jdk8-mips64-public/hotspot: agent/src/os/linux/ps

agent/src/os/linux/ps_proc.c@2394a89e89f4 (annotated)

agent/src/os/linux/ps_proc.c

Wed, 13 Feb 2013 09:46:19 +0100

author: rbackman
date: Wed, 13 Feb 2013 09:46:19 +0100
changeset 4599: 2394a89e89f4
parent 2384: 0a8e0d4345b3
child 5797: f2512d89ad0c
permissions: -rw-r--r--

8008088: SA can hang the VM
Reviewed-by: mgronlun, sla, dholmes

 /*
  * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code 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 General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
 #include <errno.h>
 #include <sys/ptrace.h>
 #include "libproc_impl.h"
 #if defined(x86_64) && !defined(amd64)
 #define amd64 1
 #endif
 #ifndef __WALL
 #define __WALL          0x40000000  // Copied from /usr/include/linux/wait.h
 #endif
 // This file has the libproc implementation specific to live process
 // For core files, refer to ps_core.c
 static inline uintptr_t align(uintptr_t ptr, size_t size) {
   return (ptr & ~(size - 1));
 }
 // ---------------------------------------------
 // ptrace functions
 // ---------------------------------------------
 // read "size" bytes of data from "addr" within the target process.
 // unlike the standard ptrace() function, process_read_data() can handle
 // unaligned address - alignment check, if required, should be done
 // before calling process_read_data.
 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
   long rslt;
   size_t i, words;
   uintptr_t end_addr = addr + size;
   uintptr_t aligned_addr = align(addr, sizeof(long));
   if (aligned_addr != addr) {
     char *ptr = (char *)&rslt;
     errno = 0;
     rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
     if (errno) {
       print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
       return false;
     }
     for (; aligned_addr != addr; aligned_addr++, ptr++);
     for (; ((intptr_t)aligned_addr % sizeof(long)) && aligned_addr < end_addr;
         aligned_addr++)
        *(buf++) = *(ptr++);
   }
   words = (end_addr - aligned_addr) / sizeof(long);
   // assert((intptr_t)aligned_addr % sizeof(long) == 0);
   for (i = 0; i < words; i++) {
     errno = 0;
     rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
     if (errno) {
       print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
       return false;
     }
     *(long *)buf = rslt;
     buf += sizeof(long);
     aligned_addr += sizeof(long);
   }
   if (aligned_addr != end_addr) {
     char *ptr = (char *)&rslt;
     errno = 0;
     rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
     if (errno) {
       print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
       return false;
     }
     for (; aligned_addr != end_addr; aligned_addr++)
        *(buf++) = *(ptr++);
   }
   return true;
 }
 // null implementation for write
 static bool process_write_data(struct ps_prochandle* ph,
                              uintptr_t addr, const char *buf , size_t size) {
   return false;
 }
 // "user" should be a pointer to a user_regs_struct
 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct user_regs_struct *user) {
   // we have already attached to all thread 'pid's, just use ptrace call
   // to get regset now. Note that we don't cache regset upfront for processes.
 // Linux on x86 and sparc are different.  On x86 ptrace(PTRACE_GETREGS, ...)
 // uses pointer from 4th argument and ignores 3rd argument.  On sparc it uses
 // pointer from 3rd argument and ignores 4th argument
 #if defined(sparc) || defined(sparcv9)
 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data)
 #else
 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)
 #endif
 #if defined(_LP64) && defined(PTRACE_GETREGS64)
 #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
 #elif defined(PTRACE_GETREGS)
 #define PTRACE_GETREGS_REQ PTRACE_GETREGS
 #elif defined(PT_GETREGS)
 #define PTRACE_GETREGS_REQ PT_GETREGS
 #endif
 #ifdef PTRACE_GETREGS_REQ
  if (ptrace_getregs(PTRACE_GETREGS_REQ, pid, user, NULL) < 0) {
    print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
    return false;
  }
  return true;
 #else
  print_debug("ptrace(PTRACE_GETREGS, ...) not supported\n");
  return false;
 #endif
 }
 static bool ptrace_continue(pid_t pid, int signal) {
   // pass the signal to the process so we don't swallow it
   if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {
     print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);
     return false;
   }
   return true;
 }
 // waits until the ATTACH has stopped the process
 // by signal SIGSTOP
 static bool ptrace_waitpid(pid_t pid) {
   int ret;
   int status;
   while (true) {
     // Wait for debuggee to stop.
     ret = waitpid(pid, &status, 0);
     if (ret == -1 && errno == ECHILD) {
       // try cloned process.
       ret = waitpid(pid, &status, __WALL);
     }
     if (ret >= 0) {
       if (WIFSTOPPED(status)) {
         // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP
         // will still be pending and delivered when the process is DETACHED and the process
         // will go to sleep.
         if (WSTOPSIG(status) == SIGSTOP) {
           // Debuggee stopped by SIGSTOP.
           return true;
         }
