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Add trace library

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Add a library which supports tracing of execution using built-in gcc
features and a microsecond timer. This can be used to record a list of
function which are executed, along with a timestamp for each. Later
this information can be sent to the host for processing.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass 2013-06-11 11:14:39 -07:00 committed by Tom Rini
parent b8bcaa3ad3
commit b2e16a85a1
5 changed files with 870 additions and 0 deletions
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361
doc/README.trace Normal file
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@ -0,0 +1,361 @@
#
# Copyright (c) 2013 The Chromium OS Authors.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundatio; either version 2 of
# the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#
Tracing in U-Boot
=================
U-Boot supports a simple tracing feature which allows a record of excecution
to be collected and sent to a host machine for analysis. At present the
main use for this is to profile boot time.
Overview
--------
The trace feature uses GCC's instrument-functions feature to trace all
function entry/exit points. These are then recorded in a memory buffer.
The memory buffer can be saved to the host over a network link using
tftpput or by writing to an attached memory device such as MMC.
On the host, the file is first converted with a tool called 'proftool',
which extracts useful information from it. The resulting trace output
resembles that emitted by Linux's ftrace feature, so can be visually
displayed by pytimechart.
Quick-start using Sandbox
-------------------------
Sandbox is a build of U-Boot that can run under Linux so it is a convenient
way of trying out tracing before you use it on your actual board. To do
this, follow these steps:
Add the following to include/configs/sandbox.h (if not already there)
#define CONFIG_TRACE
#define CONFIG_CMD_TRACE
#define CONFIG_TRACE_BUFFER_SIZE (16 << 20)
#define CONFIG_TRACE_EARLY_SIZE (8 << 20)
#define CONFIG_TRACE_EARLY
#define CONFIG_TRACE_EARLY_ADDR 0x00100000
Build sandbox U-Boot with tracing enabled:
$ make FTRACE=1 O=sandbox sandbox_config
$ make FTRACE=1 O=sandbox
Run sandbox, wait for a bit of trace information to appear, and then capture
a trace:
$ ./sandbox/u-boot
U-Boot 2013.04-rc2-00100-ga72fcef (Apr 17 2013 - 19:25:24)
DRAM: 128 MiB
trace: enabled
Using default environment
In: serial
Out: serial
Err: serial
=>trace stats
671,406 function sites
69,712 function calls
0 untracked function calls
73,373 traced function calls
16 maximum observed call depth
15 call depth limit
66,491 calls not traced due to depth
=>trace stats
671,406 function sites
1,279,450 function calls
0 untracked function calls
950,490 traced function calls (333217 dropped due to overflow)
16 maximum observed call depth
15 call depth limit
1,275,767 calls not traced due to depth
=>trace calls 0 e00000
Call list dumped to 00000000, size 0xae0a40
=>print
baudrate=115200
profbase=0
profoffset=ae0a40
profsize=e00000
stderr=serial
stdin=serial
stdout=serial
Environment size: 117/8188 bytes
=>sb save host 0 trace 0 ${profoffset}
11405888 bytes written in 10 ms (1.1 GiB/s)
=>reset
Then run proftool to convert the trace information to ftrace format.
$ ./sandbox/tools/proftool -m sandbox/System.map -p trace dump-ftrace >trace.txt
Finally run pytimechart to display it:
$ pytimechart trace.txt
Using this tool you can zoom and pan across the trace, with the function
calls on the left and little marks representing the start and end of each
function.
CONFIG Options
--------------
- CONFIG_TRACE
Enables the trace feature in U-Boot.
- CONFIG_CMD_TRACE
Enables the trace command.
- CONFIG_TRACE_BUFFER_SIZE
Size of trace buffer to allocate for U-Boot. This buffer is
used after relocation, as a place to put function tracing
information. The address of the buffer is determined by
the relocation code.
- CONFIG_TRACE_EARLY
Define this to start tracing early, before relocation.
- CONFIG_TRACE_EARLY_SIZE
Size of 'early' trace buffer. Before U-Boot has relocated
it doesn't have a proper trace buffer. On many boards
you can define an area of memory to use for the trace
buffer until the 'real' trace buffer is available after
relocation. The contents of this buffer are then copied to
the real buffer.
