The patch titled
Generic implementatation of BUG
has been added to the -mm tree. Its filename is
generic-implementatation-of-bug.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 implementatation of BUG
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
This patch adds common handling for kernel BUGs, for use by architectures as
they wish. The code is derived from arch/powerpc.
The advantages of having common BUG handling are:
- consistent BUG reporting across architectures
- shared implementation of out-of-line file/line data
This means that in inline impact of BUG is just the illegal instruction
itself, which is an improvement for i386 and x86-64.
A BUG is represented in the instruction stream as an illegal instruction,
which has file/line/function information associated with it. This extra
information is stored in the __bug_table section in the ELF file.
When the kernel gets an illegal instruction, it first confirms it might
possibly be from a BUG (ie, in kernel mode, the right illegal instruction).
It then calls report_bug(). This searches __bug_table for a matching
instruction pointer, and if found, prints the corresponding file/line/function
information.
Some architectures (powerpc) implement WARN using the same mechanism; if the
illegal instruction was the result of a WARN, then report_bug() returns 1;
otherwise it returns 0.
lib/bug.c keeps a list of loaded modules which can be searched for __bug_table
entries. The architecture must call
module_bug_finalize()/module_bug_cleanup() from its corresponding
module_finalize/cleanup functions.
This patch also converts i386, x86-64 and powerpc to use this infrastructure.
I have only tested i386; x86-64 and powerpc are not even compile-tested in
this patch.
Because powerpc also records the function name, I added this to i386 and
x86-64 for consistency. Strictly speaking the function name is redundant with
kallsyms, so perhaps it can be dropped from powerpc.
i386 implements CONFIG_DEBUG_BUGVERBOSE, but x86-64 and powerpc do not. This
should probably be made more consistent.
[akpm@xxxxxxxx: Fix CONFIG_MODULES=n]
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>
---
include/asm-generic/bug.h | 14 ++
include/asm-generic/vmlinux.lds.h | 8 +
include/linux/bug.h | 33 +++++
include/linux/module.h | 7 +
lib/Kconfig.debug | 2
lib/Makefile | 2
lib/bug.c | 163 ++++++++++++++++++++++++++++
7 files changed, 228 insertions(+), 1 deletion(-)
diff -puN include/asm-generic/bug.h~generic-implementatation-of-bug include/asm-generic/bug.h
--- a/include/asm-generic/bug.h~generic-implementatation-of-bug
+++ a/include/asm-generic/bug.h
@@ -4,6 +4,20 @@
#include <linux/compiler.h>
#ifdef CONFIG_BUG
+
+#ifdef CONFIG_GENERIC_BUG
+struct bug_entry {
+ unsigned long bug_addr;
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+ const char *file;
+ unsigned short line;
+#endif
+ unsigned short flags;
+};
+
+#define BUGFLAG_WARNING (1<<0)
+#endif /* CONFIG_GENERIC_BUG */
+
#ifndef HAVE_ARCH_BUG
#define BUG() do { \
printk("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __FUNCTION__); \
diff -puN include/asm-generic/vmlinux.lds.h~generic-implementatation-of-bug include/asm-generic/vmlinux.lds.h
--- a/include/asm-generic/vmlinux.lds.h~generic-implementatation-of-bug
+++ a/include/asm-generic/vmlinux.lds.h
@@ -195,5 +195,13 @@
.stab.indexstr 0 : { *(.stab.indexstr) } \
.comment 0 : { *(.comment) }
+#define BUG_TABLE \
+ . = ALIGN(8); \
+ __bug_table : AT(ADDR(__bug_table) - LOAD_OFFSET) { \
+ __start___bug_table = .; \
+ *(__bug_table) \
+ __stop___bug_table = .; \
+ }
+
#define NOTES \
.notes : { *(.note.*) } :note
diff -puN /dev/null include/linux/bug.h
--- /dev/null
+++ a/include/linux/bug.h
@@ -0,0 +1,33 @@
+#ifndef _LINUX_BUG_H
+#define _LINUX_BUG_H
+
+#include <asm/bug.h>
+
+#ifdef CONFIG_GENERIC_BUG
+#include <linux/module.h>
+#include <asm-generic/bug.h>
+
+static inline int is_warning_bug(const struct bug_entry *bug)
+{
+ return bug->flags & BUGFLAG_WARNING;
+}
+
+enum bug_trap_type {
+ BUG_TRAP_TYPE_NONE = 0,
+ BUG_TRAP_TYPE_WARN = 1,
+ BUG_TRAP_TYPE_BUG = 2,
+};
+
+const struct bug_entry *find_bug(unsigned long bugaddr);
+
+enum bug_trap_type report_bug(unsigned long bug_addr);
+
+int module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
+ struct module *);
+void module_bug_cleanup(struct module *);
+
+/* These are defined by the architecture */
+int is_valid_bugaddr(unsigned long addr);
+
+#endif /* CONFIG_GENERIC_BUG */
+#endif /* _LINUX_BUG_H */
diff -puN include/linux/module.h~generic-implementatation-of-bug include/linux/module.h
--- a/include/linux/module.h~generic-implementatation-of-bug
+++ a/include/linux/module.h
@@ -322,6 +322,13 @@ struct module
unsigned int taints; /* same bits as kernel:tainted */
+#ifdef CONFIG_GENERIC_BUG
+ /* Support for BUG */
+ struct list_head bug_list;
+ struct bug_entry *bug_table;
+ unsigned num_bugs;
+#endif
+
#ifdef CONFIG_MODULE_UNLOAD
/* Reference counts */
struct module_ref ref[NR_CPUS];
diff -puN lib/Kconfig.debug~generic-implementatation-of-bug lib/Kconfig.debug
--- a/lib/Kconfig.debug~generic-implementatation-of-bug
+++ a/lib/Kconfig.debug
@@ -284,7 +284,7 @@ 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
+ depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV || SUPERH || GENERIC_BUG
default !EMBEDDED
help
Say Y here to make BUG() panics output the file name and line number
diff -puN lib/Makefile~generic-implementatation-of-bug lib/Makefile
--- a/lib/Makefile~generic-implementatation-of-bug
+++ a/lib/Makefile
@@ -55,6 +55,8 @@ obj-$(CONFIG_AUDIT_GENERIC) += audit.o
obj-$(CONFIG_SWIOTLB) += swiotlb.o
+lib-$(CONFIG_GENERIC_BUG) += bug.o
+
hostprogs-y := gen_crc32table
clean-files := crc32table.h
diff -puN /dev/null lib/bug.c
--- /dev/null
+++ a/lib/bug.c
@@ -0,0 +1,163 @@
+/*
+ Generic support for BUG()
+
+ This respects the following config options:
+
+ CONFIG_BUG - emit BUG traps. Nothing happens without this.
