JDK14/Java14源码在线阅读
/*
* Copyright (c) 2003, 2019, 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 <jni.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <elf.h>
#include <link.h>
#include "libproc_impl.h"
#include "ps_core_common.h"
#include "proc_service.h"
#include "salibelf.h"
// This file has the libproc implementation to read core files.
// For live processes, refer to ps_proc.c. Portions of this is adapted
// /modelled after Solaris libproc.so (in particular Pcore.c)
//---------------------------------------------------------------------------
// functions to handle map_info
// Order mappings based on virtual address. We use this function as the
// callback for sorting the array of map_info pointers.
static int core_cmp_mapping(const void *lhsp, const void *rhsp)
{
const map_info *lhs = *((const map_info **)lhsp);
const map_info *rhs = *((const map_info **)rhsp);
if (lhs->vaddr == rhs->vaddr) {
return (0);
}
return (lhs->vaddr < rhs->vaddr ? -1 : 1);
}
// we sort map_info by starting virtual address so that we can do
// binary search to read from an address.
static bool sort_map_array(struct ps_prochandle* ph) {
size_t num_maps = ph->core->num_maps;
map_info* map = ph->core->maps;
int i = 0;
// allocate map_array
map_info** array;
if ( (array = (map_info**) malloc(sizeof(map_info*) * num_maps)) == NULL) {
print_debug("can't allocate memory for map array\n");
return false;
}
// add maps to array
while (map) {
array[i] = map;
i++;
map = map->next;
}
// sort is called twice. If this is second time, clear map array
if (ph->core->map_array) {
free(ph->core->map_array);
}
ph->core->map_array = array;
// sort the map_info array by base virtual address.
qsort(ph->core->map_array, ph->core->num_maps, sizeof (map_info*),
core_cmp_mapping);
// print map
if (is_debug()) {
int j = 0;
print_debug("---- sorted virtual address map ----\n");
for (j = 0; j < ph->core->num_maps; j++) {
print_debug("base = 0x%lx\tsize = %zu\n", ph->core->map_array[j]->vaddr,
ph->core->map_array[j]->memsz);
}
}
return true;
}
#ifndef MIN
#define MIN(x, y) (((x) < (y))? (x): (y))
#endif
static bool core_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
ssize_t resid = size;
int page_size=sysconf(_SC_PAGE_SIZE);
while (resid != 0) {
map_info *mp = core_lookup(ph, addr);
uintptr_t mapoff;
ssize_t len, rem;
off_t off;
int fd;
if (mp == NULL) {
break; /* No mapping for this address */
}
fd = mp->fd;
mapoff = addr - mp->vaddr;
len = MIN(resid, mp->memsz - mapoff);
off = mp->offset + mapoff;
if ((len = pread(fd, buf, len, off)) <= 0) {
break;
}
resid -= len;
addr += len;
buf = (char *)buf + len;
// mappings always start at page boundary. But, may end in fractional
// page. fill zeros for possible fractional page at the end of a mapping.
rem = mp->memsz % page_size;
if (rem > 0) {
rem = page_size - rem;
len = MIN(resid, rem);
resid -= len;
addr += len;
// we are not assuming 'buf' to be zero initialized.
