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: Török Edwin <edwintorok@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>hifive-unleashed-5.1
Török Edwin
Ingo Molnar
parent
a0a70c735e
commit
02b67518e2
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@ -324,7 +324,7 @@ output. To see what is available, simply cat the file:
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cat /debug/tracing/trace_options
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print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
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noblock nostacktrace nosched-tree
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noblock nostacktrace nosched-tree nouserstacktrace
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To disable one of the options, echo in the option prepended with "no".
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@ -378,6 +378,9 @@ Here are the available options:
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When a trace is recorded, so is the stack of functions.
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This allows for back traces of trace sites.
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userstacktrace - This option changes the trace.
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It records a stacktrace of the current userspace thread.
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sched-tree - TBD (any users??)
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@ -6,6 +6,7 @@
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <asm/stacktrace.h>
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static void save_stack_warning(void *data, char *msg)
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@ -83,3 +84,59 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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trace->entries[trace->nr_entries++] = ULONG_MAX;
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
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/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
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struct stack_frame {
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const void __user *next_fp;
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unsigned long return_address;
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};
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static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
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{
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int ret;
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if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
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return 0;
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ret = 1;
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pagefault_disable();
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if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
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ret = 0;
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pagefault_enable();
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return ret;
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}
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void save_stack_trace_user(struct stack_trace *trace)
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{
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/*
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* Trace user stack if we are not a kernel thread
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*/
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if (current->mm) {
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const struct pt_regs *regs = task_pt_regs(current);
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const void __user *fp = (const void __user *)regs->bp;
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if (trace->nr_entries < trace->max_entries)
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trace->entries[trace->nr_entries++] = regs->ip;
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while (trace->nr_entries < trace->max_entries) {
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struct stack_frame frame;
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frame.next_fp = NULL;
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frame.return_address = 0;
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if (!copy_stack_frame(fp, &frame))
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break;
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if ((unsigned long)fp < regs->sp)
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break;
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if (frame.return_address)
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trace->entries[trace->nr_entries++] =
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frame.return_address;
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if (fp == frame.next_fp)
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break;
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fp = frame.next_fp;
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}
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}
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if (trace->nr_entries < trace->max_entries)
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trace->entries[trace->nr_entries++] = ULONG_MAX;
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}
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@ -15,9 +15,17 @@ extern void save_stack_trace_tsk(struct task_struct *tsk,
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struct stack_trace *trace);
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extern void print_stack_trace(struct stack_trace *trace, int spaces);
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#ifdef CONFIG_X86
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extern void save_stack_trace_user(struct stack_trace *trace);
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#else
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# define save_stack_trace_user(trace) do { } while (0)
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#endif
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#else
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# define save_stack_trace(trace) do { } while (0)
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# define save_stack_trace_tsk(tsk, trace) do { } while (0)
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# define save_stack_trace_user(trace) do { } while (0)
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# define print_stack_trace(trace, spaces) do { } while (0)
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#endif
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@ -275,6 +275,7 @@ static const char *trace_options[] = {
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"ftrace_preempt",
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"branch",
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"annotate",
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"userstacktrace",
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NULL
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};
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@ -918,6 +919,44 @@ void __trace_stack(struct trace_array *tr,
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ftrace_trace_stack(tr, data, flags, skip, preempt_count());
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}
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static void ftrace_trace_userstack(struct trace_array *tr,
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struct trace_array_cpu *data,
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unsigned long flags, int pc)
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{
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struct userstack_entry *entry;
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struct stack_trace trace;
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struct ring_buffer_event *event;
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unsigned long irq_flags;
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if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
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return;
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event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
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&irq_flags);
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if (!event)
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return;
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entry = ring_buffer_event_data(event);
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tracing_generic_entry_update(&entry->ent, flags, pc);
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entry->ent.type = TRACE_USER_STACK;
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memset(&entry->caller, 0, sizeof(entry->caller));
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trace.nr_entries = 0;
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trace.max_entries = FTRACE_STACK_ENTRIES;
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trace.skip = 0;
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trace.entries = entry->caller;
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save_stack_trace_user(&trace);
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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}
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void __trace_userstack(struct trace_array *tr,
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struct trace_array_cpu *data,
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unsigned long flags)
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{
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ftrace_trace_userstack(tr, data, flags, preempt_count());
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}
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static void
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ftrace_trace_special(void *__tr, void *__data,
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unsigned long arg1, unsigned long arg2, unsigned long arg3,
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@ -941,6 +980,7 @@ ftrace_trace_special(void *__tr, void *__data,
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entry->arg3 = arg3;
