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4649079b9d
When using trace-cmd on 5.6-rt for the function graph tracer, the output was
corrupted. It gave output like this:
funcgraph_entry: func=0xffffffff depth=38982
funcgraph_entry: func=0x1ffffffff depth=16044
funcgraph_exit: func=0xffffffff overrun=0x92539aaf00000000 calltime=0x92539c9900000072 rettime=0x100000072 depth=11084
funcgraph_exit: func=0xffffffff overrun=0x9253946e00000000 calltime=0x92539e2100000072 rettime=0x72 depth=26033702
funcgraph_entry: func=0xffffffff depth=85798
funcgraph_entry: func=0x1ffffffff depth=12044
The reason was because the tracefs/events/ftrace/funcgraph_entry/exit format
file was incorrect. The -rt kernel adds more common fields to the trace
events. Namely, common_migrate_disable and common_preempt_lazy_count. Each
is one byte in size. This changes the alignment of the normal payload. Most
events are aligned normally, but the function and function graph events are
defined with a "PACKED" macro, that packs their payload. As the offsets
displayed in the format files are now calculated by an aligned field, the
aligned field for function and function graph events should be 1, not their
normal alignment.
With aligning of the funcgraph_entry event, the format file has:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:unsigned char common_migrate_disable; offset:8; size:1; signed:0;
field:unsigned char common_preempt_lazy_count; offset:9; size:1; signed:0;
field:unsigned long func; offset:16; size:8; signed:0;
field:int depth; offset:24; size:4; signed:1;
But the actual alignment is:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:unsigned char common_migrate_disable; offset:8; size:1; signed:0;
field:unsigned char common_preempt_lazy_count; offset:9; size:1; signed:0;
field:unsigned long func; offset:12; size:8; signed:0;
field:int depth; offset:20; size:4; signed:1;
Link: https://lkml.kernel.org/r/20200609220041.2a3b527f@oasis.local.home
Cc: stable@vger.kernel.org
Fixes: 04ae87a520 ("ftrace: Rework event_create_dir()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
192 lines
5.2 KiB
C
192 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* trace_export.c - export basic ftrace utilities to user space
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*
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* Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com>
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*/
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#include <linux/stringify.h>
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#include <linux/kallsyms.h>
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#include <linux/seq_file.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include "trace_output.h"
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/* Stub function for events with triggers */
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static int ftrace_event_register(struct trace_event_call *call,
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enum trace_reg type, void *data)
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{
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return 0;
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}
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#undef TRACE_SYSTEM
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#define TRACE_SYSTEM ftrace
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/*
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* The FTRACE_ENTRY_REG macro allows ftrace entry to define register
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* function and thus become accesible via perf.
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*/
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#undef FTRACE_ENTRY_REG
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#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print, regfn) \
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FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
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/* not needed for this file */
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#undef __field_struct
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#define __field_struct(type, item)
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#undef __field
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#define __field(type, item) type item;
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#undef __field_fn
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#define __field_fn(type, item) type item;
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#undef __field_desc
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#define __field_desc(type, container, item) type item;
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#undef __field_packed
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#define __field_packed(type, container, item) type item;
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#undef __array
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#define __array(type, item, size) type item[size];
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#undef __array_desc
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#define __array_desc(type, container, item, size) type item[size];
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#undef __dynamic_array
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#define __dynamic_array(type, item) type item[];
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#undef F_STRUCT
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#define F_STRUCT(args...) args
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#undef F_printk
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#define F_printk(fmt, args...) fmt, args
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#undef FTRACE_ENTRY
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#define FTRACE_ENTRY(name, struct_name, id, tstruct, print) \
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struct ____ftrace_##name { \
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tstruct \
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}; \
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static void __always_unused ____ftrace_check_##name(void) \
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{ \
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struct ____ftrace_##name *__entry = NULL; \
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\
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/* force compile-time check on F_printk() */ \
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printk(print); \
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}
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#undef FTRACE_ENTRY_DUP
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#define FTRACE_ENTRY_DUP(name, struct_name, id, tstruct, print) \
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FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
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#include "trace_entries.h"
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#undef __field_ext
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#define __field_ext(_type, _item, _filter_type) { \
