Merge tag 'for_linus-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

Pull KGDB/KDB fixes and cleanups from Jason Wessel:
 "Cleanups
   - Clean up compile warnings in kgdboc.c and x86/kernel/kgdb.c
   - Add module event hooks for simplified debugging with gdb
 Fixes
   - Fix kdb to stop paging with 'q' on bta and dmesg
   - Fix for data that scrolls off the vga console due to line wrapping
     when using the kdb pager
 New
   - The debug core registers for kernel module events which allows a
     kernel aware gdb to automatically load symbols and break on entry
     to a kernel module
   - Allow kgdboc=kdb to setup kdb on the vga console"

* tag 'for_linus-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  tty/console: fix warnings in drivers/tty/serial/kgdboc.c
  kdb,vt_console: Fix missed data due to pager overruns
  kdb: Fix dmesg/bta scroll to quit with 'q'
  kgdboc: Accept either kbd or kdb to activate the vga + keyboard kdb shell
  kgdb,x86: fix warning about unused variable
  mips,kgdb: fix recursive page fault with CONFIG_KPROBES
  kgdb: Add module event hooks

arch/mips/kernel/kgdb.c

@@ -283,6 +283,15 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
 	struct pt_regs *regs = args->regs;
 	int trap = (regs->cp0_cause & 0x7c) >> 2;
 
+#ifdef CONFIG_KPROBES
+	/*
+	 * Return immediately if the kprobes fault notifier has set
+	 * DIE_PAGE_FAULT.
+	 */
+	if (cmd == DIE_PAGE_FAULT)
+		return NOTIFY_DONE;
+#endif /* CONFIG_KPROBES */
+
 	/* Userspace events, ignore. */
 	if (user_mode(regs))
 		return NOTIFY_DONE;

arch/x86/kernel/kgdb.c

@@ -746,7 +746,9 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
 	int err;
+#ifdef CONFIG_DEBUG_RODATA
 	char opc[BREAK_INSTR_SIZE];
+#endif /* CONFIG_DEBUG_RODATA */
 
 	bpt->type = BP_BREAKPOINT;
 	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,

drivers/tty/serial/kgdboc.c

@@ -97,7 +97,8 @@ static void kgdboc_restore_input(void)
 
 static int kgdboc_register_kbd(char **cptr)
 {
-	if (strncmp(*cptr, "kbd", 3) == 0) {
+	if (strncmp(*cptr, "kbd", 3) == 0 ||
+		strncmp(*cptr, "kdb", 3) == 0) {
 		if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
 			kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
 			kdb_poll_idx++;

drivers/tty/vt/vt.c

@@ -3442,6 +3442,19 @@ int con_debug_enter(struct vc_data *vc)
 			kdb_set(2, setargs);
 		}
 	}
+	if (vc->vc_cols < 999) {
+		int colcount;
+		char cols[4];
+		const char *setargs[3] = {
+			"set",
+			"COLUMNS",
+			cols,
+		};
+		if (kdbgetintenv(setargs[0], &colcount)) {
+			snprintf(cols, 4, "%i", vc->vc_cols);
+			kdb_set(2, setargs);
+		}
+	}
 #endif /* CONFIG_KGDB_KDB */
 	return ret;
 }

include/linux/console.h

@@ -83,8 +83,14 @@ void give_up_console(const struct consw *sw);
 int con_debug_enter(struct vc_data *vc);
 int con_debug_leave(void);
 #else
-#define con_debug_enter(vc) (0)
-#define con_debug_leave() (0)
+static inline int con_debug_enter(struct vc_data *vc)
+{
+	return 0;
+}
+static inline int con_debug_leave(void)
+{
+	return 0;
+}
 #endif
 
 /* scroll */

kernel/debug/debug_core.c

@@ -696,6 +696,22 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	return ret;
 }
 