memset(buf, 0, len);
buf += len;
}
}
if (resid) {
print_debug("core read failed for %d byte(s) @ 0x%lx (%d more bytes)\n",
size, addr, resid);
return false;
} else {
return true;
}
}
// null implementation for write
static bool core_write_data(struct ps_prochandle* ph,
uintptr_t addr, const char *buf , size_t size) {
return false;
}
static bool core_get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id,
struct user_regs_struct* regs) {
// for core we have cached the lwp regs from NOTE section
thread_info* thr = ph->threads;
while (thr) {
if (thr->lwp_id == lwp_id) {
memcpy(regs, &thr->regs, sizeof(struct user_regs_struct));
return true;
}
thr = thr->next;
}
return false;
}
static ps_prochandle_ops core_ops = {
.release= core_release,
.p_pread= core_read_data,
.p_pwrite= core_write_data,
.get_lwp_regs= core_get_lwp_regs
};
// read regs and create thread from NT_PRSTATUS entries from core file
static bool core_handle_prstatus(struct ps_prochandle* ph, const char* buf, size_t nbytes) {
// we have to read prstatus_t from buf
// assert(nbytes == sizeof(prstaus_t), "size mismatch on prstatus_t");
prstatus_t* prstat = (prstatus_t*) buf;
thread_info* newthr;
print_debug("got integer regset for lwp %d\n", prstat->pr_pid);
if((newthr = add_thread_info(ph, prstat->pr_pid)) == NULL)
return false;
// copy regs
memcpy(&newthr->regs, prstat->pr_reg, sizeof(struct user_regs_struct));
if (is_debug()) {
print_debug("integer regset\n");
#ifdef i386
// print the regset
print_debug("\teax = 0x%x\n", newthr->regs.eax);
print_debug("\tebx = 0x%x\n", newthr->regs.ebx);
print_debug("\tecx = 0x%x\n", newthr->regs.ecx);
print_debug("\tedx = 0x%x\n", newthr->regs.edx);
print_debug("\tesp = 0x%x\n", newthr->regs.esp);
print_debug("\tebp = 0x%x\n", newthr->regs.ebp);
print_debug("\tesi = 0x%x\n", newthr->regs.esi);
print_debug("\tedi = 0x%x\n", newthr->regs.edi);
print_debug("\teip = 0x%x\n", newthr->regs.eip);
#endif
#if defined(amd64) || defined(x86_64)
// print the regset
print_debug("\tr15 = 0x%lx\n", newthr->regs.r15);
print_debug("\tr14 = 0x%lx\n", newthr->regs.r14);
print_debug("\tr13 = 0x%lx\n", newthr->regs.r13);
print_debug("\tr12 = 0x%lx\n", newthr->regs.r12);
print_debug("\trbp = 0x%lx\n", newthr->regs.rbp);
print_debug("\trbx = 0x%lx\n", newthr->regs.rbx);
print_debug("\tr11 = 0x%lx\n", newthr->regs.r11);
print_debug("\tr10 = 0x%lx\n", newthr->regs.r10);
print_debug("\tr9 = 0x%lx\n", newthr->regs.r9);
print_debug("\tr8 = 0x%lx\n", newthr->regs.r8);
print_debug("\trax = 0x%lx\n", newthr->regs.rax);
print_debug("\trcx = 0x%lx\n", newthr->regs.rcx);
print_debug("\trdx = 0x%lx\n", newthr->regs.rdx);
print_debug("\trsi = 0x%lx\n", newthr->regs.rsi);
print_debug("\trdi = 0x%lx\n", newthr->regs.rdi);
print_debug("\torig_rax = 0x%lx\n", newthr->regs.orig_rax);
print_debug("\trip = 0x%lx\n", newthr->regs.rip);
print_debug("\tcs = 0x%lx\n", newthr->regs.cs);
print_debug("\teflags = 0x%lx\n", newthr->regs.eflags);
print_debug("\trsp = 0x%lx\n", newthr->regs.rsp);
print_debug("\tss = 0x%lx\n", newthr->regs.ss);
print_debug("\tfs_base = 0x%lx\n", newthr->regs.fs_base);
print_debug("\tgs_base = 0x%lx\n", newthr->regs.gs_base);
print_debug("\tds = 0x%lx\n", newthr->regs.ds);
print_debug("\tes = 0x%lx\n", newthr->regs.es);
print_debug("\tfs = 0x%lx\n", newthr->regs.fs);
print_debug("\tgs = 0x%lx\n", newthr->regs.gs);
#endif
}
return true;
}
#define ROUNDUP(x, y) ((((x)+((y)-1))/(y))*(y))
// read NT_PRSTATUS entries from core NOTE segment
static bool core_handle_note(struct ps_prochandle* ph, ELF_PHDR* note_phdr) {
char* buf = NULL;
char* p = NULL;
size_t size = note_phdr->p_filesz;
// we are interested in just prstatus entries. we will ignore the rest.
