diff options
Diffstat (limited to 'linker/linker.c')
| -rw-r--r-- | linker/linker.c | 1761 |
1 files changed, 1761 insertions, 0 deletions
diff --git a/linker/linker.c b/linker/linker.c new file mode 100644 index 0000000..91435de --- /dev/null +++ b/linker/linker.c @@ -0,0 +1,1761 @@ +/* + * Copyright (C) 2008 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <linux/auxvec.h> + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <fcntl.h> +#include <errno.h> +#include <dlfcn.h> +#include <sys/stat.h> + +//#include <pthread.h> + +#include <sys/mman.h> + +#include <sys/atomics.h> + +/* special private C library header - see Android.mk */ +#include <bionic_tls.h> + +#include "linker.h" +#include "linker_debug.h" + +#include "ba.h" + +#define SO_MAX 64 + +/* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<< + * + * Do NOT use malloc() and friends or pthread_*() code here. + * Don't use printf() either; it's caused mysterious memory + * corruption in the past. + * The linker runs before we bring up libc and it's easiest + * to make sure it does not depend on any complex libc features + * + * open issues / todo: + * + * - should we do anything special for STB_WEAK symbols? + * - are we doing everything we should for ARM_COPY relocations? + * - cleaner error reporting + * - configuration for paths (LD_LIBRARY_PATH?) + * - after linking, set as much stuff as possible to READONLY + * and NOEXEC + * - linker hardcodes PAGE_SIZE and PAGE_MASK because the kernel + * headers provide versions that are negative... + * - allocate space for soinfo structs dynamically instead of + * having a hard limit (64) + * + * features to add someday: + * + * - dlopen() and friends + * +*/ + + +static int link_image(soinfo *si, unsigned wr_offset); + +static int socount = 0; +static soinfo sopool[SO_MAX]; +static soinfo *freelist = NULL; +static soinfo *solist = &libdl_info; +static soinfo *sonext = &libdl_info; + +int debug_verbosity; +static int pid; + +#if STATS +struct _link_stats linker_stats; +#endif + +#if COUNT_PAGES +unsigned bitmask[4096]; +#endif + +#ifndef PT_ARM_EXIDX +#define PT_ARM_EXIDX 0x70000001 /* .ARM.exidx segment */ +#endif + +/* + * This function is an empty stub where GDB locates a breakpoint to get notified + * about linker activity. + */ +extern void __attribute__((noinline)) rtld_db_dlactivity(void); + +extern void sched_yield(void); + +static struct r_debug _r_debug = {1, NULL, &rtld_db_dlactivity, + RT_CONSISTENT, 0}; +static struct link_map *r_debug_tail = 0; + +//static pthread_mutex_t _r_debug_lock = PTHREAD_MUTEX_INITIALIZER; + +static volatile int loader_lock = 0; + +static void insert_soinfo_into_debug_map(soinfo * info) +{ + struct link_map * map; + + /* Copy the necessary fields into the debug structure. + */ + map = &(info->linkmap); + map->l_addr = info->base; + map->l_name = (char*) info->name; + + /* Stick the new library at the end of the list. + * gdb tends to care more about libc than it does + * about leaf libraries, and ordering it this way + * reduces the back-and-forth over the wire. + */ + if (r_debug_tail) { + r_debug_tail->l_next = map; + map->l_prev = r_debug_tail; + map->l_next = 0; + } else { + _r_debug.r_map = map; + map->l_prev = 0; + map->l_next = 0; + } + r_debug_tail = map; +} + +void notify_gdb_of_load(soinfo * info) +{ + if (info->flags & FLAG_EXE) { + // GDB already knows about the main executable + return; + } + + /* yes, this is a little gross, but it does avoid + ** pulling in pthread_*() and at the moment we don't + ** dlopen() anything anyway + */ + while(__atomic_swap(1, &loader_lock) != 0) { + sched_yield(); + usleep(5000); + } + + _r_debug.r_state = RT_ADD; + rtld_db_dlactivity(); + + insert_soinfo_into_debug_map(info); + + _r_debug.r_state = RT_CONSISTENT; + rtld_db_dlactivity(); + + __atomic_swap(0, &loader_lock); +} + +void notify_gdb_of_libraries() +{ + _r_debug.r_state = RT_ADD; + rtld_db_dlactivity(); + _r_debug.r_state = RT_CONSISTENT; + rtld_db_dlactivity(); +} + +static soinfo *alloc_info(const char *name) +{ + soinfo *si; + + if(strlen(name) >= SOINFO_NAME_LEN) { + ERROR("%5d library name %s too long\n", pid, name); + return 0; + } + + /* The freelist is populated when we call free_info(), which in turn is + done only by dlclose(), which is not likely to be used. + */ + if (!freelist) { + if(socount == SO_MAX) { + ERROR("%5d too many libraries when loading %s\n", pid, name); + return NULL; + } + freelist = sopool + socount++; + freelist->next = NULL; + } + + si = freelist; + freelist = freelist->next; + + /* Make sure we get a clean block of soinfo */ + memset(si, 0, sizeof(soinfo)); + strcpy((char*) si->name, name); + sonext->next = si; + si->ba_index = -1; /* by default, prelinked */ + si->next = NULL; + si->refcount = 0; + sonext = si; + + TRACE("%5d name %s: allocated soinfo @ %p\n", pid, name, si); + return si; +} + +static void free_info(soinfo *si) +{ + soinfo *prev = NULL, *trav; + + TRACE("%5d name %s: freeing soinfo @ %p\n", pid, si->name, si); + + for(trav = solist; trav != NULL; trav = trav->next){ + if (trav == si) + break; + prev = trav; + } + if (trav == NULL) { + /* si was not ni solist */ + ERROR("%5d name %s is not in solist!