kgdb: Always process the whole breakpoint list on activate or deactivate

This patch fixes 2 edge cases in using kgdb in conjunction with gdb. 1) kgdb_deactivate_sw_breakpoints() should process the entire array of breakpoints. The failure to do so results in breakpoints that you cannot remove, because a break point can only be removed if its state flag is set to BP_SET. The easy way to duplicate this problem is to plant a break point in a kernel module and then unload the kernel module. 2) kgdb_activate_sw_breakpoints() should process the entire array of breakpoints. The failure to do so results in missed breakpoints when a breakpoint cannot be activated. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

kgdb: Always process the whole breakpoint list on activate or deactivate
This patch fixes 2 edge cases in using kgdb in conjunction with gdb. 1) kgdb_deactivate_sw_breakpoints() should process the entire array of breakpoints. The failure to do so results in breakpoints that you cannot remove, because a break point can only be removed if its state flag is set to BP_SET. The easy way to duplicate this problem is to plant a break point in a kernel module and then unload the kernel module. 2) kgdb_activate_sw_breakpoints() should process the entire array of breakpoints. The failure to do so results in missed breakpoints when a breakpoint cannot be activated. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Jason Wessel
1 parent d625e9c0d7
Showing 1 changed file with 15 additions and 8 deletions Side-by-side Diff
kernel/kgdb.c
@@ -625,7 +625,8 @@
 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++) {
  
@@ -635,13 +636,16 @@
 		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)
@@ -688,7 +692,8 @@
 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++) {
  
@@ -697,13 +702,15 @@
 		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)
...	...	@@ -625,7 +625,8 @@
625	625	static int kgdb_activate_sw_breakpoints(void)
626	626	{
627	627	unsigned long addr;
628		- int error = 0;
	628	+ int error;
	629	+ int ret = 0;
629	630	int i;
630	631
631	632	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
632	633
...	...	@@ -635,13 +636,16 @@
635	636	addr = kgdb_break[i].bpt_addr;
636	637	error = kgdb_arch_set_breakpoint(addr,
637	638	kgdb_break[i].saved_instr);
638		- if (error)
639		- return error;
	639	+ if (error) {
	640	+ ret = error;
	641	+ printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
	642	+ continue;
	643	+ }
640	644
641	645	kgdb_flush_swbreak_addr(addr);
642	646	kgdb_break[i].state = BP_ACTIVE;
643	647	}
644		- return 0;
	648	+ return ret;
645	649	}
646	650
647	651	static int kgdb_set_sw_break(unsigned long addr)
...	...	@@ -688,7 +692,8 @@
688	692	static int kgdb_deactivate_sw_breakpoints(void)
689	693	{
690	694	unsigned long addr;
691		- int error = 0;
	695	+ int error;
	696	+ int ret = 0;
692	697	int i;
693	698
694	699	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
695	700
...	...	@@ -697,13 +702,15 @@
697	702	addr = kgdb_break[i].bpt_addr;
698	703	error = kgdb_arch_remove_breakpoint(addr,
699	704	kgdb_break[i].saved_instr);
700		- if (error)
701		- return error;
	705	+ if (error) {
	706	+ printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
	707	+ ret = error;
	708	+ }
702	709
703	710	kgdb_flush_swbreak_addr(addr);
704	711	kgdb_break[i].state = BP_SET;
705	712	}
706		- return 0;
	713	+ return ret;
707	714	}
708	715
709	716	static int kgdb_remove_sw_break(unsigned long addr)