/*
 * jvmti_agent.c: JVMTI agent interface
 *
 * Adapted from the Oprofile code in opagent.c:
 * This 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.
 *
 * This 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Copyright 2007 OProfile authors
 * Jens Wilke
 * Daniel Hansel
 * Copyright IBM Corporation 2007
 */
#include <sys/types.h>
#include <sys/stat.h> /* for mkdir() */
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <limits.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <sys/mman.h>
#include <syscall.h> /* for gettid() */
#include <err.h>
#include <linux/kernel.h>

#include "jvmti_agent.h"
#include "../util/jitdump.h"

#define JIT_LANG "java"

static char jit_path[PATH_MAX];
static void *marker_addr;

static inline pid_t gettid(void)
{
        return (pid_t)syscall(__NR_gettid);
}

static int get_e_machine(struct jitheader *hdr)
{
        ssize_t sret;
        char id[16];
        int fd, ret = -1;
        struct {
                uint16_t e_type;
                uint16_t e_machine;
        } info;

        fd = open("/proc/self/exe", O_RDONLY);
        if (fd == -1)
                return -1;

        sret = read(fd, id, sizeof(id));
        if (sret != sizeof(id))
                goto error;

        /* check ELF signature */
        if (id[0] != 0x7f || id[1] != 'E' || id[2] != 'L' || id[3] != 'F')
                goto error;

        sret = read(fd, &info, sizeof(info));
        if (sret != sizeof(info))
                goto error;

        hdr->elf_mach = info.e_machine;
        ret = 0;
error:
        close(fd);
        return ret;
}

static int use_arch_timestamp;

static inline uint64_t
get_arch_timestamp(void)
{
#if defined(__i386__) || defined(__x86_64__)
        unsigned int low, high;

        asm volatile("rdtsc" : "=a" (low), "=d" (high));

        return low | ((uint64_t)high) << 32;
#else
        return 0;
#endif
}

#define NSEC_PER_SEC    1000000000
static int perf_clk_id = CLOCK_MONOTONIC;

static inline uint64_t
timespec_to_ns(const struct timespec *ts)
{
        return ((uint64_t) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
}

static inline uint64_t
perf_get_timestamp(void)
{
        struct timespec ts;
        int ret;

        if (use_arch_timestamp)
                return get_arch_timestamp();

        ret = clock_gettime(perf_clk_id, &ts);
        if (ret)
                return 0;

        return timespec_to_ns(&ts);
}

static int
create_jit_cache_dir(void)
{
        char str[32];
        char *base, *p;
        struct tm tm;
        time_t t;
        int ret;

        time(&t);
        localtime_r(&t, &tm);

        base = getenv("JITDUMPDIR");
        if (!base)
                base = getenv("HOME");
        if (!base)
                base = ".";

        strftime(str, sizeof(str), JIT_LANG"-jit-%Y%m%d", &tm);

        ret = snprintf(jit_path, PATH_MAX, "%s/.debug/", base);
        if (ret >= PATH_MAX) {
                warnx("jvmti: cannot generate jit cache dir because %s/.debug/"
                        " is too long, please check the cwd, JITDUMPDIR, and"
                        " HOME variables", base);
                return -1;
        }
        ret = mkdir(jit_path, 0755);
        if (ret == -1) {
                if (errno != EEXIST) {
                        warn("jvmti: cannot create jit cache dir %s", jit_path);
                        return -1;
                }
        }

        ret = snprintf(jit_path, PATH_MAX, "%s/.debug/jit", base);
        if (ret >= PATH_MAX) {
                warnx("jvmti: cannot generate jit cache dir because"
                        " %s/.debug/jit is too long, please check the cwd,"
                        " JITDUMPDIR, and HOME variables", base);
                return -1;
        }
        ret = mkdir(jit_path, 0755);
        if (ret == -1) {
                if (errno != EEXIST) {
                        warn("jvmti: cannot create jit cache dir %s", jit_path);
                        return -1;
                }
        }

        ret = snprintf(jit_path, PATH_MAX, "%s/.debug/jit/%s.XXXXXXXX", base, str);
        if (ret >= PATH_MAX) {
                warnx("jvmti: cannot generate jit cache dir because"
                        " %s/.debug/jit/%s.XXXXXXXX is too long, please check"
                        " the cwd, JITDUMPDIR, and HOME variables",
                        base, str);
                return -1;
        }
        p = mkdtemp(jit_path);
        if (p != jit_path) {
                warn("jvmti: cannot create jit cache dir %s", jit_path);
                return -1;
        }

        return 0;
}

static int
perf_open_marker_file(int fd)
{
        long pgsz;

        pgsz = sysconf(_SC_PAGESIZE);
        if (pgsz == -1)
                return -1;