\n", pid, si->name); + return; + } + + /* prev will never be NULL, because the first entry in solist is + always the static libdl_info. + */ + prev->next = si->next; + if (si == sonext) sonext = prev; + si->next = freelist; + freelist = si; +} + +#ifndef LINKER_TEXT_BASE +#error "linker's makefile must define LINKER_TEXT_BASE" +#endif +#ifndef LINKER_AREA_SIZE +#error "linker's makefile must define LINKER_AREA_SIZE" +#endif +#define LINKER_BASE ((LINKER_TEXT_BASE) & 0xfff00000) +#define LINKER_TOP (LINKER_BASE + (LINKER_AREA_SIZE)) + +const char *addr_to_name(unsigned addr) +{ + soinfo *si; + + for(si = solist; si != 0; si = si->next){ + if((addr >= si->base) && (addr < (si->base + si->size))) { + return si->name; + } + } + + if((addr >= LINKER_BASE) && (addr < LINKER_TOP)){ + return "linker"; + } + + return ""; +} + +/* For a given PC, find the .so that it belongs to. + * Returns the base address of the .ARM.exidx section + * for that .so, and the number of 8-byte entries + * in that section (via *pcount). + * + * Intended to be called by libc's __gnu_Unwind_Find_exidx(). + * + * This function is exposed via dlfcn.c and libdl.so. + */ +#ifdef ANDROID_ARM_LINKER +_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int *pcount) +{ + soinfo *si; + unsigned addr = (unsigned)pc; + + if ((addr < LINKER_BASE) || (addr >= LINKER_TOP)) { + for (si = solist; si != 0; si = si->next){ + if ((addr >= si->base) && (addr < (si->base + si->size))) { + *pcount = si->ARM_exidx_count; + return (_Unwind_Ptr)(si->base + (unsigned long)si->ARM_exidx); + } + } + } + *pcount = 0; + return NULL; +} +#elif defined(ANDROID_X86_LINKER) +/* Here, we only have to provide a callback to iterate across all the + * loaded libraries. gcc_eh does the rest. */ +int +dl_iterate_phdr(int (*cb)(struct dl_phdr_info *info, size_t size, void *data), + void *data) +{ + soinfo *si; + struct dl_phdr_info dl_info; + int rv = 0; + + for (si = solist; si != NULL; si = si->next) { + dl_info.dlpi_addr = si->linkmap.l_addr; + dl_info.dlpi_name = si->linkmap.l_name; + dl_info.dlpi_phdr = si->phdr; + dl_info.dlpi_phnum = si->phnum; + rv = cb(&dl_info, sizeof (struct dl_phdr_info), data); + if (rv != 0) + break; + } + return rv; +} +#endif + +static Elf32_Sym *_elf_lookup(soinfo *si, unsigned hash, const char *name) +{ + Elf32_Sym *s; + Elf32_Sym *symtab = si->symtab; + const char *strtab = si->strtab; + unsigned n; + + TRACE_TYPE(LOOKUP, "%5d SEARCH %s in %s@0x%08x %08x %d\n", pid, + name, si->name, si->base, hash, hash % si->nbucket); + n = hash % si->nbucket; + + for(n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]){ + s = symtab + n; + if(strcmp(strtab + s->st_name, name)) continue; + + /* only concern ourselves with global symbols */ + switch(ELF32_ST_BIND(s->st_info)){ + case STB_GLOBAL: + /* no section == undefined */ + if(s->st_shndx == 0) continue; + + case STB_WEAK: + TRACE_TYPE(LOOKUP, "%5d FOUND %s in %s (%08x) %d\n", pid, + name, si->name, s->st_value, s->st_size); + return s; + } + } + + return 0; +} + +static unsigned elfhash(const char *_name) +{ + const unsigned char *name = (const unsigned char *) _name; + unsigned h = 0, g; + + while(*name) { + h = (h << 4) + *name++; + g = h & 0xf0000000; + h ^= g; + h ^= g >> 24; + } + return h; +} + +static Elf32_Sym * +_do_lookup_in_so(soinfo *si, const char *name, unsigned *elf_hash) +{ + if (*elf_hash == 0) + *elf_hash = elfhash(name); + return _elf_lookup (si, *elf_hash, name); +} + +/* This is used by dl_sym() */ +Elf32_Sym *lookup_in_library(soinfo *si, const char *name) +{ + unsigned unused = 0; + return _do_lookup_in_so(si, name, &unused); +} + +static Elf32_Sym * +_do_lookup(soinfo *user_si, const char *name, unsigned *base) +{ + unsigned elf_hash = 0; + Elf32_Sym *s = NULL; + soinfo *si; + + /* Look for symbols in the local scope first (the object who is + * searching). This happens with C++ templates on i386 for some + * reason. */ + if (user_si) { + s = _do_lookup_in_so(user_si, name, &elf_hash); + if (s != NULL) + *base = user_si->base; + } + + for(si = solist; (s == NULL) && (si != NULL); si = si->next) + { + if((si->flags & FLAG_ERROR) || (si == user_si)) + continue; + s = _do_lookup_in_so(si, name, &elf_hash); + if (s != NULL) { + *base = si->base; + break; + } + } + + if (s != NULL) { + TRACE_TYPE(LOOKUP, "%5d %s s->st_value = 0x%08x, " + "si->base = 0x%08x\n", pid, name, s->st_value, si->base); + return s; + } + + return 0; +} + +/* This is used by dl_sym() */ +Elf32_Sym *lookup(const char *name, unsigned *base) +{ + return _do_lookup(NULL, name, base); +} + +#if 0 +static void dump(soinfo *si) +{ + Elf32_Sym *s = si->symtab; + unsigned n; + + for(n = 0; n < si->nchain; n++) { + TRACE("%5d %04d> %08x: %02x %04x %08x %08x %s\n", pid, n, s, + s->st_info, s->st_shndx, s->st_value, s->st_size, + si->strtab + s->st_name); + s++; + } +} +#endif + +static const char *sopaths[] = { + "/system/lib", + "/lib", + 0 +}; + +static int _open_lib(const char *name) +{ + int fd; + struct stat filestat; + + if ((stat(name, &filestat) >= 0) && S_ISREG(filestat.st_mode)) { + if ((fd = open(name, O_RDONLY)) >= 0) + return fd; + } + + return -1; +} + +/* TODO: Need to add support for initializing the so search path with + * LD_LIBRARY_PATH env variable for non-setuid programs. */ +static int open_library(const char *name) +{ + int fd; + char buf[512]; + const char **path; + + TRACE("[ %5d opening %s ]\n", pid, name); + + if(name == 0) return -1; + if(strlen(name) > 256) return -1; + + if ((name[0] == '/') && ((fd = _open_lib(name)) >= 0)) + return fd; + + for (path = sopaths; *path; path++) { + snprintf(buf, sizeof(buf), "%s/%s", *path, name); + if ((fd = _open_lib(buf)) >= 0) + return fd; + } + + return -1; +} + +/* temporary space for holding the first page of the shared lib + * which contains the elf header (with the pht). */ +static unsigned char __header[PAGE_SIZE]; + +typedef struct { + long mmap_addr; + char tag[4]; /* 'P', 'R', 'E', ' ' */ +} prelink_info_t; + +/* Returns the requested base address if the library is prelinked, + * and 0 otherwise. */ +static unsigned long +is_prelinked(int fd, const char *name) +{ + off_t sz; + prelink_info_t info; + + sz = lseek(fd, -sizeof(prelink_info_t), SEEK_END); + if (sz < 0) { + ERROR("lseek() failed!