/*
* task_attach.c - example of how to attach to another task for monitoring
*
* Copyright (c) 2002-2006 Hewlett-Packard Development Company, L.P.
* Contributed by Stephane Eranian <eranian@hpl.hp.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <sys/types.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdarg.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <perfmon/pfmlib.h>
#include <perfmon/perfmon.h>
#include "detect_pmcs.h"
#define NUM_PMCS PFMLIB_MAX_PMCS
#define NUM_PMDS PFMLIB_MAX_PMDS
#define MAX_EVT_NAME_LEN 128
static void fatal_error(char *fmt,...) __attribute__((noreturn));
static void
fatal_error(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(1);
}
int
parent(pid_t pid)
{
pfmlib_input_param_t inp;
pfmlib_output_param_t outp;
pfarg_ctx_t ctx[1];
pfarg_pmc_t pc[NUM_PMCS];
pfarg_pmd_t pd[NUM_PMDS];
pfarg_load_t load_args;
pfarg_msg_t msg;
unsigned int i, num_counters;
int status, ret;
int ctx_fd;
char name[MAX_EVT_NAME_LEN];
memset(pc, 0, sizeof(pc));
memset(pd, 0, sizeof(pd));
memset(ctx, 0, sizeof(ctx));
memset(&inp,0, sizeof(inp));
memset(&outp,0, sizeof(outp));
memset(&load_args,0, sizeof(load_args));
pfm_get_num_counters(&num_counters);
if (pfm_get_cycle_event(&inp.pfp_events[0]) != PFMLIB_SUCCESS) {
fatal_error("cannot find cycle event\n");
}
if (pfm_get_inst_retired_event(&inp.pfp_events[1]) != PFMLIB_SUCCESS) {
fatal_error("cannot find inst retired event\n");
}
i = 2;
/*
* set the privilege mode:
* PFM_PLM3 : user level
* PFM_PLM0 : kernel level
*/
inp.pfp_dfl_plm = PFM_PLM3;
if (i > num_counters) {
i = num_counters;
printf("too many events provided (max=%d events), using first %d event(s)\n", num_counters, i);
}
/*
* how many counters we use
*/
inp.pfp_event_count = i;
/*
* now create a context. we will later attach it to the task we are creating.
*/
ctx_fd = pfm_create_context(ctx, NULL, NULL, 0);
if (ctx_fd == -1) {
if (errno == ENOSYS) {
fatal_error("Your kernel does not have performance monitoring support!\n");
}
fatal_error("Can't create PFM context %s\n", strerror(errno));
}
/*
* build the pfp_unavail_pmcs bitmask by looking
* at what perfmon has available. It is not always
* the case that all PMU registers are actually available
* to applications. For instance, on IA-32 platforms, some
* registers may be reserved for the NMI watchdog timer.
*
* With this bitmap, the library knows which registers NOT to
* use. Of source, it is possible that no valid assignement may
* be possible if certina PMU registers are not available.
*/
detect_unavail_pmcs(ctx_fd, &inp.pfp_unavail_pmcs);
/*
* let the library figure out the values for the PMCS
*/
if ((ret=pfm_dispatch_events(&inp, NULL, &outp, NULL)) != PFMLIB_SUCCESS) {
fatal_error("cannot configure events: %s\n", pfm_strerror(ret));
}
/*
* Now prepare the argument to initialize the PMDs and PMCS.
* We must pfp_pmc_count to determine the number of PMC to intialize.
* We must use pfp_event_count to determine the number of PMD to initialize.
* Some events causes extra PMCs to be used, so pfp_pmc_count may be >= pfp_event_count.
*
* This step is new compared to libpfm-2.x. It is necessary because the library no
* longer knows about the kernel data structures.
*/
for (i=0; i < outp.pfp_pmc_count; i++) {
pc[i].reg_num = outp.pfp_pmcs[i].reg_num;
pc[i].reg_value = outp.pfp_pmcs[i].reg_value;
}
for(i=0; i < outp.pfp_pmd_count; i++)
pd[i].reg_num = outp.pfp_pmds[i].reg_num;
/*
* Now program the registers
*
* We don't use the save variable to indicate the number of elements passed to
* the kernel because, as we said earlier, pc may contain more elements than
* the number of events we specified, i.e., contains more thann counting monitors.
