KGDB/KDB New:

* KDB: improved searching
    * No longer enter debug core on panic if panic timeout is set
 
 KGDB/KDB regressions / cleanups
    * fix pdf doc build errors
    * prevent junk characters on kdb console from printk levels
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Merge tag 'for_linux-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

Pull kgdb/kdb updates from Jason Wessel:
 "KGDB/KDB New:
   - KDB: improved searching
   - No longer enter debug core on panic if panic timeout is set

  KGDB/KDB regressions / cleanups
   - fix pdf doc build errors
   - prevent junk characters on kdb console from printk levels"

* tag 'for_linux-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  kgdb, docs: Fix <para> pdfdocs build errors
  debug: prevent entering debug mode on panic/exception.
  kdb: Const qualifier for kdb_getstr's prompt argument
  kdb: Provide forward search at more prompt
  kdb: Fix a prompt management bug when using | grep
  kdb: Remove stack dump when entering kgdb due to NMI
  kdb: Avoid printing KERN_ levels to consoles
  kdb: Fix off by one error in kdb_cpu()
  kdb: fix incorrect counts in KDB summary command output

Documentation/DocBook/kgdb.tmpl

@@ -197,6 +197,7 @@
    may be configured as a kernel built-in or a kernel loadable module.
    You can only make use of <constant>kgdbwait</constant> and early
    debugging if you build kgdboc into the kernel as a built-in.
+   </para>
    <para>Optionally you can elect to activate kms (Kernel Mode
    Setting) integration.  When you use kms with kgdboc and you have a
    video driver that has atomic mode setting hooks, it is possible to
@@ -206,7 +207,6 @@
    crashes or doing analysis of memory with kdb while allowing the
    full graphics console applications to run.
    </para>
-   </para>
    <sect2 id="kgdbocArgs">
    <title>kgdboc arguments</title>
    <para>Usage: <constant>kgdboc=[kms][[,]kbd][[,]serial_device][,baud]</constant></para>
@@ -284,7 +284,6 @@
    </listitem>
    </orderedlist>
    </para>
-   </sect3>
    <para>NOTE: Kgdboc does not support interrupting the target via the
    gdb remote protocol.  You must manually send a sysrq-g unless you
    have a proxy that splits console output to a terminal program.
@@ -305,6 +304,7 @@
     as well as on the initial connect, or to use a debugger proxy that
     allows an unmodified gdb to do the debugging.
    </para>
+   </sect3>
    </sect2>
    </sect1>
    <sect1 id="kgdbwait">
@@ -350,12 +350,12 @@
    </para>
    </listitem>
    </orderedlist>
+  </para>
    <para>IMPORTANT NOTE: You cannot use kgdboc + kgdbcon on a tty that is an
    active system console.  An example of incorrect usage is <constant>console=ttyS0,115200 kgdboc=ttyS0 kgdbcon</constant>
    </para>
    <para>It is possible to use this option with kgdboc on a tty that is not a system console.
    </para>
-  </para>
   </sect1>
    <sect1 id="kgdbreboot">
    <title>Run time parameter: kgdbreboot</title>

include/linux/kdb.h

@@ -156,8 +156,14 @@ typedef enum {
 	KDB_REASON_SYSTEM_NMI,	/* In NMI due to SYSTEM cmd; regs valid */
 } kdb_reason_t;
 
+enum kdb_msgsrc {
+	KDB_MSGSRC_INTERNAL, /* direct call to kdb_printf() */
+	KDB_MSGSRC_PRINTK, /* trapped from printk() */
+};
+
 extern int kdb_trap_printk;
-extern __printf(1, 0) int vkdb_printf(const char *fmt, va_list args);
+extern __printf(2, 0) int vkdb_printf(enum kdb_msgsrc src, const char *fmt,
+				      va_list args);
 extern __printf(1, 2) int kdb_printf(const char *, ...);
 typedef __printf(1, 2) int (*kdb_printf_t)(const char *, ...);
 

kernel/debug/debug_core.c

@@ -604,7 +604,7 @@ return_normal:
 		   online_cpus)
 		cpu_relax();
 	if (!time_left)
-		pr_crit("KGDB: Timed out waiting for secondary CPUs.\n");
+		pr_crit("Timed out waiting for secondary CPUs.\n");
 