        /*
         * we mmap the jitdump to create an MMAP RECORD in perf.data file.
         * The mmap is captured either live (perf record running when we mmap)
         * or  in deferred mode, via /proc/PID/maps
         * the MMAP record is used as a marker of a jitdump file for more meta
         * data info about the jitted code. Perf report/annotate detect this
         * special filename and process the jitdump file.
         *
         * mapping must be PROT_EXEC to ensure it is captured by perf record
         * even when not using -d option
         */
        marker_addr = mmap(NULL, pgsz, PROT_READ|PROT_EXEC, MAP_PRIVATE, fd, 0);
        return (marker_addr == MAP_FAILED) ? -1 : 0;
}

static void
perf_close_marker_file(void)
{
        long pgsz;

        if (!marker_addr)
                return;

        pgsz = sysconf(_SC_PAGESIZE);
        if (pgsz == -1)
                return;

        munmap(marker_addr, pgsz);
}

static void
init_arch_timestamp(void)
{
        char *str = getenv("JITDUMP_USE_ARCH_TIMESTAMP");

        if (!str || !*str || !strcmp(str, "0"))
                return;

        use_arch_timestamp = 1;
}

void *jvmti_open(void)
{
        char dump_path[PATH_MAX];
        struct jitheader header;
        int fd, ret;
        FILE *fp;

        init_arch_timestamp();

        /*
         * check if clockid is supported
         */
        if (!perf_get_timestamp()) {
                if (use_arch_timestamp)
                        warnx("jvmti: arch timestamp not supported");
                else
                        warnx("jvmti: kernel does not support %d clock id", perf_clk_id);
        }

        memset(&header, 0, sizeof(header));

        /*
         * jitdump file dir
         */
        if (create_jit_cache_dir() < 0)
                return NULL;

        /*
         * jitdump file name
         */
        ret = snprintf(dump_path, PATH_MAX, "%s/jit-%i.dump", jit_path, getpid());
        if (ret >= PATH_MAX) {
                warnx("jvmti: cannot generate jitdump file full path because"
                        " %s/jit-%i.dump is too long, please check the cwd,"
                        " JITDUMPDIR, and HOME variables", jit_path, getpid());
                return NULL;
        }

        fd = open(dump_path, O_CREAT|O_TRUNC|O_RDWR, 0666);
        if (fd == -1)
                return NULL;

        /*
         * create perf.data maker for the jitdump file
         */
        if (perf_open_marker_file(fd)) {
                warnx("jvmti: failed to create marker file");
                return NULL;
        }

        fp = fdopen(fd, "w+");
        if (!fp) {
                warn("jvmti: cannot create %s", dump_path);
                close(fd);
                goto error;
        }

        warnx("jvmti: jitdump in %s", dump_path);

        if (get_e_machine(&header)) {
                warn("get_e_machine failed\n");
                goto error;
        }

        header.magic      = JITHEADER_MAGIC;
        header.version    = JITHEADER_VERSION;
        header.total_size = sizeof(header);
        header.pid        = getpid();

        header.timestamp = perf_get_timestamp();

        if (use_arch_timestamp)
                header.flags |= JITDUMP_FLAGS_ARCH_TIMESTAMP;

        if (!fwrite(&header, sizeof(header), 1, fp)) {
                warn("jvmti: cannot write dumpfile header");
                goto error;
        }
        return fp;
error:
        fclose(fp);
        return NULL;
}

int
jvmti_close(void *agent)
{
        struct jr_code_close rec;
        FILE *fp = agent;

