556 lines
17 KiB
C
556 lines
17 KiB
C
/* Profiling of shared libraries.
|
||
Copyright (C) 1997-2002, 2003, 2004, 2006 Free Software Foundation, Inc.
|
||
This file is part of the GNU C Library.
|
||
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
|
||
Based on the BSD mcount implementation.
|
||
|
||
The GNU C Library is free software; you can redistribute it and/or
|
||
modify it under the terms of the GNU Lesser General Public
|
||
License as published by the Free Software Foundation; either
|
||
version 2.1 of the License, or (at your option) any later version.
|
||
|
||
The GNU C Library 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
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public
|
||
License along with the GNU C Library; if not, write to the Free
|
||
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
||
02111-1307 USA. */
|
||
|
||
#include <assert.h>
|
||
#include <errno.h>
|
||
#include <fcntl.h>
|
||
#include <inttypes.h>
|
||
#include <limits.h>
|
||
#include <stdio.h>
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
#include <unistd.h>
|
||
#include <ldsodefs.h>
|
||
#include <sys/gmon.h>
|
||
#include <sys/gmon_out.h>
|
||
#include <sys/mman.h>
|
||
#include <sys/param.h>
|
||
#include <sys/stat.h>
|
||
#include <atomic.h>
|
||
|
||
/* The LD_PROFILE feature has to be implemented different to the
|
||
normal profiling using the gmon/ functions. The problem is that an
|
||
arbitrary amount of processes simulataneously can be run using
|
||
profiling and all write the results in the same file. To provide
|
||
this mechanism one could implement a complicated mechanism to merge
|
||
the content of two profiling runs or one could extend the file
|
||
format to allow more than one data set. For the second solution we
|
||
would have the problem that the file can grow in size beyond any
|
||
limit and both solutions have the problem that the concurrency of
|
||
writing the results is a big problem.
|
||
|
||
Another much simpler method is to use mmap to map the same file in
|
||
all using programs and modify the data in the mmap'ed area and so
|
||
also automatically on the disk. Using the MAP_SHARED option of
|
||
mmap(2) this can be done without big problems in more than one
|
||
file.
|
||
|
||
This approach is very different from the normal profiling. We have
|
||
to use the profiling data in exactly the way they are expected to
|
||
be written to disk. But the normal format used by gprof is not usable
|
||
to do this. It is optimized for size. It writes the tags as single
|
||
bytes but this means that the following 32/64 bit values are
|
||
unaligned.
|
||
|
||
Therefore we use a new format. This will look like this
|
||
|
||
0 1 2 3 <- byte is 32 bit word
|
||
0000 g m o n
|
||
0004 *version* <- GMON_SHOBJ_VERSION
|
||
0008 00 00 00 00
|
||
000c 00 00 00 00
|
||
0010 00 00 00 00
|
||
|
||
0014 *tag* <- GMON_TAG_TIME_HIST
|
||
0018 ?? ?? ?? ??
|
||
?? ?? ?? ?? <- 32/64 bit LowPC
|
||
0018+A ?? ?? ?? ??
|
||
?? ?? ?? ?? <- 32/64 bit HighPC
|
||
0018+2*A *histsize*
|
||
001c+2*A *profrate*
|
||
0020+2*A s e c o
|
||
0024+2*A n d s \0
|
||
0028+2*A \0 \0 \0 \0
|
||
002c+2*A \0 \0 \0
|
||
002f+2*A s
|
||
|
||
0030+2*A ?? ?? ?? ?? <- Count data
|
||
... ...
|
||
0030+2*A+K ?? ?? ?? ??
|
||
|
||
0030+2*A+K *tag* <- GMON_TAG_CG_ARC
|
||
0034+2*A+K *lastused*
|
||
0038+2*A+K ?? ?? ?? ??
|
||
?? ?? ?? ?? <- FromPC#1
|
||
0038+3*A+K ?? ?? ?? ??
|
||
?? ?? ?? ?? <- ToPC#1
|
||
0038+4*A+K ?? ?? ?? ?? <- Count#1
|
||
... ... ...
