Merge "linker: avoid mapping the whole library before load."
This commit is contained in:
David 'Digit' Turner
Android (Google) Code Review
commit
ff9ff758ad
1 changed files with 61 additions and 111 deletions
172
linker/linker.c
172
linker/linker.c
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@ -50,6 +50,7 @@
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#include "linker_debug.h"
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#include "linker_environ.h"
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#include "linker_format.h"
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#include "linker_phdr.h"
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#define ALLOW_SYMBOLS_FROM_MAIN 1
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#define SO_MAX 128
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@ -701,81 +702,6 @@ verify_elf_header(const Elf32_Ehdr* hdr)
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}
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/* get_lib_extents
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* Retrieves the base (*base) address where the ELF object should be
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* mapped and its overall memory size (*total_sz).
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*
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* Args:
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* fd: Opened file descriptor for the library
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* name: The name of the library
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* _hdr: Pointer to the header page of the library
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* total_sz: Total size of the memory that should be allocated for
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* this library
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*
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* Returns:
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* -1 if there was an error while trying to get the lib extents.
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* The possible reasons are:
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* - Could not determine if the library was prelinked.
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* - The library provided is not a valid ELF object
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* 0 if the library did not request a specific base offset (normal
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* for non-prelinked libs)
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* > 0 if the library requests a specific address to be mapped to.
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* This indicates a pre-linked library.
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*/
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static unsigned
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get_lib_extents(int fd, const char *name, void *__hdr, unsigned *total_sz)
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{
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unsigned req_base;
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unsigned min_vaddr = 0xffffffff;
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unsigned max_vaddr = 0;
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unsigned char *_hdr = (unsigned char *)__hdr;
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Elf32_Ehdr *ehdr = (Elf32_Ehdr *)_hdr;
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Elf32_Phdr *phdr;
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int cnt;
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TRACE("[ %5d Computing extents for '%s'. ]\n", pid, name);
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if (verify_elf_header(ehdr) < 0) {
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DL_ERR("%5d - %s is not a valid ELF object", pid, name);
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return (unsigned)-1;
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}
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req_base = (unsigned) is_prelinked(fd, name);
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if (req_base == (unsigned)-1)
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return -1;
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else if (req_base != 0) {
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TRACE("[ %5d - Prelinked library '%s' requesting base @ 0x%08x ]\n",
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pid, name, req_base);
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} else {
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TRACE("[ %5d - Non-prelinked library '%s' found. ]\n", pid, name);
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}
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phdr = (Elf32_Phdr *)(_hdr + ehdr->e_phoff);
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/* find the min/max p_vaddrs from all the PT_LOAD segments so we can
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* get the range. */
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for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) {
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if (phdr->p_type == PT_LOAD) {
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if ((phdr->p_vaddr + phdr->p_memsz) > max_vaddr)
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max_vaddr = phdr->p_vaddr + phdr->p_memsz;
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if (phdr->p_vaddr < min_vaddr)
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min_vaddr = phdr->p_vaddr;
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}
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}
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if ((min_vaddr == 0xffffffff) && (max_vaddr == 0)) {
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DL_ERR("%5d - No loadable segments found in %s.", pid, name);
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return (unsigned)-1;
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}
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/* truncate min_vaddr down to page boundary */
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min_vaddr = PAGE_START(min_vaddr);
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/* round max_vaddr up to the next page */
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max_vaddr = PAGE_END(max_vaddr);
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*total_sz = (max_vaddr - min_vaddr);
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return (unsigned)req_base;
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}
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/* reserve_mem_region
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*
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* This function reserves a chunk of memory to be used for mapping in
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@ -826,20 +752,15 @@ static int soinfo_alloc_mem_region(soinfo *si)
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void *base = mmap(NULL, si->size, PROT_NONE,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if (base == MAP_FAILED) {
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DL_ERR("%5d mmap of library '%s' failed: %d (%s)\n",
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pid, si->name,
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DL_ERR("%5d mmap of library '%s' failed (%d bytes): %d (%s)\n",
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pid, si->name, si->size,
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errno, strerror(errno));
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goto err;
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return -1;
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}
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si->base = (unsigned) base;
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PRINT("%5d mapped library '%s' to %08x via kernel allocator.\n",
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pid, si->name, si->base);
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return 0;
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err:
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DL_ERR("OOPS: %5d cannot map library '%s'. no vspace available.",
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pid, si->name);
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return -1;
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}
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#define MAYBE_MAP_FLAG(x,from,to) (((x) & (from)) ? (to) : 0)
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@ -861,11 +782,10 @@ err:
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* 0 on success, -1 on failure.