// Advance the seek pointer to the start of the PT_NOTE data
if (lseek(ph->core->core_fd, note_phdr->p_offset, SEEK_SET) == (off_t)-1) {
print_debug("failed to lseek to PT_NOTE data\n");
return false;
}
// Now process the PT_NOTE structures. Each one is preceded by
// an Elf{32/64}_Nhdr structure describing its type and size.
if ( (buf = (char*) malloc(size)) == NULL) {
print_debug("can't allocate memory for reading core notes\n");
goto err;
}
// read notes into buffer
if (read(ph->core->core_fd, buf, size) != size) {
print_debug("failed to read notes, core file must have been truncated\n");
goto err;
}
p = buf;
while (p < buf + size) {
ELF_NHDR* notep = (ELF_NHDR*) p;
char* descdata = p + sizeof(ELF_NHDR) + ROUNDUP(notep->n_namesz, 4);
print_debug("Note header with n_type = %d and n_descsz = %u\n",
notep->n_type, notep->n_descsz);
if (notep->n_type == NT_PRSTATUS) {
if (core_handle_prstatus(ph, descdata, notep->n_descsz) != true) {
return false;
}
} else if (notep->n_type == NT_AUXV) {
// Get first segment from entry point
ELF_AUXV *auxv = (ELF_AUXV *)descdata;
while (auxv->a_type != AT_NULL) {
if (auxv->a_type == AT_ENTRY) {
// Set entry point address to address of dynamic section.
// We will adjust it in read_exec_segments().
ph->core->dynamic_addr = auxv->a_un.a_val;
break;
}
auxv++;
}
}
p = descdata + ROUNDUP(notep->n_descsz, 4);
}
free(buf);
return true;
err:
if (buf) free(buf);
return false;
}
// read all segments from core file
static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
int i = 0;
ELF_PHDR* phbuf = NULL;
ELF_PHDR* core_php = NULL;
if ((phbuf = read_program_header_table(ph->core->core_fd, core_ehdr)) == NULL)
return false;
/*
* Now iterate through the program headers in the core file.
* We're interested in two types of Phdrs: PT_NOTE (which
* contains a set of saved /proc structures), and PT_LOAD (which
* represents a memory mapping from the process's address space).
*
* Difference b/w Solaris PT_NOTE and Linux/BSD PT_NOTE:
*
* In Solaris there are two PT_NOTE segments the first PT_NOTE (if present)
* contains /proc structs in the pre-2.6 unstructured /proc format. the last
* PT_NOTE has data in new /proc format.
*
* In Solaris, there is only one pstatus (process status). pstatus contains
* integer register set among other stuff. For each LWP, we have one lwpstatus
* entry that has integer regset for that LWP.
*
* Linux threads are actually 'clone'd processes. To support core analysis
* of "multithreaded" process, Linux creates more than one pstatus (called
* "prstatus") entry in PT_NOTE. Each prstatus entry has integer regset for one
* "thread". Please refer to Linux kernel src file 'fs/binfmt_elf.c', in particular
* function "elf_core_dump".
*/
for (core_php = phbuf, i = 0; i < core_ehdr->e_phnum; i++) {
switch (core_php->p_type) {
case PT_NOTE:
if (core_handle_note(ph, core_php) != true) {
goto err;
}
break;
case PT_LOAD: {
if (core_php->p_filesz != 0) {
if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
}
break;
}
}
core_php++;
}
free(phbuf);
return true;
err:
free(phbuf);
return false;
}
// read segments of a shared object
static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* lib_ehdr, uintptr_t lib_base) {
int i = 0;
ELF_PHDR* phbuf;
ELF_PHDR* lib_php = NULL;
int page_size = sysconf(_SC_PAGE_SIZE);
if ((phbuf = read_program_header_table(lib_fd, lib_ehdr)) == NULL) {
return false;
}
// we want to process only PT_LOAD segments that are not writable.