        if (!fp) {
                warnx("jvmti: invalid fd in close_agent");
                return -1;
        }

        rec.p.id = JIT_CODE_CLOSE;
        rec.p.total_size = sizeof(rec);

        rec.p.timestamp = perf_get_timestamp();

        if (!fwrite(&rec, sizeof(rec), 1, fp))
                return -1;

        fclose(fp);

        fp = NULL;

        perf_close_marker_file();

        return 0;
}

int
jvmti_write_code(void *agent, char const *sym,
        uint64_t vma, void const *code, unsigned int const size)
{
        static int code_generation = 1;
        struct jr_code_load rec;
        size_t sym_len;
        FILE *fp = agent;
        int ret = -1;

        /* don't care about 0 length function, no samples */
        if (size == 0)
                return 0;

        if (!fp) {
                warnx("jvmti: invalid fd in write_native_code");
                return -1;
        }

        sym_len = strlen(sym) + 1;

        rec.p.id           = JIT_CODE_LOAD;
        rec.p.total_size   = sizeof(rec) + sym_len;
        rec.p.timestamp    = perf_get_timestamp();

        rec.code_size  = size;
        rec.vma        = vma;
        rec.code_addr  = vma;
        rec.pid        = getpid();
        rec.tid        = gettid();

        if (code)
                rec.p.total_size += size;

        /*
         * If JVM is multi-threaded, nultiple concurrent calls to agent
         * may be possible, so protect file writes
         */
        flockfile(fp);

        /*
         * get code index inside lock to avoid race condition
         */
        rec.code_index = code_generation++;

        ret = fwrite_unlocked(&rec, sizeof(rec), 1, fp);
        fwrite_unlocked(sym, sym_len, 1, fp);

        if (code)
                fwrite_unlocked(code, size, 1, fp);

        funlockfile(fp);

        ret = 0;

        return ret;
}

int
jvmti_write_debug_info(void *agent, uint64_t code,
    int nr_lines, jvmti_line_info_t *li,
    const char * const * file_names)
{
        struct jr_code_debug_info rec;
        size_t sret, len, size, flen = 0;
        uint64_t addr;
        FILE *fp = agent;
        int i;

        /*
         * no entry to write
         */
        if (!nr_lines)
                return 0;

        if (!fp) {
                warnx("jvmti: invalid fd in write_debug_info");
                return -1;
        }

        for (i = 0; i < nr_lines; ++i) {
            flen += strlen(file_names[i]) + 1;
        }

        rec.p.id        = JIT_CODE_DEBUG_INFO;
        size            = sizeof(rec);
        rec.p.timestamp = perf_get_timestamp();
        rec.code_addr   = (uint64_t)(uintptr_t)code;
        rec.nr_entry    = nr_lines;

        /*
         * on disk source line info layout:
         * uint64_t : addr
         * int      : line number
         * int      : column discriminator
         * file[]   : source file name
         */
        size += nr_lines * sizeof(struct debug_entry);
        size += flen;
        rec.p.total_size = size;

        /*
         * If JVM is multi-threaded, nultiple concurrent calls to agent
         * may be possible, so protect file writes
         */
        flockfile(fp);

        sret = fwrite_unlocked(&rec, sizeof(rec), 1, fp);
        if (sret != 1)
                goto error;

        for (i = 0; i < nr_lines; i++) {

                addr = (uint64_t)li[i].pc;
                len  = sizeof(addr);
                sret = fwrite_unlocked(&addr, len, 1, fp);
                if (sret != 1)
                        goto error;

                len  = sizeof(li[0].line_number);
                sret = fwrite_unlocked(&li[i].line_number, len, 1, fp);
                if (sret != 1)
                        goto error;

                len  = sizeof(li[0].discrim);
                sret = fwrite_unlocked(&li[i].discrim, len, 1, fp);
                if (sret != 1)
                        goto error;

                sret = fwrite_unlocked(file_names[i], strlen(file_names[i]) + 1, 1, fp);
                if (sret != 1)
                        goto error;
        }
        funlockfile(fp);
        return 0;
error:
        funlockfile(fp);
        return -1;
}