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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ftrace_trace_stack(tr, data, irq_flags, 4, pc);
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ftrace_trace_userstack(tr, data, irq_flags, pc);
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trace_wake_up();
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}
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@ -979,6 +1019,7 @@ tracing_sched_switch_trace(struct trace_array *tr,
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entry->next_cpu = task_cpu(next);
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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ftrace_trace_stack(tr, data, flags, 5, pc);
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ftrace_trace_userstack(tr, data, flags, pc);
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}
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void
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@ -1008,6 +1049,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
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entry->next_cpu = task_cpu(wakee);
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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ftrace_trace_stack(tr, data, flags, 6, pc);
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ftrace_trace_userstack(tr, data, flags, pc);
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trace_wake_up();
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}
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@ -1387,6 +1429,31 @@ seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
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return ret;
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}
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static int
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seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
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unsigned long sym_flags)
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{
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int ret = 1;
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unsigned i;
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for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
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unsigned long ip = entry->caller[i];
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if (ip == ULONG_MAX || !ret)
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break;
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if (i)
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ret = trace_seq_puts(s, " <- ");
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if (!ip) {
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ret = trace_seq_puts(s, "??");
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continue;
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}
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if (ret /*&& (sym_flags & TRACE_ITER_SYM_ADDR)*/)
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ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
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}
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return ret;
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}
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static void print_lat_help_header(struct seq_file *m)
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{
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seq_puts(m, "# _------=> CPU# \n");
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@ -1702,6 +1769,16 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
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field->line);
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break;
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}
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case TRACE_USER_STACK: {
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struct userstack_entry *field;
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trace_assign_type(field, entry);
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seq_print_userip_objs(field, s, sym_flags);
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if (entry->flags & TRACE_FLAG_CONT)
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trace_seq_print_cont(s, iter);
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break;
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}
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default:
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trace_seq_printf(s, "Unknown type %d\n", entry->type);
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}
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@ -1853,6 +1930,19 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
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field->line);
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break;
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}
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case TRACE_USER_STACK: {
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struct userstack_entry *field;
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trace_assign_type(field, entry);
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ret = seq_print_userip_objs(field, s, sym_flags);
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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ret = trace_seq_putc(s, '\n');
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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break;
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}
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}
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return TRACE_TYPE_HANDLED;
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}
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@ -1912,6 +2002,7 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
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break;
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}
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case TRACE_SPECIAL:
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case TRACE_USER_STACK:
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case TRACE_STACK: {
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struct special_entry *field;
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@ -2000,6 +2091,7 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
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break;
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}
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case TRACE_SPECIAL:
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case TRACE_USER_STACK:
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case TRACE_STACK: {
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struct special_entry *field;
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@ -2054,6 +2146,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
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break;
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}
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case TRACE_SPECIAL:
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case TRACE_USER_STACK:
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case TRACE_STACK: {
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struct special_entry *field;
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@ -26,6 +26,7 @@ enum trace_type {
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TRACE_BOOT_CALL,
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TRACE_BOOT_RET,
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TRACE_FN_RET,
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TRACE_USER_STACK,
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__TRACE_LAST_TYPE
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};
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@ -42,6 +43,7 @@ struct trace_entry {
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unsigned char flags;
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unsigned char preempt_count;
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int pid;
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int tgid;
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};
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/*
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@ -99,6 +101,11 @@ struct stack_entry {
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unsigned long caller[FTRACE_STACK_ENTRIES];
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};
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struct userstack_entry {
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struct trace_entry ent;
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unsigned long caller[FTRACE_STACK_ENTRIES];
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};
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/*
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* ftrace_printk entry:
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*/
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@ -240,6 +247,7 @@ extern void __ftrace_bad_type(void);
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IF_ASSIGN(var, ent, struct ctx_switch_entry, 0); \
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IF_ASSIGN(var, ent, struct trace_field_cont, TRACE_CONT); \
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IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK); \
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IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
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IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT); \
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IF_ASSIGN(var, ent, struct special_entry, 0); \
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IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \
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@ -500,6 +508,7 @@ enum trace_iterator_flags {
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TRACE_ITER_PREEMPTONLY = 0x800,
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TRACE_ITER_BRANCH = 0x1000,
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TRACE_ITER_ANNOTATE = 0x2000,
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TRACE_ITER_USERSTACKTRACE = 0x4000
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};
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/*
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