// i.e., text segments. The read/write/exec (data) segments would
// have been already added from core file segments.
for (lib_php = phbuf, i = 0; i < lib_ehdr->e_phnum; i++) {
if ((lib_php->p_type == PT_LOAD) && !(lib_php->p_flags & PF_W) && (lib_php->p_filesz != 0)) {
uintptr_t target_vaddr = lib_php->p_vaddr + lib_base;
map_info *existing_map = core_lookup(ph, target_vaddr);
if (existing_map == NULL){
if (add_map_info(ph, lib_fd, lib_php->p_offset,
target_vaddr, lib_php->p_memsz) == NULL) {
goto err;
}
} else {
// Coredump stores value of p_memsz elf field
// rounded up to page boundary.
if ((existing_map->memsz != page_size) &&
(existing_map->fd != lib_fd) &&
(ROUNDUP(existing_map->memsz, page_size) != ROUNDUP(lib_php->p_memsz, page_size))) {
print_debug("address conflict @ 0x%lx (existing map size = %ld, size = %ld, flags = %d)\n",
target_vaddr, existing_map->memsz, lib_php->p_memsz, lib_php->p_flags);
goto err;
}
/* replace PT_LOAD segment with library segment */
print_debug("overwrote with new address mapping (memsz %ld -> %ld)\n",
existing_map->memsz, ROUNDUP(lib_php->p_memsz, page_size));
existing_map->fd = lib_fd;
existing_map->offset = lib_php->p_offset;
existing_map->memsz = ROUNDUP(lib_php->p_memsz, page_size);
}
}
lib_php++;
}
free(phbuf);
return true;
err:
free(phbuf);
return false;
}
// process segments from interpreter (ld.so or ld-linux.so)
static bool read_interp_segments(struct ps_prochandle* ph) {
ELF_EHDR interp_ehdr;
if (read_elf_header(ph->core->interp_fd, &interp_ehdr) != true) {
print_debug("interpreter is not a valid ELF file\n");
return false;
}
if (read_lib_segments(ph, ph->core->interp_fd, &interp_ehdr, ph->core->ld_base_addr) != true) {
print_debug("can't read segments of interpreter\n");
return false;
}
return true;
}
// process segments of a a.out
static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
int i = 0;
ELF_PHDR* phbuf = NULL;
ELF_PHDR* exec_php = NULL;
if ((phbuf = read_program_header_table(ph->core->exec_fd, exec_ehdr)) == NULL) {
return false;
}
for (exec_php = phbuf, i = 0; i < exec_ehdr->e_phnum; i++) {
switch (exec_php->p_type) {
// add mappings for PT_LOAD segments
case PT_LOAD: {
// add only non-writable segments of non-zero filesz
if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
}
break;
}
// read the interpreter and it's segments
case PT_INTERP: {
char interp_name[BUF_SIZE + 1];
// BUF_SIZE is PATH_MAX + NAME_MAX + 1.
if (exec_php->p_filesz > BUF_SIZE) {
goto err;
}
if (pread(ph->core->exec_fd, interp_name,
exec_php->p_filesz, exec_php->p_offset) != exec_php->p_filesz) {
print_debug("Unable to read in the ELF interpreter\n");
goto err;
}
interp_name[exec_php->p_filesz] = '\0';
print_debug("ELF interpreter %s\n", interp_name);
// read interpreter segments as well
if ((ph->core->interp_fd = pathmap_open(interp_name)) < 0) {
print_debug("can't open runtime loader\n");
goto err;
}
break;
}
// from PT_DYNAMIC we want to read address of first link_map addr
case PT_DYNAMIC: {
if (exec_ehdr->e_type == ET_EXEC) {
ph->core->dynamic_addr = exec_php->p_vaddr;
} else { // ET_DYN
// dynamic_addr has entry point of executable.