|
||
0038+(2*(CN-1)+2)*A+(CN-1)*4+K ?? ?? ?? ??
|
||
?? ?? ?? ?? <- FromPC#CGN
|
||
0038+(2*(CN-1)+3)*A+(CN-1)*4+K ?? ?? ?? ??
|
||
?? ?? ?? ?? <- ToPC#CGN
|
||
0038+(2*CN+2)*A+(CN-1)*4+K ?? ?? ?? ?? <- Count#CGN
|
||
|
||
We put (for now?) no basic block information in the file since this would
|
||
introduce rase conditions among all the processes who want to write them.
|
||
|
||
`K' is the number of count entries which is computed as
|
||
|
||
textsize / HISTFRACTION
|
||
|
||
`CG' in the above table is the number of call graph arcs. Normally,
|
||
the table is sparse and the profiling code writes out only the those
|
||
entries which are really used in the program run. But since we must
|
||
not extend this table (the profiling file) we'll keep them all here.
|
||
So CN can be executed in advance as
|
||
|
||
MINARCS <= textsize*(ARCDENSITY/100) <= MAXARCS
|
||
|
||
Now the remaining question is: how to build the data structures we can
|
||
work with from this data. We need the from set and must associate the
|
||
froms with all the associated tos. We will do this by constructing this
|
||
data structures at the program start. To do this we'll simply visit all
|
||
entries in the call graph table and add it to the appropriate list. */
|
||
|
||
extern int __profile_frequency (void);
|
||
libc_hidden_proto (__profile_frequency)
|
||
|
||
/* We define a special type to address the elements of the arc table.
|
||
This is basically the `gmon_cg_arc_record' format but it includes
|
||
the room for the tag and it uses real types. */
|
||
struct here_cg_arc_record
|
||
{
|
||
uintptr_t from_pc;
|
||
uintptr_t self_pc;
|
||
uint32_t count;
|
||
} __attribute__ ((packed));
|
||
|
||
static struct here_cg_arc_record *data;
|
||
|
||
/* Nonzero if profiling is under way. */
|
||
static int running;
|
||
|
||
/* This is the number of entry which have been incorporated in the toset. */
|
||
static uint32_t narcs;
|
||
/* This is a pointer to the object representing the number of entries
|
||
currently in the mmaped file. At no point of time this has to be the
|
||
same as NARCS. If it is equal all entries from the file are in our
|
||
lists. */
|
||
static volatile uint32_t *narcsp;
|
||
|
||
|
||
struct here_fromstruct
|
||
{
|
||
struct here_cg_arc_record volatile *here;
|
||
uint16_t link;
|
||
};
|
||
|
||
static volatile uint16_t *tos;
|
||
|
||
static struct here_fromstruct *froms;
|
||
static uint32_t fromlimit;
|
||
static volatile uint32_t fromidx;
|
||
|
||
static uintptr_t lowpc;
|
||
static size_t textsize;
|
||
static unsigned int log_hashfraction;
|
||
|
||
|
||
|
||
/* Set up profiling data to profile object desribed by MAP. The output
|
||
file is found (or created) in OUTPUT_DIR. */
|
||
void
|
||
internal_function
|
||
_dl_start_profile (void)
|
||
{
|
||
char *filename;
|
||
int fd;
|
||
struct stat64 st;
|
||
const ElfW(Phdr) *ph;
|
||
ElfW(Addr) mapstart = ~((ElfW(Addr)) 0);
|
||
ElfW(Addr) mapend = 0;
|
||
struct gmon_hdr gmon_hdr;
