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rt-thread/components/lwp/lwp_elf.c

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/*
* Copyright (c) 2006-2025 RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2023-08-23 zhangsz first version
*/
#include <rtthread.h>
#ifdef RT_USING_LDSO
#include <dfs_file.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <lwp_elf.h>
#include "lwp.h"
#include "lwp_arch.h"
#ifdef ARCH_MM_MMU
#include <lwp_user_mm.h>
#endif
#ifdef RT_USING_VDSO
#include <vdso.h>
#endif
#define DBG_TAG "load.elf"
#ifdef ELF_DEBUG_ENABLE
#define DBG_LVL DBG_LOG
#else
#define DBG_LVL DBG_INFO
#endif
#include <rtdbg.h>
#define ELF_INVALID_FD -1
#define ELF_PHDR_NUM_MAX 128
#define FILE_LENGTH_MAX 0xC0000000
#define MEM_SIZE_MAX 0xC0000000
#define ELF_PATH_MAX 256
#define FLF_PATH_MIN 1
#define ELF_PAGESTART(_v) ((_v) & ~(rt_ubase_t)(ARCH_PAGE_SIZE - 1))
#define ELF_PAGEOFFSET(_v) ((_v) & (ARCH_PAGE_SIZE - 1))
#define ELF_PAGEALIGN(_v) (((_v) + ARCH_PAGE_SIZE - 1) & ~(ARCH_PAGE_SIZE - 1))
#define ELF_EXEC_LOAD_ADDR USER_VADDR_START
#define ELF_INTERP_LOAD_ADDR LDSO_LOAD_VADDR
#define ELF_AUX_ENT(aux, id, val) \
do \
{ \
rt_base_t a = id; \
lwp_data_put(lwp, aux++, &a, sizeof(rt_ubase_t)); \
a = val; \
lwp_data_put(lwp, aux++, &a, sizeof(rt_ubase_t)); \
} while (0)
/**
* @brief Structure to hold information about an ELF file.
*
*/
typedef struct
{
int fd; /* File descriptor for the ELF file */
char *filename; /* Path to the ELF file */
rt_size_t file_len; /* Length of the ELF file */
Elf_Ehdr ehdr; /* ELF header */
Elf_Phdr *phdr; /* Pointer to the program header table */
rt_ubase_t map_size; /* Total size required for memory mapping */
} elf_info_t;
/**
* @brief Structure to hold information about an ELF executable and its interpreter.
*/
typedef struct
{
struct rt_lwp *lwp; /* Pointer to the Light Weight Process (LWP) structure */
struct process_aux *aux; /* Pointer to auxiliary process information */
elf_info_t exec_info; /* Information about the main ELF executable */
elf_info_t interp_info; /* Information about the ELF interpreter (if any) */
rt_ubase_t load_addr; /* Base address where the ELF is loaded */
rt_ubase_t e_entry; /* Entry point address of the ELF */
rt_ubase_t interp_base; /* Base address of the interpreter */
} elf_load_info_t;
/**
* @brief Dump the contents of a user-space memory region for debugging.
*
* This function reads and prints the contents of a specified user-space memory region
* in hexadecimal format. It is primarily used for debugging ELF loading and execution.
*
* @param lwp Pointer to the Light Weight Process (LWP) structure.
* @param va Virtual address of the memory region to dump.
* @param len Length of the memory region to dump.
*/
static void elf_user_dump(struct rt_lwp *lwp, void *va, size_t len)
{
#ifdef ELF_DEBUG_DUMP
uint8_t *k_va;
int ret;
if (len < 16)
len = 16;
rt_kprintf("\r\n");
rt_kprintf("%s : user va : %p, len : 0x%x(%d)\n", __func__, va, len, len);
k_va = rt_malloc(len);
if (k_va == RT_NULL)
{
rt_kprintf("%s : malloc failed\n", __func__);
return;
}
rt_memset(k_va, 0, len);
ret = lwp_data_get(lwp, k_va, va, len);
if (ret != len)
{
rt_kprintf("%s : lwp_get_from_user failed, ret = %d\n", __func__, ret);
return;
}
rt_kprintf("%s : k_va : %p\n", __func__, k_va);
for (size_t i = 0; i < len; i += 16)
{
rt_kprintf(" %02x %02x %02x %02x %02x %02x %02x %02x ", k_va[i], k_va[i+1], k_va[i+2], k_va[i+3],
k_va[i+4], k_va[i+5], k_va[i+6], k_va[i+7]);
rt_kprintf(" %02x %02x %02x %02x %02x %02x %02x %02x \n", k_va[i+8], k_va[i+9], k_va[i+10], k_va[i+11],
k_va[i+12], k_va[i+13], k_va[i+14], k_va[i+15]);
}
rt_kprintf("\r\n");
rt_free(k_va);
#endif
}
/**
* @brief Generate a random offset for ELF loading.