- CONFIG_TRACE_EARLY_ADDR
Address of early trace buffer
Building U-Boot with Tracing Enabled
------------------------------------
Pass 'FTRACE=1' to the U-Boot Makefile to actually instrument the code.
This is kept as a separate option so that it is easy to enable/disable
instrumenting from the command line instead of having to change board
config files.
Collecting Trace Data
---------------------
When you run U-Boot on your board it will collect trace data up to the
limit of the trace buffer size you have specified. Once that is exhausted
no more data will be collected.
Collecting trace data has an affect on execution time/performance. You
will notice this particularly with trvial functions - the overhead of
recording their execution may even exceed their normal execution time.
In practice this doesn't matter much so long as you are aware of the
effect. Once you have done your optimisations, turn off tracing before
doing end-to-end timing.
The best time to start tracing is right at the beginning of U-Boot. The
best time to stop tracing is right at the end. In practice it is hard
to achieve these ideals.
This implementation enables tracing early in board_init_f(). This means
that it captures most of the board init process, missing only the
early architecture-specific init. However, it also misses the entire
SPL stage if there is one.
U-Boot typically ends with a 'bootm' command which loads and runs an
OS. There is useful trace data in the execution of that bootm
command. Therefore this implementation provides a way to collect trace
data after bootm has finished processing, but just before it jumps to
the OS. In practical terms, U-Boot runs the 'fakegocmd' environment
variable at this point. This variable should have a short script which
collects the trace data and writes it somewhere.
Trace data collection relies on a microsecond timer, accesed through
timer_get_us(). So the first think you should do is make sure that
this produces sensible results for your board. Suitable sources for
this timer include high resolution timers, PWMs or profile timers if
available. Most modern SOCs have a suitable timer for this. Make sure
that you mark this timer (and anything it calls) with
__attribute__((no_instrument_function)) so that the trace library can
use it without causing an infinite loop.
Commands
--------
The trace command has variable sub-commands:
- stats
Display tracing statistics
- pause
Pause tracing
- resume
Resume tracing
- funclist [<addr> <size>]
Dump a list of functions into the buffer
- calls [<addr> <size>]
Dump function call trace into buffer
If the address and size are not given, these are obtained from environment
variables (see below). In any case the environment variables are updated
after the command runs.
Environment Variables
---------------------
The following are used:
- profbase
Base address of trace output buffer
- profoffset
Offset of first unwritten byte in trace output buffer
- profsize
Size of trace output buffer
All of these are set by the 'trace calls' command.
These variables keep track of the amount of data written to the trace
output buffer by the 'trace' command. The trace commands which write data
to the output buffer can use these to specify the buffer to write to, and
update profoffset each time. This allows successive commands to append data
to the same buffer, for example:
trace funclist 10000 e00000
trace calls
(the latter command appends more data to the buffer).
- fakegocmd
Specifies commands to run just before booting the OS. This
is a useful time to write the trace data to the host for
processing.
Writing Out Trace Data
----------------------
Once the trace data is in an output buffer in memory there are various ways
to transmit it to the host. Notably you can use tftput to send the data
over a network link:
fakegocmd=trace pause; usb start; set autoload n; bootp;
trace calls 10000000 1000000;
tftpput ${profbase} ${profoffset} 192.168.1.4:/tftpboot/calls
This starts up USB (to talk to an attached USB Ethernet dongle), writes
a trace log to address 10000000 and sends it to a host machine using
TFTP. After this, U-Boot will boot the OS normally, albeit a little
later.
Converting Trace Output Data
----------------------------
The trace output data is kept in a binary format which is not documented
here. To convert it into something useful, you can use proftool.
This tool must be given the U-Boot map file and the trace data received
from running that U-Boot. It produces a text output file.
Options
-m <map_file>
Specify U-Boot map file
-p <trace_file>
Specifiy profile/trace file
Commands:
- dump-ftrace
Write a text dump of the file in Linux ftrace format to stdout
Viewing the Trace Data
----------------------
You can use pytimechart for this (sudo apt-get pytimechart might work on
your Debian-style machine, and use your favourite search engine to obtain
documentation). It expects the file to have a .txt extension. The program
has terse user interface but is very convenient for viewing U-Boot
profile information.
