// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/string.h>
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <err.h>
#include <jvmti.h>
#ifdef HAVE_JVMTI_CMLR
#include <jvmticmlr.h>
#endif
#include <limits.h>
#include "jvmti_agent.h"
static int has_line_numbers;
void *jvmti_agent;
static void print_error(jvmtiEnv *jvmti, const char *msg, jvmtiError ret)
{
char *err_msg = NULL;
jvmtiError err;
err = (*jvmti)->GetErrorName(jvmti, ret, &err_msg);
if (err == JVMTI_ERROR_NONE) {
warnx("%s failed with %s", msg, err_msg);
(*jvmti)->Deallocate(jvmti, (unsigned char *)err_msg);
} else {
warnx("%s failed with an unknown error %d", msg, ret);
}
}
#ifdef HAVE_JVMTI_CMLR
static jvmtiError
do_get_line_number(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
jvmti_line_info_t *tab)
{
jint i, nr_lines = 0;
jvmtiLineNumberEntry *loc_tab = NULL;
jvmtiError ret;
jint src_line = -1;
ret = (*jvmti)->GetLineNumberTable(jvmti, m, &nr_lines, &loc_tab);
if (ret == JVMTI_ERROR_ABSENT_INFORMATION || ret == JVMTI_ERROR_NATIVE_METHOD) {
/* No debug information for this method */
return ret;
} else if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetLineNumberTable", ret);
return ret;
}
for (i = 0; i < nr_lines && loc_tab[i].start_location <= bci; i++) {
src_line = i;
}
if (src_line != -1) {
tab->pc = (unsigned long)pc;
tab->line_number = loc_tab[src_line].line_number;
tab->discrim = 0; /* not yet used */
tab->methodID = m;
ret = JVMTI_ERROR_NONE;
} else {
ret = JVMTI_ERROR_ABSENT_INFORMATION;
}
(*jvmti)->Deallocate(jvmti, (unsigned char *)loc_tab);
return ret;
}
static jvmtiError
get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **tab, int *nr_lines)
{
const jvmtiCompiledMethodLoadRecordHeader *hdr;
jvmtiCompiledMethodLoadInlineRecord *rec;
PCStackInfo *c;
jint ret;
int nr_total = 0;
int i, lines_total = 0;
if (!(tab && nr_lines))
return JVMTI_ERROR_NULL_POINTER;
/*
* Phase 1 -- get the number of lines necessary
*/
for (hdr = compile_info; hdr != NULL; hdr = hdr->next) {
if (hdr->kind == JVMTI_CMLR_INLINE_INFO) {
rec = (jvmtiCompiledMethodLoadInlineRecord *)hdr;
nr_total += rec->numpcs;
}
}
if (nr_total == 0)
return JVMTI_ERROR_NOT_FOUND;
/*
* Phase 2 -- allocate big enough line table
*/
*tab = malloc(nr_total * sizeof(**tab));
if (!*tab)
return JVMTI_ERROR_OUT_OF_MEMORY;
for (hdr = compile_info; hdr != NULL; hdr = hdr->next) {
if (hdr->kind == JVMTI_CMLR_INLINE_INFO) {
rec = (jvmtiCompiledMethodLoadInlineRecord *)hdr;
for (i = 0; i < rec->numpcs; i++) {
c = rec->pcinfo + i;
/*
* c->methods is the stack of inlined method calls
* at c->pc. [0] is the leaf method. Caller frames
* are ignored at the moment.
