bug: Add BUG_FORMAT infrastructure

Add BUG_FORMAT; an architecture opt-in feature that allows adding the
WARN_printf() format string to the bug_entry table.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.223371452@infradead.org

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 2d9f61346dab8c1dfcf60a821321421d3f6efea0..c7a1407b8669f51230ba9f8af59c3e82f11af067 100644 (file)
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -42,6 +42,13 @@ struct bug_entry {
 #else
        signed int      bug_addr_disp;
 #endif
+#ifdef HAVE_ARCH_BUG_FORMAT
+#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
+       const char      *format;
+#else
+       signed int      format_disp;
+#endif
+#endif
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
        const char      *file;

diff --git a/lib/bug.c b/lib/bug.c
index b1f07459c2ee36ee018074d3bd2261b8e35b81a1..6e57199ed1f7fd325e47d7c0559f14200936433b 100644 (file)
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -139,6 +139,19 @@ void bug_get_file_line(struct bug_entry *bug, const char **file,
 #endif
 }
 
+static const char *bug_get_format(struct bug_entry *bug)
+{
+       const char *format = NULL;
+#ifdef HAVE_ARCH_BUG_FORMAT
+#ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
+       format = (const char *)&bug->format_disp + bug->format_disp;
+#else
+       format = bug->format;
+#endif
+#endif
+       return format;
+}
+
 struct bug_entry *find_bug(unsigned long bugaddr)
 {
        struct bug_entry *bug;
@@ -150,11 +163,19 @@ struct bug_entry *find_bug(unsigned long bugaddr)
        return module_find_bug(bugaddr);
 }
 
+static void __warn_printf(const char *fmt)
+{
+       if (!fmt)
+               return;
+
+       printk("%s", fmt);
+}
+
 static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *regs)
 {
-       struct bug_entry *bug;
-       const char *file;
-       unsigned line, warning, once, done;
+       bool warning, once, done, no_cut, has_args;
+       const char *file, *fmt;
+       unsigned line;
 
        if (!is_valid_bugaddr(bugaddr))
                return BUG_TRAP_TYPE_NONE;
@@ -166,10 +187,12 @@ static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *re
        disable_trace_on_warning();
 
        bug_get_file_line(bug, &file, &line);
+       fmt = bug_get_format(bug);
 
-       warning = (bug->flags & BUGFLAG_WARNING) != 0;
-       once = (bug->flags & BUGFLAG_ONCE) != 0;
-       done = (bug->flags & BUGFLAG_DONE) != 0;
+       warning  = bug->flags & BUGFLAG_WARNING;
+       once     = bug->flags & BUGFLAG_ONCE;
+       done     = bug->flags & BUGFLAG_DONE;
+       no_cut   = bug->flags & BUGFLAG_NO_CUT_HERE;
 
        if (warning && once) {
                if (done)
@@ -187,8 +210,10 @@ static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *re
         * "cut here" line now. WARN() issues its own "cut here" before the
         * extra debugging message it writes before triggering the handler.
         */
-       if ((bug->flags & BUGFLAG_NO_CUT_HERE) == 0)
+       if (!no_cut) {
                printk(KERN_DEFAULT CUT_HERE);
+               __warn_printf(fmt);
+       }
 
        if (warning) {
                /* this is a WARN_ON rather than BUG/BUG_ON */