// Thus we should substract it.
ph->core->dynamic_addr += exec_php->p_vaddr - exec_ehdr->e_entry;
}
print_debug("address of _DYNAMIC is 0x%lx\n", ph->core->dynamic_addr);
break;
}
} // switch
exec_php++;
} // for
free(phbuf);
return true;
err:
free(phbuf);
return false;
}
#define FIRST_LINK_MAP_OFFSET offsetof(struct r_debug, r_map)
#define LD_BASE_OFFSET offsetof(struct r_debug, r_ldbase)
#define LINK_MAP_ADDR_OFFSET offsetof(struct link_map, l_addr)
#define LINK_MAP_NAME_OFFSET offsetof(struct link_map, l_name)
#define LINK_MAP_LD_OFFSET offsetof(struct link_map, l_ld)
#define LINK_MAP_NEXT_OFFSET offsetof(struct link_map, l_next)
#define INVALID_LOAD_ADDRESS -1L
#define ZERO_LOAD_ADDRESS 0x0L
// Calculate the load address of shared library
// on prelink-enabled environment.
//
// In case of GDB, it would be calculated by offset of link_map.l_ld
// and the address of .dynamic section.
// See GDB implementation: lm_addr_check @ solib-svr4.c
static uintptr_t calc_prelinked_load_address(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* elf_ehdr, uintptr_t link_map_addr) {
ELF_PHDR *phbuf;
uintptr_t lib_ld;
uintptr_t lib_dyn_addr = 0L;
uintptr_t load_addr;
int i;
phbuf = read_program_header_table(lib_fd, elf_ehdr);
if (phbuf == NULL) {
print_debug("can't read program header of shared object\n");
return INVALID_LOAD_ADDRESS;
}
// Get the address of .dynamic section from shared library.
for (i = 0; i < elf_ehdr->e_phnum; i++) {
if (phbuf[i].p_type == PT_DYNAMIC) {
lib_dyn_addr = phbuf[i].p_vaddr;
break;
}
}
free(phbuf);
if (ps_pdread(ph, (psaddr_t)link_map_addr + LINK_MAP_LD_OFFSET,
&lib_ld, sizeof(uintptr_t)) != PS_OK) {
print_debug("can't read address of dynamic section in shared object\n");
return INVALID_LOAD_ADDRESS;
}
// Return the load address which is calculated by the address of .dynamic
// and link_map.l_ld .
load_addr = lib_ld - lib_dyn_addr;
print_debug("lib_ld = 0x%lx, lib_dyn_addr = 0x%lx -> lib_base_diff = 0x%lx\n", lib_ld, lib_dyn_addr, load_addr);
return load_addr;
}
// read shared library info from runtime linker's data structures.
// This work is done by librtlb_db in Solaris
static bool read_shared_lib_info(struct ps_prochandle* ph) {
uintptr_t addr = ph->core->dynamic_addr;
uintptr_t debug_base;
uintptr_t first_link_map_addr;
uintptr_t ld_base_addr;
uintptr_t link_map_addr;
uintptr_t lib_base_diff;
uintptr_t lib_base;
uintptr_t lib_name_addr;
char lib_name[BUF_SIZE];
ELF_DYN dyn;
ELF_EHDR elf_ehdr;
int lib_fd;
// _DYNAMIC has information of the form
// [tag] [data] [tag] [data] .....
// Both tag and data are pointer sized.
// We look for dynamic info with DT_DEBUG. This has shared object info.