*/
ret = do_get_line_number(jvmti, c->pc,
c->methods[0],
c->bcis[0],
*tab + lines_total);
if (ret == JVMTI_ERROR_NONE)
lines_total++;
}
}
}
*nr_lines = lines_total;
return JVMTI_ERROR_NONE;
}
#else /* HAVE_JVMTI_CMLR */
static jvmtiError
get_line_numbers(jvmtiEnv *jvmti __maybe_unused, const void *compile_info __maybe_unused,
jvmti_line_info_t **tab __maybe_unused, int *nr_lines __maybe_unused)
{
return JVMTI_ERROR_NONE;
}
#endif /* HAVE_JVMTI_CMLR */
static void
copy_class_filename(const char * class_sign, const char * file_name, char * result, size_t max_length)
{
/*
* Assume path name is class hierarchy, this is a common practice with Java programs
*/
if (*class_sign == 'L') {
int j, i = 0;
char *p = strrchr(class_sign, '/');
if (p) {
/* drop the 'L' prefix and copy up to the final '/' */
for (i = 0; i < (p - class_sign); i++)
result[i] = class_sign[i+1];
}
/*
* append file name, we use loops and not string ops to avoid modifying
* class_sign which is used later for the symbol name
*/
for (j = 0; i < (max_length - 1) && file_name && j < strlen(file_name); j++, i++)
result[i] = file_name[j];
result[i] = '\0';
} else {
/* fallback case */
strlcpy(result, file_name, max_length);
}
}
static jvmtiError
get_source_filename(jvmtiEnv *jvmti, jmethodID methodID, char ** buffer)
{
jvmtiError ret;
jclass decl_class;
char *file_name = NULL;
char *class_sign = NULL;
char fn[PATH_MAX];
size_t len;
ret = (*jvmti)->GetMethodDeclaringClass(jvmti, methodID, &decl_class);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetMethodDeclaringClass", ret);
return ret;
}
ret = (*jvmti)->GetSourceFileName(jvmti, decl_class, &file_name);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetSourceFileName", ret);
return ret;
}
ret = (*jvmti)->GetClassSignature(jvmti, decl_class, &class_sign, NULL);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetClassSignature", ret);
goto free_file_name_error;
}
copy_class_filename(class_sign, file_name, fn, PATH_MAX);
len = strlen(fn);
*buffer = malloc((len + 1) * sizeof(char));
if (!*buffer) {
print_error(jvmti, "GetClassSignature", ret);
ret = JVMTI_ERROR_OUT_OF_MEMORY;
goto free_class_sign_error;
}
strcpy(*buffer, fn);
ret = JVMTI_ERROR_NONE;
free_class_sign_error:
(*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
free_file_name_error:
(*jvmti)->Deallocate(jvmti, (unsigned char *)file_name);
return ret;
}
static jvmtiError
fill_source_filenames(jvmtiEnv *jvmti, int nr_lines,
const jvmti_line_info_t * line_tab,
char ** file_names)
{
int index;
jvmtiError ret;
for (index = 0; index < nr_lines; ++index) {
ret = get_source_filename(jvmti, line_tab[index].methodID, &(file_names[index]));
if (ret != JVMTI_ERROR_NONE)
return ret;
}
return JVMTI_ERROR_NONE;
}
static void JNICALL
compiled_method_load_cb(jvmtiEnv *jvmti,
jmethodID method,
jint code_size,
void const *code_addr,
jint map_length,
jvmtiAddrLocationMap const *map,
const void *compile_info)
{
jvmti_line_info_t *line_tab = NULL;
char ** line_file_names = NULL;
jclass decl_class;
char *class_sign = NULL;
char *func_name = NULL;
char *func_sign = NULL;
uint64_t addr = (uint64_t)(uintptr_t)code_addr;
jvmtiError ret;
int nr_lines = 0; /* in line_tab[] */
size_t len;
int output_debug_info = 0;
ret = (*jvmti)->GetMethodDeclaringClass(jvmti, method,
&decl_class);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetMethodDeclaringClass", ret);
return;
}
if (has_line_numbers && map && map_length) {
ret = get_line_numbers(jvmti, compile_info, &line_tab, &nr_lines);
if (ret != JVMTI_ERROR_NONE) {
if (ret != JVMTI_ERROR_NOT_FOUND) {
warnx("jvmti: cannot get line table for method");
}
nr_lines = 0;
} else if (nr_lines > 0) {
line_file_names = malloc(sizeof(char*) * nr_lines);
if (!line_file_names) {
warnx("jvmti: cannot allocate space for line table method names");
} else {
