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/*
* ELF-related support code, bitness-independent.
*/
/*
* Oracle Linux DTrace.
* Copyright (c) 2013, 2024, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
#include <sys/types.h>
#include <inttypes.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <elf.h>
#include <link.h>
#include <platform.h>
#ifndef NATIVE_BITNESS_ONLY
#define BITS 32
#include "elfish_impl.h"
#undef BITS
#endif
#define BITS 64
#include "elfish_impl.h"
#undef BITS
/*
* Determine ISA-related info about the ELF file, and stash it in the
* ps_prochandle.
*/
int
Pread_isa_info(struct ps_prochandle *P, const char *procname)
{
int fd, err;
Elf64_Ehdr hdr;
if ((fd = open(procname, O_RDONLY)) < 0) {
_dprintf("Cannot open %s: %s\n", procname, strerror(errno));
return -1;
}
while ((err = read(fd, &hdr, sizeof(hdr))) < 0 && errno == EINTR);
if (err < 0) {
_dprintf("%s is not an ELF file\n", procname);
close(fd);
return -1;
}
close(fd);
if (memcmp(&hdr, ELFMAG, SELFMAG) != 0) {
_dprintf("%s is not an ELF file\n", procname);
return -1;
}
P->elf64 = hdr.e_ident[EI_CLASS] == ELFCLASS64;
P->elf_machine = hdr.e_machine;
#ifdef NATIVE_BITNESS_ONLY
if (!P->elf64) {
_dprintf("%s: cannot trace 32-bit processes on this platform.\n",
procname);
return -1;
}
#endif
return 0;
}
/*
* Re-read the /proc/<pid>/auxv file and store its contents in P->auxv.
*/
void
Preadauxvec(struct ps_prochandle *P)
{
int auxv_size = P->elf64 ? sizeof(Elf64_auxv_t) : sizeof(Elf32_auxv_t);
char auxfile[PATH_MAX + MAXLEN_PID + strlen("/auxv") + 1];
ssize_t i;
int fd;
char buf[sizeof(Elf64_auxv_t)];
if (P->state == PS_DEAD)
return;
free(P->auxv);
P->auxv = NULL;
P->nauxv = 0;
snprintf(auxfile, sizeof(auxfile), "%s/%d/auxv", procfs_path,
(int)P->pid);
if ((fd = open(auxfile, O_RDONLY)) < 0) {
_dprintf("Cannot open auxiliary vector file %s: %s\n",
auxfile, strerror(errno));
return;
}
/*
* First, count the number of entries in auxv.
*
* We assume no short or interrupted reads in /proc (if < page size,
* anyway).
*/
errno = 0;
for (P->nauxv = 0; read(fd, buf, auxv_size) == auxv_size; P->nauxv++);
if ((errno != 0) || lseek(fd, 0, SEEK_SET) == -1) {
_dprintf("Error reading from auxv: %s\n", strerror(errno));
close(fd);
return;
}
_dprintf("%i: %u auxv entries.\n", P->pid, P->nauxv);
if ((P->auxv = malloc(P->nauxv * sizeof(auxv_t))) == NULL) {
_dprintf("Out of memory allocating aux vector\n");
close(fd);
return;
}
for (i = 0; i < P->nauxv && read(fd, buf, auxv_size) == auxv_size;
i++) {
if (P->elf64) {
Elf64_auxv_t *auxv = (Elf64_auxv_t *)buf;
P->auxv[i].a_type = auxv->a_type;
P->auxv[i].a_un.a_val = auxv->a_un.a_val;
} else {
Elf32_auxv_t *auxv = (Elf32_auxv_t *)buf;
P->auxv[i].a_type = auxv->a_type;
P->auxv[i].a_un.a_val = auxv->a_un.a_val;
}
}
close(fd);
}
/*
* Return a requested element from the process's aux vector.
* Return -1 on failure (this is adequate for our purposes).
*/
uint64_t
Pgetauxval(struct ps_prochandle *P, int type)
{
auxv_t *auxv;
ssize_t nauxv;
if (Pstate(P) == PS_DEAD)
return -1;
if (P->auxv == NULL)
Preadauxvec(P);
if (P->auxv == NULL)
return -1;
for (auxv = P->auxv, nauxv = P->nauxv;
nauxv > 0 && auxv->a_type != AT_NULL;
auxv++, nauxv--) {
if (auxv->a_type == type)
return auxv->a_un.a_val;
}
return -1;
}
uintptr_t
r_debug(struct ps_prochandle *P)
{
if (Pstate(P) == PS_DEAD)
return 0;
if (P->r_debug_addr)
return P->r_debug_addr;
if (P->elf64)
P->r_debug_addr = r_debug_elf64(P);
#ifndef NATIVE_BITNESS_ONLY
else
P->r_debug_addr = r_debug_elf32(P);
#endif
return P->r_debug_addr;
}
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