| 0,0 → 1,457 |
|---|
| /* |
| * Copyright (c) 2006 Sergey Bondari |
| * Copyright (c) 2006 Jakub Jermar |
| * Copyright (c) 2008 Jiri Svoboda |
| * 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. |
| * - The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. |
| */ |
| |
| /** @addtogroup generic |
| * @{ |
| */ |
| |
| /** |
| * @file |
| * @brief Userspace ELF loader. |
| * |
| * This module allows loading ELF binaries (both executables and |
| * shared objects) from VFS. The current implementation allocates |
| * anonymous memory, fills it with segment data and then adjusts |
| * the memory areas' flags to the final value. In the future, |
| * the segments will be mapped directly from the file. |
| */ |
| |
| #include <stdio.h> |
| #include <sys/types.h> |
| #include <align.h> |
| #include <assert.h> |
| #include <as.h> |
| #include <unistd.h> |
| #include <fcntl.h> |
| |
| #include "elf.h" |
| #include "pcb.h" |
| #include "elf_load.h" |
| #include "arch.h" |
| |
| static char *error_codes[] = { |
| "no error", |
| "invalid image", |
| "address space error", |
| "incompatible image", |
| "unsupported image type", |
| "irrecoverable error" |
| }; |
| |
| static unsigned int elf_load(elf_ld_t *elf, size_t so_bias); |
| static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry); |
| static int section_header(elf_ld_t *elf, elf_section_header_t *entry); |
| static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry); |
| |
| /** Load ELF binary from a file. |
| * |
| * Load an ELF binary from the specified file. If the file is |
| * an executable program, it is loaded unbiased. If it is a shared |
| * object, it is loaded with the bias @a so_bias. Some information |
| * extracted from the binary is stored in a elf_info_t structure |
| * pointed to by @a info. |
| * |
| * @param file_name Path to the ELF file. |
| * @param so_bias Bias to use if the file is a shared object. |
| * @param info Pointer to a structure for storing information |
| * extracted from the binary. |
| * |
| * @return EOK on success or negative error code. |
| */ |
| int elf_load_file(char *file_name, size_t so_bias, elf_info_t *info) |
| { |
| elf_ld_t elf; |
| |
| int fd; |
| int rc; |
| |
| // printf("open and read '%s'...\n", file_name); |
| |
| fd = open(file_name, O_RDONLY); |
| if (fd < 0) { |
| printf("failed opening file\n"); |
| return -1; |
| } |
| |
| elf.fd = fd; |
| elf.info = info; |
| |
| rc = elf_load(&elf, so_bias); |
| |
| close(fd); |
| |
| return rc; |
| } |
| |
| /** Run an ELF executable. |
| * |
| * Transfers control to the entry point of an ELF executable loaded |
| * earlier with elf_load_file(). This function does not return. |
| * |
| * @param info Info structure filled earlier by elf_load_file() |
| */ |
| void elf_run(elf_info_t *info) |
| { |
| program_run(info->entry); |
| |
| /* not reached */ |
| } |
| |
| /** Create the program control block (PCB). |
| * |
| * Create and install the program control block, initialising it |
| * with program information from @a info. |
| * |
| * @param info Program info structure |
| * @return EOK on success or negative error code |
| */ |
| int elf_create_pcb(elf_info_t *info) |
| { |
| pcb_t *pcb; |
| void *a; |
| |
| pcb = __pcb_get(); |
| |
| a = as_area_create(pcb, sizeof(pcb_t), AS_AREA_READ | AS_AREA_WRITE); |
| if (a == (void *)(-1)) { |
| printf("elf_create_pcb: memory mapping failed\n"); |
| return EE_MEMORY; |
| } |
| |
| pcb->entry = info->entry; |
| pcb->dynamic = info->dynamic; |
| |
| return 0; |
| } |
| |
| |
| /** Load an ELF binary. |
| * |
| * The @a elf structure contains the loader state, including |
| * an open file, from which the binary will be loaded, |
| * a pointer to the @c info structure etc. |
| * |
| * @param elf Pointer to loader state buffer. |
| * @param so_bias Bias to use if the file is a shared object. |
| * @return EE_OK on success or EE_xx error code. |
| */ |