memset(line_file_names, 0, sizeof(char*) * nr_lines);
ret = fill_source_filenames(jvmti, nr_lines, line_tab, line_file_names);
if (ret != JVMTI_ERROR_NONE) {
warnx("jvmti: fill_source_filenames failed");
} else {
output_debug_info = 1;
}
}
}
}
ret = (*jvmti)->GetClassSignature(jvmti, decl_class,
&class_sign, NULL);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetClassSignature", ret);
goto error;
}
ret = (*jvmti)->GetMethodName(jvmti, method, &func_name,
&func_sign, NULL);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "GetMethodName", ret);
goto error;
}
/*
* write source line info record if we have it
*/
if (output_debug_info)
if (jvmti_write_debug_info(jvmti_agent, addr, nr_lines, line_tab, (const char * const *) line_file_names))
warnx("jvmti: write_debug_info() failed");
len = strlen(func_name) + strlen(class_sign) + strlen(func_sign) + 2;
{
char str[len];
snprintf(str, len, "%s%s%s", class_sign, func_name, func_sign);
if (jvmti_write_code(jvmti_agent, str, addr, code_addr, code_size))
warnx("jvmti: write_code() failed");
}
error:
(*jvmti)->Deallocate(jvmti, (unsigned char *)func_name);
(*jvmti)->Deallocate(jvmti, (unsigned char *)func_sign);
(*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
free(line_tab);
while (line_file_names && (nr_lines > 0)) {
if (line_file_names[nr_lines - 1]) {
free(line_file_names[nr_lines - 1]);
}
nr_lines -= 1;
}
free(line_file_names);
}
static void JNICALL
code_generated_cb(jvmtiEnv *jvmti,
char const *name,
void const *code_addr,
jint code_size)
{
uint64_t addr = (uint64_t)(unsigned long)code_addr;
int ret;
ret = jvmti_write_code(jvmti_agent, name, addr, code_addr, code_size);
if (ret)
warnx("jvmti: write_code() failed for code_generated");
}
JNIEXPORT jint JNICALL
Agent_OnLoad(JavaVM *jvm, char *options, void *reserved __maybe_unused)
{
jvmtiEventCallbacks cb;
jvmtiCapabilities caps1;
jvmtiJlocationFormat format;
jvmtiEnv *jvmti = NULL;
jint ret;
jvmti_agent = jvmti_open();
if (!jvmti_agent) {
warnx("jvmti: open_agent failed");
return -1;
}
/*
* Request a JVMTI interface version 1 environment
*/
ret = (*jvm)->GetEnv(jvm, (void *)&jvmti, JVMTI_VERSION_1);
if (ret != JNI_OK) {
warnx("jvmti: jvmti version 1 not supported");
return -1;
}
/*
* acquire method_load capability, we require it
* request line numbers (optional)
*/
memset(&caps1, 0, sizeof(caps1));
caps1.can_generate_compiled_method_load_events = 1;
ret = (*jvmti)->AddCapabilities(jvmti, &caps1);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "AddCapabilities", ret);
return -1;
}
ret = (*jvmti)->GetJLocationFormat(jvmti, &format);
if (ret == JVMTI_ERROR_NONE && format == JVMTI_JLOCATION_JVMBCI) {
memset(&caps1, 0, sizeof(caps1));
caps1.can_get_line_numbers = 1;
caps1.can_get_source_file_name = 1;
ret = (*jvmti)->AddCapabilities(jvmti, &caps1);
if (ret == JVMTI_ERROR_NONE)
has_line_numbers = 1;
} else if (ret != JVMTI_ERROR_NONE)
print_error(jvmti, "GetJLocationFormat", ret);
memset(&cb, 0, sizeof(cb));
cb.CompiledMethodLoad = compiled_method_load_cb;
cb.DynamicCodeGenerated = code_generated_cb;
ret = (*jvmti)->SetEventCallbacks(jvmti, &cb, sizeof(cb));
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "SetEventCallbacks", ret);
return -1;
}
ret = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_COMPILED_METHOD_LOAD, NULL);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "SetEventNotificationMode(METHOD_LOAD)", ret);
return -1;
}
ret = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
if (ret != JVMTI_ERROR_NONE) {
print_error(jvmti, "SetEventNotificationMode(CODE_GENERATED)", ret);
return -1;
}
return 0;
}
JNIEXPORT void JNICALL
Agent_OnUnload(JavaVM *jvm __maybe_unused)
{
int ret;
ret = jvmti_close(jvmti_agent);
if (ret)
errx(1, "Error: op_close_agent()");
}
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