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.type = #_type, .name = #_item, \
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.size = sizeof(_type), .align = __alignof__(_type), \
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is_signed_type(_type), .filter_type = _filter_type },
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#undef __field_ext_packed
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#define __field_ext_packed(_type, _item, _filter_type) { \
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.type = #_type, .name = #_item, \
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.size = sizeof(_type), .align = 1, \
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is_signed_type(_type), .filter_type = _filter_type },
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#undef __field
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#define __field(_type, _item) __field_ext(_type, _item, FILTER_OTHER)
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#undef __field_fn
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#define __field_fn(_type, _item) __field_ext(_type, _item, FILTER_TRACE_FN)
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#undef __field_desc
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#define __field_desc(_type, _container, _item) __field_ext(_type, _item, FILTER_OTHER)
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#undef __field_packed
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#define __field_packed(_type, _container, _item) __field_ext_packed(_type, _item, FILTER_OTHER)
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#undef __array
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#define __array(_type, _item, _len) { \
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.type = #_type"["__stringify(_len)"]", .name = #_item, \
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.size = sizeof(_type[_len]), .align = __alignof__(_type), \
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is_signed_type(_type), .filter_type = FILTER_OTHER },
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#undef __array_desc
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#define __array_desc(_type, _container, _item, _len) __array(_type, _item, _len)
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#undef __dynamic_array
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#define __dynamic_array(_type, _item) { \
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.type = #_type "[]", .name = #_item, \
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.size = 0, .align = __alignof__(_type), \
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is_signed_type(_type), .filter_type = FILTER_OTHER },
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#undef FTRACE_ENTRY
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#define FTRACE_ENTRY(name, struct_name, id, tstruct, print) \
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static struct trace_event_fields ftrace_event_fields_##name[] = { \
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tstruct \
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{} };
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#include "trace_entries.h"
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#undef __entry
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#define __entry REC
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#undef __field
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#define __field(type, item)
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#undef __field_fn
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#define __field_fn(type, item)
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#undef __field_desc
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#define __field_desc(type, container, item)
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#undef __field_packed
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#define __field_packed(type, container, item)
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#undef __array
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#define __array(type, item, len)
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#undef __array_desc
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#define __array_desc(type, container, item, len)
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#undef __dynamic_array
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#define __dynamic_array(type, item)
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#undef F_printk
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#define F_printk(fmt, args...) __stringify(fmt) ", " __stringify(args)
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#undef FTRACE_ENTRY_REG
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#define FTRACE_ENTRY_REG(call, struct_name, etype, tstruct, print, regfn) \
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static struct trace_event_class __refdata event_class_ftrace_##call = { \
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.system = __stringify(TRACE_SYSTEM), \
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.fields_array = ftrace_event_fields_##call, \
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.fields = LIST_HEAD_INIT(event_class_ftrace_##call.fields),\
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.reg = regfn, \
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}; \
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\
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struct trace_event_call __used event_##call = { \
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.class = &event_class_ftrace_##call, \
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{ \
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.name = #call, \
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}, \
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.event.type = etype, \
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.print_fmt = print, \
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.flags = TRACE_EVENT_FL_IGNORE_ENABLE, \
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}; \
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static struct trace_event_call __used \
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__attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
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#undef FTRACE_ENTRY
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#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print) \
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FTRACE_ENTRY_REG(call, struct_name, etype, \
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PARAMS(tstruct), PARAMS(print), NULL)
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bool ftrace_event_is_function(struct trace_event_call *call)
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{
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return call == &event_function;
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}
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#include "trace_entries.h"
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