Merge tag 'for_linus-3.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

Pull kgdb/kdb fixes from Jason Wessel:
 "These have been around since 3.17 and in kgdb-next for the last 9
  weeks and some will go back to -stable.

  Summary of changes:

  Cleanups
   - kdb: Remove unused command flags, repeat flags and KDB_REPEAT_NONE

  Fixes
   - kgdb/kdb: Allow access on a single core, if a CPU round up is
     deemed impossible, which will allow inspection of the now "trashed"
     kernel
   - kdb: Add enable mask for the command groups
   - kdb: access controls to restrict sensitive commands"

* tag 'for_linus-3.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  kernel/debug/debug_core.c: Logging clean-up
  kgdb: timeout if secondary CPUs ignore the roundup
  kdb: Allow access to sensitive commands to be restricted by default
  kdb: Add enable mask for groups of commands
  kdb: Categorize kdb commands (similar to SysRq categorization)
  kdb: Remove KDB_REPEAT_NONE flag
  kdb: Use KDB_REPEAT_* values as flags
  kdb: Rename kdb_register_repeat() to kdb_register_flags()
  kdb: Rename kdb_repeat_t to kdb_cmdflags_t, cmd_repeat to cmd_flags
  kdb: Remove currently unused kdbtab_t->cmd_flags

include/linux/kdb.h

@@ -13,11 +13,54 @@
  * Copyright (C) 2009 Jason Wessel <jason.wessel@windriver.com>
  */
 
+/* Shifted versions of the command enable bits are be used if the command
+ * has no arguments (see kdb_check_flags). This allows commands, such as
+ * go, to have different permissions depending upon whether it is called
+ * with an argument.
+ */
+#define KDB_ENABLE_NO_ARGS_SHIFT 10
+
 typedef enum {
-	KDB_REPEAT_NONE = 0,	/* Do not repeat this command */
-	KDB_REPEAT_NO_ARGS,	/* Repeat the command without arguments */
-	KDB_REPEAT_WITH_ARGS,	/* Repeat the command including its arguments */
-} kdb_repeat_t;
+	KDB_ENABLE_ALL = (1 << 0), /* Enable everything */
+	KDB_ENABLE_MEM_READ = (1 << 1),
+	KDB_ENABLE_MEM_WRITE = (1 << 2),
+	KDB_ENABLE_REG_READ = (1 << 3),
+	KDB_ENABLE_REG_WRITE = (1 << 4),
+	KDB_ENABLE_INSPECT = (1 << 5),
+	KDB_ENABLE_FLOW_CTRL = (1 << 6),
+	KDB_ENABLE_SIGNAL = (1 << 7),
+	KDB_ENABLE_REBOOT = (1 << 8),
+	/* User exposed values stop here, all remaining flags are
+	 * exclusively used to describe a commands behaviour.
+	 */
+
+	KDB_ENABLE_ALWAYS_SAFE = (1 << 9),
+	KDB_ENABLE_MASK = (1 << KDB_ENABLE_NO_ARGS_SHIFT) - 1,
+
+	KDB_ENABLE_ALL_NO_ARGS = KDB_ENABLE_ALL << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_MEM_READ_NO_ARGS = KDB_ENABLE_MEM_READ
+				      << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_MEM_WRITE_NO_ARGS = KDB_ENABLE_MEM_WRITE
+				       << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_REG_READ_NO_ARGS = KDB_ENABLE_REG_READ
+				      << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_REG_WRITE_NO_ARGS = KDB_ENABLE_REG_WRITE
+				       << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_INSPECT_NO_ARGS = KDB_ENABLE_INSPECT
+				     << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_FLOW_CTRL_NO_ARGS = KDB_ENABLE_FLOW_CTRL
+				       << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_SIGNAL_NO_ARGS = KDB_ENABLE_SIGNAL
+				    << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_REBOOT_NO_ARGS = KDB_ENABLE_REBOOT
+				    << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_ALWAYS_SAFE_NO_ARGS = KDB_ENABLE_ALWAYS_SAFE
+					 << KDB_ENABLE_NO_ARGS_SHIFT,
+	KDB_ENABLE_MASK_NO_ARGS = KDB_ENABLE_MASK << KDB_ENABLE_NO_ARGS_SHIFT,
+
+	KDB_REPEAT_NO_ARGS = 0x40000000, /* Repeat the command w/o arguments */
+	KDB_REPEAT_WITH_ARGS = 0x80000000, /* Repeat the command with args */
+} kdb_cmdflags_t;
 
 typedef int (*kdb_func_t)(int, const char **);
 