*/
if (pfm_write_pmcs(ctx_fd, pc, outp.pfp_pmc_count) == -1)
fatal_error("pfm_write_pmcs error errno %d\n",errno);
/*
* To be read, each PMD must be either written or declared
* as being part of a sample (reg_smpl_pmds)
*/
if (pfm_write_pmds(ctx_fd, pd, outp.pfp_pmd_count) == -1)
fatal_error("pfm_write_pmds error errno %d\n",errno);
ret = ptrace(PTRACE_ATTACH, pid, NULL, 0);
if (ret == -1) {
fatal_error("cannot attach to %d: %s\n", pid, strerror(errno));
}
/*
* wait for the child to be actually stopped
*/
waitpid(pid, &status, WUNTRACED);
/*
* check if process exited early
*/
if (WIFEXITED(status)) {
fatal_error("command process %d exited too early with status %d\n", pid, WEXITSTATUS(status));
}
/*
* the task is stopped at this point
*/
/*
* now we load (i.e., attach) the context to ourself
*/
load_args.load_pid = pid;
if (pfm_load_context(ctx_fd, &load_args) == -1) {
fatal_error("pfm_load_context error errno %d\n",errno);
}
/*
* activate monitoring. The task is still STOPPED at this point. Monitoring
* will not take effect until the execution of the task is resumed.
*/
if (pfm_start(ctx_fd, NULL) == -1) {
fatal_error("pfm_start error errno %d\n",errno);
}
/*
* now resume execution of the task, effectively activating
* monitoring.
*/
ptrace(PTRACE_DETACH, pid, NULL, 0);
/*
* now the task is running
*/
/*
* We cannot simply do a waitpid() because we may be attaching to a process
* totally unrelated to our program. Instead we use a perfmon facility that
* notifies us when the monitoring task is exiting.
*
* When a task with a monitoring context attached to it exits, a PFM_MSG_END
* is generated. It can be retrieve with a simple read() on the context's descriptor.
*
* Another reason why you might return from the read is if there was a counter
* overflow, unlikely in this example.
*
* To measure only for short period of time, use select or poll with a timeout,
* see task_attach_timeout.c
*
*/
ret = read(ctx_fd, &msg, sizeof(msg));
if (ret == -1) {
fatal_error("cannot read from descriptor: %s\n", strerror(errno));
}
if (msg.type != PFM_MSG_END) {
fatal_error("unexpected msg type : %d\n", msg.type);
}
/*
* the task has exited, we can simply read the results
*/
/*
* now simply read the results.
*/
if (pfm_read_pmds(ctx_fd, pd, inp.pfp_event_count) == -1) {
fatal_error("pfm_read_pmds error errno %d\n",errno);
return -1;
}
/*
* print the results
*
* It is important to realize, that the first event we specified may not
* be in PMD4. Not all events can be measured by any monitor. That's why
* we need to use the pc[] array to figure out where event i was allocated.
*
*/
for (i=0; i < inp.pfp_event_count; i++) {
pfm_get_full_event_name(&inp.pfp_events[i], name, MAX_EVT_NAME_LEN);
printf("PMD%-3u %20"PRIu64" %s\n",
pd[i].reg_num,
pd[i].reg_value,
name);
}
/*
* free the context
*/
close(ctx_fd);
return 0;
}
int
main(int argc, char **argv)
{
pfmlib_options_t pfmlib_options;
pid_t pid;
int ret;
if (argc < 2) {
fatal_error("usage: %s pid\n", argv[0]);
}
pid = atoi(argv[1]);
/*
* pass options to library (optional)
*/
memset(&pfmlib_options, 0, sizeof(pfmlib_options));
pfmlib_options.pfm_debug = 0; /* set to 1 for debug */
pfm_set_options(&pfmlib_options);
/*
* Initialize pfm library (required before we can use it)
*/
ret = pfm_initialize();
if (ret != PFMLIB_SUCCESS)
fatal_error("Cannot initialize library: %s\n", pfm_strerror(ret));
return parent(pid);
}