+ CONFIG_GENERIC_BUG - enable this code.
+ CONFIG_DEBUG_BUGVERBOSE - emit full file+line information for each BUG
+
+ CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable
+ (though they're generally always on).
+
+ CONFIG_GENERIC_BUG is set by each architecture using this code.
+
+ To use this, your architecture must:
+
+ 1. Set up the config options:
+ - Enable CONFIG_GENERIC_BUG if CONFIG_BUG
+
+ 2. Implement BUG (and optionally BUG_ON, WARN, WARN_ON)
+ - Define HAVE_ARCH_BUG
+ - Implement BUG() to generate a faulting instruction
+ - NOTE: struct bug_entry does not have "file" or "line" entries
+ when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate
+ the values accordingly.
+
+ 3. Implement the trap
+ - In the illegal instruction trap handler (typically), verify
+ that the fault was in kernel mode, and call report_bug()
+ - report_bug() will return whether it was a false alarm, a warning,
+ or an actual bug.
+ - You must implement the is_valid_bugaddr(bugaddr) callback which
+ returns true if the eip is a real kernel address, and it points
+ to the expected BUG trap instruction.
+
+ Jeremy Fitzhardinge <jeremy@xxxxxxxx> 2006
+ */
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/bug.h>
+
+extern const struct bug_entry __start___bug_table[], __stop___bug_table[];
+
+#ifdef CONFIG_MODULES
+static LIST_HEAD(module_bug_list);
+
+static const struct bug_entry *module_find_bug(unsigned long bugaddr)
+{
+ struct module *mod;
+
+ list_for_each_entry(mod, &module_bug_list, bug_list) {
+ const struct bug_entry *bug = mod->bug_table;
+ unsigned i;
+
+ for (i = 0; i < mod->num_bugs; ++i, ++bug)
+ if (bugaddr == bug->bug_addr)
+ return bug;
+ }
+ return NULL;
+}
+
+int module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+ struct module *mod)
+{
+ char *secstrings;
+ unsigned int i;
+
+ mod->bug_table = NULL;
+ mod->num_bugs = 0;
+
+ /* Find the __bug_table section, if present */
+ secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+ for (i = 1; i < hdr->e_shnum; i++) {
+ if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
+ continue;
+ mod->bug_table = (void *) sechdrs[i].sh_addr;
+ mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
+ break;
+ }
+
+ /*
+ * Strictly speaking this should have a spinlock to protect against
+ * traversals, but since we only traverse on BUG()s, a spinlock
+ * could potentially lead to deadlock and thus be counter-productive.
+ */
+ list_add(&mod->bug_list, &module_bug_list);
+
+ return 0;
+}
+
+void module_bug_cleanup(struct module *mod)
+{
+ list_del(&mod->bug_list);
+}
+
+#else
+
+static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)
+{
+ return NULL;
+}
+#endif
+
+const struct bug_entry *find_bug(unsigned long bugaddr)
+{
+ const struct bug_entry *bug;
+
+ for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
+ if (bugaddr == bug->bug_addr)
+ return bug;
+
+ return module_find_bug(bugaddr);
+}
+
+enum bug_trap_type report_bug(unsigned long bugaddr)
+{
+ const struct bug_entry *bug;
+ const char *file;
+ unsigned line, warning;
+
+ if (!is_valid_bugaddr(bugaddr))
+ return BUG_TRAP_TYPE_NONE;
+
+ bug = find_bug(bugaddr);
+
+ printk(KERN_EMERG "------------[ cut here ]------------\n");
+
+ file = NULL;
+ line = 0;
+ warning = 0;
+
+ if (bug) {
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+ file = bug->file;
+ line = bug->line;
+#endif
+ warning = (bug->flags & BUGFLAG_WARNING) != 0;
+ }
+
+ if (warning) {
+ /* this is a WARN_ON rather than BUG/BUG_ON */
+ if (file)
+ printk(KERN_ERR "Badness at %s:%u\n",
+ file, line);
+ else
+ printk(KERN_ERR "Badness at %p "
+ "[verbose debug info unavailable]\n",
+ (void *)bugaddr);
+
+ dump_stack();
+ return BUG_TRAP_TYPE_WARN;
+ }
+
+ if (file)
+ printk(KERN_CRIT "kernel BUG at %s:%u!\n",
+ file, line);
+ else
+ printk(KERN_CRIT "Kernel BUG at %p "
+ "[verbose debug info unavailable]\n",
+ (void *)bugaddr);
+
+ return BUG_TRAP_TYPE_BUG;
+}
_
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
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
