1 files changed, 163 insertions, 0 deletions

diff --git a/lib/bug.c b/lib/bug.c
new file mode 100644
index 000000000000..014b582c5c4b
--- /dev/null
+++ b/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@goop.org> 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;
+}