\n"); + return 0; + } + + if (read(fd, &info, sizeof(info)) != sizeof(info)) { + WARN("Could not read prelink_info_t structure for `%s`\n", name); + return 0; + } + + if (strncmp(info.tag, "PRE ", 4)) { + WARN("`%s` is not a prelinked library\n", name); + return 0; + } + + return (unsigned long)info.mmap_addr; +} + +/* verify_elf_object + * Verifies if the object @ base is a valid ELF object + * + * Args: + * + * Returns: + * 0 on success + * -1 if no valid ELF object is found @ base. + */ +static int +verify_elf_object(void *base, const char *name) +{ + Elf32_Ehdr *hdr = (Elf32_Ehdr *) base; + + if (hdr->e_ident[EI_MAG0] != ELFMAG0) return -1; + if (hdr->e_ident[EI_MAG1] != ELFMAG1) return -1; + if (hdr->e_ident[EI_MAG2] != ELFMAG2) return -1; + if (hdr->e_ident[EI_MAG3] != ELFMAG3) return -1; + + /* TODO: Should we verify anything else in the header? */ + + return 0; +} + + +/* get_lib_extents + * Retrieves the base (*base) address where the ELF object should be + * mapped and its overall memory size (*total_sz). + * + * Args: + * fd: Opened file descriptor for the library + * name: The name of the library + * _hdr: Pointer to the header page of the library + * total_sz: Total size of the memory that should be allocated for + * this library + * + * Returns: + * -1 if there was an error while trying to get the lib extents. + * The possible reasons are: + * - Could not determine if the library was prelinked. + * - The library provided is not a valid ELF object + * 0 if the library did not request a specific base offset (normal + * for non-prelinked libs) + * > 0 if the library requests a specific address to be mapped to. + * This indicates a pre-linked library. + */ +static unsigned +get_lib_extents(int fd, const char *name, void *__hdr, unsigned *total_sz) +{ + unsigned req_base; + unsigned min_vaddr = 0xffffffff; + unsigned max_vaddr = 0; + unsigned char *_hdr = (unsigned char *)__hdr; + Elf32_Ehdr *ehdr = (Elf32_Ehdr *)_hdr; + Elf32_Phdr *phdr; + int cnt; + + TRACE("[ %5d Computing extents for '%s'. ]\n", pid, name); + if (verify_elf_object(_hdr, name) < 0) { + ERROR("%5d - %s is not a valid ELF object\n", pid, name); + return (unsigned)-1; + } + + req_base = (unsigned) is_prelinked(fd, name); + if (req_base == (unsigned)-1) + return -1; + else if (req_base != 0) { + TRACE("[ %5d - Prelinked library '%s' requesting base @ 0x%08x ]\n", + pid, name, req_base); + } else { + TRACE("[ %5d - Non-prelinked library '%s' found. ]\n", pid, name); + } + + phdr = (Elf32_Phdr *)(_hdr + ehdr->e_phoff); + + /* find the min/max p_vaddrs from all the PT_LOAD segments so we can + * get the range. */ + for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) { + if (phdr->p_type == PT_LOAD) { + if ((phdr->p_vaddr + phdr->p_memsz) > max_vaddr) + max_vaddr = phdr->p_vaddr + phdr->p_memsz; + if (phdr->p_vaddr < min_vaddr) + min_vaddr = phdr->p_vaddr; + } + } + + if ((min_vaddr == 0xffffffff) && (max_vaddr == 0)) { + ERROR("%5d - No loadable segments found in %s.\n", pid, name); + return (unsigned)-1; + } + + /* truncate min_vaddr down to page boundary */ + min_vaddr &= ~PAGE_MASK; + + /* round max_vaddr up to the next page */ + max_vaddr = (max_vaddr + PAGE_SIZE - 1) & ~PAGE_MASK; + + *total_sz = (max_vaddr - min_vaddr); + return (unsigned)req_base; +} + +/* alloc_mem_region + * + * This function reserves a chunk of memory to be used for mapping in + * the shared library. We reserve the entire memory region here, and + * then the rest of the linker will relocate the individual loadable + * segments into the correct locations within this memory range. + * + * Args: + * si->base: The requested base of the allocation. If 0, a sane one will be + * chosen in the range LIBBASE <= base < LIBLAST. + * si->size: The size of the allocation. + * + * Returns: + * -1 on failure, and 0 on success. On success, si->base will contain + * the virtual address at which the library will be mapped. + */ + +static int reserve_mem_region(soinfo *si) +{ + void *base = mmap((void *)si->base, si->size, PROT_READ | PROT_EXEC, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (base == MAP_FAILED) { + ERROR("%5d can NOT map (%sprelinked) library '%s' at 0x%08x " + "as requested, will try general pool: %d (%s)\n", + pid, (si->base ? "" : "non-"), si->name, si->base, + errno, strerror(errno)); + return -1; + } else if (base != (void *)si->base) { + ERROR("OOPS: %5d %sprelinked library '%s' mapped at 0x%08x, " + "not at 0x%08x\n", pid, (si->base ? "" : "non-"), + si->name, (unsigned)base, si->base); + munmap(base, si->size); + return -1; + } + return 0; +} + +static int +alloc_mem_region(soinfo *si) +{ + if (si->base) { + /* Attempt to mmap a prelinked library. */ + si->ba_index = -1; + return reserve_mem_region(si); + } + + /* This is not a prelinked library, so we attempt to allocate space + for it from the buddy allocator, which manages the area between + LIBBASE and LIBLAST. + */ + si->ba_index = ba_allocate(si->size); + if(si->ba_index >= 0) { + si->base = ba_start_addr(si->ba_index); + PRINT("%5d mapping library '%s' at %08x (index %d) " \ + "through buddy allocator.\n", + pid, si->name, si->base, si->ba_index); + if (reserve_mem_region(si) < 0) { + ba_free(si->ba_index); + si->ba_index = -1; + si->base = 0; + goto err; + } + return 0; + } + +err: + ERROR("OOPS: %5d cannot map library '%s'. no vspace available.\n", + pid, si->name); + return -1; +} + +#define MAYBE_MAP_FLAG(x,from,to) (((x) & (from)) ? (to) : 0) +#define PFLAGS_TO_PROT(x) (MAYBE_MAP_FLAG((x), PF_X, PROT_EXEC) | \ + MAYBE_MAP_FLAG((x), PF_R, PROT_READ) | \ + MAYBE_MAP_FLAG((x), PF_W, PROT_WRITE)) +/* load_segments + * + * This function loads all the loadable (PT_LOAD) segments into memory + * at their appropriate memory offsets off the base address. + * + * Args: + * fd: Open file descriptor to the library to load. + * header: Pointer to a header page that contains the ELF header. + * This is needed since we haven't mapped in the real file yet. + * si: ptr to soinfo struct describing the shared object. + * + * Returns: + * 0 on success, -1 on failure. + */ +static int +load_segments(int fd, void *header, soinfo *si) +{ + Elf32_Ehdr *ehdr = (Elf32_Ehdr *)header; + Elf32_Phdr *phdr = (Elf32_Phdr *)((unsigned char *)header + ehdr->e_phoff); + unsigned char *base = (unsigned char *)si->base; + int cnt; + unsigned len; + unsigned char *tmp; + unsigned char *pbase; + unsigned char *extra_base; + unsigned extra_len; + unsigned total_sz = 0; + + si->wrprotect_start = 0xffffffff; + si->wrprotect_end = 0; + + TRACE("[ %5d - Begin loading segments for '%s' @ 0x%08x ]\n", + pid, si->name, (unsigned)si->base); + /* Now go through all the PT_LOAD segments