|
||
struct gmon_hist_hdr hist_hdr;
|
||
char *hist, *cp;
|
||
size_t idx;
|
||
size_t tossize;
|
||
size_t fromssize;
|
||
uintptr_t highpc;
|
||
uint16_t *kcount;
|
||
size_t kcountsize;
|
||
struct gmon_hdr *addr = NULL;
|
||
off_t expected_size;
|
||
/* See profil(2) where this is described. */
|
||
int s_scale;
|
||
#define SCALE_1_TO_1 0x10000L
|
||
const char *errstr = NULL;
|
||
|
||
/* Compute the size of the sections which contain program code. */
|
||
for (ph = GL(dl_profile_map)->l_phdr;
|
||
ph < &GL(dl_profile_map)->l_phdr[GL(dl_profile_map)->l_phnum]; ++ph)
|
||
if (ph->p_type == PT_LOAD && (ph->p_flags & PF_X))
|
||
{
|
||
ElfW(Addr) start = (ph->p_vaddr & ~(GLRO(dl_pagesize) - 1));
|
||
ElfW(Addr) end = ((ph->p_vaddr + ph->p_memsz + GLRO(dl_pagesize) - 1)
|
||
& ~(GLRO(dl_pagesize) - 1));
|
||
|
||
if (start < mapstart)
|
||
mapstart = start;
|
||
if (end > mapend)
|
||
mapend = end;
|
||
}
|
||
|
||
/* Now we can compute the size of the profiling data. This is done
|
||
with the same formulars as in `monstartup' (see gmon.c). */
|
||
running = 0;
|
||
lowpc = ROUNDDOWN (mapstart + GL(dl_profile_map)->l_addr,
|
||
HISTFRACTION * sizeof (HISTCOUNTER));
|
||
highpc = ROUNDUP (mapend + GL(dl_profile_map)->l_addr,
|
||
HISTFRACTION * sizeof (HISTCOUNTER));
|
||
textsize = highpc - lowpc;
|
||
kcountsize = textsize / HISTFRACTION;
|
||
if ((HASHFRACTION & (HASHFRACTION - 1)) == 0)
|
||
{
|
||
/* If HASHFRACTION is a power of two, mcount can use shifting
|
||
instead of integer division. Precompute shift amount.
|
||
|
||
This is a constant but the compiler cannot compile the
|
||
expression away since the __ffs implementation is not known
|
||
to the compiler. Help the compiler by precomputing the
|
||
usual cases. */
|
||
assert (HASHFRACTION == 2);
|
||
|
||
if (sizeof (*froms) == 8)
|
||
log_hashfraction = 4;
|
||
else if (sizeof (*froms) == 16)
|
||
log_hashfraction = 5;
|
||
else
|
||
log_hashfraction = __ffs (HASHFRACTION * sizeof (*froms)) - 1;
|
||
}
|
||
else
|
||
log_hashfraction = -1;
|
||
tossize = textsize / HASHFRACTION;
|
||
fromlimit = textsize * ARCDENSITY / 100;
|
||
if (fromlimit < MINARCS)
|
||
fromlimit = MINARCS;
|
||
if (fromlimit > MAXARCS)
|
||
fromlimit = MAXARCS;
|
||
fromssize = fromlimit * sizeof (struct here_fromstruct);
|
||
|
||
expected_size = (sizeof (struct gmon_hdr)
|
||
+ 4 + sizeof (struct gmon_hist_hdr) + kcountsize
|
||
+ 4 + 4 + fromssize * sizeof (struct here_cg_arc_record));
|
||
|
||
/* Create the gmon_hdr we expect or write. */
|
||
memset (&gmon_hdr, '\0', sizeof (struct gmon_hdr));
|
||
memcpy (&gmon_hdr.cookie[0], GMON_MAGIC, sizeof (gmon_hdr.cookie));
|
||
*(int32_t *) gmon_hdr.version = GMON_SHOBJ_VERSION;
|
||
|
||
/* Create the hist_hdr we expect or write. */
|
||
*(char **) hist_hdr.low_pc = (char *) mapstart;
|
||
*(char **) hist_hdr.high_pc = (char *) mapend;
|
||
*(int32_t *) hist_hdr.hist_size = kcountsize / sizeof (HISTCOUNTER);
|
||
*(int32_t *) hist_hdr.prof_rate = __profile_frequency ();
