Commit 02b67518 authored by Török Edwin's avatar Török Edwin Committed by Ingo Molnar
Browse files

tracing: add support for userspace stacktraces in tracing/iter_ctrl



Impact: add new (default-off) tracing visualization feature

Usage example:

 mount -t debugfs nodev /sys/kernel/debug
 cd /sys/kernel/debug/tracing
 echo userstacktrace >iter_ctrl
 echo sched_switch >current_tracer
 echo 1 >tracing_enabled
 .... run application ...
 echo 0 >tracing_enabled

Then read one of 'trace','latency_trace','trace_pipe'.

To get the best output you can compile your userspace programs with
frame pointers (at least glibc + the app you are tracing).
Signed-off-by: default avatarTörök Edwin <edwintorok@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a0a70c73
......@@ -324,7 +324,7 @@ output. To see what is available, simply cat the file:
cat /debug/tracing/trace_options
print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
noblock nostacktrace nosched-tree
noblock nostacktrace nosched-tree nouserstacktrace
To disable one of the options, echo in the option prepended with "no".
......@@ -378,6 +378,9 @@ Here are the available options:
When a trace is recorded, so is the stack of functions.
This allows for back traces of trace sites.
userstacktrace - This option changes the trace.
It records a stacktrace of the current userspace thread.
sched-tree - TBD (any users??)
......
......@@ -6,6 +6,7 @@
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/stacktrace.h>
static void save_stack_warning(void *data, char *msg)
......@@ -83,3 +84,59 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
struct stack_frame {
const void __user *next_fp;
unsigned long return_address;
};
static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
{
int ret;
if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
return 0;
ret = 1;
pagefault_disable();
if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
ret = 0;
pagefault_enable();
return ret;
}
void save_stack_trace_user(struct stack_trace *trace)
{
/*
* Trace user stack if we are not a kernel thread
*/
if (current->mm) {
const struct pt_regs *regs = task_pt_regs(current);
const void __user *fp = (const void __user *)regs->bp;
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = regs->ip;
while (trace->nr_entries < trace->max_entries) {
struct stack_frame frame;
frame.next_fp = NULL;
frame.return_address = 0;
if (!copy_stack_frame(fp, &frame))
break;
if ((unsigned long)fp < regs->sp)
break;
if (frame.return_address)
trace->entries[trace->nr_entries++] =
frame.return_address;
if (fp == frame.next_fp)
break;
fp = frame.next_fp;
}
}
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}
......@@ -15,9 +15,17 @@ extern void save_stack_trace_tsk(struct task_struct *tsk,
struct stack_trace *trace);
extern void print_stack_trace(struct stack_trace *trace, int spaces);
#ifdef CONFIG_X86
extern void save_stack_trace_user(struct stack_trace *trace);
#else
# define save_stack_trace_user(trace) do { } while (0)
#endif
#else
# define save_stack_trace(trace) do { } while (0)
# define save_stack_trace_tsk(tsk, trace) do { } while (0)
# define save_stack_trace_user(trace) do { } while (0)
# define print_stack_trace(trace, spaces) do { } while (0)
#endif
......
......@@ -275,6 +275,7 @@ static const char *trace_options[] = {
"ftrace_preempt",
"branch",
"annotate",
"userstacktrace",
NULL
};
......@@ -918,6 +919,44 @@ void __trace_stack(struct trace_array *tr,
ftrace_trace_stack(tr, data, flags, skip, preempt_count());
}
static void ftrace_trace_userstack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags, int pc)
{
struct userstack_entry *entry;
struct stack_trace trace;
struct ring_buffer_event *event;
unsigned long irq_flags;
if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
return;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_USER_STACK;
memset(&entry->caller, 0, sizeof(entry->caller));
trace.nr_entries = 0;
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.skip = 0;
trace.entries = entry->caller;
