Atsushi Nemoto wrote:
>
> Subject: [PATCH] dump_stack() based on prologue code analysis
>
> Instead of dump all possible address in the stack, unwind the stack
> frame based on prologue code analysis, as like as get_wchan() does.
> While the code analysis might fail for some reason, there is a new
> kernel option "raw_show_trace" to disable this feature.
>
my comments included with this patch...(you can find the plain patch
at the end of this email)
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 8709a46..3bb4d47 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -365,15 +365,15 @@ #else
mfinfo[0].func = schedule;
schedule_frame = &mfinfo[0];
#endif
- for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++) {
- struct mips_frame_info *info = &mfinfo[i];
- if (get_frame_info(info)) {
- /* leaf or unknown */
- if (info->func == schedule)
- printk("Can't analyze prologue code at %p\n",
- info->func);
- }
- }
+ for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
+ get_frame_info(mfinfo + i);
+
+ /*
+ * Without schedule() frame info, result given by
+ * thread_saved_pc() and get_wchan() are not reliable.
+ */
+ if (schedule_frame->pc_offset < 0)
+ printk("Can't analyze schedule() prologue at %p\n", schedule);
>>>>>>>>>>>>>
I just put the test out of the loop and add a comment.
<<<<<<<<<<<<<
mfinfo_num = i;
return 0;
@@ -446,14 +446,15 @@ #endif
#ifdef CONFIG_KALLSYMS
/* used by show_frametrace() */
-unsigned long unwind_stack(struct task_struct *task,
- unsigned long **sp, unsigned long pc)
+unsigned long unwind_stack(struct task_struct *task, unsigned long **sp,
+ unsigned long pc, struct pt_regs *regs)
{
unsigned long stack_page;
struct mips_frame_info info;
char *modname;
char namebuf[KSYM_NAME_LEN + 1];
unsigned long size, ofs;
+ int rv;
stack_page = (unsigned long)task_stack_page(task);
if (!stack_page)
@@ -466,18 +467,21 @@ unsigned long unwind_stack(struct task_s
info.func = (void *)(pc - ofs);
info.func_size = ofs; /* analyze from start to ofs */
- if (get_frame_info(&info)) {
- /* leaf or unknown */
- *sp += info.frame_size / sizeof(long);
+ rv = get_frame_info(&info);
+ if (rv < 0)
return 0;
- }
+
if ((unsigned long)*sp < stack_page ||
(unsigned long)*sp + info.frame_size / sizeof(long) >
stack_page + THREAD_SIZE - 32)
return 0;
- pc = (*sp)[info.pc_offset];
+ if (rv) /* leaf */
+ pc = regs->regs[31];
+ else /* nested */
+ pc = (*sp)[info.pc_offset];
+
*sp += info.frame_size / sizeof(long);
- return pc;
+ return __kernel_text_address(pc) ? pc : 0;
>>>>>>>>>>>>>
I pass regs to unwind_stack(), that simplify the caller because
it needn't to deal with leaf or nested case. Simply test for pc
is 0.
<<<<<<<<<<<<<
}
#endif
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7aa9dfc..bbd1cf9 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -73,13 +73,8 @@ void (*board_nmi_handler_setup)(void);
void (*board_ejtag_handler_setup)(void);
void (*board_bind_eic_interrupt)(int irq, int regset);
-/*
- * These constant is for searching for possible module text segments.
- * MODULE_RANGE is a guess of how much space is likely to be vmalloced.
- */
-#define MODULE_RANGE (8*1024*1024)
>>>>>>>>>>>>>
seems to be unused now...