|
||
if (sizeof (hist_hdr.dimen) >= sizeof ("seconds"))
|
||
{
|
||
memcpy (hist_hdr.dimen, "seconds", sizeof ("seconds"));
|
||
memset (hist_hdr.dimen + sizeof ("seconds"), '\0',
|
||
sizeof (hist_hdr.dimen) - sizeof ("seconds"));
|
||
}
|
||
else
|
||
strncpy (hist_hdr.dimen, "seconds", sizeof (hist_hdr.dimen));
|
||
hist_hdr.dimen_abbrev = 's';
|
||
|
||
/* First determine the output name. We write in the directory
|
||
OUTPUT_DIR and the name is composed from the shared objects
|
||
soname (or the file name) and the ending ".profile". */
|
||
filename = (char *) alloca (strlen (GLRO(dl_profile_output)) + 1
|
||
+ strlen (GLRO(dl_profile)) + sizeof ".profile");
|
||
cp = __stpcpy (filename, GLRO(dl_profile_output));
|
||
*cp++ = '/';
|
||
__stpcpy (__stpcpy (cp, GLRO(dl_profile)), ".profile");
|
||
|
||
#ifdef O_NOFOLLOW
|
||
# define EXTRA_FLAGS | O_NOFOLLOW
|
||
#else
|
||
# define EXTRA_FLAGS
|
||
#endif
|
||
fd = __open (filename, O_RDWR | O_CREAT EXTRA_FLAGS, DEFFILEMODE);
|
||
if (fd == -1)
|
||
{
|
||
char buf[400];
|
||
int errnum;
|
||
|
||
/* We cannot write the profiling data so don't do anything. */
|
||
errstr = "%s: cannot open file: %s\n";
|
||
print_error:
|
||
errnum = errno;
|
||
if (fd != -1)
|
||
__close (fd);
|
||
_dl_error_printf (errstr, filename,
|
||
__strerror_r (errnum, buf, sizeof buf));
|
||
return;
|
||
}
|
||
|
||
if (__fxstat64 (_STAT_VER, fd, &st) < 0 || !S_ISREG (st.st_mode))
|
||
{
|
||
/* Not stat'able or not a regular file => don't use it. */
|
||
errstr = "%s: cannot stat file: %s\n";
|
||
goto print_error;
|
||
}
|
||
|
||
/* Test the size. If it does not match what we expect from the size
|
||
values in the map MAP we don't use it and warn the user. */
|
||
if (st.st_size == 0)
|
||
{
|
||
/* We have to create the file. */
|
||
char buf[GLRO(dl_pagesize)];
|
||
|
||
memset (buf, '\0', GLRO(dl_pagesize));
|
||
|
||
if (__lseek (fd, expected_size & ~(GLRO(dl_pagesize) - 1), SEEK_SET) == -1)
|
||
{
|
||
cannot_create:
|
||
errstr = "%s: cannot create file: %s\n";
|
||
goto print_error;
|
||
}
|
||
|
||
if (TEMP_FAILURE_RETRY (__libc_write (fd, buf, (expected_size
|
||
& (GLRO(dl_pagesize)
|
||
- 1))))
|
||
< 0)
|
||
goto cannot_create;
|
||
}
|
||
else if (st.st_size != expected_size)
|
||
{
|
||
__close (fd);
|
||
wrong_format:
|
||
|
||
if (addr != NULL)
|
||
__munmap ((void *) addr, expected_size);
|
||
|
||
_dl_error_printf ("%s: file is no correct profile data file for `%s'\n",
|
||
filename, GLRO(dl_profile));
|
||
return;
|
||
}
|
||
|
||
addr = (struct gmon_hdr *) __mmap (NULL, expected_size, PROT_READ|PROT_WRITE,
|
||
MAP_SHARED|MAP_FILE, fd, 0);
|
||
if (addr == (struct gmon_hdr *) MAP_FAILED)
|
||
{
|
||
errstr = "%s: cannot map file: %s\n";
|
||
goto print_error;
|
||
}
|
||
|
||
/* We don't need the file descriptor anymore. */
|
||
__close (fd);
|
||
|
||
/* Pointer to data after the header. */
|
||
hist = (char *) (addr + 1);
|
||
kcount = (uint16_t *) ((char *) hist + sizeof (uint32_t)