and map them into memory + * at the appropriate locations. */ + for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) { + if (phdr->p_type == PT_LOAD) { + DEBUG_DUMP_PHDR(phdr, "PT_LOAD", pid); + /* we want to map in the segment on a page boundary */ + tmp = base + (phdr->p_vaddr & (~PAGE_MASK)); + /* add the # of bytes we masked off above to the total length. */ + len = phdr->p_filesz + (phdr->p_vaddr & PAGE_MASK); + + TRACE("[ %d - Trying to load segment from '%s' @ 0x%08x " + "(0x%08x). p_vaddr=0x%08x p_offset=0x%08x ]\n", pid, si->name, + (unsigned)tmp, len, phdr->p_vaddr, phdr->p_offset); + pbase = mmap(tmp, len, PFLAGS_TO_PROT(phdr->p_flags), + MAP_PRIVATE | MAP_FIXED, fd, + phdr->p_offset & (~PAGE_MASK)); + if (pbase == MAP_FAILED) { + ERROR("%d failed to map segment from '%s' @ 0x%08x (0x%08x). " + "p_vaddr=0x%08x p_offset=0x%08x\n", pid, si->name, + (unsigned)tmp, len, phdr->p_vaddr, phdr->p_offset); + goto fail; + } + + /* If 'len' didn't end on page boundary, and it's a writable + * segment, zero-fill the rest. */ + if ((len & PAGE_MASK) && (phdr->p_flags & PF_W)) + memset((void *)(pbase + len), 0, PAGE_SIZE - (len & PAGE_MASK)); + + /* Check to see if we need to extend the map for this segment to + * cover the diff between filesz and memsz (i.e. for bss). + * + * base _+---------------------+ page boundary + * . . + * | | + * . . + * pbase _+---------------------+ page boundary + * | | + * . . + * base + p_vaddr _| | + * . \ \ . + * . | filesz | . + * pbase + len _| / | | + * <0 pad> . . . + * extra_base _+------------|--------+ page boundary + * / . . . + * | . . . + * | +------------|--------+ page boundary + * extra_len-> | | | | + * | . | memsz . + * | . | . + * \ _| / | + * . . + * | | + * _+---------------------+ page boundary + */ + tmp = (unsigned char *)(((unsigned)pbase + len + PAGE_SIZE - 1) & + (~PAGE_MASK)); + if (tmp < (base + phdr->p_vaddr + phdr->p_memsz)) { + extra_len = base + phdr->p_vaddr + phdr->p_memsz - tmp; + TRACE("[ %5d - Need to extend segment from '%s' @ 0x%08x " + "(0x%08x) ]\n", pid, si->name, (unsigned)tmp, extra_len); + /* map in the extra page(s) as anonymous into the range. + * This is probably not necessary as we already mapped in + * the entire region previously, but we just want to be + * sure. This will also set the right flags on the region + * (though we can probably accomplish the same thing with + * mprotect). + */ + extra_base = mmap((void *)tmp, extra_len, + PFLAGS_TO_PROT(phdr->p_flags), + MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, + -1, 0); + if (extra_base == MAP_FAILED) { + ERROR("[ %5d - failed to extend segment from '%s' @ 0x%08x " + "(0x%08x) ]\n", pid, si->name, (unsigned)tmp, + extra_len); + goto fail; + } + /* TODO: Check if we need to memset-0 this region. + * Anonymous mappings are zero-filled copy-on-writes, so we + * shouldn't need to. */ + TRACE("[ %5d - Segment from '%s' extended @ 0x%08x " + "(0x%08x)\n", pid, si->name, (unsigned)extra_base, + extra_len); + } + /* set the len here to show the full extent of the segment we + * just loaded, mostly for debugging */ + len = (((unsigned)base + phdr->p_vaddr + phdr->p_memsz + + PAGE_SIZE - 1) & (~PAGE_MASK)) - (unsigned)pbase; + TRACE("[ %5d - Successfully loaded segment from '%s' @ 0x%08x " + "(0x%08x). p_vaddr=0x%08x p_offset=0x%08x\n", pid, si->name, + (unsigned)pbase, len, phdr->p_vaddr, phdr->p_offset); + total_sz += len; + /* Make the section writable just in case we'll have to write to + * it during relocation (i.e. text segment). However, we will + * remember what range of addresses should be write protected. + * + */ + if (!(phdr->p_flags & PF_W)) { + if ((unsigned)pbase < si->wrprotect_start) + si->wrprotect_start = (unsigned)pbase; + if (((unsigned)pbase + len) > si->wrprotect_end) + si->wrprotect_end = (unsigned)pbase + len; + mprotect(pbase, len, + PFLAGS_TO_PROT(phdr->p_flags) | PROT_WRITE); + } + } else if (phdr->p_type == PT_DYNAMIC) { + DEBUG_DUMP_PHDR(phdr, "PT_DYNAMIC", pid); + /* this segment contains the dynamic linking information */ + si->dynamic = (unsigned *)(base + phdr->p_vaddr); + } else { +#ifdef ANDROID_ARM_LINKER + if (phdr->p_type == PT_ARM_EXIDX) { + DEBUG_DUMP_PHDR(phdr, "PT_ARM_EXIDX", pid); + /* exidx entries (used for stack unwinding) are 8 bytes each. + */ + si->ARM_exidx = (unsigned *)phdr->p_vaddr; + si->ARM_exidx_count = phdr->p_memsz / 8; + } +#endif + } + + } + + /* Sanity check */ + if (total_sz > si->size) { + ERROR("%5d - Total length (0x%08x) of mapped segments from '%s' is " + "greater than what was allocated (0x%08x). THIS IS BAD!\n", + pid, total_sz, si->name, si->size); + goto fail; + } + + TRACE("[ %5d - Finish loading segments for '%s' @ 0x%08x. " + "Total memory footprint: 0x%08x bytes ]\n", pid, si->name, + (unsigned)si->base, si->size); + return 0; + +fail: + /* We can just blindly unmap the entire region even though some things + * were mapped in originally with anonymous and others could have been + * been mapped in from the file before we failed. The kernel will unmap + * all the pages in the range, irrespective of how they got there. + */ + munmap((void *)si->base, si->size); + si->flags |= FLAG_ERROR; + return -1; +} + +/* TODO: Implement this to take care of the fact that Android ARM + * ELF objects shove everything into a single loadable segment that has the + * write bit set. wr_offset is then used to set non-(data|bss) pages to be + * non-writable. + */ +#if 0 +static unsigned +get_wr_offset(int fd, const char *name, Elf32_Ehdr *ehdr) +{ + Elf32_Shdr *shdr_start; + Elf32_Shdr *shdr; + int shdr_sz = ehdr->e_shnum * sizeof(Elf32_Shdr); + int cnt; + unsigned wr_offset = 0xffffffff; + + shdr_start = mmap(0, shdr_sz, PROT_READ, MAP_PRIVATE, fd, + ehdr->e_shoff & (~PAGE_MASK)); + if (shdr_start == MAP_FAILED) { + WARN("%5d - Could not read section header info from '%s'. Will not " + "not be able to determine write-protect offset.