Workflow Suggestions
--------------------
The following suggestions may be helpful if you are trying to reduce boot
time:
1. Enable CONFIG_BOOTSTAGE and CONFIG_BOOTSTAGE_REPORT. This should get
you are helpful overall snapshot of the boot time.
2. Build U-Boot with tracing and run it. Note the difference in boot time
(it is common for tracing to add 10% to the time)
3. Collect the trace information as descibed above. Use this to find where
all the time is being spent.
4. Take a look at that code and see if you can optimise it. Perhaps it is
possible to speed up the initialisation of a device, or remove an unused
feature.
5. Rebuild, run and collect again. Compare your results.
6. Keep going until you run out of steam, or your boot is fast enough.
Configuring Trace
-----------------
There are a few parameters in the code that you may want to consider.
There is a function call depth limit (set to 15 by default). When the
stack depth goes above this then no tracing information is recorded.
The maximum depth reached is recorded and displayed by the 'trace stats'
command.
Future Work
-----------
Tracing could be a little tidier in some areas, for example providing
run-time configuration options for trace.
Some other features that might be useful:
- Trace filter to select which functions are recorded
- Sample-based profiling using a timer interrupt
- Better control over trace depth
- Compression of trace information
Simon Glass <sjg@chromium.org>
April 2013

4
include/common.h
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@ -750,6 +750,10 @@ void irq_install_handler(int, interrupt_handler_t *, void *);
void irq_free_handler (int);
void reset_timer (void);
ulong get_timer (ulong base);
/* Return value of monotonic microsecond timer */
unsigned long timer_get_us(void);
void enable_interrupts (void);
int disable_interrupts (void);

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include/trace.h Normal file
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/*
* Copyright (c) 2012 The Chromium OS Authors.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#ifndef __TRACE_H
#define __TRACE_H
enum {
/*
* This affects the granularity of our trace. We can bin function
* entry points into groups on the basis that functions typically
* have a minimum size, so entry points can't appear any closer
* than this to each other.
*
* The value here assumes a minimum instruction size of 4 bytes,
* or that instructions are 2 bytes but there are at least 2 of
* them in every function.
*
* Increasing this value reduces the number of functions we can
* resolve, but reduces the size of the uintptr_t array used for
* our function list, which is the length of the code divided by
* this value.
*/
FUNC_SITE_SIZE = 4, /* distance between function sites */
};
enum trace_chunk_type {
TRACE_CHUNK_FUNCS,
TRACE_CHUNK_CALLS,
};
/* A trace record for a function, as written to the profile output file */
struct trace_output_func {
uint32_t offset; /* Function offset into code */
uint32_t call_count; /* Number of times called */
};
/* A header at the start of the trace output buffer */
struct trace_output_hdr {
enum trace_chunk_type type; /* Record type */
uint32_t rec_count; /* Number of records */
};
/* Print statistics about traced function calls */
void trace_print_stats(void);
/**
* Dump a list of functions and call counts into a buffer
*
* Each record in the buffer is a struct trace_func_stats. The 'needed'
* parameter returns the number of bytes needed to complete the operation,
* which may be more than buff_size if your buffer is too small.
*
* @param buff Buffer in which to place data, or NULL to count size
* @param buff_size Size of buffer
* @param needed Returns number of bytes used / needed
* @return 0 if ok, -1 on error (buffer exhausted)
*/
int trace_list_functions(void *buff, int buff_size, unsigned *needed);
/* Flags for ftrace_record */
enum ftrace_flags {
FUNCF_EXIT = 0UL << 30,
FUNCF_ENTRY = 1UL << 30,
FUNCF_TEXTBASE = 2UL << 30,
FUNCF_TIMESTAMP_MASK = 0x3fffffff,
};
#define TRACE_CALL_TYPE(call) ((call)->flags & 0xc0000000UL)
/* Information about a single function entry/exit */
struct trace_call {
uint32_t func; /* Function offset */
uint32_t caller; /* Caller function offset */
uint32_t flags; /* Flags and timestamp */
};
int trace_list_calls(void *buff, int buff_size, unsigned int *needed);
/**
* Turn function tracing on and off
*
* Don't enable trace if it has not been initialised.