|
||
+ sizeof (struct gmon_hist_hdr));
|
||
|
||
/* Compute pointer to array of the arc information. */
|
||
narcsp = (uint32_t *) ((char *) kcount + kcountsize + sizeof (uint32_t));
|
||
data = (struct here_cg_arc_record *) ((char *) narcsp + sizeof (uint32_t));
|
||
|
||
if (st.st_size == 0)
|
||
{
|
||
/* Create the signature. */
|
||
memcpy (addr, &gmon_hdr, sizeof (struct gmon_hdr));
|
||
|
||
*(uint32_t *) hist = GMON_TAG_TIME_HIST;
|
||
memcpy (hist + sizeof (uint32_t), &hist_hdr,
|
||
sizeof (struct gmon_hist_hdr));
|
||
|
||
narcsp[-1] = GMON_TAG_CG_ARC;
|
||
}
|
||
else
|
||
{
|
||
/* Test the signature in the file. */
|
||
if (memcmp (addr, &gmon_hdr, sizeof (struct gmon_hdr)) != 0
|
||
|| *(uint32_t *) hist != GMON_TAG_TIME_HIST
|
||
|| memcmp (hist + sizeof (uint32_t), &hist_hdr,
|
||
sizeof (struct gmon_hist_hdr)) != 0
|
||
|| narcsp[-1] != GMON_TAG_CG_ARC)
|
||
goto wrong_format;
|
||
}
|
||
|
||
/* Allocate memory for the froms data and the pointer to the tos records. */
|
||
tos = (uint16_t *) calloc (tossize + fromssize, 1);
|
||
if (tos == NULL)
|
||
{
|
||
__munmap ((void *) addr, expected_size);
|
||
_dl_fatal_printf ("Out of memory while initializing profiler\n");
|
||
/* NOTREACHED */
|
||
}
|
||
|
||
froms = (struct here_fromstruct *) ((char *) tos + tossize);
|
||
fromidx = 0;
|
||
|
||
/* Now we have to process all the arc count entries. BTW: it is
|
||
not critical whether the *NARCSP value changes meanwhile. Before
|
||
we enter a new entry in to toset we will check that everything is
|
||
available in TOS. This happens in _dl_mcount.
|
||
|
||
Loading the entries in reverse order should help to get the most
|
||
frequently used entries at the front of the list. */
|
||
for (idx = narcs = MIN (*narcsp, fromlimit); idx > 0; )
|
||
{
|
||
size_t to_index;
|
||
size_t newfromidx;
|
||
--idx;
|
||
to_index = (data[idx].self_pc / (HASHFRACTION * sizeof (*tos)));
|
||
newfromidx = fromidx++;
|
||
froms[newfromidx].here = &data[idx];
|
||
froms[newfromidx].link = tos[to_index];
|
||
tos[to_index] = newfromidx;
|
||
}
|
||
|
||
/* Setup counting data. */
|
||
if (kcountsize < highpc - lowpc)
|
||
{
|
||
#if 0
|
||
s_scale = ((double) kcountsize / (highpc - lowpc)) * SCALE_1_TO_1;
|
||
#else
|
||
size_t range = highpc - lowpc;
|
||
size_t quot = range / kcountsize;
|
||
|
||
if (quot >= SCALE_1_TO_1)
|
||
s_scale = 1;
|
||
else if (quot >= SCALE_1_TO_1 / 256)
|
||
s_scale = SCALE_1_TO_1 / quot;
|
||
else if (range > ULONG_MAX / 256)
|
||
s_scale = (SCALE_1_TO_1 * 256) / (range / (kcountsize / 256));
|
||
else
|
||
s_scale = (SCALE_1_TO_1 * 256) / ((range * 256) / kcountsize);
|
||
#endif
|
||
}
|
||
else
|
||
s_scale = SCALE_1_TO_1;
|
||
|
||
/* Start the profiler. */
|
||
__profil ((void *) kcount, kcountsize, lowpc, s_scale);
|
||
|
||
/* Turn on profiling. */
|
||
running = 1;
|
||
}
|
||
|
||
|
||
void
|
||
_dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
|
||
{
|
||
volatile uint16_t *topcindex;