 	/*
 	 * At this point the primary processor is completely
@@ -696,6 +696,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 
 	if (arch_kgdb_ops.enable_nmi)
 		arch_kgdb_ops.enable_nmi(0);
+	/*
+	 * Avoid entering the debugger if we were triggered due to an oops
+	 * but panic_timeout indicates the system should automatically
+	 * reboot on panic. We don't want to get stuck waiting for input
+	 * on such systems, especially if its "just" an oops.
+	 */
+	if (signo != SIGTRAP && panic_timeout)
+		return 1;
 
 	memset(ks, 0, sizeof(struct kgdb_state));
 	ks->cpu			= raw_smp_processor_id();
@@ -828,6 +836,15 @@ static int kgdb_panic_event(struct notifier_block *self,
 			    unsigned long val,
 			    void *data)
 {
+	/*
+	 * Avoid entering the debugger if we were triggered due to a panic
+	 * We don't want to get stuck waiting for input from user in such case.
+	 * panic_timeout indicates the system should automatically
+	 * reboot on panic.
+	 */
+	if (panic_timeout)
+		return NOTIFY_DONE;
+
 	if (dbg_kdb_mode)
 		kdb_printf("PANIC: %s\n", (char *)data);
 	kgdb_breakpoint();

kernel/debug/kdb/kdb_io.c

@@ -439,7 +439,7 @@ poll_again:
  *	substituted for %d, %x or %o in the prompt.
  */
 
-char *kdb_getstr(char *buffer, size_t bufsize, char *prompt)
+char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
 {
 	if (prompt && kdb_prompt_str != prompt)
 		strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
@@ -548,7 +548,7 @@ static int kdb_search_string(char *searched, char *searchfor)
 	return 0;
 }
 
-int vkdb_printf(const char *fmt, va_list ap)
+int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
 {
 	int diag;
 	int linecount;
@@ -680,6 +680,12 @@ int vkdb_printf(const char *fmt, va_list ap)
 			size_avail = sizeof(kdb_buffer) - len;
 			goto kdb_print_out;
 		}
+		if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH)
+			/*
+			 * This was a interactive search (using '/' at more
+			 * prompt) and it has completed. Clear the flag.
+			 */
+			kdb_grepping_flag = 0;
 		/*
 		 * at this point the string is a full line and
 		 * should be printed, up to the null.
@@ -691,19 +697,20 @@ kdb_printit:
 	 * Write to all consoles.
 	 */
 	retlen = strlen(kdb_buffer);
+	cp = (char *) printk_skip_level(kdb_buffer);
 	if (!dbg_kdb_mode && kgdb_connected) {
-		gdbstub_msg_write(kdb_buffer, retlen);
+		gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
 	} else {
 		if (dbg_io_ops && !dbg_io_ops->is_console) {
-			len = retlen;
-			cp = kdb_buffer;
+			len = retlen - (cp - kdb_buffer);
+			cp2 = cp;
 			while (len--) {
-				dbg_io_ops->write_char(*cp);
-				cp++;
+				dbg_io_ops->write_char(*cp2);
+				cp2++;
 			}
 		}
 		while (c) {
-			c->write(c, kdb_buffer, retlen);
+			c->write(c, cp, retlen - (cp - kdb_buffer));
 			touch_nmi_watchdog();
 			c = c->next;
 		}
@@ -711,7 +718,10 @@ kdb_printit:
 	if (logging) {
 		saved_loglevel = console_loglevel;
 		console_loglevel = CONSOLE_LOGLEVEL_SILENT;
-		printk(KERN_INFO "%s", kdb_buffer);
+		if (printk_get_level(kdb_buffer) || src == KDB_MSGSRC_PRINTK)
+			printk("%s", kdb_buffer);
+		else
+			pr_info("%s", kdb_buffer);
 	}
 
 	if (KDB_STATE(PAGER)) {
@@ -794,11 +804,23 @@ kdb_printit:
 			kdb_nextline = linecount - 1;
 			kdb_printf("\r");
 			suspend_grep = 1; /* for this recursion */
+		} else if (buf1[0] == '/' && !kdb_grepping_flag) {
+			kdb_printf("\r");
+			kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
+				   kdbgetenv("SEARCHPROMPT") ?: "search> ");
+			*strchrnul(kdb_grep_string, '\n') = '\0';
+			kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
+			suspend_grep = 1; /* for this recursion */
 		} else if (buf1[0] && buf1[0] != '\n') {
 			/* user hit something other than enter */
 			suspend_grep = 1; /* for this recursion */
-			kdb_printf("\nOnly 'q' or 'Q' are processed at more "
-				   "prompt, input ignored\n");
+			if (buf1[0] != '/')
+				kdb_printf(
+				    "\nOnly 'q', 'Q' or '/' are processed at "
+				    "more prompt, input ignored\n");
+			else
+				kdb_printf("\n'/' cannot be used during | "
+					   "grep filtering, input ignored\n");
 		} else if (kdb_grepping_flag) {
 			/* user hit enter */
 			suspend_grep = 1; /* for this recursion */
@@ -844,7 +866,7 @@ int kdb_printf(const char *fmt, ...)
 	int r;
 
 	va_start(ap, fmt);
-	r = vkdb_printf(fmt, ap);
+	r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
 	va_end(ap);
 
 	return r;

kernel/debug/kdb/kdb_main.c

@@ -50,8 +50,7 @@
 static int kdb_cmd_enabled = CONFIG_KDB_DEFAULT_ENABLE;
 module_param_named(cmd_enable, kdb_cmd_enabled, int, 0600);
 
