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* Fixed checking for DR6 bits after a debug exception (we were and'ing

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with the bit number, not the respective mask).
* Added a small hack to allow single stepping to work in qemu.
  Apparently the BS bit in DR6 is not set when the debug exception
  is handled. So we always assume that a single step event occurred,
  when we couldn't recognize any other event, if the hack is enabled.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@11998 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold
2005-03-25 18:48:51 +00:00
parent 99dbd8b489
commit 85001a7cc6
2 changed files with 40 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
headers/private/kernel/arch/x86/arch_user_debugger.h
+4
View File
@@ -5,6 +5,8 @@
#ifndef _KERNEL_ARCH_X86_USER_DEBUGGER_H
#define _KERNEL_ARCH_X86_USER_DEBUGGER_H
#define ARCH_INIT_USER_DEBUG i386_init_user_debug
// number of breakpoints the CPU supports
// Actually it supports 4, but DR3 is used to hold the struct thread*.
enum {
@@ -127,6 +129,8 @@ extern void i386_reinit_user_debug_after_context_switch(struct thread *thread);
extern int i386_handle_debug_exception(struct iframe *frame);
extern int i386_handle_breakpoint_exception(struct iframe *frame);
extern void i386_init_user_debug();
#ifdef __cplusplus
}
#endif
src/kernel/core/arch/x86/arch_user_debugger.cpp
+36 -3
View File
@@ -6,10 +6,18 @@
#include <string.h>
#include <debugger.h>
#include <driver_settings.h>
#include <int.h>
#include <thread.h>
#include <arch/user_debugger.h>
//#define TRACE_ARCH_USER_DEBUGGER
#ifdef TRACE_ARCH_USER_DEBUGGER
# define TRACE(x) dprintf x
#else
# define TRACE(x) ;
#endif
#define B_NO_MORE_BREAKPOINTS B_ERROR
#define B_NO_MORE_WATCHPOINTS B_ERROR
#define B_BAD_WATCHPOINT_ALIGNMENT B_ERROR
@@ -39,6 +47,10 @@ static const uint32 sDR6B[4] = {
X86_DR6_B0, X86_DR6_B1, X86_DR6_B2, X86_DR6_B3
};
// Enables a hack to make single stepping work under qemu. Set via kernel
// driver settings.
static bool sQEmuSingleStepHack = false;
void
arch_clear_team_debug_info(struct arch_team_debug_info *info)
@@ -344,6 +356,9 @@ i386_init_user_debug_at_kernel_exit(struct iframe *frame)
frame->flags |= (1 << X86_EFLAGS_TF);
else
frame->flags &= ~(1 << X86_EFLAGS_TF);
// ToDo: Move into a function called from thread_hit_debug_event().
// No need to have that here in the code executed for ever kernel->user
// mode switch.
RELEASE_TEAM_DEBUG_INFO_LOCK(thread->team->debug_info);
RELEASE_THREAD_LOCK();
@@ -398,6 +413,8 @@ i386_handle_debug_exception(struct iframe *frame)
asm("movl %%dr6, %0" : "=r"(dr6));
asm("movl %%dr7, %0" : "=r"(dr7));
TRACE(("i386_handle_debug_exception(): DR6: %lx, DR7: %lx\n", dr6, dr7));
// check, which exception condition applies
if (dr6 & X86_DR6_BREAKPOINT_MASK) {
// breakpoint
@@ -426,7 +443,7 @@ i386_handle_debug_exception(struct iframe *frame)
else
user_debug_breakpoint_hit(false);
} else if (dr6 & X86_DR6_BD) {
} else if (dr6 & (1 << X86_DR6_BD)) {
// general detect exception
// Occurs only, if GD in DR7 is set (which we don't do) and someone
// tries to write to the debug registers.
@@ -435,7 +452,7 @@ i386_handle_debug_exception(struct iframe *frame)
enable_interrupts();
} else if (dr6 & X86_DR6_BS) {
} else if ((dr6 & (1 << X86_DR6_BS)) || sQEmuSingleStepHack) {
// single step
// enable interrupts and notify the debugger
@@ -443,7 +460,7 @@ i386_handle_debug_exception(struct iframe *frame)
user_debug_single_stepped();
} else if (dr6 & X86_DR6_BT) {
} else if (dr6 & (1 << X86_DR6_BT)) {
// task switch
// Occurs only, if T in EFLAGS is set (which we don't do).
dprintf("i386_handle_debug_exception(): ignoring spurious task switch "
@@ -468,9 +485,25 @@ i386_handle_debug_exception(struct iframe *frame)
int
i386_handle_breakpoint_exception(struct iframe *frame)
{
TRACE(("i386_handle_breakpoint_exception()\n"));
enable_interrupts();
user_debug_breakpoint_hit(true);
return B_HANDLED_INTERRUPT;
}
void
i386_init_user_debug()
{
// get debug settings
if (void *handle = load_driver_settings("kernel")) {
sQEmuSingleStepHack = get_driver_boolean_parameter(handle,
"qemu_single_step_hack", false, false);;
unload_driver_settings(handle);
}
}