*
* @param enabled 1 to enable trace, 0 to disable
*/
void trace_set_enabled(int enabled);
#ifdef CONFIG_TRACE_EARLY
int trace_early_init(void);
#else
static inline int trace_early_init(void)
{
return 0;
}
#endif
/**
* Init the trace system
*
* This should be called after relocation with a suitably large buffer
* (typically as large as the U-Boot text area)
*
* @param buff Pointer to trace buffer
* @param buff_size Size of trace buffer
*/
int trace_init(void *buff, size_t buff_size);
#endif

1
lib/Makefile
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@ -71,6 +71,7 @@ COBJS-y += linux_string.o
COBJS-$(CONFIG_REGEX) += slre.o
COBJS-y += string.o
COBJS-y += time.o
COBJS-$(CONFIG_TRACE) += trace.o
COBJS-$(CONFIG_BOOTP_PXE) += uuid.o
COBJS-y += vsprintf.o
COBJS-$(CONFIG_RANDOM_MACADDR) += rand.o

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lib/trace.c Normal file
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@ -0,0 +1,379 @@
/*
* Copyright (c) 2012 The Chromium OS Authors.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <trace.h>
#include <asm/io.h>
#include <asm/sections.h>
DECLARE_GLOBAL_DATA_PTR;
static char trace_enabled __attribute__((section(".data")));
static char trace_inited __attribute__((section(".data")));
/* The header block at the start of the trace memory area */
struct trace_hdr {
int func_count; /* Total number of function call sites */
u64 call_count; /* Total number of tracked function calls */
u64 untracked_count; /* Total number of untracked function calls */
int funcs_used; /* Total number of functions used */
/*
* Call count for each function. This is indexed by the word offset
* of the function from gd->relocaddr
*/
uintptr_t *call_accum;
/* Function trace list */
struct trace_call *ftrace; /* The function call records */
ulong ftrace_size; /* Num. of ftrace records we have space for */
ulong ftrace_count; /* Num. of ftrace records written */
ulong ftrace_too_deep_count; /* Functions that were too deep */
int depth;
int depth_limit;
int max_depth;
};
static struct trace_hdr *hdr; /* Pointer to start of trace buffer */
static inline uintptr_t __attribute__((no_instrument_function))
func_ptr_to_num(void *func_ptr)
{
uintptr_t offset = (uintptr_t)func_ptr;
#ifdef CONFIG_SANDBOX
offset -= (uintptr_t)&_init;
#else
if (gd->flags & GD_FLG_RELOC)
offset -= gd->relocaddr;
else
offset -= CONFIG_SYS_TEXT_BASE;
#endif
return offset / FUNC_SITE_SIZE;
}
static void __attribute__((no_instrument_function)) add_ftrace(void *func_ptr,
void *caller, ulong flags)
{
if (hdr->depth > hdr->depth_limit) {
hdr->ftrace_too_deep_count++;
return;
}
if (hdr->ftrace_count < hdr->ftrace_size) {
struct trace_call *rec = &hdr->ftrace[hdr->ftrace_count];
rec->func = func_ptr_to_num(func_ptr);
rec->caller = func_ptr_to_num(caller);
rec->flags = flags | (timer_get_us() & FUNCF_TIMESTAMP_MASK);
}
hdr->ftrace_count++;
}
static void __attribute__((no_instrument_function)) add_textbase(void)
{
if (hdr->ftrace_count < hdr->ftrace_size) {
struct trace_call *rec = &hdr->ftrace[hdr->ftrace_count];
rec->func = CONFIG_SYS_TEXT_BASE;
rec->caller = 0;
rec->flags = FUNCF_TEXTBASE;
}
hdr->ftrace_count++;
}
/**
* This is called on every function entry
*
* We add to our tally for this function and add to the list of called
* functions.