\n", pid, name); + return (unsigned)-1; + } + + for(cnt = 0, shdr = shdr_start; cnt < ehdr->e_shnum; ++cnt, ++shdr) { + if ((shdr->sh_type != SHT_NULL) && (shdr->sh_flags & SHF_WRITE) && + (shdr->sh_addr < wr_offset)) { + wr_offset = shdr->sh_addr; + } + } + + munmap(shdr_start, shdr_sz); + return wr_offset; +} +#endif + +static soinfo * +load_library(const char *name) +{ + int fd = open_library(name); + int cnt; + unsigned ext_sz; + unsigned req_base; + soinfo *si = NULL; + Elf32_Ehdr *hdr; + + if(fd == -1) + return NULL; + + /* We have to read the ELF header to figure out what to do with this image + */ + if (lseek(fd, 0, SEEK_SET) < 0) { + ERROR("lseek() failed!\n"); + goto fail; + } + + if ((cnt = read(fd, &__header[0], PAGE_SIZE)) < 0) { + ERROR("read() failed!\n"); + goto fail; + } + + /* Parse the ELF header and get the size of the memory footprint for + * the library */ + req_base = get_lib_extents(fd, name, &__header[0], &ext_sz); + if (req_base == (unsigned)-1) + goto fail; + TRACE("[ %5d - '%s' (%s) wants base=0x%08x sz=0x%08x ]\n", pid, name, + (req_base ? "prelinked" : "not pre-linked"), req_base, ext_sz); + + /* Now configure the soinfo struct where we'll store all of our data + * for the ELF object. If the loading fails, we waste the entry, but + * same thing would happen if we failed during linking. Configuring the + * soinfo struct here is a lot more convenient. + */ + si = alloc_info(name); + if (si == NULL) + goto fail; + + /* Carve out a chunk of memory where we will map in the individual + * segments */ + si->base = req_base; + si->size = ext_sz; + si->flags = 0; + si->entry = 0; + si->dynamic = (unsigned *)-1; + if (alloc_mem_region(si) < 0) + goto fail; + + TRACE("[ %5d allocated memory for %s @ %p (0x%08x) ]\n", + pid, name, (void *)si->base, (unsigned) ext_sz); + + /* Now actually load the library's segments into right places in memory */ + if (load_segments(fd, &__header[0], si) < 0) { + if (si->ba_index >= 0) { + ba_free(si->ba_index); + si->ba_index = -1; + } + goto fail; + } + + /* this might not be right. Technically, we don't even need this info + * once we go through 'load_segments'. */ + hdr = (Elf32_Ehdr *)si->base; + si->phdr = (Elf32_Phdr *)((unsigned char *)si->base + hdr->e_phoff); + si->phnum = hdr->e_phnum; + /**/ + + close(fd); + return si; + +fail: + if (si) free_info(si); + close(fd); + return NULL; +} + +static soinfo * +init_library(soinfo *si) +{ + unsigned wr_offset = 0xffffffff; + + /* At this point we know that whatever is loaded @ base is a valid ELF + * shared library whose segments are properly mapped in. */ + TRACE("[ %5d init_library base=0x%08x sz=0x%08x name='%s') ]\n", + pid, si->base, si->size, si->name); + + if (si->base < LIBBASE || si->base >= LIBLAST) + si->flags |= FLAG_PRELINKED; + + if(link_image(si, wr_offset)) { + /* We failed to link. However, we can only restore libbase + ** if no additional libraries have moved it since we updated it. + */ + munmap((void *)si->base, si->size); + return NULL; + } + + return si; +} + +soinfo *find_library(const char *name) +{ + soinfo *si; + + for(si = solist; si != 0; si = si->next){ + if(!strcmp(name, si->name)) { + if(si->flags & FLAG_ERROR) return 0; + if(si->flags & FLAG_LINKED) return si; + ERROR("OOPS: %5d recursive link to '%s'\n", pid, si->name); + return 0; + } + } + + TRACE("[ %5d '%s' has not been loaded yet. Locating...]\n", pid, name); + si = load_library(name); + if(si == NULL) + return NULL; + return init_library(si); +} + +/* TODO: + * notify gdb of unload + * for non-prelinked libraries, find a way to decrement libbase + */ +static void call_destructors(soinfo *si); +unsigned unload_library(soinfo *si) +{ + unsigned *d; + if (si->refcount == 1) { + TRACE("%5d unloading '%s'\n", pid, si->name); + call_destructors(si); + + for(d = si->dynamic; *d; d += 2) { + if(d[0] == DT_NEEDED){ + TRACE("%5d %s needs to unload %s\n", pid, + si->name, si->strtab + d[1]); + soinfo *lsi = find_library(si->strtab + d[1]); + if(lsi) + unload_library(lsi); + else + ERROR("%5d could not unload '%s'\n", + pid, si->strtab + d[1]); + } + } + + munmap((char *)si->base, si->size); + if (si->ba_index >= 0) { + PRINT("%5d releasing library '%s' address space at %08x "\ + "through buddy allocator.\n", + pid, si->name, si->base); + ba_free(si->ba_index); + } + free_info(si); + si->refcount = 0; + } + else { + si->refcount--; + PRINT("%5d not unloading '%s', decrementing refcount to %d\n", + pid, si->name, si->refcount); + } + return si->refcount; +} + +/* TODO: don't use unsigned for addrs below. It works, but is not + * ideal. They should probably be either uint32_t, Elf32_Addr, or unsigned + * long. + */ +static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count) +{ + Elf32_Sym *symtab = si->symtab; + const char *strtab = si->strtab; + Elf32_Sym *s; + unsigned base; + Elf32_Rel *start = rel; + unsigned idx; + + for (idx = 0; idx < count; ++idx) { + unsigned type = ELF32_R_TYPE(rel->r_info); + unsigned sym = ELF32_R_SYM(rel->r_info); + unsigned reloc = (unsigned)(rel->r_offset + si->base); + unsigned sym_addr = 0; + char *sym_name = NULL; + + DEBUG("%5d Processing '%s' relocation at index %d\n", pid, + si->name, idx); + if(sym != 0) { + s = _do_lookup(si, strtab + symtab[sym].st_name, &base); + if(s == 0) { + ERROR("%5d cannot locate '%s'...\n", pid, sym_name); + return -1; + } +#if 0 + if((base == 0) && (si->base != 0)){ + /* linking from libraries to main image is bad */ + ERROR("%5d cannot locate '%s'...