<<<<<<<<<<<<<
-static void show_trace(unsigned long *stack)
+static void show_trace(unsigned long *sp)
{
const int field = 2 * sizeof(unsigned long);
unsigned long addr;
@@ -88,8 +83,8 @@ static void show_trace(unsigned long *st
#ifdef CONFIG_KALLSYMS
printk("\n");
#endif
- while (!kstack_end(stack)) {
- addr = *stack++;
+ while (!kstack_end(sp)) {
+ addr = *sp++;
>>>>>>>>>>>>>
now show_trace calls sp sp. (nothing is too late)
<<<<<<<<<<<<<
if (__kernel_text_address(addr)) {
printk(" [<%0*lx>] ", field, addr);
print_symbol("%s\n", addr);
@@ -107,32 +102,27 @@ static int __init set_raw_show_trace(cha
}
__setup("raw_show_trace", set_raw_show_trace);
-extern unsigned long unwind_stack(struct task_struct *task,
- unsigned long **sp, unsigned long pc);
-static void show_frametrace(struct task_struct *task, struct pt_regs *regs)
+extern unsigned long unwind_stack(struct task_struct *task, unsigned long **sp,
+ unsigned long pc, struct pt_regs *regs);
+
+static void show_backtrace(struct task_struct *task, struct pt_regs *regs)
>>>>>>>>>>>>>
Just renamed show_stacktrace() into show_backtrace(). I think we
usually use the latter no ?
<<<<<<<<<<<<<
{
- const int field = 2 * sizeof(unsigned long);
- unsigned long *stack = (long *)regs->regs[29];
+ unsigned long *sp = (long *)regs->regs[29];
unsigned long pc = regs->cp0_epc;
- int top = 1;
if (raw_show_trace || !__kernel_text_address(pc)) {
- show_trace(stack);
+ show_trace(sp);
return;
}
printk("Call Trace:\n");
- while (__kernel_text_address(pc)) {
- printk(" [<%0*lx>] ", field, pc);
+ do {
+ printk(" [<%0*lx>] ", 2*sizeof(unsigned long), pc);
print_symbol("%s\n", pc);
- pc = unwind_stack(task, &stack, pc);
- if (top && pc == 0)
- pc = regs->regs[31]; /* leaf? */
- top = 0;
- }
+ } while ((pc = unwind_stack(task, &sp, pc, regs)));
>>>>>>>>>>>>>
Now don't deal with leaf case since unwind_stack() does it for us.
<<<<<<<<<<<<<
printk("\n");
}
#else
-#define show_frametrace(task, r) show_trace((long *)(r)->regs[29]);
+#define show_backtrace(task, r) show_trace((long *)(r)->regs[29]);
#endif
/*
@@ -165,7 +155,7 @@ static void show_stacktrace(struct task_
i++;
}
printk("\n");
- show_frametrace(task, regs);
+ show_backtrace(task, regs);
}
static noinline void prepare_frametrace(struct pt_regs *regs)
@@ -216,7 +206,7 @@ #ifdef CONFIG_KALLSYMS
if (!raw_show_trace) {
struct pt_regs regs;
prepare_frametrace(®s);
- show_frametrace(current, ®s);
+ show_backtrace(current, ®s);
return;
}
#endif
Here is the plain patch.
-- >8 --
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 8709a46..3bb4d47 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -365,15 +365,15 @@ #else
mfinfo[0].func = schedule;
schedule_frame = &mfinfo[0];
#endif
- for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++) {
- struct mips_frame_info *info = &mfinfo[i];
- if (get_frame_info(info)) {
- /* leaf or unknown */
- if (info->func == schedule)
- printk("Can't analyze prologue code at %p\n",
- info->func);
- }
- }
+ for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
+ get_frame_info(mfinfo + i);
+
+ /*
+ * Without schedule() frame info, result given by
+ * thread_saved_pc() and get_wchan() are not reliable.
