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Re: [Qemu-devel] [PATCH] i386: fix breakpoints handling in icount mode
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] i386: fix breakpoints handling in icount mode |
Date: |
Mon, 12 Jan 2015 09:55:31 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 |
On 12/01/2015 09:30, Jan Kiszka wrote:
> I think this would only cure a symptom, but it doesn't explain why we
> now hit cpu_handle_guest_debug which we do not before the patch:
That means we now exit with EXCP_DEBUG and we didn't before?
Something like this would be a more complete fix (it works if you have
both gdb and CPU breakpoints), but I'm not sure if it's also a band-aid
for the symptoms.
diff --git a/cpu-exec.c b/cpu-exec.c
index a4f0eff..56139ac 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -302,7 +302,7 @@ static inline TranslationBlock *tb_find_fast(CPUArchState
*env)
return tb;
}
-static void cpu_handle_debug_exception(CPUArchState *env)
+static int cpu_handle_debug_exception(CPUArchState *env)
{
CPUState *cpu = ENV_GET_CPU(env);
CPUClass *cc = CPU_GET_CLASS(cpu);
@@ -314,7 +314,7 @@ static void cpu_handle_debug_exception(CPUArchState *env)
}
}
- cc->debug_excp_handler(cpu);
+ return cc->debug_excp_handler(cpu);
}
/* main execution loop */
@@ -375,12 +375,15 @@ int cpu_exec(CPUArchState *env)
if (cpu->exception_index >= 0) {
if (cpu->exception_index >= EXCP_INTERRUPT) {
/* exit request from the cpu execution loop */
- ret = cpu->exception_index;
- if (ret == EXCP_DEBUG) {
- cpu_handle_debug_exception(env);
+ if (cpu->exception_index == EXCP_DEBUG) {
+ ret = cpu_handle_debug_exception(env);
+ } else {
+ ret = cpu->exception_index;
+ }
+ if (ret >= 0) {
+ cpu->exception_index = -1;
+ break;
}
- cpu->exception_index = -1;
- break;
} else {
#if defined(CONFIG_USER_ONLY)
/* if user mode only, we simulate a fake exception
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 2098f1c..c1d6c20 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -95,7 +95,8 @@ struct TranslationBlock;
* @get_phys_page_debug: Callback for obtaining a physical address.
* @gdb_read_register: Callback for letting GDB read a register.
* @gdb_write_register: Callback for letting GDB write a register.
- * @debug_excp_handler: Callback for handling debug exceptions.
+ * @debug_excp_handler: Callback for handling debug exceptions. Should
+ * return either #EXCP_DEBUG or zero.
* @vmsd: State description for migration.
* @gdb_num_core_regs: Number of core registers accessible to GDB.
* @gdb_core_xml_file: File name for core registers GDB XML description.
@@ -140,7 +141,7 @@ typedef struct CPUClass {
hwaddr (*get_phys_page_debug)(CPUState *cpu, vaddr addr);
int (*gdb_read_register)(CPUState *cpu, uint8_t *buf, int reg);
int (*gdb_write_register)(CPUState *cpu, uint8_t *buf, int reg);
- void (*debug_excp_handler)(CPUState *cpu);
+ int (*debug_excp_handler)(CPUState *cpu);
int (*write_elf64_note)(WriteCoreDumpFunction f, CPUState *cpu,
int cpuid, void *opaque);
diff --git a/qom/cpu.c b/qom/cpu.c
index 9c68fa4..e86fec5 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -193,6 +193,11 @@ static bool cpu_common_virtio_is_big_endian(CPUState *cpu)
return target_words_bigendian();
}
+static int cpu_common_debug_excp_handler(CPUState *cpu)
+{
+ return EXCP_DEBUG;
+}
+
static void cpu_common_noop(CPUState *cpu)
{
}
@@ -340,7 +345,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
k->gdb_read_register = cpu_common_gdb_read_register;
k->gdb_write_register = cpu_common_gdb_write_register;
k->virtio_is_big_endian = cpu_common_virtio_is_big_endian;
- k->debug_excp_handler = cpu_common_noop;
+ k->debug_excp_handler = cpu_common_debug_excp_handler;
k->cpu_exec_enter = cpu_common_noop;
k->cpu_exec_exit = cpu_common_noop;
k->cpu_exec_interrupt = cpu_common_exec_interrupt;
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 2bed914..40b7f79 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -732,7 +732,7 @@ static bool check_breakpoints(ARMCPU *cpu)
return false;
}
-void arm_debug_excp_handler(CPUState *cs)
+int arm_debug_excp_handler(CPUState *cs)
{
/* Called by core code when a watchpoint or breakpoint fires;
* need to check which one and raise the appropriate exception.
