Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  kgdb: Always process the whole breakpoint list on activate or deactivate
  kgdb: continue and warn on signal passing from gdb
  kgdb,x86: do not set kgdb_single_step on x86
  kgdb: allow for cpu switch when single stepping
  kgdb,i386: Fix corner case access to ss with NMI watch dog exception
  kgdb: Replace strstr() by strchr() for single-character needles
  kgdbts: Read buffer overflow
  kgdb: Read buffer overflow
  kgdb,x86: remove redundant test

arch/x86/kernel/kgdb.c

@@ -86,9 +86,15 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 	gdb_regs[GDB_DS]	= regs->ds;
 	gdb_regs[GDB_ES]	= regs->es;
 	gdb_regs[GDB_CS]	= regs->cs;
-	gdb_regs[GDB_SS]	= __KERNEL_DS;
 	gdb_regs[GDB_FS]	= 0xFFFF;
 	gdb_regs[GDB_GS]	= 0xFFFF;
+	if (user_mode_vm(regs)) {
+		gdb_regs[GDB_SS] = regs->ss;
+		gdb_regs[GDB_SP] = regs->sp;
+	} else {
+		gdb_regs[GDB_SS] = __KERNEL_DS;
+		gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
+	}
 #else
 	gdb_regs[GDB_R8]	= regs->r8;
 	gdb_regs[GDB_R9]	= regs->r9;
@@ -101,8 +107,8 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 	gdb_regs32[GDB_PS]	= regs->flags;
 	gdb_regs32[GDB_CS]	= regs->cs;
 	gdb_regs32[GDB_SS]	= regs->ss;
-#endif
 	gdb_regs[GDB_SP]	= kernel_stack_pointer(regs);
+#endif
 }
 
 /**
@@ -220,8 +226,7 @@ static void kgdb_correct_hw_break(void)
 			dr7 |= ((breakinfo[breakno].len << 2) |
 				 breakinfo[breakno].type) <<
 			       ((breakno << 2) + 16);
-			if (breakno >= 0 && breakno <= 3)
-				set_debugreg(breakinfo[breakno].addr, breakno);
+			set_debugreg(breakinfo[breakno].addr, breakno);
 
 		} else {
 			if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {
@@ -395,7 +400,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
 		/* set the trace bit if we're stepping */
 		if (remcomInBuffer[0] == 's') {
 			linux_regs->flags |= X86_EFLAGS_TF;
-			kgdb_single_step = 1;
 			atomic_set(&kgdb_cpu_doing_single_step,
 				   raw_smp_processor_id());
 		}

drivers/misc/kgdbts.c

@@ -712,6 +712,12 @@ static int run_simple_test(int is_get_char, int chr)
 
 	/* End of packet == #XX so look for the '#' */
 	if (put_buf_cnt > 3 && put_buf[put_buf_cnt - 3] == '#') {
+		if (put_buf_cnt >= BUFMAX) {
+			eprintk("kgdbts: ERROR: put buffer overflow on"
+				" '%s' line %i\n", ts.name, ts.idx);
+			put_buf_cnt = 0;
+			return 0;
+		}
 		put_buf[put_buf_cnt] = '\0';
 		v2printk("put%i: %s\n", ts.idx, put_buf);
 		/* Trigger check here */
@@ -885,16 +891,16 @@ static void kgdbts_run_tests(void)
 	int nmi_sleep = 0;
 	int i;
 
-	ptr = strstr(config, "F");
+	ptr = strchr(config, 'F');
 	if (ptr)
 		fork_test = simple_strtol(ptr + 1, NULL, 10);
-	ptr = strstr(config, "S");
+	ptr = strchr(config, 'S');
 	if (ptr)
 		do_sys_open_test = simple_strtol(ptr + 1, NULL, 10);
-	ptr = strstr(config, "N");
+	ptr = strchr(config, 'N');
 	if (ptr)
 		nmi_sleep = simple_strtol(ptr+1, NULL, 10);
-	ptr = strstr(config, "I");
+	ptr = strchr(config, 'I');
 	if (ptr)
 		sstep_test = simple_strtol(ptr+1, NULL, 10);
 

kernel/kgdb.c

@@ -129,6 +129,7 @@ struct task_struct		*kgdb_usethread;
 struct task_struct		*kgdb_contthread;
 
 int				kgdb_single_step;
+pid_t				kgdb_sstep_pid;
 