+ */
+ if (schedule_frame->pc_offset < 0)
+ printk("Can't analyze schedule() prologue at %p\n", schedule);
mfinfo_num = i;
return 0;
@@ -446,14 +446,15 @@ #endif
#ifdef CONFIG_KALLSYMS
/* used by show_frametrace() */
-unsigned long unwind_stack(struct task_struct *task,
- unsigned long **sp, unsigned long pc)
+unsigned long unwind_stack(struct task_struct *task, unsigned long **sp,
+ unsigned long pc, struct pt_regs *regs)
{
unsigned long stack_page;
struct mips_frame_info info;
char *modname;
char namebuf[KSYM_NAME_LEN + 1];
unsigned long size, ofs;
+ int rv;
stack_page = (unsigned long)task_stack_page(task);
if (!stack_page)
@@ -466,18 +467,21 @@ unsigned long unwind_stack(struct task_s
info.func = (void *)(pc - ofs);
info.func_size = ofs; /* analyze from start to ofs */
- if (get_frame_info(&info)) {
- /* leaf or unknown */
- *sp += info.frame_size / sizeof(long);
+ rv = get_frame_info(&info);
+ if (rv < 0)
return 0;
- }
+
if ((unsigned long)*sp < stack_page ||
(unsigned long)*sp + info.frame_size / sizeof(long) >
stack_page + THREAD_SIZE - 32)
return 0;
- pc = (*sp)[info.pc_offset];
+ if (rv) /* leaf */
+ pc = regs->regs[31];
+ else /* nested */
+ pc = (*sp)[info.pc_offset];
+
*sp += info.frame_size / sizeof(long);
- return pc;
+ return __kernel_text_address(pc) ? pc : 0;
}
#endif
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7aa9dfc..bbd1cf9 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -73,13 +73,8 @@ void (*board_nmi_handler_setup)(void);
void (*board_ejtag_handler_setup)(void);
void (*board_bind_eic_interrupt)(int irq, int regset);
-/*
- * These constant is for searching for possible module text segments.
- * MODULE_RANGE is a guess of how much space is likely to be vmalloced.
- */
-#define MODULE_RANGE (8*1024*1024)
-static void show_trace(unsigned long *stack)
+static void show_trace(unsigned long *sp)
{
const int field = 2 * sizeof(unsigned long);
unsigned long addr;
@@ -88,8 +83,8 @@ static void show_trace(unsigned long *st
#ifdef CONFIG_KALLSYMS
printk("\n");
#endif
- while (!kstack_end(stack)) {
- addr = *stack++;
+ while (!kstack_end(sp)) {
+ addr = *sp++;
if (__kernel_text_address(addr)) {
printk(" [<%0*lx>] ", field, addr);
print_symbol("%s\n", addr);
@@ -107,32 +102,27 @@ static int __init set_raw_show_trace(cha
}
__setup("raw_show_trace", set_raw_show_trace);
-extern unsigned long unwind_stack(struct task_struct *task,
- unsigned long **sp, unsigned long pc);
-static void show_frametrace(struct task_struct *task, struct pt_regs *regs)
+extern unsigned long unwind_stack(struct task_struct *task, unsigned long **sp,
+ unsigned long pc, struct pt_regs *regs);
+
+static void show_backtrace(struct task_struct *task, struct pt_regs *regs)
{
- const int field = 2 * sizeof(unsigned long);
- unsigned long *stack = (long *)regs->regs[29];
+ unsigned long *sp = (long *)regs->regs[29];
unsigned long pc = regs->cp0_epc;
- int top = 1;
if (raw_show_trace || !__kernel_text_address(pc)) {
- show_trace(stack);
+ show_trace(sp);
return;
}
printk("Call Trace:\n");
- while (__kernel_text_address(pc)) {
- printk(" [<%0*lx>] ", field, pc);
+ do {
+ printk(" [<%0*lx>] ", 2*sizeof(unsigned long), pc);
print_symbol("%s\n", pc);
- pc = unwind_stack(task, &stack, pc);
- if (top && pc == 0)
- pc = regs->regs[31]; /* leaf? */
- top = 0;
- }
+ } while ((pc = unwind_stack(task, &sp, pc, regs)));
printk("\n");
}
#else
-#define show_frametrace(task, r) show_trace((long *)(r)->regs[29]);
+#define show_backtrace(task, r) show_trace((long *)(r)->regs[29]);
#endif
/*
@@ -165,7 +155,7 @@ static void show_stacktrace(struct task_
i++;
}
printk("\n");
- show_frametrace(task, regs);
+ show_backtrace(task, regs);
}
static noinline void prepare_frametrace(struct pt_regs *regs)
@@ -216,7 +206,7 @@ #ifdef CONFIG_KALLSYMS
if (!raw_show_trace) {
struct pt_regs regs;
prepare_frametrace(®s);
- show_frametrace(current, ®s);
+ show_backtrace(current, ®s);
return;
}
#endif
