The patch titled
Generic BUG for x86-64
has been added to the -mm tree. Its filename is
generic-bug-for-x86-64.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Generic BUG for x86-64
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
This makes x86-64 use the generic BUG machinery. The most significant
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.
Unfortunately there's no way to tell gcc that the "ud2" instruction won't
return, so the BUG macro includes a goto loop. This will generate a real jmp
instruction, which is never used. The net effect is that each BUG site
contains a ud2 and jmp instruction (4 bytes).
[akpm@xxxxxxxx: build fixes]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Andi Kleen <ak@xxxxxx>
Cc: Hugh Dickens <hugh@xxxxxxxxxxx>
Cc: Michael Ellerman <michael@xxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/x86_64/Kconfig | 5 +++
arch/x86_64/kernel/module.c | 5 ++-
arch/x86_64/kernel/traps.c | 36 +++++++----------------
arch/x86_64/kernel/vmlinux.lds.S | 2 +
include/asm-x86_64/bug.h | 44 ++++++++++++++---------------
5 files changed, 45 insertions(+), 47 deletions(-)
diff -puN arch/x86_64/Kconfig~generic-bug-for-x86-64 arch/x86_64/Kconfig
--- a/arch/x86_64/Kconfig~generic-bug-for-x86-64
+++ a/arch/x86_64/Kconfig
@@ -100,6 +100,11 @@ config AUDIT_ARCH
bool
default y
+config GENERIC_BUG
+ bool
+ default y
+ depends on BUG
+
source "init/Kconfig"
diff -puN arch/x86_64/kernel/module.c~generic-bug-for-x86-64 arch/x86_64/kernel/module.c
--- a/arch/x86_64/kernel/module.c~generic-bug-for-x86-64
+++ a/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 -puN arch/x86_64/kernel/traps.c~generic-bug-for-x86-64 arch/x86_64/kernel/traps.c
--- a/arch/x86_64/kernel/traps.c~generic-bug-for-x86-64
+++ a/arch/x86_64/kernel/traps.c
@@ -29,6 +29,7 @@
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/unwind.h>
+#include <linux/bug.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@@ -508,30 +509,15 @@ 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)
@@ -612,7 +598,9 @@ void die(const char * str, struct pt_reg
{
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 -puN arch/x86_64/kernel/vmlinux.lds.S~generic-bug-for-x86-64 arch/x86_64/kernel/vmlinux.lds.S
--- a/arch/x86_64/kernel/vmlinux.lds.S~generic-bug-for-x86-64
+++ a/arch/x86_64/kernel/vmlinux.lds.S
@@ -50,6 +50,8 @@ SECTIONS
RODATA
+ BUG_TABLE
+
#ifdef CONFIG_STACK_UNWIND
. = ALIGN(8);
.eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {
diff -puN include/asm-x86_64/bug.h~generic-bug-for-x86-64 include/asm-x86_64/bug.h
--- a/include/asm-x86_64/bug.h~generic-bug-for-x86-64
+++ a/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) { }
_
Patches currently in -mm which might be from jeremy@xxxxxxxx are
origin.patch
x86-remove-default_ldt-and-simplify-ldt-setting.patch
generic-implementatation-of-bug.patch
generic-bug-for-i386.patch
generic-bug-for-x86-64.patch
generic-bug-for-powerpc.patch
bug-test-1.patch
-
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