When in the kernel debugger we do now record the relevant information

(fault address, pc, read/write) when a page fault occurs, and print them
in case this caused the termination of a debugger command.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26949 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/debug.h

@@ -69,6 +69,18 @@ struct debugger_module_info {
 
 extern int dbg_register_file[B_MAX_CPU_COUNT][14];
 
+typedef struct debug_page_fault_info {
+	addr_t	fault_address;
+	addr_t	pc;
+	uint32	flags;
+} debug_page_fault_info;
+
+// debug_page_fault_info::flags
+#define DEBUG_PAGE_FAULT_WRITE		0x01	/* write fault */
+#define DEBUG_PAGE_FAULT_NO_INFO	0x02	/* fault address and read/write
+											   unknown */
+
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -83,6 +95,9 @@ extern void debug_puts(const char *s, int32 length);
 extern bool debug_debugger_running(void);
 extern bool debug_screen_output_enabled(void);
 extern void debug_stop_screen_debug_output(void);
+extern void debug_set_page_fault_info(addr_t faultAddress, addr_t pc,
+				uint32 flags);
+extern debug_page_fault_info* debug_get_page_fault_info();
 
 extern void	kputs(const char *string);
 extern void	kputs_unfiltered(const char *string);
@@ -109,11 +124,11 @@ extern status_t	add_debugger_command_alias(const char* newName,
 					const char* oldName, const char* description);
 extern bool		print_debugger_command_usage(const char* command);
 
-extern void		_user_debug_output(const char *userString);
-
 extern void debug_set_demangle_hook(const char *(*hook)(const char *));
 extern const char *debug_demangle(const char *);
 
+extern void		_user_debug_output(const char *userString);
+
 #ifdef __cplusplus
 }
 #endif

src/system/kernel/arch/x86/arch_int.c

@@ -838,6 +838,8 @@ page_fault_exception(struct iframe* frame)
 	if (kernelDebugger) {
 		// if this thread has a fault handler, we're allowed to be here
 		if (thread && thread->fault_handler != 0) {
+			debug_set_page_fault_info(cr2, frame->eip,
+				(frame->error_code & 0x2) != 0 ? DEBUG_PAGE_FAULT_WRITE : 0);
 			frame->eip = thread->fault_handler;
 			return;
 		}

src/system/kernel/debug/debug.cpp

@@ -49,6 +49,8 @@ extern "C" int kgets(char *buffer, int length);
 int dbg_register_file[B_MAX_CPU_COUNT][14];
 	/* XXXmpetit -- must be made generic */
 
+static debug_page_fault_info sPageFaultInfo;
+
 static bool sSerialDebugEnabled = true;
 static bool sSyslogOutputEnabled = true;
 static bool sBlueScreenEnabled = false;
@@ -1132,6 +1134,22 @@ debug_init_post_modules(struct kernel_args *args)
 }
 
 
+void
+debug_set_page_fault_info(addr_t faultAddress, addr_t pc, uint32 flags)
+{
+	sPageFaultInfo.fault_address = faultAddress;
+	sPageFaultInfo.pc = pc;
+	sPageFaultInfo.flags = flags;
+}
+
+
+debug_page_fault_info*
+debug_get_page_fault_info()
+{
+	return &sPageFaultInfo;
+}
+
+
 //	#pragma mark - public API
 
 
@@ -1392,6 +1410,22 @@ kprintf_unfiltered(const char *format, ...)
 }
 
 
+extern void
+debug_set_demangle_hook(const char *(*hook)(const char *))
+{
+	sDemangleHook = hook;
+}
+
+
+extern const char *
+debug_demangle(const char *sym)
+{
+	if (sDemangleHook)
+		return sDemangleHook(sym);
+	return sym;
+}
+
+
 //	#pragma mark -
 //	userland syscalls
 
@@ -1451,20 +1485,3 @@ dump_block(const char *buffer, int size, const char *prefix)
 		dprintf("\n");
 	}
 }
-
-
-extern void
-debug_set_demangle_hook(const char *(*hook)(const char *))
-{
-	sDemangleHook = hook;
-}
-
-
-extern const char *
-debug_demangle(const char *sym)
-{
-	if (sDemangleHook)
-		return sDemangleHook(sym);
-	return sym;
-}
-

src/system/kernel/debug/debug_commands.cpp

@@ -299,8 +299,19 @@ error:
 				INVOKE_COMMAND_FAULT);
 
 		case INVOKE_COMMAND_FAULT:
-			kprintf_unfiltered("\n[*** READ/WRITE FAULT ***]\n");
+		{
+			debug_page_fault_info* info = debug_get_page_fault_info();
+			if ((info->flags & DEBUG_PAGE_FAULT_NO_INFO) == 0) {
+				kprintf_unfiltered("\n[*** %s FAULT at %#lx, pc: %#lx ***]\n",
+					(info->flags & DEBUG_PAGE_FAULT_NO_INFO) != 0
+						? "WRITE" : "READ",
+					info->fault_address, info->pc);
+			} else {
+				kprintf_unfiltered("\n[*** READ/WRITE FAULT (?), "
+					"pc: %#lx ***]\n", info->pc);
+			}
 			break;
+		}
 		case INVOKE_COMMAND_ERROR:
 			// command aborted (no page fault)
 			break;