@@ -62,6 +105,7 @@ extern atomic_t kdb_event;
 #define KDB_BADLENGTH	(-19)
 #define KDB_NOBP	(-20)
 #define KDB_BADADDR	(-21)
+#define KDB_NOPERM	(-22)
 
 /*
  * kdb_diemsg
@@ -146,17 +190,17 @@ static inline const char *kdb_walk_kallsyms(loff_t *pos)
 
 /* Dynamic kdb shell command registration */
 extern int kdb_register(char *, kdb_func_t, char *, char *, short);
-extern int kdb_register_repeat(char *, kdb_func_t, char *, char *,
-			       short, kdb_repeat_t);
+extern int kdb_register_flags(char *, kdb_func_t, char *, char *,
+			      short, kdb_cmdflags_t);
 extern int kdb_unregister(char *);
 #else /* ! CONFIG_KGDB_KDB */
 static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
 static inline void kdb_init(int level) {}
 static inline int kdb_register(char *cmd, kdb_func_t func, char *usage,
 			       char *help, short minlen) { return 0; }
-static inline int kdb_register_repeat(char *cmd, kdb_func_t func, char *usage,
+static inline int kdb_register_flags(char *cmd, kdb_func_t func, char *usage,
 				     char *help, short minlen,
-				      kdb_repeat_t repeat) { return 0; }
+				     kdb_cmdflags_t flags) { return 0; }
 static inline int kdb_unregister(char *cmd) { return 0; }
 #endif	/* CONFIG_KGDB_KDB */
 enum {

kernel/debug/debug_core.c

@@ -27,6 +27,9 @@
  * version 2. This program is licensed "as is" without any warranty of any
  * kind, whether express or implied.
  */
+
+#define pr_fmt(fmt) "KGDB: " fmt
+
 #include <linux/pid_namespace.h>
 #include <linux/clocksource.h>
 #include <linux/serial_core.h>
@@ -196,8 +199,8 @@ int __weak kgdb_validate_break_address(unsigned long addr)
 		return err;
 	err = kgdb_arch_remove_breakpoint(&tmp);
 	if (err)
-		printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
-		   "memory destroyed at: %lx", addr);
+		pr_err("Critical breakpoint error, kernel memory destroyed at: %lx\n",
+		       addr);
 	return err;
 }
 
@@ -256,7 +259,7 @@ int dbg_activate_sw_breakpoints(void)
 		error = kgdb_arch_set_breakpoint(&kgdb_break[i]);
 		if (error) {
 			ret = error;
-			printk(KERN_INFO "KGDB: BP install failed: %lx",
+			pr_info("BP install failed: %lx\n",
 				kgdb_break[i].bpt_addr);
 			continue;
 		}
@@ -319,7 +322,7 @@ int dbg_deactivate_sw_breakpoints(void)
 			continue;
 		error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
 		if (error) {
-			printk(KERN_INFO "KGDB: BP remove failed: %lx\n",
+			pr_info("BP remove failed: %lx\n",
 				kgdb_break[i].bpt_addr);
 			ret = error;
 		}
@@ -367,7 +370,7 @@ int dbg_remove_all_break(void)
 			goto setundefined;
 		error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
 		if (error)
-			printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
+			pr_err("breakpoint remove failed: %lx\n",
 			       kgdb_break[i].bpt_addr);
 setundefined:
 		kgdb_break[i].state = BP_UNDEFINED;
@@ -400,9 +403,9 @@ static int kgdb_io_ready(int print_wait)
 	if (print_wait) {
 #ifdef CONFIG_KGDB_KDB
 		if (!dbg_kdb_mode)
-			printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
+			pr_crit("waiting... or $3#33 for KDB\n");
 #else
-		printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
+		pr_crit("Waiting for remote debugger\n");
 #endif
 	}
 	return 1;
@@ -430,8 +433,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
 		exception_level = 0;
 		kgdb_skipexception(ks->ex_vector, ks->linux_regs);
 		dbg_activate_sw_breakpoints();
-		printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
-			addr);
+		pr_crit("re-enter error: breakpoint removed %lx\n", addr);
 		WARN_ON_ONCE(1);
 
 		return 1;
@@ -444,7 +446,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
 		panic("Recursive entry to debugger");
 	}
 