save_stack_trace_user(&trace);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
}
void __trace_userstack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags)
{
ftrace_trace_userstack(tr, data, flags, preempt_count());
}
static void
ftrace_trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3,
......@@ -941,6 +980,7 @@ ftrace_trace_special(void *__tr, void *__data,
entry->arg3 = arg3;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, irq_flags, 4, pc);
ftrace_trace_userstack(tr, data, irq_flags, pc);
trace_wake_up();
}
......@@ -979,6 +1019,7 @@ tracing_sched_switch_trace(struct trace_array *tr,
entry->next_cpu = task_cpu(next);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 5, pc);
ftrace_trace_userstack(tr, data, flags, pc);
}
void
......@@ -1008,6 +1049,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
entry->next_cpu = task_cpu(wakee);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 6, pc);
ftrace_trace_userstack(tr, data, flags, pc);
trace_wake_up();
}
......@@ -1387,6 +1429,31 @@ seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
return ret;
}
static int
seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
unsigned long sym_flags)
{
int ret = 1;
unsigned i;
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
unsigned long ip = entry->caller[i];
if (ip == ULONG_MAX || !ret)
break;
if (i)
ret = trace_seq_puts(s, " <- ");
if (!ip) {
ret = trace_seq_puts(s, "??");
continue;
}
if (ret /*&& (sym_flags & TRACE_ITER_SYM_ADDR)*/)
ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
}
return ret;
}
static void print_lat_help_header(struct seq_file *m)
{
seq_puts(m, "# _------=> CPU# \n");
......@@ -1702,6 +1769,16 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
field->line);
break;
}
case TRACE_USER_STACK: {
struct userstack_entry *field;
trace_assign_type(field, entry);
seq_print_userip_objs(field, s, sym_flags);
if (entry->flags & TRACE_FLAG_CONT)
trace_seq_print_cont(s, iter);
break;
}
default:
trace_seq_printf(s, "Unknown type %d\n", entry->type);
}
......@@ -1853,6 +1930,19 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
field->line);
break;
}
case TRACE_USER_STACK: {
struct userstack_entry *field;
trace_assign_type(field, entry);
ret = seq_print_userip_objs(field, s, sym_flags);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_putc(s, '\n');
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
}
return TRACE_TYPE_HANDLED;
}
......@@ -1912,6 +2002,7 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
break;
}
case TRACE_SPECIAL:
case TRACE_USER_STACK:
case TRACE_STACK: {
struct special_entry *field;
......@@ -2000,6 +2091,7 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
break;
}
case TRACE_SPECIAL:
case TRACE_USER_STACK:
case TRACE_STACK: {
struct special_entry *field;
......@@ -2054,6 +2146,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
break;
}
case TRACE_SPECIAL:
case TRACE_USER_STACK:
case TRACE_STACK: {
struct special_entry *field;
......
......@@ -26,6 +26,7 @@ enum trace_type {
TRACE_BOOT_CALL,
TRACE_BOOT_RET,
TRACE_FN_RET,
TRACE_USER_STACK,
__TRACE_LAST_TYPE
};
......@@ -42,6 +43,7 @@ struct trace_entry {
unsigned char flags;
unsigned char preempt_count;
int pid;
int tgid;
};
/*
......@@ -99,6 +101,11 @@ struct stack_entry {
unsigned long caller[FTRACE_STACK_ENTRIES];
};
struct userstack_entry {
struct trace_entry ent;
unsigned long caller[FTRACE_STACK_ENTRIES];
};
/*
* ftrace_printk entry:
*/
......@@ -240,6 +247,7 @@ extern void __ftrace_bad_type(void);
IF_ASSIGN(var, ent, struct ctx_switch_entry, 0); \
IF_ASSIGN(var, ent, struct trace_field_cont, TRACE_CONT); \
IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK); \
IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT); \
IF_ASSIGN(var, ent, struct special_entry, 0); \
IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \
......@@ -500,6 +508,7 @@ enum trace_iterator_flags {
TRACE_ITER_PREEMPTONLY = 0x800,
TRACE_ITER_BRANCH = 0x1000,
TRACE_ITER_ANNOTATE = 0x2000,
TRACE_ITER_USERSTACKTRACE = 0x4000
};
/*
......
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