+/*
+ * GDB places a breakpoint at this function to know dynamically
+ * loaded objects. It's not defined static so that only one instance with this
+ * name exists in the kernel.
+ */
+
+static int module_event(struct notifier_block *self, unsigned long val,
+	void *data)
+{
+	return 0;
+}
+
+static struct notifier_block dbg_module_load_nb = {
+	.notifier_call	= module_event,
+};
+
 int kgdb_nmicallback(int cpu, void *regs)
 {
 #ifdef CONFIG_SMP
@@ -824,6 +840,7 @@ static void kgdb_register_callbacks(void)
 		kgdb_arch_init();
 		if (!dbg_is_early)
 			kgdb_arch_late();
+		register_module_notifier(&dbg_module_load_nb);
 		register_reboot_notifier(&dbg_reboot_notifier);
 		atomic_notifier_chain_register(&panic_notifier_list,
 					       &kgdb_panic_event_nb);
@@ -847,6 +864,7 @@ static void kgdb_unregister_callbacks(void)
 	if (kgdb_io_module_registered) {
 		kgdb_io_module_registered = 0;
 		unregister_reboot_notifier(&dbg_reboot_notifier);
+		unregister_module_notifier(&dbg_module_load_nb);
 		atomic_notifier_chain_unregister(&panic_notifier_list,
 					       &kgdb_panic_event_nb);
 		kgdb_arch_exit();

kernel/debug/kdb/kdb_bt.c

@@ -129,6 +129,8 @@ kdb_bt(int argc, const char **argv)
 		}
 		/* Now the inactive tasks */
 		kdb_do_each_thread(g, p) {
+			if (KDB_FLAG(CMD_INTERRUPT))
+				return 0;
 			if (task_curr(p))
 				continue;
 			if (kdb_bt1(p, mask, argcount, btaprompt))

kernel/debug/kdb/kdb_io.c

@@ -552,6 +552,7 @@ int vkdb_printf(const char *fmt, va_list ap)
 {
 	int diag;
 	int linecount;
+	int colcount;
 	int logging, saved_loglevel = 0;
 	int saved_trap_printk;
 	int got_printf_lock = 0;
@@ -584,6 +585,10 @@ int vkdb_printf(const char *fmt, va_list ap)
 	if (diag || linecount <= 1)
 		linecount = 24;
 
+	diag = kdbgetintenv("COLUMNS", &colcount);
+	if (diag || colcount <= 1)
+		colcount = 80;
+
 	diag = kdbgetintenv("LOGGING", &logging);
 	if (diag)
 		logging = 0;
@@ -690,7 +695,7 @@ int vkdb_printf(const char *fmt, va_list ap)
 		gdbstub_msg_write(kdb_buffer, retlen);
 	} else {
 		if (dbg_io_ops && !dbg_io_ops->is_console) {
-			len = strlen(kdb_buffer);
+			len = retlen;
 			cp = kdb_buffer;
 			while (len--) {
 				dbg_io_ops->write_char(*cp);
@@ -709,11 +714,29 @@ int vkdb_printf(const char *fmt, va_list ap)
 		printk(KERN_INFO "%s", kdb_buffer);
 	}
 
-	if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n'))
+	if (KDB_STATE(PAGER)) {
+		/*
+		 * Check printed string to decide how to bump the
+		 * kdb_nextline to control when the more prompt should
+		 * show up.
+		 */
+		int got = 0;
+		len = retlen;
+		while (len--) {
+			if (kdb_buffer[len] == '\n') {
 				kdb_nextline++;
+				got = 0;
+			} else if (kdb_buffer[len] == '\r') {
+				got = 0;
+			} else {
+				got++;
+			}
+		}
+		kdb_nextline += got / (colcount + 1);
+	}
 
 	/* check for having reached the LINES number of printed lines */
-	if (kdb_nextline == linecount) {
+	if (kdb_nextline >= linecount) {
 		char buf1[16] = "";
 
 		/* Watch out for recursion here.  Any routine that calls
@@ -765,7 +788,7 @@ int vkdb_printf(const char *fmt, va_list ap)
 			kdb_grepping_flag = 0;
 			kdb_printf("\n");
 		} else if (buf1[0] == ' ') {
-			kdb_printf("\n");
+			kdb_printf("\r");
 			suspend_grep = 1; /* for this recursion */
 		} else if (buf1[0] == '\n') {
 			kdb_nextline = linecount - 1;

kernel/debug/kdb/kdb_main.c

@@ -2101,6 +2101,8 @@ static int kdb_dmesg(int argc, const char **argv)
 		}
 		if (!lines--)
 			break;
+		if (KDB_FLAG(CMD_INTERRUPT))
+			return 0;
 
 		kdb_printf("%.*s\n", (int)len - 1, buf);
 	}