-	printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
+	pr_crit("re-enter exception: ALL breakpoints killed\n");
 #ifdef CONFIG_KGDB_KDB
 	/* Allow kdb to debug itself one level */
 	return 0;
@@ -471,6 +473,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
 	int cpu;
 	int trace_on = 0;
 	int online_cpus = num_online_cpus();
+	u64 time_left;
 
 	kgdb_info[ks->cpu].enter_kgdb++;
 	kgdb_info[ks->cpu].exception_state |= exception_state;
@@ -595,9 +598,13 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
 	/*
 	 * Wait for the other CPUs to be notified and be waiting for us:
 	 */
-	while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
-				atomic_read(&slaves_in_kgdb)) != online_cpus)
+	time_left = loops_per_jiffy * HZ;
+	while (kgdb_do_roundup && --time_left &&
+	       (atomic_read(&masters_in_kgdb) + atomic_read(&slaves_in_kgdb)) !=
+		   online_cpus)
 		cpu_relax();
+	if (!time_left)
+		pr_crit("KGDB: Timed out waiting for secondary CPUs.\n");
 
 	/*
 	 * At this point the primary processor is completely
@@ -795,15 +802,15 @@ static struct console kgdbcons = {
 static void sysrq_handle_dbg(int key)
 {
 	if (!dbg_io_ops) {
-		printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
+		pr_crit("ERROR: No KGDB I/O module available\n");
 		return;
 	}
 	if (!kgdb_connected) {
 #ifdef CONFIG_KGDB_KDB
 		if (!dbg_kdb_mode)
-			printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
+			pr_crit("KGDB or $3#33 for KDB\n");
 #else
-		printk(KERN_CRIT "Entering KGDB\n");
+		pr_crit("Entering KGDB\n");
 #endif
 	}
 
@@ -945,7 +952,7 @@ static void kgdb_initial_breakpoint(void)
 {
 	kgdb_break_asap = 0;
 
-	printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
+	pr_crit("Waiting for connection from remote gdb...\n");
 	kgdb_breakpoint();
 }
 
@@ -964,8 +971,7 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
 	if (dbg_io_ops) {
 		spin_unlock(&kgdb_registration_lock);
 
-		printk(KERN_ERR "kgdb: Another I/O driver is already "
-				"registered with KGDB.\n");
+		pr_err("Another I/O driver is already registered with KGDB\n");
 		return -EBUSY;
 	}
 
@@ -981,8 +987,7 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
 
 	spin_unlock(&kgdb_registration_lock);
 
-	printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
-	       new_dbg_io_ops->name);
+	pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name);
 
 	/* Arm KGDB now. */
 	kgdb_register_callbacks();
@@ -1017,8 +1022,7 @@ void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
 
 	spin_unlock(&kgdb_registration_lock);
 
-	printk(KERN_INFO
-		"kgdb: Unregistered I/O driver %s, debugger disabled.\n",
+	pr_info("Unregistered I/O driver %s, debugger disabled\n",
 		old_dbg_io_ops->name);
 }
 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);

kernel/debug/kdb/kdb_bp.c

@@ -531,22 +531,29 @@ void __init kdb_initbptab(void)
 	for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++)
 		bp->bp_free = 1;
 