\n", + pid, strtab + symtab[sym].st_name); + return -1; + } +#endif + if ((s->st_shndx == SHN_UNDEF) && (s->st_value != 0)) { + ERROR("%5d In '%s', shndx=%d && value=0x%08x. We do not " + "handle this yet\n", pid, si->name, s->st_shndx, + s->st_value); + return -1; + } + sym_addr = (unsigned)(s->st_value + base); + sym_name = (char *)(strtab + symtab[sym].st_name); + COUNT_RELOC(RELOC_SYMBOL); + } else { + s = 0; + } + +/* TODO: This is ugly. Split up the relocations by arch into + * different files. + */ + switch(type){ +#if defined(ANDROID_ARM_LINKER) + case R_ARM_JUMP_SLOT: + COUNT_RELOC(RELOC_ABSOLUTE); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO JMP_SLOT %08x <- %08x %s\n", pid, + reloc, sym_addr, sym_name); + *((unsigned*)reloc) = sym_addr; + break; + case R_ARM_GLOB_DAT: + COUNT_RELOC(RELOC_ABSOLUTE); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO GLOB_DAT %08x <- %08x %s\n", pid, + reloc, sym_addr, sym_name); + *((unsigned*)reloc) = sym_addr; + break; + case R_ARM_ABS32: + COUNT_RELOC(RELOC_ABSOLUTE); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO ABS %08x <- %08x %s\n", pid, + reloc, sym_addr, sym_name); + *((unsigned*)reloc) += sym_addr; + break; +#elif defined(ANDROID_X86_LINKER) + case R_386_JUMP_SLOT: + COUNT_RELOC(RELOC_ABSOLUTE); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO JMP_SLOT %08x <- %08x %s\n", pid, + reloc, sym_addr, sym_name); + *((unsigned*)reloc) = sym_addr; + break; + case R_386_GLOB_DAT: + COUNT_RELOC(RELOC_ABSOLUTE); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO GLOB_DAT %08x <- %08x %s\n", pid, + reloc, sym_addr, sym_name); + *((unsigned*)reloc) = sym_addr; + break; +#endif /* ANDROID_*_LINKER */ + +#if defined(ANDROID_ARM_LINKER) + case R_ARM_RELATIVE: +#elif defined(ANDROID_X86_LINKER) + case R_386_RELATIVE: +#endif /* ANDROID_*_LINKER */ + COUNT_RELOC(RELOC_RELATIVE); + MARK(rel->r_offset); + if(sym){ + ERROR("%5d odd RELATIVE form...\n", pid); + return -1; + } + TRACE_TYPE(RELO, "%5d RELO RELATIVE %08x <- +%08x\n", pid, + reloc, si->base); + *((unsigned*)reloc) += si->base; + break; + +#if defined(ANDROID_X86_LINKER) + case R_386_32: + COUNT_RELOC(RELOC_RELATIVE); + MARK(rel->r_offset); + + TRACE_TYPE(RELO, "%5d RELO R_386_32 %08x <- +%08x %s\n", pid, + reloc, sym_addr, sym_name); + *((unsigned *)reloc) += (unsigned)sym_addr; + break; + + case R_386_PC32: + COUNT_RELOC(RELOC_RELATIVE); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO R_386_PC32 %08x <- " + "+%08x (%08x - %08x) %s\n", pid, reloc, + (sym_addr - reloc), sym_addr, reloc, sym_name); + *((unsigned *)reloc) += (unsigned)(sym_addr - reloc); + break; +#endif /* ANDROID_X86_LINKER */ + +#ifdef ANDROID_ARM_LINKER + case R_ARM_COPY: + COUNT_RELOC(RELOC_COPY); + MARK(rel->r_offset); + TRACE_TYPE(RELO, "%5d RELO %08x <- %d @ %08x %s\n", pid, + reloc, s->st_size, sym_addr, sym_name); + memcpy((void*)reloc, (void*)sym_addr, s->st_size); + break; +#endif /* ANDROID_ARM_LINKER */ + + default: + ERROR("%5d unknown reloc type %d @ %p (%d)\n", + pid, type, rel, (int) (rel - start)); + return -1; + } + rel++; + } + return 0; +} + +static void call_array(unsigned *ctor, int count) +{ + int n; + for(n = count; n > 0; n--){ + TRACE("[ %5d Looking at ctor *0x%08x == 0x%08x ]\n", pid, + (unsigned)ctor, (unsigned)*ctor); + void (*func)() = (void (*)()) *ctor++; + if(((int) func == 0) || ((int) func == -1)) continue; + TRACE("[ %5d Calling func @ 0x%08x ]\n", pid, (unsigned)func); + func(); + } +} + +static void call_constructors(soinfo *si) +{ + /* TODO: THE ORIGINAL CODE SEEMED TO CALL THE INIT FUNCS IN THE WRONG ORDER. + * Old order: init, init_array, preinit_array.. + * Correct order: preinit_array, init, init_array. + * Verify WHY. + */ + + if (si->flags & FLAG_EXE) { + TRACE("[ %5d Calling preinit_array @ 0x%08x [%d] for '%s' ]\n", + pid, (unsigned)si->preinit_array, si->preinit_array_count, + si->name); + call_array(si->preinit_array, si->preinit_array_count); + TRACE("[ %5d Done calling preinit_array for '%s' ]\n", pid, si->name); + } else { + if (si->preinit_array) { + ERROR("%5d Shared library '%s' has a preinit_array table @ 0x%08x." + " This is INVALID.\n", pid, si->name, + (unsigned)si->preinit_array); + } + } + + // If we have an init section, then we should call it now, to make sure + // that all the funcs in the .ctors section get run. + // Note: For ARM, we shouldn't have a .ctor section (should be empty) + // when we have an (pre)init_array section, but let's be compatible with + // old (non-eabi) binaries and try the _init (DT_INIT) anyway. + if (si->init_func) { + TRACE("[ %5d Calling init_func @ 0x%08x for '%s' ]\n", pid, + (unsigned)si->init_func, si->name); + si->init_func(); + TRACE("[ %5d Done calling init_func for '%s' ]\n", pid, si->name); + } + + if (si->init_array) { + TRACE("[ %5d Calling init_array @ 0x%08x [%d] for '%s' ]\n", pid, + (unsigned)si->init_array, si->init_array_count, si->name); + call_array(si->init_array, si->init_array_count); + TRACE("[ %5d Done calling init_array for '%s' ]\n", pid, si->name); + } +} + +static void call_destructors(soinfo *si) +{ + if (si->fini_array) { + TRACE("[ %5d Calling fini_array @ 0x%08x [%d] for '%s' ]\n", pid, + (unsigned)si->fini_array, si->fini_array_count, si->name); + call_array(si->fini_array, si->fini_array_count); + TRACE("[ %5d Done calling fini_array for '%s' ]\n", pid, si->name); + } + + // If we have an fini section, then we should call it now, to make sure + // that all the funcs in the .dtors section get run. + // Note: For ARM, we shouldn't have a .dtor section (should be empty) + // when we have an fini_array section, but let's be compatible with + // old (non-eabi) binaries and try the _fini (DT_FINI) anyway. + if (si->fini_func) { + TRACE("[ %5d Calling fini_func @ 0x%08x for '%s' ]\n", pid, + (unsigned)si->fini_func, si->name); + si->fini_func(); + TRACE("[ %5d Done calling fini_func for '%s' ]\n", pid, si->name); + } +} + +/* Force any of the closed stdin, stdout and stderr to be associated with + /dev/null. */ +static int nullify_closed_stdio (void) +{ + int dev_null, i, status; + int return_value = 0; + + dev_null = open("/dev/null", O_RDWR); + if (dev_null < 0) { + ERROR("Cannot open /dev/null.