PATCH[3/3 RFC] PERF, Add remapping support for jit'ed code to perf

[Carl Love]

This is a repost to LKML of the patches I sent to the linux-perf-users mailing list. 
I am reposting it to lkml per Arnaldo Carvalho's request.

The following is the jit library for the callbacks to capture the jit
code information.  This version is just for test purposes.  It causes
a remapping on each symbol load to test the perf map re-mapping code.
It shows how the remap messages are sent to the perf.data file.  I have
developed another version that only sends the remap requests when it is
really needed.  The purpose of this post is really to get feedback on
the proof of concept for adding the jit remap capability.

----------------------------------------------------------------------


/*
 * Agent library to collect jit code for the perf tool
 * 
 *
 *
 */

#include <stdio.h>
#include "/home/carll/JAVA_INCLUDES/include/jvmti.h"
#include "perf-jit-support.h"
#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>
#include <linux/prctl.h>
#include <fcntl.h>
#include <pthread.h>


#define TRUE  1
#define FALSE 0

/* This call back library is still under development.  The library inserts
 * a remap request after pr_count symbols have loaded.  This is just to force
 * remap requests to be sent to test the remapping in the perf code.
 *
 * This code will be updated to only send the remap request when the mapping
 * has changed to reuse an address range.  As long as new symbols do not use
 * an address range for a previously loaded and unloaded method no remap is 
 * required.  
 * 
 * This library is being submitted as is for the moment to show how the remap
 * requests are sent to perf.
 */

static int debug = TRUE;
static int symbol_count = 0, pr_count = 1;
static pthread_mutex_t perf_mutex = PTHREAD_MUTEX_INITIALIZER;
static FILE *perf_file = NULL;

/* flags for informatiion we can access */
static int source_file_name_avail = FALSE;

typedef void (*call_back) (int, int);

call_back back = NULL;

void set_callback_function(call_back back_arg) {
  back = back_arg;
}

void print_callback_function(void) {
  fprintf(stderr, " the call back function address is %p\n", back);
}

static int print_error(jvmtiError error, char const * msg)
{
  fprintf(stderr, "  %s:  err code %i\n", msg, error);
  fflush(stderr);
  return 0;

}


static void JNICALL
compiled_method_load_handler(jvmtiEnv * jvmti,
                             jmethodID method,
                             jint code_size,
                             void const * code_addr,
                             jint map_length,
                             jvmtiAddrLocationMap const * map,
                             void const * compile_info)
{

  jvmtiError rtn;
  jclass class_type;
  char * thread_ptr = NULL;
  char * class_signature_ptr = NULL;
  char * source_file_name = NULL;
  char * method_signature_ptr = NULL;
  char * method_name = NULL;

  char filename[20];
  char methodname[20];
  static FILE *perf_file_tmp;

  struct jit_data_st jit_data;
  struct sym_data_st sym_data, sym_data_array[200];

  int i, error;
  unsigned long zero = 0, size;

  if (debug)
    fprintf(stderr, "Called compiled_method_load_handler\n");

  rtn = (*jvmti)->GetMethodDeclaringClass(jvmti, method,
                                          &class_type);
  if (back == NULL) {
    fprintf(stderr, "call back function is NULL\n");
  } else {
    fprintf(stderr, "call back function is not NULL\n");
    back (1, 2);
  }

  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: GetMethodDeclaringClass() failed");
  }

  rtn = (*jvmti)->GetClassSignature(jvmti, class_type,
                                    &class_signature_ptr, NULL);
  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: GetClassSignature() failed");
    (*jvmti)->Deallocate(jvmti, (unsigned char *) class_signature_ptr);
  }

  rtn = (*jvmti)->GetMethodName(jvmti, method, &method_name,
                                &method_signature_ptr, NULL);
  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: GetMethodName() failed");
    (*jvmti)->Deallocate(jvmti, (unsigned char *) class_signature_ptr);
    (*jvmti)->Deallocate(jvmti, (unsigned char *) method_signature_ptr);
  }

  /* get additional info if available */
  if (source_file_name_avail == TRUE) {
    //    rtn = (*jvmti)->GetSourceFileName(jvmti, class_type,
    //                                &sym_data.source_code_filename);
    // Work on gathering the source code.  FIX
    ;
  }

  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: GetSourceFileName() failed");
    source_file_name_avail == FALSE;
  }

  strcpy(sym_data.method_name, method_name);
  sym_data.virtual_mem_addr = (uint64_t)(uintptr_t) code_addr;
  sym_data.code_size = code_size;

  if (debug) {
    fprintf(stderr, "PID = %d\n", getpid());
    fprintf(stderr, "compiled_method_load_handler: class_type = %p\n",
            class_type);
    fprintf(stderr, "class signature = %s, method name = %s\n",
            class_signature_ptr, sym_data.method_name);

    fprintf(stderr, "method_signature = %s\n", method_signature_ptr);

    if (source_file_name_avail == TRUE)
      fprintf(stderr, "source file name = %s\n",
              sym_data.source_code_filename);

    fprintf(stderr, "code address = %p, code size = %x\n",
            sym_data.virtual_mem_addr, sym_data.code_size);
    fprintf(stderr, "\n");
  }

  size = (unsigned long) sizeof(sym_data);