| static unsigned int elf_load(elf_ld_t *elf, size_t so_bias) |
| { |
| elf_header_t header_buf; |
| elf_header_t *header = &header_buf; |
| int i, rc; |
| |
| rc = read(elf->fd, header, sizeof(elf_header_t)); |
| if (rc < 0) { |
| printf("read error\n"); |
| return EE_INVALID; |
| } |
| |
| elf->header = header; |
| |
| // printf("ELF-load:"); |
| /* Identify ELF */ |
| if (header->e_ident[EI_MAG0] != ELFMAG0 || |
| header->e_ident[EI_MAG1] != ELFMAG1 || |
| header->e_ident[EI_MAG2] != ELFMAG2 || |
| header->e_ident[EI_MAG3] != ELFMAG3) { |
| printf("invalid header\n"); |
| return EE_INVALID; |
| } |
| |
| /* Identify ELF compatibility */ |
| if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || |
| header->e_machine != ELF_MACHINE || |
| header->e_ident[EI_VERSION] != EV_CURRENT || |
| header->e_version != EV_CURRENT || |
| header->e_ident[EI_CLASS] != ELF_CLASS) { |
| printf("incompatible data/version/class\n"); |
| return EE_INCOMPATIBLE; |
| } |
| |
| if (header->e_phentsize != sizeof(elf_segment_header_t)) { |
| printf("e_phentsize:%d != %d\n", header->e_phentsize, |
| sizeof(elf_segment_header_t)); |
| return EE_INCOMPATIBLE; |
| } |
| |
| if (header->e_shentsize != sizeof(elf_section_header_t)) { |
| printf("e_shentsize:%d != %d\n", header->e_shentsize, |
| sizeof(elf_section_header_t)); |
| return EE_INCOMPATIBLE; |
| } |
| |
| /* Check if the object type is supported. */ |
| if (header->e_type != ET_EXEC && header->e_type != ET_DYN) { |
| printf("Object type %d is not supported\n", header->e_type); |
| return EE_UNSUPPORTED; |
| } |
| |
| /* Shared objects can be loaded with a bias */ |
| // printf("Object type: %d\n", header->e_type); |
| if (header->e_type == ET_DYN) |
| elf->bias = so_bias; |
| else |
| elf->bias = 0; |
| |
| // printf("Bias set to 0x%x\n", elf->bias); |
| elf->info->interp = NULL; |
| elf->info->dynamic = NULL; |
| |
| // printf("parse segments\n"); |
| |
| /* Walk through all segment headers and process them. */ |
| for (i = 0; i < header->e_phnum; i++) { |
| elf_segment_header_t segment_hdr; |
| |
| /* Seek to start of segment header */ |
| lseek(elf->fd, header->e_phoff |
| + i * sizeof(elf_segment_header_t), SEEK_SET); |
| |
| rc = read(elf->fd, &segment_hdr, sizeof(elf_segment_header_t)); |
| if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
| |
| rc = segment_header(elf, &segment_hdr); |
| if (rc != EE_OK) |
| return rc; |
| } |
| |
| // printf("parse sections\n"); |
| |
| /* Inspect all section headers and proccess them. */ |
| for (i = 0; i < header->e_shnum; i++) { |
| elf_section_header_t section_hdr; |
| |
| /* Seek to start of section header */ |
| lseek(elf->fd, header->e_shoff |
| + i * sizeof(elf_section_header_t), SEEK_SET); |
| |
| rc = read(elf->fd, §ion_hdr, sizeof(elf_section_header_t)); |
| if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
| |
| rc = section_header(elf, §ion_hdr); |
| if (rc != EE_OK) |
| return rc; |
| } |
| |
| elf->info->entry = |
| (entry_point_t)((uint8_t *)header->e_entry + elf->bias); |
| |
| // printf("done\n"); |
| |
| return EE_OK; |
| } |
| |
| /** Print error message according to error code. |
| * |
| * @param rc Return code returned by elf_load(). |
| * |
| * @return NULL terminated description of error. |
| */ |
| char *elf_error(unsigned int rc) |
| { |
| assert(rc < sizeof(error_codes) / sizeof(char *)); |
| |
| return error_codes[rc]; |
| } |
| |
| /** Process segment header. |
| * |
| * @param entry Segment header. |
| * |
| * @return EE_OK on success, error code otherwise. |
| */ |
| static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry) |
| { |
| switch (entry->p_type) { |
| case PT_NULL: |
| case PT_PHDR: |
| break; |
| case PT_LOAD: |
| return load_segment(elf, entry); |
| break; |
| case PT_INTERP: |
| /* Assume silently interp == "/rtld.so" */ |
| elf->info->interp = "/rtld.so"; |
| break; |
| case PT_DYNAMIC: |
| case PT_SHLIB: |
| case PT_NOTE: |