\n"); + return -1; + } + TRACE("[ %5d Opened /dev/null file-descriptor=%d]\n", pid, dev_null); + + /* If any of the stdio file descriptors is valid and not associated + with /dev/null, dup /dev/null to it. */ + for (i = 0; i < 3; i++) { + /* If it is /dev/null already, we are done. */ + if (i == dev_null) + continue; + + TRACE("[ %5d Nullifying stdio file descriptor %d]\n", pid, i); + /* The man page of fcntl does not say that fcntl(..,F_GETFL) + can be interrupted but we do this just to be safe. */ + do { + status = fcntl(i, F_GETFL); + } while (status < 0 && errno == EINTR); + + /* If file is openned, we are good. */ + if (status >= 0) + continue; + + /* The only error we allow is that the file descriptor does not + exist, in which case we dup /dev/null to it. */ + if (errno != EBADF) { + ERROR("nullify_stdio: unhandled error %s\n", strerror(errno)); + return_value = -1; + continue; + } + + /* Try dupping /dev/null to this stdio file descriptor and + repeat if there is a signal. Note that any errors in closing + the stdio descriptor are lost. */ + do { + status = dup2(dev_null, i); + } while (status < 0 && errno == EINTR); + + if (status < 0) { + ERROR("nullify_stdio: dup2 error %s\n", strerror(errno)); + return_value = -1; + continue; + } + } + + /* If /dev/null is not one of the stdio file descriptors, close it. */ + if (dev_null > 2) { + TRACE("[ %5d Closing /dev/null file-descriptor=%d]\n", pid, dev_null); + do { + status = close(dev_null); + } while (status < 0 && errno == EINTR); + + if (status < 0) { + ERROR("nullify_stdio: close error %s\n", strerror(errno)); + return_value = -1; + } + } + + return return_value; +} + +static int link_image(soinfo *si, unsigned wr_offset) +{ + unsigned *d; + Elf32_Phdr *phdr = si->phdr; + int phnum = si->phnum; + + INFO("[ %5d linking %s ]\n", pid, si->name); + DEBUG("%5d si->base = 0x%08x si->flags = 0x%08x\n", pid, + si->base, si->flags); + + if (si->flags & FLAG_EXE) { + /* Locate the needed program segments (DYNAMIC/ARM_EXIDX) for + * linkage info if this is the executable. If this was a + * dynamic lib, that would have been done at load time. + * + * TODO: It's unfortunate that small pieces of this are + * repeated from the load_library routine. Refactor this just + * slightly to reuse these bits. + */ + si->size = 0; + for(; phnum > 0; --phnum, ++phdr) { +#ifdef ANDROID_ARM_LINKER + if(phdr->p_type == PT_ARM_EXIDX) { + /* exidx entries (used for stack unwinding) are 8 bytes each. + */ + si->ARM_exidx = (unsigned *)phdr->p_vaddr; + si->ARM_exidx_count = phdr->p_memsz / 8; + } +#endif + if (phdr->p_type == PT_LOAD) { + /* For the executable, we use the si->size field only in + dl_unwind_find_exidx(), so the meaning of si->size + is not the size of the executable; it is the last + virtual address of the loadable part of the executable; + since si->base == 0 for an executable, we use the + range [0, si->size) to determine whether a PC value + falls within the executable section. Of course, if + a value is below phdr->p_vaddr, it's not in the + executable section, but a) we shouldn't be asking for + such a value anyway, and b) if we have to provide + an EXIDX for such a value, then the executable's + EXIDX is probably the better choice. + */ + DEBUG_DUMP_PHDR(phdr, "PT_LOAD", pid); + if (phdr->p_vaddr + phdr->p_memsz > si->size) + si->size = phdr->p_vaddr + phdr->p_memsz; + /* try to remember what range of addresses should be write + * protected */ + if (!(phdr->p_flags & PF_W)) { + unsigned _end; + + if (phdr->p_vaddr < si->wrprotect_start) + si->wrprotect_start = phdr->p_vaddr; + _end = (((phdr->p_vaddr + phdr->p_memsz + PAGE_SIZE - 1) & + (~PAGE_MASK))); + if (_end > si->wrprotect_end) + si->wrprotect_end = _end; + } + } else if (phdr->p_type == PT_DYNAMIC) { + if (si->dynamic != (unsigned *)-1) { + ERROR("%5d multiple PT_DYNAMIC segments found in '%s'. " + "Segment at 0x%08x, previously one found at 0x%08x\n", + pid, si->name, si->base + phdr->p_vaddr, + (unsigned)si->dynamic); + goto fail; + } + DEBUG_DUMP_PHDR(phdr, "PT_DYNAMIC", pid); + si->dynamic = (unsigned *) (si->base + phdr->p_vaddr); + } + } + } + + if (si->dynamic == (unsigned *)-1) { + ERROR("%5d missing PT_DYNAMIC?!\n", pid); + goto fail; + } + + DEBUG("%5d dynamic = %p\n", pid, si->dynamic); + + /* extract useful information from dynamic section */ + for(d = si->dynamic; *d; d++){ + DEBUG("%5d d = %p, d[0] = 0x%08x d[1] = 0x%08x\n", pid, d, d[0], d[1]); + switch(*d++){ + case DT_HASH: + si->nbucket = ((unsigned *) (si->base + *d))[0]; + si->nchain = ((unsigned *) (si->base + *d))[1]; + si->bucket = (unsigned *) (si->base + *d + 8); + si->chain = (unsigned *) (si->base + *d + 8 + si->nbucket * 4); + break; + case DT_STRTAB: + si->strtab = (const char *) (si->base + *d); + break; + case DT_SYMTAB: + si->symtab = (Elf32_Sym *) (si->base + *d); + break; + case DT_PLTREL: + if(*d != DT_REL) { + ERROR("DT_RELA not supported\n"); + goto fail; + } + break; + case DT_JMPREL: + si->plt_rel = (Elf32_Rel*) (si->base + *d); + break; + case DT_PLTRELSZ: + si->plt_rel_count = *d / 8; + break; + case DT_REL: + si->rel = (Elf32_Rel*) (si->base + *d); + break; + case DT_RELSZ: + si->rel_count = *d / 8; + break; + case DT_PLTGOT: + /* Save this in case we decide to do lazy binding. We don't yet. */ + si->plt_got = (unsigned *)(si->base + *d); + break; + case DT_DEBUG: + // Set the DT_DEBUG entry to the addres of _r_debug for GDB + *d = (int) &_r_debug; + break; + case DT_RELA: + ERROR("%5d DT_RELA not supported\n", pid); + goto fail; + case DT_INIT: + si->init_func = (void (*)(void))(si->base + *d); + DEBUG("%5d %s constructors (init func) found at %p\n", + pid, si->name, si->init_func); + break; + case DT_FINI: + si->fini_func = (void (*)(void))(si->base + *d); + DEBUG("%5d %s destructors (fini func) found at %p\n", + pid, si->name, si->fini_func); + break; + case DT_INIT_ARRAY: + si->init_array = (unsigned *)(si->base + *d); + DEBUG("%5d %s constructors (init_array) found at %p\n", + pid, si->name, si->init_array); + break; + case DT_INIT_ARRAYSZ: + si->init_array_count = ((unsigned)*d) / sizeof(Elf32_Addr); + break; + case DT_FINI_ARRAY: + si->fini_array = (unsigned *)(si->base + *d); + DEBUG("%5d %s destructors (fini_array) found at %p\n", + pid, si->name, si->fini_array); + break; + case DT_FINI_ARRAYSZ: + si->fini_array_count = ((unsigned)*d) / sizeof(Elf32_Addr); + break; + case DT_PREINIT_ARRAY: + si->preinit_array = (unsigned *)(si->base + *d); + DEBUG("%5d %s constructors (preinit_array) found at %p\n", + pid, si->name, si->preinit_array); + break; + case DT_PREINIT_ARRAYSZ: + si->preinit_array_count = ((unsigned)*d) / sizeof(Elf32_Addr); + break; + case DT_TEXTREL: + /* TODO: make use of this. */ + /* this means that we might have to write into where the text + * segment was loaded during relocation... Do something with + * it. + */ + DEBUG("%5d Text segment should be writable during relocation.