* Removed most of the special-casing for kernel breakpoints in the kernel

enter/exit code. There's no real reason not to keep kernel breakpoints
  enabled when in userland (unless there are breakpoints installed for the
  team, of course).
* Enabled kernel breakpoints by default (check your kernel_debug_config.h,
  if you have overridden it!), since they don't really add any overhead
  anymore.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30206 a95241bf-73f2-0310-859d-f6bbb57e9c96

build/config_headers/kernel_debug_config.h

@@ -18,8 +18,8 @@
 // benaphore-style.
 #define KDEBUG							KDEBUG_LEVEL_2
 
-// Enable this to get support for kernel breakpoints.
+// Set to 0 to disable support for kernel breakpoints.
-#define KERNEL_BREAKPOINTS				0
+#define KERNEL_BREAKPOINTS				1
 
 
 // block/file cache

src/system/kernel/arch/x86/arch_interrupts.S

@@ -98,16 +98,11 @@
 						   original eax/edx values */				\
 	iret
 
-#if KERNEL_BREAKPOINTS
+#define DISABLE_BREAKPOINTS()											\
-#	define DISABLE_BREAKPOINTS()											\
+	testl	$THREAD_FLAGS_BREAKPOINTS_INSTALLED, THREAD_flags(%edi);	\
-		call	x86_exit_user_debug_at_kernel_entry;
+	jz		1f;															\
-#else
+	call	x86_exit_user_debug_at_kernel_entry;						\
-#	define DISABLE_BREAKPOINTS()											\
+  1:
-		testl	$THREAD_FLAGS_BREAKPOINTS_INSTALLED, THREAD_flags(%edi);	\
-		jz		1f;															\
-		call	x86_exit_user_debug_at_kernel_entry;						\
-	  1:
-#endif	// KERNEL_BREAKPOINTS
 
 #define COPY_SYSCALL_PARAMETERS()										\
 	/* make room for the syscall params */								\
@@ -311,14 +306,10 @@ STATIC_FUNCTION(int_bottom_user):
 	cmp		$USER_CODE_SEG, IFRAME_cs(%ebp)
 	jne		1f
 
-#if KERNEL_BREAKPOINTS
-	jmp		kernel_exit_work
-#else
 	testl	$(THREAD_FLAGS_DEBUGGER_INSTALLED | THREAD_FLAGS_SIGNALS_PENDING \
 			| THREAD_FLAGS_DEBUG_THREAD | THREAD_FLAGS_BREAKPOINTS_DEFINED) \
 			, THREAD_flags(%edi)
 	jnz		kernel_exit_work
-#endif
 1:
 
 	cli								// disable interrupts
@@ -422,16 +413,12 @@ STATIC_FUNCTION(handle_syscall):
 
 	TRACE_POST_SYSCALL()
 
-#if KERNEL_BREAKPOINTS
-	jmp		post_syscall_work
-#else
 	testl	$(THREAD_FLAGS_DEBUGGER_INSTALLED | THREAD_FLAGS_SIGNALS_PENDING \
 			| THREAD_FLAGS_DEBUG_THREAD | THREAD_FLAGS_BREAKPOINTS_DEFINED \
 			| THREAD_FLAGS_64_BIT_SYSCALL_RETURN \
 			| THREAD_FLAGS_RESTART_SYSCALL | THREAD_FLAGS_SYSCALL_RESTARTED) \
 			, THREAD_flags(%edi)
 	jnz		post_syscall_work
-#endif
 
 	cli								// disable interrupts
 
@@ -507,10 +494,8 @@ FUNCTION_END(handle_syscall)
   1:
 
 	// install breakpoints, if defined
-#if !KERNEL_BREAKPOINTS
 	testl	$THREAD_FLAGS_BREAKPOINTS_DEFINED, THREAD_flags(%edi)
 	jz		1f
-#endif
 	push	%ebp
 	call	x86_init_user_debug_at_kernel_exit
   1:

src/system/kernel/arch/x86/arch_user_debugger.cpp

@@ -516,7 +516,7 @@ arch_update_thread_single_step()
 {
 	if (struct iframe* frame = i386_get_user_iframe()) {
 		struct thread* thread = thread_get_current_thread();
-	
+
 		// set/clear TF in EFLAGS depending on if single stepping is desired
 		if (thread->debug_info.flags & B_THREAD_DEBUG_SINGLE_STEP)
 			frame->flags |= (1 << X86_EFLAGS_TF);
@@ -710,17 +710,18 @@ x86_init_user_debug_at_kernel_exit(struct iframe *frame)
 {
 	struct thread *thread = thread_get_current_thread();
 
-#if !KERNEL_BREAKPOINTS
 	if (!(thread->flags & THREAD_FLAGS_BREAKPOINTS_DEFINED))
 		return;
-#endif
+
+	// disable kernel breakpoints
+	disable_breakpoints();
 
 	GRAB_THREAD_LOCK();
 	GRAB_TEAM_DEBUG_INFO_LOCK(thread->team->debug_info);
 
 	arch_team_debug_info &teamInfo = thread->team->debug_info.arch_info;
 
-	// install the breakpoints
+	// install the user breakpoints
 	install_breakpoints(teamInfo);
 
 	atomic_or(&thread->flags, THREAD_FLAGS_BREAKPOINTS_INSTALLED);
@@ -738,22 +739,19 @@ x86_exit_user_debug_at_kernel_entry()
 {
 	struct thread *thread = thread_get_current_thread();
 
-#if !KERNEL_BREAKPOINTS
 	if (!(thread->flags & THREAD_FLAGS_BREAKPOINTS_INSTALLED))
 		return;
-#endif
 
 	GRAB_THREAD_LOCK();
 
-	// disable breakpoints
+	// disable user breakpoints
 	disable_breakpoints();
 
-#if KERNEL_BREAKPOINTS
+	// install kernel breakpoints
 	struct team* kernelTeam = team_get_kernel_team();
 	GRAB_TEAM_DEBUG_INFO_LOCK(kernelTeam->debug_info);
 	install_breakpoints(kernelTeam->debug_info.arch_info);
 	RELEASE_TEAM_DEBUG_INFO_LOCK(kernelTeam->debug_info);
-#endif
 
 	atomic_and(&thread->flags, ~THREAD_FLAGS_BREAKPOINTS_INSTALLED);
 
@@ -762,7 +760,7 @@ x86_exit_user_debug_at_kernel_entry()
 
 
 /**
- *	Interrupts are disabled and will be enabled by the function.
+ *	Interrupts are disabled and will possibly be enabled by the function.
  */
 void
 x86_handle_debug_exception(struct iframe *frame)
@@ -839,7 +837,7 @@ x86_handle_debug_exception(struct iframe *frame)
 
 
 /**
- *	Interrupts are disabled and will be enabled by the function.
+ *	Interrupts are disabled and will possibly be enabled by the function.
  */
 void
 x86_handle_breakpoint_exception(struct iframe *frame)