*
* @param func_ptr Pointer to function being entered
* @param caller Pointer to function which called this function
*/
void __attribute__((no_instrument_function)) __cyg_profile_func_enter(
void *func_ptr, void *caller)
{
if (trace_enabled) {
int func;
add_ftrace(func_ptr, caller, FUNCF_ENTRY);
func = func_ptr_to_num(func_ptr);
if (func < hdr->func_count) {
hdr->call_accum[func]++;
hdr->call_count++;
} else {
hdr->untracked_count++;
}
hdr->depth++;
if (hdr->depth > hdr->depth_limit)
hdr->max_depth = hdr->depth;
}
}
/**
* This is called on every function exit
*
* We do nothing here.
*
* @param func_ptr Pointer to function being entered
* @param caller Pointer to function which called this function
*/
void __attribute__((no_instrument_function)) __cyg_profile_func_exit(
void *func_ptr, void *caller)
{
if (trace_enabled) {
add_ftrace(func_ptr, caller, FUNCF_EXIT);
hdr->depth--;
}
}
/**
* Produce a list of called functions
*
* The information is written into the supplied buffer - a header followed
* by a list of function records.
*
* @param buff Buffer to place list into
* @param buff_size Size of buffer
* @param needed Returns size of buffer needed, which may be
* greater than buff_size if we ran out of space.
* @return 0 if ok, -1 if space was exhausted
*/
int trace_list_functions(void *buff, int buff_size, unsigned int *needed)
{
struct trace_output_hdr *output_hdr = NULL;
void *end, *ptr = buff;
int func;
int upto;
end = buff ? buff + buff_size : NULL;
/* Place some header information */
if (ptr + sizeof(struct trace_output_hdr) < end)
output_hdr = ptr;
ptr += sizeof(struct trace_output_hdr);
/* Add information about each function */
for (func = upto = 0; func < hdr->func_count; func++) {
int calls = hdr->call_accum[func];
if (!calls)
continue;
if (ptr + sizeof(struct trace_output_func) < end) {
struct trace_output_func *stats = ptr;
stats->offset = func * FUNC_SITE_SIZE;
stats->call_count = calls;
upto++;
}
ptr += sizeof(struct trace_output_func);
}
/* Update the header */
if (output_hdr) {
output_hdr->rec_count = upto;
output_hdr->type = TRACE_CHUNK_FUNCS;
}
/* Work out how must of the buffer we used */
*needed = ptr - buff;
if (ptr > end)
return -1;
return 0;
}
int trace_list_calls(void *buff, int buff_size, unsigned *needed)
{
struct trace_output_hdr *output_hdr = NULL;
void *end, *ptr = buff;
int rec, upto;
int count;
end = buff ? buff + buff_size : NULL;
/* Place some header information */
if (ptr + sizeof(struct trace_output_hdr) < end)
output_hdr = ptr;
ptr += sizeof(struct trace_output_hdr);
/* Add information about each call */
count = hdr->ftrace_count;
if (count > hdr->ftrace_size)
count = hdr->ftrace_size;
for (rec = upto = 0; rec < count; rec++) {
if (ptr + sizeof(struct trace_call) < end) {
struct trace_call *call = &hdr->ftrace[rec];
struct trace_call *out = ptr;
out->func = call->func * FUNC_SITE_SIZE;
out->caller = call->caller * FUNC_SITE_SIZE;
out->flags = call->flags;
upto++;
}
ptr += sizeof(struct trace_call);
}
/* Update the header */
if (output_hdr) {
output_hdr->rec_count = upto;
output_hdr->type = TRACE_CHUNK_CALLS;
}
/* Work out how must of the buffer we used */
*needed = ptr - buff;
if (ptr > end)
return -1;
return 0;
}
/* Print basic information about tracing */
void trace_print_stats(void)
{
ulong count;
#ifndef FTRACE
puts("Warning: make U-Boot with FTRACE to enable function instrumenting.\n");