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*/
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static int
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soinfo_load_segments(soinfo* si, int fd, void* header)
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soinfo_load_segments(soinfo* si, int fd, const Elf32_Phdr* phdr_table, int phdr_count, Elf32_Addr ehdr_phoff)
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{
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Elf32_Ehdr *ehdr = (Elf32_Ehdr *)header;
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Elf32_Phdr *phdr = (Elf32_Phdr *)((unsigned char *)header + ehdr->e_phoff);
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Elf32_Phdr *phdr0 = 0; /* program header for the first LOAD segment */
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const Elf32_Phdr *phdr = phdr_table;
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const Elf32_Phdr *phdr0 = 0; /* program header for the first LOAD segment */
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Elf32_Addr base;
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int cnt;
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unsigned len;
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@ -881,7 +801,7 @@ soinfo_load_segments(soinfo* si, int fd, void* header)
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TRACE("[ %5d - Begin loading segments for '%s' @ 0x%08x ]\n",
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pid, si->name, (unsigned)si->base);
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for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) {
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for (cnt = 0; cnt < phdr_count; ++cnt, ++phdr) {
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if (phdr->p_type == PT_LOAD) {
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phdr0 = phdr;
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@ -902,8 +822,8 @@ soinfo_load_segments(soinfo* si, int fd, void* header)
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/* Now go through all the PT_LOAD segments and map them into memory
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* at the appropriate locations. */
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phdr = (Elf32_Phdr *)((unsigned char *)header + ehdr->e_phoff);
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for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) {
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phdr = phdr_table;
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for (cnt = 0; cnt < phdr_count; ++cnt, ++phdr) {
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if (phdr->p_type == PT_LOAD) {
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DEBUG_DUMP_PHDR(phdr, "PT_LOAD", pid);
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/* we want to map in the segment on a page boundary */
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@ -1054,8 +974,8 @@ soinfo_load_segments(soinfo* si, int fd, void* header)
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* phdr ehdr->e_phoff
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*/
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si->phdr = (Elf32_Phdr *)(base + phdr0->p_vaddr +
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ehdr->e_phoff - phdr0->p_offset);
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si->phnum = ehdr->e_phnum;
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ehdr_phoff - phdr0->p_offset);
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si->phnum = phdr_count;
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TRACE("[ %5d - Finish loading segments for '%s' @ 0x%08x. "
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"Total memory footprint: 0x%08x bytes ]\n", pid, si->name,
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@ -1108,44 +1028,72 @@ get_wr_offset(int fd, const char *name, Elf32_Ehdr *ehdr)
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}
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#endif
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static soinfo *
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load_library(const char *name)
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{
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int fd = open_library(name);
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int cnt;
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int ret, cnt;
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unsigned ext_sz;
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unsigned req_base;
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const char *bname;
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struct stat sb;
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soinfo *si = NULL;
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Elf32_Ehdr *hdr = MAP_FAILED;
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Elf32_Ehdr header[1];
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int phdr_count;
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void* phdr_mmap = NULL;
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Elf32_Addr phdr_size;
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const Elf32_Phdr* phdr_table;
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if (fd == -1) {
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DL_ERR("Library '%s' not found", name);
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return NULL;
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}
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/* We have to read the ELF header to figure out what to do with this image.
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* Map entire file for this. There won't be much difference in physical
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* memory usage or performance.
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*/
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if (fstat(fd, &sb) < 0) {
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DL_ERR("%5d fstat() failed! (%s)", pid, strerror(errno));
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/* Read the ELF header first */
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ret = TEMP_FAILURE_RETRY(read(fd, (void*)header, sizeof(header)));
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if (ret < 0) {
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DL_ERR("%5d can't read file %s: %s", pid, name, strerror(errno));
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goto fail;
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}
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if (ret != (int)sizeof(header)) {
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DL_ERR("%5d too small to be an ELF executable: %s", pid, name);
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goto fail;
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}
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if (verify_elf_header(header) < 0) {
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DL_ERR("%5d not a valid ELF executable: %s", pid, name);
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goto fail;
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}
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hdr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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if (hdr == MAP_FAILED) {
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DL_ERR("%5d failed to mmap() header of '%s' (%s)",
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pid, name, strerror(errno));
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/* Then read the program header table */
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ret = phdr_table_load(fd, header->e_phoff, header->e_phnum,
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&phdr_mmap, &phdr_size, &phdr_table);
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if (ret < 0) {
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DL_ERR("%5d can't load program header table: %s: %s", pid,
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name, strerror(errno));
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goto fail;
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}
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phdr_count = header->e_phnum;
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/* Get the load extents and the prelinked load address, if any */
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ext_sz = phdr_table_get_load_size(phdr_table, phdr_count);
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if (ext_sz == 0) {
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DL_ERR("%5d no loadable segments in file: %s", pid, name);
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goto fail;
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}
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/* Parse the ELF header and get the size of the memory footprint for
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* the library */
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req_base = get_lib_extents(fd, name, hdr, &ext_sz);
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if (req_base == (unsigned)-1)
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req_base = (unsigned) is_prelinked(fd, name);
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if (req_base == (unsigned)-1) {
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DL_ERR("%5d can't read end of library: %s: %s", pid, name,
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strerror(errno));
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goto fail;
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}
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if (req_base != 0) {
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TRACE("[ %5d - Prelinked library '%s' requesting base @ 0x%08x ]\n",
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pid, name, req_base);
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} else {
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TRACE("[ %5d - Non-prelinked library '%s' found. ]\n", pid, name);
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}
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TRACE("[ %5d - '%s' (%s) wants base=0x%08x sz=0x%08x ]\n", pid, name,
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(req_base ? "prelinked" : "not pre-linked"), req_base, ext_sz);
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@ -1174,17 +1122,19 @@ load_library(const char *name)
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pid, name, (void *)si->base, (unsigned) ext_sz);
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/* Now actually load the library's segments into right places in memory */
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if (soinfo_load_segments(si, fd, hdr) < 0) {
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if (soinfo_load_segments(si, fd, phdr_table, phdr_count, header->e_phoff) < 0) {
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goto fail;
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}
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munmap(hdr, sb.st_size);
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phdr_table_unload(phdr_mmap, phdr_size);
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close(fd);
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return si;
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fail:
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if (si) soinfo_free(si);
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if (hdr != MAP_FAILED) munmap(hdr, sb.st_size);
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if (phdr_mmap != NULL) {
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phdr_table_unload(phdr_mmap, phdr_size);
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}
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close(fd);
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return NULL;
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}
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