// refer to struct r_debug in link.h
dyn.d_tag = DT_NULL;
while (dyn.d_tag != DT_DEBUG) {
if (ps_pdread(ph, (psaddr_t) addr, &dyn, sizeof(ELF_DYN)) != PS_OK) {
print_debug("can't read debug info from _DYNAMIC\n");
return false;
}
addr += sizeof(ELF_DYN);
}
// we have got Dyn entry with DT_DEBUG
debug_base = dyn.d_un.d_ptr;
// at debug_base we have struct r_debug. This has first link map in r_map field
if (ps_pdread(ph, (psaddr_t) debug_base + FIRST_LINK_MAP_OFFSET,
&first_link_map_addr, sizeof(uintptr_t)) != PS_OK) {
print_debug("can't read first link map address\n");
return false;
}
// read ld_base address from struct r_debug
if (ps_pdread(ph, (psaddr_t) debug_base + LD_BASE_OFFSET, &ld_base_addr,
sizeof(uintptr_t)) != PS_OK) {
print_debug("can't read ld base address\n");
return false;
}
ph->core->ld_base_addr = ld_base_addr;
print_debug("interpreter base address is 0x%lx\n", ld_base_addr);
// now read segments from interp (i.e ld.so or ld-linux.so or ld-elf.so)
if (read_interp_segments(ph) != true) {
return false;
}
// after adding interpreter (ld.so) mappings sort again
if (sort_map_array(ph) != true) {
return false;
}
print_debug("first link map is at 0x%lx\n", first_link_map_addr);
link_map_addr = first_link_map_addr;
while (link_map_addr != 0) {
// read library base address of the .so. Note that even though <sys/link.h> calls
// link_map->l_addr as "base address", this is * not * really base virtual
// address of the shared object. This is actually the difference b/w the virtual
// address mentioned in shared object and the actual virtual base where runtime
// linker loaded it. We use "base diff" in read_lib_segments call below.
if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_ADDR_OFFSET,
&lib_base_diff, sizeof(uintptr_t)) != PS_OK) {
print_debug("can't read shared object base address diff\n");
return false;
}
// read address of the name
if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NAME_OFFSET,
&lib_name_addr, sizeof(uintptr_t)) != PS_OK) {
print_debug("can't read address of shared object name\n");
return false;
}
// read name of the shared object
lib_name[0] = '\0';
if (lib_name_addr != 0 &&
read_string(ph, (uintptr_t) lib_name_addr, lib_name, sizeof(lib_name)) != true) {
print_debug("can't read shared object name\n");
// don't let failure to read the name stop opening the file. If something is really wrong
// it will fail later.
}
if (lib_name[0] != '\0') {
// ignore empty lib names
lib_fd = pathmap_open(lib_name);
if (lib_fd < 0) {
print_debug("can't open shared object %s\n", lib_name);
// continue with other libraries...
} else {
if (read_elf_header(lib_fd, &elf_ehdr)) {
if (lib_base_diff == ZERO_LOAD_ADDRESS ) {
lib_base_diff = calc_prelinked_load_address(ph, lib_fd, &elf_ehdr, link_map_addr);
if (lib_base_diff == INVALID_LOAD_ADDRESS) {
close(lib_fd);
return false;
}
}
lib_base = lib_base_diff + find_base_address(lib_fd, &elf_ehdr);
print_debug("reading library %s @ 0x%lx [ 0x%lx ]\n",
lib_name, lib_base, lib_base_diff);
// while adding library mappings we need to use "base difference".
if (! read_lib_segments(ph, lib_fd, &elf_ehdr, lib_base_diff)) {
print_debug("can't read shared object's segments\n");
close(lib_fd);
return false;
}
add_lib_info_fd(ph, lib_name, lib_fd, lib_base);
// Map info is added for the library (lib_name) so
// we need to re-sort it before calling the p_pdread.
if (sort_map_array(ph) != true)
return false;
} else {
print_debug("can't read ELF header for shared object %s\n", lib_name);
close(lib_fd);
// continue with other libraries...
}
}
}
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