@@ -756,9 +756,9 @@ void arm_debug_excp_handler(CPUState *cs)
}
env->exception.vaddress = wp_hit->hitaddr;
raise_exception(env, EXCP_DATA_ABORT);
- } else {
- cpu_resume_from_signal(cs, NULL);
+ return 0;
}
+ cpu_resume_from_signal(cs, NULL);
}
} else {
if (check_breakpoints(cpu)) {
@@ -771,8 +771,10 @@ void arm_debug_excp_handler(CPUState *cs)
}
/* FAR is UNKNOWN, so doesn't need setting */
raise_exception(env, EXCP_PREFETCH_ABORT);
+ return 0;
}
}
+ return EXCP_DEBUG;
}
/* ??? Flag setting arithmetic is awkward because we need to do comparisons.
diff --git a/target-i386/helper.c b/target-i386/helper.c
index 4f1ddf7..a313424 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -1004,17 +1004,19 @@ bool check_hw_breakpoints(CPUX86State *env, bool
force_dr6_update)
return hit_enabled;
}
-void breakpoint_handler(CPUState *cs)
+int breakpoint_handler(CPUState *cs)
{
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
CPUBreakpoint *bp;
+ int ret = EXCP_DEBUG;
if (cs->watchpoint_hit) {
if (cs->watchpoint_hit->flags & BP_CPU) {
cs->watchpoint_hit = NULL;
if (check_hw_breakpoints(env, false)) {
raise_exception(env, EXCP01_DB);
+ ret = 0;
} else {
cpu_resume_from_signal(cs, NULL);
}
@@ -1025,11 +1027,13 @@ void breakpoint_handler(CPUState *cs)
if (bp->flags & BP_CPU) {
check_hw_breakpoints(env, true);
raise_exception(env, EXCP01_DB);
+ ret = 0;
}
break;
}
}
}
+ return ret;
}
typedef struct MCEInjectionParams {
diff --git a/target-lm32/helper.c b/target-lm32/helper.c
index 7a41f29..088d3fa 100644
--- a/target-lm32/helper.c
+++ b/target-lm32/helper.c
@@ -125,17 +125,19 @@ static bool check_watchpoints(CPULM32State *env)
return false;
}
-void lm32_debug_excp_handler(CPUState *cs)
+int lm32_debug_excp_handler(CPUState *cs)
{
LM32CPU *cpu = LM32_CPU(cs);
CPULM32State *env = &cpu->env;
CPUBreakpoint *bp;
+ int ret = EXCP_DEBUG;
if (cs->watchpoint_hit) {
if (cs->watchpoint_hit->flags & BP_CPU) {
cs->watchpoint_hit = NULL;
if (check_watchpoints(env)) {
raise_exception(env, EXCP_WATCHPOINT);
+ ret = 0;
} else {
cpu_resume_from_signal(cs, NULL);
}
@@ -145,11 +147,13 @@ void lm32_debug_excp_handler(CPUState *cs)
if (bp->pc == env->pc) {
if (bp->flags & BP_CPU) {
raise_exception(env, EXCP_BREAKPOINT);
+ ret = 0;
}
break;
}
}
}
+ return ret;
}
void lm32_cpu_do_interrupt(CPUState *cs)
diff --git a/target-xtensa/helper.c b/target-xtensa/helper.c
index d84d259..52f50a2 100644
--- a/target-xtensa/helper.c
+++ b/target-xtensa/helper.c
@@ -79,7 +79,7 @@ static uint32_t check_hw_breakpoints(CPUXtensaState *env)
return 0;
}
-void xtensa_breakpoint_handler(CPUState *cs)
+int xtensa_breakpoint_handler(CPUState *cs)
{
XtensaCPU *cpu = XTENSA_CPU(cs);
CPUXtensaState *env = &cpu->env;
@@ -92,10 +92,12 @@ void xtensa_breakpoint_handler(CPUState *cs)
cause = check_hw_breakpoints(env);
if (cause) {
debug_exception_env(env, cause);
+ return 0;
}
cpu_resume_from_signal(cs, NULL);
}
}
+ return EXCP_DEBUG;
}
XtensaCPU *cpu_xtensa_init(const char *cpu_model)