\n", + pid); + break; + } + } + + DEBUG("%5d si->base = 0x%08x, si->strtab = %p, si->symtab = %p\n", + pid, si->base, si->strtab, si->symtab); + + if((si->strtab == 0) || (si->symtab == 0)) { + ERROR("%5d missing essential tables\n", pid); + goto fail; + } + + for(d = si->dynamic; *d; d += 2) { + if(d[0] == DT_NEEDED){ + DEBUG("%5d %s needs %s\n", pid, si->name, si->strtab + d[1]); + soinfo *lsi = find_library(si->strtab + d[1]); + if(lsi == 0) { + ERROR("%5d could not load '%s'\n", pid, si->strtab + d[1]); + goto fail; + } + lsi->refcount++; + } + } + + if(si->plt_rel) { + DEBUG("[ %5d relocating %s plt ]\n", pid, si->name ); + if(reloc_library(si, si->plt_rel, si->plt_rel_count)) + goto fail; + } + if(si->rel) { + DEBUG("[ %5d relocating %s ]\n", pid, si->name ); + if(reloc_library(si, si->rel, si->rel_count)) + goto fail; + } + + si->flags |= FLAG_LINKED; + DEBUG("[ %5d finished linking %s ]\n", pid, si->name); + +#if 0 + /* This is the way that the old dynamic linker did protection of + * non-writable areas. It would scan section headers and find where + * .text ended (rather where .data/.bss began) and assume that this is + * the upper range of the non-writable area. This is too coarse, + * and is kept here for reference until we fully move away from single + * segment elf objects. See the code in get_wr_offset (also #if'd 0) + * that made this possible. + */ + if(wr_offset < 0xffffffff){ + mprotect((void*) si->base, wr_offset, PROT_READ | PROT_EXEC); + } +#else + /* TODO: Verify that this does the right thing in all cases, as it + * presently probably does not. It is possible that an ELF image will + * come with multiple read-only segments. What we ought to do is scan + * the program headers again and mprotect all the read-only segments. + * To prevent re-scanning the program header, we would have to build a + * list of loadable segments in si, and then scan that instead. */ + if (si->wrprotect_start != 0xffffffff && si->wrprotect_end != 0) { + mprotect((void *)si->wrprotect_start, + si->wrprotect_end - si->wrprotect_start, + PROT_READ | PROT_EXEC); + } +#endif + + /* If this is a SET?ID program, dup /dev/null to opened stdin, + stdout and stderr to close a security hole described in: + + ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc + + */ + if (getuid() != geteuid() || getgid() != getegid()) + nullify_closed_stdio (); + call_constructors(si); + notify_gdb_of_load(si); + return 0; + +fail: + ERROR("failed to link %s\n", si->name); + si->flags |= FLAG_ERROR; + return -1; +} + +int main(int argc, char **argv) +{ + return 0; +} + +#define ANDROID_TLS_SLOTS BIONIC_TLS_SLOTS + +static void * __tls_area[ANDROID_TLS_SLOTS]; + +unsigned __linker_init(unsigned **elfdata) +{ + static soinfo linker_soinfo; + + int argc = (int) *elfdata; + char **argv = (char**) (elfdata + 1); + unsigned *vecs = (unsigned*) (argv + argc + 1); + soinfo *si; + struct link_map * map; + + pid = getpid(); + +#if TIMING + struct timeval t0, t1; + gettimeofday(&t0, 0); +#endif + + __set_tls(__tls_area); + ((unsigned *)__get_tls())[TLS_SLOT_THREAD_ID] = gettid(); + + debugger_init(); + + /* skip past the environment */ + while(vecs[0] != 0) { + if(!strncmp((char*) vecs[0], "DEBUG=", 6)) { + debug_verbosity = atoi(((char*) vecs[0]) + 6); + } + vecs++; + } + vecs++; + + INFO("[ android linker & debugger ]\n"); + DEBUG("%5d elfdata @ 0x%08x\n", pid, (unsigned)elfdata); + + si = alloc_info(argv[0]); + if(si == 0) { + exit(-1); + } + + /* bootstrap the link map, the main exe always needs to be first */ + si->flags |= FLAG_EXE; + map = &(si->linkmap); + + map->l_addr = 0; + map->l_name = argv[0]; + map->l_prev = NULL; + map->l_next = NULL; + + _r_debug.r_map = map; + r_debug_tail = map; + + /* gdb expects the linker to be in the debug shared object list, + * and we need to make sure that the reported load address is zero. + * Without this, gdb gets the wrong idea of where rtld_db_dlactivity() + * is. Don't use alloc_info(), because the linker shouldn't + * be on the soinfo list. + */ + strcpy((char*) linker_soinfo.name, "/system/bin/linker"); + linker_soinfo.flags = 0; + linker_soinfo.base = 0; // This is the important part; must be zero. + insert_soinfo_into_debug_map(&linker_soinfo); + + /* extract information passed from the kernel */ + while(vecs[0] != 0){ + switch(vecs[0]){ + case AT_PHDR: + si->phdr = (Elf32_Phdr*) vecs[1]; + break; + case AT_PHNUM: + si->phnum = (int) vecs[1]; + break; + case AT_ENTRY: + si->entry = vecs[1]; + break; + } + vecs += 2; + } + + ba_init(); + + si->base = 0; + si->dynamic = (unsigned *)-1; + si->wrprotect_start = 0xffffffff; + si->wrprotect_end = 0; + + if(link_image(si, 0)){ + ERROR("CANNOT LINK EXECUTABLE '%s'\n", argv[0]); + exit(-1); + } + +#if TIMING + gettimeofday(&t1,NULL); + PRINT("LINKER TIME: %s: %d microseconds\n", argv[0], (int) ( + (((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) - + (((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec) + )); +#endif +#if STATS + PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol\n", argv[0], + linker_stats.reloc[RELOC_ABSOLUTE], + linker_stats.reloc[RELOC_RELATIVE], + linker_stats.reloc[RELOC_COPY], + linker_stats.reloc[RELOC_SYMBOL]); +#endif +#if COUNT_PAGES + { + unsigned n; + unsigned i; + unsigned count = 0; + for(n = 0; n < 4096; n++){ + if(bitmask[n]){ + unsigned x = bitmask[n]; + for(i = 0; i < 8; i++){ + if(x & 1) count++; + x >>= 1; + } + } + } + PRINT("PAGES MODIFIED: %s: %d (%dKB)\n", argv[0], count, count * 4); + } +#endif + +#if TIMING || STATS || COUNT_PAGES + fflush(stdout); +#endif + + TRACE("[ %5d Ready to execute '%s' @ 0x%08x ]\n", pid, si->name, + si->entry); + return si->entry; +} |