puts("You will likely get zeroed data here\n");
#endif
if (!trace_inited) {
printf("Trace is disabled\n");
return;
}
print_grouped_ull(hdr->func_count, 10);
puts(" function sites\n");
print_grouped_ull(hdr->call_count, 10);
puts(" function calls\n");
print_grouped_ull(hdr->untracked_count, 10);
puts(" untracked function calls\n");
count = min(hdr->ftrace_count, hdr->ftrace_size);
print_grouped_ull(count, 10);
puts(" traced function calls");
if (hdr->ftrace_count > hdr->ftrace_size) {
printf(" (%lu dropped due to overflow)",
hdr->ftrace_count - hdr->ftrace_size);
}
puts("\n");
printf("%15d maximum observed call depth\n", hdr->max_depth);
printf("%15d call depth limit\n", hdr->depth_limit);
print_grouped_ull(hdr->ftrace_too_deep_count, 10);
puts(" calls not traced due to depth\n");
}
void __attribute__((no_instrument_function)) trace_set_enabled(int enabled)
{
trace_enabled = enabled != 0;
}
/**
* Init the tracing system ready for used, and enable it
*
* @param buff Pointer to trace buffer
* @param buff_size Size of trace buffer
*/
int __attribute__((no_instrument_function)) trace_init(void *buff,
size_t buff_size)
{
ulong func_count = gd->mon_len / FUNC_SITE_SIZE;
size_t needed;
int was_disabled = !trace_enabled;
if (!was_disabled) {
#ifdef CONFIG_TRACE_EARLY
char *end;
ulong used;
/*
* Copy over the early trace data if we have it. Disable
* tracing while we are doing this.
*/
trace_enabled = 0;
hdr = map_sysmem(CONFIG_TRACE_EARLY_ADDR,
CONFIG_TRACE_EARLY_SIZE);
end = (char *)&hdr->ftrace[hdr->ftrace_count];
used = end - (char *)hdr;
printf("trace: copying %08lx bytes of early data from %x to %08lx\n",
used, CONFIG_TRACE_EARLY_ADDR,
(ulong)map_to_sysmem(buff));
memcpy(buff, hdr, used);
#else
puts("trace: already enabled\n");
return -1;
#endif
}
hdr = (struct trace_hdr *)buff;
needed = sizeof(*hdr) + func_count * sizeof(uintptr_t);
if (needed > buff_size) {
printf("trace: buffer size %zd bytes: at least %zd needed\n",
buff_size, needed);
return -1;
}
if (was_disabled)
memset(hdr, '\0', needed);
hdr->func_count = func_count;
hdr->call_accum = (uintptr_t *)(hdr + 1);
/* Use any remaining space for the timed function trace */
hdr->ftrace = (struct trace_call *)(buff + needed);
hdr->ftrace_size = (buff_size - needed) / sizeof(*hdr->ftrace);
add_textbase();
puts("trace: enabled\n");
hdr->depth_limit = 15;
trace_enabled = 1;
trace_inited = 1;
return 0;
}
#ifdef CONFIG_TRACE_EARLY
int __attribute__((no_instrument_function)) trace_early_init(void)
{
ulong func_count = gd->mon_len / FUNC_SITE_SIZE;
size_t buff_size = CONFIG_TRACE_EARLY_SIZE;
size_t needed;
/* We can ignore additional calls to this function */
if (trace_enabled)
return 0;
hdr = map_sysmem(CONFIG_TRACE_EARLY_ADDR, CONFIG_TRACE_EARLY_SIZE);
needed = sizeof(*hdr) + func_count * sizeof(uintptr_t);
if (needed > buff_size) {
printf("trace: buffer size is %zd bytes, at least %zd needed\n",
buff_size, needed);
return -1;
}
memset(hdr, '\0', needed);
hdr->call_accum = (uintptr_t *)(hdr + 1);
hdr->func_count = func_count;
/* Use any remaining space for the timed function trace */
hdr->ftrace = (struct trace_call *)((char *)hdr + needed);
hdr->ftrace_size = (buff_size - needed) / sizeof(*hdr->ftrace);
add_textbase();
hdr->depth_limit = 200;
printf("trace: early enable at %08x\n", CONFIG_TRACE_EARLY_ADDR);
trace_enabled = 1;
return 0;
}
#endif