         if (!ptrace_continue(pid, WSTOPSIG(status))) {
           print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));
           return false;
         }
       } else {
         print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);
         return false;
       }
     } else {
       switch (errno) {
         case EINTR:
           continue;
           break;
         case ECHILD:
           print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
           break;
         case EINVAL:
           print_debug("waitpid() failed. Invalid options argument.\n");
           break;
         default:
           print_debug("waitpid() failed. Unexpected error %d\n",errno);
           break;
       }
       return false;
     }
   }
 }
 // attach to a process/thread specified by "pid"
 static bool ptrace_attach(pid_t pid) {
   if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) {
     print_debug("ptrace(PTRACE_ATTACH, ..) failed for %d\n", pid);
     return false;
   } else {
     return ptrace_waitpid(pid);
   }
 }
 // -------------------------------------------------------
 // functions for obtaining library information
 // -------------------------------------------------------
 /*
  * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring
  * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_.
  * RETURN VALUE: total number of substrings (always <= _n_)
  * NOTE: string _str_ is modified if _delim_!=_new_delim_
  */
 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim)
 {
    int i;
    for(i = 0; i < n; i++) ptrs[i] = NULL;
    if (str == NULL || n < 1 ) return 0;
    i = 0;
    // skipping leading blanks
    while(*str&&*str==delim) str++;
    while(*str&&i<n){
      ptrs[i++] = str;
      while(*str&&*str!=delim) str++;
      while(*str&&*str==delim) *(str++) = new_delim;
    }
    return i;
 }
 /*
  * fgets without storing '\n' at the end of the string
  */
 static char * fgets_no_cr(char * buf, int n, FILE *fp)
 {
    char * rslt = fgets(buf, n, fp);
    if (rslt && buf && *buf){
        char *p = strchr(buf, '\0');
        if (*--p=='\n') *p='\0';
    }
    return rslt;
 }
 // callback for read_thread_info
 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
   return add_thread_info(ph, pthread_id, lwp_id) != NULL;
 }
 static bool read_lib_info(struct ps_prochandle* ph) {
   char fname[32];
   char buf[256];
   FILE *fp = NULL;
   sprintf(fname, "/proc/%d/maps", ph->pid);
   fp = fopen(fname, "r");
   if (fp == NULL) {
     print_debug("can't open /proc/%d/maps file\n", ph->pid);
     return false;
   }
   while(fgets_no_cr(buf, 256, fp)){
     char * word[6];
     int nwords = split_n_str(buf, 6, word, ' ', '\0');
     if (nwords > 5 && find_lib(ph, word[5]) == false) {
        intptr_t base;
        lib_info* lib;
 #ifdef _LP64
        sscanf(word[0], "%lx", &base);
 #else
        sscanf(word[0], "%x", &base);
 #endif
        if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL)
           continue; // ignore, add_lib_info prints error
        // we don't need to keep the library open, symtab is already
        // built. Only for core dump we need to keep the fd open.
        close(lib->fd);
        lib->fd = -1;
     }
   }
   fclose(fp);
   return true;
 }
 // detach a given pid
 static bool ptrace_detach(pid_t pid) {
   if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) {
     print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
     return false;
   } else {
     return true;
   }
 }
 // detach all pids of a ps_prochandle
 static void detach_all_pids(struct ps_prochandle* ph) {
   thread_info* thr = ph->threads;
   while (thr) {
      ptrace_detach(thr->lwp_id);
      thr = thr->next;
   }
 }
 static void process_cleanup(struct ps_prochandle* ph) {
   detach_all_pids(ph);
 }
 static ps_prochandle_ops process_ops = {
   .release=  process_cleanup,
   .p_pread=  process_read_data,
   .p_pwrite= process_write_data,
   .get_lwp_regs= process_get_lwp_regs
 };
 // attach to the process. One and only one exposed stuff
 struct ps_prochandle* Pgrab(pid_t pid) {
   struct ps_prochandle* ph = NULL;
   thread_info* thr = NULL;
   if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
      print_debug("can't allocate memory for ps_prochandle\n");
      return NULL;
   }
   if (ptrace_attach(pid) != true) {
      free(ph);
      return NULL;
   }
   // initialize ps_prochandle
   ph->pid = pid;
   // initialize vtable
   ph->ops = &process_ops;
   // read library info and symbol tables, must do this before attaching threads,
   // as the symbols in the pthread library will be used to figure out
   // the list of threads within the same process.
   read_lib_info(ph);
   // read thread info
   read_thread_info(ph, add_new_thread);
   // attach to the threads
   thr = ph->threads;
   while (thr) {
      // don't attach to the main thread again
      if (ph->pid != thr->lwp_id && ptrace_attach(thr->lwp_id) != true) {
         // even if one attach fails, we get return NULL
         Prelease(ph);
         return NULL;
      }
      thr = thr->next;
   }
   return ph;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

agent/src/os/linux/ps_proc.c@2394a89e89f4 (annotated)

agent/src/os/linux/ps_proc.c