-#define GREP_LEN 256
-char kdb_grep_string[GREP_LEN];
+char kdb_grep_string[KDB_GREP_STRLEN];
 int kdb_grepping_flag;
 EXPORT_SYMBOL(kdb_grepping_flag);
 int kdb_grep_leading;
@@ -870,7 +869,7 @@ static void parse_grep(const char *str)
 	len = strlen(cp);
 	if (!len)
 		return;
-	if (len >= GREP_LEN) {
+	if (len >= KDB_GREP_STRLEN) {
 		kdb_printf("search string too long\n");
 		return;
 	}
@@ -915,13 +914,12 @@ int kdb_parse(const char *cmdstr)
 	char *cp;
 	char *cpp, quoted;
 	kdbtab_t *tp;
-	int i, escaped, ignore_errors = 0, check_grep;
+	int i, escaped, ignore_errors = 0, check_grep = 0;
 
 	/*
 	 * First tokenize the command string.
 	 */
 	cp = (char *)cmdstr;
-	kdb_grepping_flag = check_grep = 0;
 
 	if (KDB_FLAG(CMD_INTERRUPT)) {
 		/* Previous command was interrupted, newline must not
@@ -1247,7 +1245,6 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
 		kdb_printf("due to NonMaskable Interrupt @ "
 			   kdb_machreg_fmt "\n",
 			   instruction_pointer(regs));
-		kdb_dumpregs(regs);
 		break;
 	case KDB_REASON_SSTEP:
 	case KDB_REASON_BREAK:
@@ -1281,6 +1278,9 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
 		 */
 		kdb_nextline = 1;
 		KDB_STATE_CLEAR(SUPPRESS);
+		kdb_grepping_flag = 0;
+		/* ensure the old search does not leak into '/' commands */
+		kdb_grep_string[0] = '\0';
 
 		cmdbuf = cmd_cur;
 		*cmdbuf = '\0';
@@ -2256,7 +2256,7 @@ static int kdb_cpu(int argc, const char **argv)
 	/*
 	 * Validate cpunum
 	 */
-	if ((cpunum > NR_CPUS) || !kgdb_info[cpunum].enter_kgdb)
+	if ((cpunum >= CONFIG_NR_CPUS) || !kgdb_info[cpunum].enter_kgdb)
 		return KDB_BADCPUNUM;
 
 	dbg_switch_cpu = cpunum;
@@ -2583,7 +2583,7 @@ static int kdb_summary(int argc, const char **argv)
 #define K(x) ((x) << (PAGE_SHIFT - 10))
 	kdb_printf("\nMemTotal:       %8lu kB\nMemFree:        %8lu kB\n"
 		   "Buffers:        %8lu kB\n",
-		   val.totalram, val.freeram, val.bufferram);
+		   K(val.totalram), K(val.freeram), K(val.bufferram));
 	return 0;
 }
 

kernel/debug/kdb/kdb_private.h

@@ -196,7 +196,9 @@ extern int kdb_main_loop(kdb_reason_t, kdb_reason_t,
 
 /* Miscellaneous functions and data areas */
 extern int kdb_grepping_flag;
+#define KDB_GREPPING_FLAG_SEARCH 0x8000
 extern char kdb_grep_string[];
+#define KDB_GREP_STRLEN 256
 extern int kdb_grep_leading;
 extern int kdb_grep_trailing;
 extern char *kdb_cmds[];
@@ -209,7 +211,7 @@ extern void kdb_ps1(const struct task_struct *p);
 extern void kdb_print_nameval(const char *name, unsigned long val);
 extern void kdb_send_sig_info(struct task_struct *p, struct siginfo *info);
 extern void kdb_meminfo_proc_show(void);
-extern char *kdb_getstr(char *, size_t, char *);
+extern char *kdb_getstr(char *, size_t, const char *);
 extern void kdb_gdb_state_pass(char *buf);
 
 /* Defines for kdb_symbol_print */

kernel/printk/printk.c

@@ -1811,7 +1811,7 @@ int vprintk_default(const char *fmt, va_list args)
 
 #ifdef CONFIG_KGDB_KDB
 	if (unlikely(kdb_trap_printk)) {
-		r = vkdb_printf(fmt, args);
+		r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
 		return r;
 	}
 #endif