From 98b14f8a6a92e75a9a6958543e93d7b4fcdf64bb Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Tue, 1 Mar 2005 23:56:52 +0000
Subject: [PATCH] * Made i386_get_current_iframe() static again, since it
 wasn't what was   needed to get the topmost user iframe. Added
 i386_get_user_iframe() for   exactly that purpose. * Added reinitialization
 of user debugging for the new thread when   switching the context.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@11523 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 headers/private/kernel/arch/x86/arch_thread.h |  2 +-
 src/kernel/core/arch/x86/arch_thread.c        | 30 ++++++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/headers/private/kernel/arch/x86/arch_thread.h b/headers/private/kernel/arch/x86/arch_thread.h
index 9f85bfe634..2465c19688 100644
--- a/headers/private/kernel/arch/x86/arch_thread.h
+++ b/headers/private/kernel/arch/x86/arch_thread.h
@@ -17,7 +17,7 @@ extern "C" {
 
 void i386_push_iframe(struct thread *t, struct iframe *frame);
 void i386_pop_iframe(struct thread *t);
-struct iframe *i386_get_current_iframe(void);
+struct iframe *i386_get_user_iframe(void);
 
 void i386_return_from_signal();
 void i386_end_return_from_signal();
diff --git a/src/kernel/core/arch/x86/arch_thread.c b/src/kernel/core/arch/x86/arch_thread.c
index 3a24cf9e03..92a36797d3 100755
--- a/src/kernel/core/arch/x86/arch_thread.c
+++ b/src/kernel/core/arch/x86/arch_thread.c
@@ -9,6 +9,7 @@
 
 #include <thread.h>
 #include <arch/thread.h>
+#include <arch/user_debugger.h>
 #include <arch_cpu.h>
 #include <kernel.h>
 #include <debug.h>
@@ -78,7 +79,7 @@ i386_pop_iframe(struct thread *thread)
  *	from standard kernel threads.
  */
 
-struct iframe *
+static struct iframe *
 i386_get_current_iframe(void)
 {
 	struct thread *thread = thread_get_current_thread();
@@ -88,6 +89,28 @@ i386_get_current_iframe(void)
 }
 
 
+/**	\brief Returns the current thread's topmost (i.e. most recent)
+ *	userland->kernel transition iframe (usually the first one, save for
+ *	interrupts in signal handlers).
+ *	\return The iframe, or \c NULL, if there is no such iframe (e.g. when
+ *			the thread is a kernel thread).
+ */
+struct iframe *
+i386_get_user_iframe(void)
+{
+	struct thread *thread = thread_get_current_thread();
+	int i;
+
+	for (i = thread->arch_info.iframe_ptr - 1; i >= 0; i--) {
+		struct iframe *frame = thread->arch_info.iframes[i];
+		if (frame->cs == USER_CODE_SEG) 
+			return frame;
+	}
+
+	return NULL;
+}
+
+
 static inline void
 set_fs_register(uint32 segment)
 {
@@ -247,6 +270,11 @@ arch_thread_context_switch(struct thread *t_from, struct thread *t_to)
 	if (((uint32)new_pgdir % B_PAGE_SIZE) != 0)
 		panic("arch_thread_context_switch: bad pgdir 0x%lx\n", new_pgdir);
 
+	// reinit debugging; necessary, if the thread was preempted after
+	// initializing debugging before returning to userland
+	if (t_to->team->aspace != NULL)
+		i386_reinit_user_debug_after_context_switch(t_to);
+
 	i386_fsave_swap(t_from->arch_info.fpu_state, t_to->arch_info.fpu_state);
 	i386_context_switch(&t_from->arch_info, &t_to->arch_info, (addr_t)new_pgdir);
 }