  /* check if the perf file is open */
  if (perf_file == NULL) {
    sprintf(filename, "/tmp/perf-%d.map", getpid());
    fprintf(stderr, "CARLL, symbol file %s\n", filename);

    perf_file = fopen(filename, "w");

    if (perf_file == NULL) {
      fprintf(stderr, "ERROR, could not open %s\n", filename);
    }
  }

  sym_data_array[symbol_count].virtual_mem_addr = sym_data.virtual_mem_addr;
  sym_data_array[symbol_count].code_size = sym_data.code_size;
  strcpy(sym_data_array[symbol_count].method_name, sym_data.method_name);
  printf("CARLL, here 3\n");
  fflush(stdout);
  
  printf("CARLL, source_file_name_avail = %d\n", source_file_name_avail);
  fflush(stdout);

  if (source_file_name_avail == TRUE) {
    ;  
  }

  pthread_mutex_lock(&perf_mutex);

  if ((symbol_count % pr_count == 0) && (symbol_count != 0)){
    fclose(perf_file);
    sprintf(filename, "/tmp/perf-%d-%d.map", getpid(),
            (symbol_count/pr_count));
    perf_file = fopen(filename, "w");

    if (perf_file == NULL) {
      fprintf(stderr, "ERROR, could not open %s\n", filename);
    } 

    /* Send notification to perf.data file saying remap has occured.  Do
     * this as soon as possible so samples will be correctly aligned to 
     * the old/new maps.
     */
    strcpy(jit_data.map_filename, filename);  
    jit_data.pid = getpid();
    jit_data.tid = getpid()+1;   // temporary hack, the gettid() isn't compiling
    //      jit_data.tid = gettid();  // gettid() UNDEFINED, FIX, hack for now

    error = prctl(PR_TASK_PERF_UEVENT, zero, size,
                  (unsigned long)(&jit_data),   zero);
    if (error)
      fprintf(stderr, "ERROR, perf remap with file = %s FALED\n", filename);
    
    for (i = 0; i <= symbol_count; i++) {
      fprintf(perf_file, "%llx %x %s\n",
              sym_data_array[i].virtual_mem_addr,
              sym_data_array[i].code_size,
              sym_data_array[i].method_name);
    }
    fflush(stdout);

  } else {
    fprintf(perf_file, "%llx %x %s\n",
            sym_data.virtual_mem_addr,
            sym_data.code_size,
            sym_data.method_name);
  }
  pthread_mutex_unlock(&perf_mutex);

  symbol_count++;
}

static void JNICALL
compiled_method_unload_handler(jvmtiEnv * jvmti_env,
                               jmethodID method,
                               void const * code_addr)
{
  if (debug)
    fprintf(stderr, "called compiled_method_unload_handler addr=%p\n",
            code_addr);
}



JNIEXPORT jint JNICALL
Agent_OnLoad(JavaVM * jvm, char * options, void * reserved)
{
  jint  rc;
  jvmtiEventCallbacks callbacks;
  jvmtiEnv * jvmti = NULL;
  jvmtiError rtn;
  jvmtiCapabilities capabilities;

  if (options) {
    /* check the passed options */
    if (strcmp("debug", options) == 0)
      debug = TRUE;
  }

  if (debug)
    fprintf(stderr, "Called Agent_OnLoad for libjvmti-perf\n");

  rc = (*jvm)->GetEnv(jvm, (void *)&jvmti, JVMTI_VERSION_1);

  if (rc != JNI_OK) {
    print_error(rtn, "Error: GetEnv failed");
    return -1;
  }

  /* setup capabilities */
  memset(&capabilities, '\0', sizeof(capabilities));
  capabilities.can_generate_compiled_method_load_events = 1;
  rtn = (*jvmti)->AddCapabilities(jvmti, &capabilities);

  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: AddCapabilities, can_generate_compiled_method_load_events failed");
    return -1;
  }

  capabilities.can_get_source_file_name = 1;
  rtn = (*jvmti)->AddCapabilities(jvmti, &capabilities);

  if (rtn == JVMTI_ERROR_NONE)
    source_file_name_avail = TRUE;

  if (debug) {
    fprintf(stderr, "Capabilities: \n");

    if (source_file_name_avail == TRUE)  
      fprintf(stderr, " get_source_file_name\n");

    fprintf(stderr, "\n\n");
  }
  /* setup callbacks to collect information needed by perf */
  memset(&callbacks, 0, sizeof(callbacks));
  callbacks.CompiledMethodLoad = compiled_method_load_handler;
  callbacks.CompiledMethodUnload = compiled_method_unload_handler;

  rtn = (*jvmti)->SetEventCallbacks(jvmti, &callbacks,
                                      sizeof(callbacks));

  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: SetEventCallbacks failed");
    return -1;
  }

  rtn = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
                                           JVMTI_EVENT_COMPILED_METHOD_LOAD,
                                           NULL);

  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: Enabling method load callback failed");
    return -1;
  }

  rtn = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
                                           JVMTI_EVENT_COMPILED_METHOD_UNLOAD,
                                           NULL);
  if (rtn != JVMTI_ERROR_NONE) {
    print_error(rtn, "Error: Enabling method unload callback failed");
    return -1;
  }

  return 0;  /* success */
}




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