 /* Our I/O buffers. */
 static char			remcom_in_buffer[BUFMAX];
@@ -541,12 +542,17 @@ static struct task_struct *getthread(struct pt_regs *regs, int tid)
 	 */
 	if (tid == 0 || tid == -1)
 		tid = -atomic_read(&kgdb_active) - 2;
-	if (tid < 0) {
+	if (tid < -1 && tid > -NR_CPUS - 2) {
 		if (kgdb_info[-tid - 2].task)
 			return kgdb_info[-tid - 2].task;
 		else
 			return idle_task(-tid - 2);
 	}
+	if (tid <= 0) {
+		printk(KERN_ERR "KGDB: Internal thread select error\n");
+		dump_stack();
+		return NULL;
+	}
 
 	/*
 	 * find_task_by_pid_ns() does not take the tasklist lock anymore
@@ -619,7 +625,8 @@ static void kgdb_flush_swbreak_addr(unsigned long addr)
 static int kgdb_activate_sw_breakpoints(void)
 {
 	unsigned long addr;
-	int error = 0;
+	int error;
+	int ret = 0;
 	int i;
 
 	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
@@ -629,13 +636,16 @@ static int kgdb_activate_sw_breakpoints(void)
 		addr = kgdb_break[i].bpt_addr;
 		error = kgdb_arch_set_breakpoint(addr,
 				kgdb_break[i].saved_instr);
-		if (error)
-			return error;
+		if (error) {
+			ret = error;
+			printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
+			continue;
+		}
 
 		kgdb_flush_swbreak_addr(addr);
 		kgdb_break[i].state = BP_ACTIVE;
 	}
-	return 0;
+	return ret;
 }
 
 static int kgdb_set_sw_break(unsigned long addr)
@@ -682,7 +692,8 @@ static int kgdb_set_sw_break(unsigned long addr)
 static int kgdb_deactivate_sw_breakpoints(void)
 {
 	unsigned long addr;
-	int error = 0;
+	int error;
+	int ret = 0;
 	int i;
 
 	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
@@ -691,13 +702,15 @@ static int kgdb_deactivate_sw_breakpoints(void)
 		addr = kgdb_break[i].bpt_addr;
 		error = kgdb_arch_remove_breakpoint(addr,
 					kgdb_break[i].saved_instr);
-		if (error)
-			return error;
+		if (error) {
+			printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
+			ret = error;
+		}
 
 		kgdb_flush_swbreak_addr(addr);
 		kgdb_break[i].state = BP_SET;
 	}
-	return 0;
+	return ret;
 }
 
 static int kgdb_remove_sw_break(unsigned long addr)
@@ -1204,8 +1217,10 @@ static int gdb_cmd_exception_pass(struct kgdb_state *ks)
 		return 1;
 
 	} else {
-		error_packet(remcom_out_buffer, -EINVAL);
-		return 0;
+		kgdb_msg_write("KGDB only knows signal 9 (pass)"
+			" and 15 (pass and disconnect)\n"
+			"Executing a continue without signal passing\n", 0);
+		remcom_in_buffer[0] = 'c';
 	}
 
 	/* Indicate fall through */
@@ -1395,6 +1410,7 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	struct kgdb_state kgdb_var;
 	struct kgdb_state *ks = &kgdb_var;
 	unsigned long flags;
+	int sstep_tries = 100;
 	int error = 0;
 	int i, cpu;
 
@@ -1425,13 +1441,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 		cpu_relax();
 
 	/*
-	 * Do not start the debugger connection on this CPU if the last
-	 * instance of the exception handler wanted to come into the
-	 * debugger on a different CPU via a single step
+	 * For single stepping, try to only enter on the processor
+	 * that was single stepping.  To gaurd against a deadlock, the
+	 * kernel will only try for the value of sstep_tries before
+	 * giving up and continuing on.
 	 */
 	if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
-	    atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
-
+	    (kgdb_info[cpu].task &&
+	     kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
 		atomic_set(&kgdb_active, -1);
 		touch_softlockup_watchdog();
 		clocksource_touch_watchdog();
@@ -1524,6 +1541,13 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	}
 
 kgdb_restore:
+	if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
+		int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
+		if (kgdb_info[sstep_cpu].task)
+			kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
+		else
+			kgdb_sstep_pid = 0;
+	}
 	/* Free kgdb_active */
 	atomic_set(&kgdb_active, -1);
 	touch_softlockup_watchdog();