-	kdb_register_repeat("bp", kdb_bp, "[<vaddr>]",
-		"Set/Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
-	kdb_register_repeat("bl", kdb_bp, "[<vaddr>]",
-		"Display breakpoints", 0, KDB_REPEAT_NO_ARGS);
+	kdb_register_flags("bp", kdb_bp, "[<vaddr>]",
+		"Set/Display breakpoints", 0,
+		KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
+	kdb_register_flags("bl", kdb_bp, "[<vaddr>]",
+		"Display breakpoints", 0,
+		KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
 	if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)
-		kdb_register_repeat("bph", kdb_bp, "[<vaddr>]",
-		"[datar [length]|dataw [length]]   Set hw brk", 0, KDB_REPEAT_NO_ARGS);
-	kdb_register_repeat("bc", kdb_bc, "<bpnum>",
-		"Clear Breakpoint", 0, KDB_REPEAT_NONE);
-	kdb_register_repeat("be", kdb_bc, "<bpnum>",
-		"Enable Breakpoint", 0, KDB_REPEAT_NONE);
-	kdb_register_repeat("bd", kdb_bc, "<bpnum>",
-		"Disable Breakpoint", 0, KDB_REPEAT_NONE);
-
-	kdb_register_repeat("ss", kdb_ss, "",
-		"Single Step", 1, KDB_REPEAT_NO_ARGS);
+		kdb_register_flags("bph", kdb_bp, "[<vaddr>]",
+		"[datar [length]|dataw [length]]   Set hw brk", 0,
+		KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
+	kdb_register_flags("bc", kdb_bc, "<bpnum>",
+		"Clear Breakpoint", 0,
+		KDB_ENABLE_FLOW_CTRL);
+	kdb_register_flags("be", kdb_bc, "<bpnum>",
+		"Enable Breakpoint", 0,
+		KDB_ENABLE_FLOW_CTRL);
+	kdb_register_flags("bd", kdb_bc, "<bpnum>",
+		"Disable Breakpoint", 0,
+		KDB_ENABLE_FLOW_CTRL);
+
+	kdb_register_flags("ss", kdb_ss, "",
+		"Single Step", 1,
+		KDB_ENABLE_FLOW_CTRL | KDB_REPEAT_NO_ARGS);
 	/*
 	 * Architecture dependent initialization.
 	 */

kernel/debug/kdb/kdb_debugger.c

@@ -129,6 +129,10 @@ int kdb_stub(struct kgdb_state *ks)
 		ks->pass_exception = 1;
 		KDB_FLAG_SET(CATASTROPHIC);
 	}
+	/* set CATASTROPHIC if the system contains unresponsive processors */
+	for_each_online_cpu(i)
+		if (!kgdb_info[i].enter_kgdb)
+			KDB_FLAG_SET(CATASTROPHIC);
 	if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
 		KDB_STATE_CLEAR(SSBPT);
 		KDB_STATE_CLEAR(DOING_SS);

kernel/debug/kdb/kdb_private.h

@@ -172,10 +172,9 @@ typedef struct _kdbtab {
 	kdb_func_t cmd_func;		/* Function to execute command */
 	char    *cmd_usage;		/* Usage String for this command */
 	char    *cmd_help;		/* Help message for this command */
-	short    cmd_flags;		/* Parsing flags */
 	short    cmd_minlen;		/* Minimum legal # command
 					 * chars required */
-	kdb_repeat_t cmd_repeat;	/* Does command auto repeat on enter? */
+	kdb_cmdflags_t cmd_flags;	/* Command behaviour flags */
 } kdbtab_t;
 
 extern int kdb_bt(int, const char **);	/* KDB display back trace */

kernel/trace/trace_kdb.c

@@ -132,8 +132,8 @@ static int kdb_ftdump(int argc, const char **argv)
 
 static __init int kdb_ftrace_register(void)
 {
-	kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
-			    "Dump ftrace log", 0, KDB_REPEAT_NONE);
+	kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
+			    "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE);
 	return 0;
 }
 

lib/Kconfig.kgdb

@@ -73,6 +73,31 @@ config KGDB_KDB
 	help
 	  KDB frontend for kernel
 
+config KDB_DEFAULT_ENABLE
+	hex "KDB: Select kdb command functions to be enabled by default"
+	depends on KGDB_KDB
+	default 0x1
+	help
+	  Specifiers which kdb commands are enabled by default. This may
+	  be set to 1 or 0 to enable all commands or disable almost all
+	  commands.
+
+	  Alternatively the following bitmask applies:
+
+	    0x0002 - allow arbitrary reads from memory and symbol lookup
+	    0x0004 - allow arbitrary writes to memory
+	    0x0008 - allow current register state to be inspected
+	    0x0010 - allow current register state to be modified
+	    0x0020 - allow passive inspection (backtrace, process list, lsmod)
+	    0x0040 - allow flow control management (breakpoint, single step)
+	    0x0080 - enable signalling of processes
+	    0x0100 - allow machine to be rebooted
+
+	  The config option merely sets the default at boot time. Both
+	  issuing 'echo X > /sys/module/kdb/parameters/cmd_enable' or
+          setting with kdb.cmd_enable=X kernel command line option will
+	  override the default settings.
+
 config KDB_KEYBOARD
 	bool "KGDB_KDB: keyboard as input device"
 	depends on VT && KGDB_KDB