|
||
size_t i, fromindex;
|
||
struct here_fromstruct *fromp;
|
||
|
||
if (! running)
|
||
return;
|
||
|
||
/* Compute relative addresses. The shared object can be loaded at
|
||
any address. The value of frompc could be anything. We cannot
|
||
restrict it in any way, just set to a fixed value (0) in case it
|
||
is outside the allowed range. These calls show up as calls from
|
||
<external> in the gprof output. */
|
||
frompc -= lowpc;
|
||
if (frompc >= textsize)
|
||
frompc = 0;
|
||
selfpc -= lowpc;
|
||
if (selfpc >= textsize)
|
||
goto done;
|
||
|
||
/* Getting here we now have to find out whether the location was
|
||
already used. If yes we are lucky and only have to increment a
|
||
counter (this also has to be atomic). If the entry is new things
|
||
are getting complicated... */
|
||
|
||
/* Avoid integer divide if possible. */
|
||
if ((HASHFRACTION & (HASHFRACTION - 1)) == 0)
|
||
i = selfpc >> log_hashfraction;
|
||
else
|
||
i = selfpc / (HASHFRACTION * sizeof (*tos));
|
||
|
||
topcindex = &tos[i];
|
||
fromindex = *topcindex;
|
||
|
||
if (fromindex == 0)
|
||
goto check_new_or_add;
|
||
|
||
fromp = &froms[fromindex];
|
||
|
||
/* We have to look through the chain of arcs whether there is already
|
||
an entry for our arc. */
|
||
while (fromp->here->from_pc != frompc)
|
||
{
|
||
if (fromp->link != 0)
|
||
do
|
||
fromp = &froms[fromp->link];
|
||
while (fromp->link != 0 && fromp->here->from_pc != frompc);
|
||
|
||
if (fromp->here->from_pc != frompc)
|
||
{
|
||
topcindex = &fromp->link;
|
||
|
||
check_new_or_add:
|
||
/* Our entry is not among the entries we read so far from the
|
||
data file. Now see whether we have to update the list. */
|
||
while (narcs != *narcsp && narcs < fromlimit)
|
||
{
|
||
size_t to_index;
|
||
size_t newfromidx;
|
||
to_index = (data[narcs].self_pc
|
||
/ (HASHFRACTION * sizeof (*tos)));
|
||
newfromidx = catomic_exchange_and_add (&fromidx, 1) + 1;
|
||
froms[newfromidx].here = &data[narcs];
|
||
froms[newfromidx].link = tos[to_index];
|
||
tos[to_index] = newfromidx;
|
||
catomic_increment (&narcs);
|
||
}
|
||
|
||
/* If we still have no entry stop searching and insert. */
|
||
if (*topcindex == 0)
|
||
{
|
||
uint_fast32_t newarc = catomic_exchange_and_add (narcsp, 1);
|
||
|
||
/* In rare cases it could happen that all entries in FROMS are
|
||
occupied. So we cannot count this anymore. */
|
||
if (newarc >= fromlimit)
|
||
goto done;
|
||
|
||
*topcindex = catomic_exchange_and_add (&fromidx, 1) + 1;
|
||
fromp = &froms[*topcindex];
|
||
|
||
fromp->here = &data[newarc];
|
||
data[newarc].from_pc = frompc;
|
||
data[newarc].self_pc = selfpc;
|
||
data[newarc].count = 0;
|
||
fromp->link = 0;
|
||
catomic_increment (&narcs);
|
||
|
||
break;
|
||
}
|
||
|
||
fromp = &froms[*topcindex];
|
||
}
|
||
else
|
||
/* Found in. */
|
||
break;
|
||
}
|
||
|
||
/* Increment the counter. */
|
||
catomic_increment (&fromp->here->count);
|
||
|
||
done:
|
||
;
|
||
}
|
||
INTDEF(_dl_mcount)
|