| case PT_LOPROC: |
| case PT_HIPROC: |
| default: |
| printf("segment p_type %d unknown\n", entry->p_type); |
| return EE_UNSUPPORTED; |
| break; |
| } |
| return EE_OK; |
| } |
| |
| /** Load segment described by program header entry. |
| * |
| * @param elf Loader state. |
| * @param entry Program header entry describing segment to be loaded. |
| * |
| * @return EE_OK on success, error code otherwise. |
| */ |
| int load_segment(elf_ld_t *elf, elf_segment_header_t *entry) |
| { |
| void *a; |
| int flags = 0; |
| uintptr_t bias; |
| uintptr_t base; |
| size_t mem_sz; |
| int rc; |
| |
| // printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr, |
| // entry->p_memsz); |
| |
| bias = elf->bias; |
| |
| if (entry->p_align > 1) { |
| if ((entry->p_offset % entry->p_align) != |
| (entry->p_vaddr % entry->p_align)) { |
| printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n", |
| entry->p_offset % entry->p_align, |
| entry->p_vaddr % entry->p_align |
| ); |
| return EE_INVALID; |
| } |
| } |
| |
| /* Final flags that will be set for the memory area */ |
| |
| if (entry->p_flags & PF_X) |
| flags |= AS_AREA_EXEC; |
| if (entry->p_flags & PF_W) |
| flags |= AS_AREA_WRITE; |
| if (entry->p_flags & PF_R) |
| flags |= AS_AREA_READ; |
| flags |= AS_AREA_CACHEABLE; |
| |
| base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE); |
| mem_sz = entry->p_memsz + (entry->p_vaddr - base); |
| |
| // printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias, |
| // entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE)); |
| |
| /* |
| * For the course of loading, the area needs to be readable |
| * and writeable. |
| */ |
| a = as_area_create((uint8_t *)base + bias, |
| mem_sz, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE); |
| if (a == (void *)(-1)) { |
| printf("memory mapping failed\n"); |
| return EE_MEMORY; |
| } |
| |
| // printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n", |
| // entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a); |
| |
| /* |
| * Load segment data |
| */ |
| // printf("seek to %d\n", entry->p_offset); |
| rc = lseek(elf->fd, entry->p_offset, SEEK_SET); |
| if (rc < 0) { printf("seek error\n"); return EE_INVALID; } |
| |
| // printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias); |
| /* rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz); |
| if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/ |
| |
| /* Long reads are not possible yet. Load segment picewise */ |
| |
| unsigned left, now; |
| uint8_t *dp; |
| |
| left = entry->p_filesz; |
| dp = (uint8_t *)(entry->p_vaddr + bias); |
| |
| while (left > 0) { |
| now = 16384; |
| if (now > left) now = left; |
| |
| // printf("read %d...", now); |
| rc = read(elf->fd, dp, now); |
| // printf("->%d\n", rc); |
| |
| if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
| |
| left -= now; |
| dp += now; |
| } |
| |
| // printf("set area flags to %d\n", flags); |
| rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags); |
| if (rc != 0) { |
| printf("failed to set memory area flags\n"); |
| return EE_MEMORY; |
| } |
| |
| return EE_OK; |
| } |
| |
| /** Process section header. |
| * |
| * @param elf Loader state. |
| * @param entry Segment header. |
| * |
| * @return EE_OK on success, error code otherwise. |
| */ |
| static int section_header(elf_ld_t *elf, elf_section_header_t *entry) |
| { |
| switch (entry->sh_type) { |
| case SHT_PROGBITS: |
| if (entry->sh_flags & SHF_TLS) { |
| /* .tdata */ |
| } |
| break; |
| case SHT_NOBITS: |
| if (entry->sh_flags & SHF_TLS) { |
| /* .tbss */ |
| } |
| break; |
| case SHT_DYNAMIC: |
| /* Record pointer to dynamic section into info structure */ |
| elf->info->dynamic = |
| (void *)((uint8_t *)entry->sh_addr + elf->bias); |
| printf("dynamic section found at 0x%x\n", |
| (uintptr_t)elf->info->dynamic); |
| break; |
| default: |
| break; |
| } |
| |
| return EE_OK; |
| } |
| |
| /** @} |
| */ |