) { }