*
* @return Random offset aligned to page size.
*/
rt_ubase_t elf_random_offset(void)
{
#ifdef ELF_LOAD_RANDOMIZE
return (rt_tick_get() % 65535) * ARCH_PAGE_SIZE;
#else
return ELF_PAGEALIGN(0);
#endif
}
/**
* @brief Map a file into the process's address space.
*
* This function maps a file into the process's virtual memory using the specified
* address, size, protection flags, and offset. It ensures the mapping is properly
* aligned and verifies the mapping operation.
*
* @param lwp Pointer to the Light Weight Process (LWP) structure.
* @param fd File descriptor of the file to map.
* @param load_addr Desired virtual address for mapping.
* @param map_size Size of the memory mapping.
* @param prot Memory protection flags (e.g., PROT_READ, PROT_WRITE).
* @param flags Mapping flags (e.g., MAP_FIXED, MAP_PRIVATE).
* @param offset File offset where mapping should begin.
*
* @return Virtual address where the file is mapped on success, NULL on failure.
*/
static void *file_mmap(struct rt_lwp *lwp, int fd, rt_ubase_t load_addr,
rt_ubase_t map_size, size_t prot, size_t flags, rt_ubase_t offset)
{
uint8_t *map_va;
map_va = (uint8_t *)lwp_mmap2(lwp, (void *)load_addr, map_size, prot, flags, fd, offset >> ARCH_PAGE_SHIFT);
if (!map_va || (map_va != (uint8_t *)load_addr))
{
LOG_E("%s : lwp map user failed!", __func__);
return RT_NULL;
}
LOG_D(" %s : map va = %p load_addr : %p size : 0x%x", __func__, map_va, load_addr, map_size);
return map_va;
}
static int elf_file_open(const char *filename)
{
int fd = -1;
fd = open(filename, O_BINARY | O_RDONLY, 0);
if (fd < 0)
{
LOG_E("%s : elf file [%s] open failed!", __func__, filename);
}
return fd;
}
static int elf_file_close(int fd)
{
return close(fd);
}
/**
* @brief Get the length of an ELF file.
*
* @param filename Path to the ELF file.
* @param file_len Pointer to store the file length.
* @return RT_EOK on success, -RT_ERROR on failure.
*/
static int elf_file_length(char *filename, rt_size_t *file_len)
{
int ret;
struct stat s = { 0 };
ret = stat(filename, &s);
if (ret != 0)
{
LOG_E("%s : error", __func__);
return -RT_ERROR;
}
*file_len = (rt_size_t)s.st_size;
return RT_EOK;
}
/**
* @brief Read data from an ELF file at a specific offset.
*
* @param fd File descriptor of the ELF file.
* @param buffer Pointer to the buffer where the read data will be stored.
* @param size Number of bytes to read.
* @param offset File offset where reading should begin.
* @return RT_EOK on success, -RT_ERROR if seek or read operations fail.
*/
static int elf_file_read(rt_int32_t fd, rt_uint8_t *buffer, size_t size, off_t offset)
{
ssize_t read_len;
off_t pos;
if (size > 0)
{
pos = lseek(fd, offset, SEEK_SET);
if (pos != offset)
{
LOG_E("%s : seek file offset: 0x%x failed", __func__, offset);
return -RT_ERROR;
}
read_len = read(fd, buffer, size);
if (read_len != size)
{
LOG_E("%s : read from offset: 0x%x error", __func__, offset);
return -RT_ERROR;
}
}
return RT_EOK;
}
/**
* @brief Validate an ELF header.
*
* @param ehdr Pointer to the ELF header to validate.
* @param file_len Length of the ELF file.
* @return RT_EOK if valid, -RT_ERROR if invalid.
*/
static rt_int32_t elf_check_ehdr(const Elf_Ehdr *ehdr, rt_uint32_t file_len)
{
if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
{
LOG_E("%s : e_ident error", __func__);
return -RT_ERROR;
}
if ((ehdr->e_type != ET_EXEC) && (ehdr->e_type != ET_DYN))
{
LOG_E("%s : e_type error", __func__);
return -RT_ERROR;
}
if (ehdr->e_machine == EM_NONE)
{
LOG_E("%s : e_machine is EM_NONE", __func__);
return -RT_ERROR;
}
if (ehdr->e_phnum > ELF_PHDR_NUM_MAX)
{
LOG_E("%s : e_phnum error", __func__);
return -RT_ERROR;
}
if (ehdr->e_phoff > file_len)
{
LOG_E("%s : e_phoff error", __func__);
return -RT_ERROR;
}
LOG_D("%s : e_entry : 0x%x", __func__, ehdr->e_entry);
return RT_EOK;
}
/**
* @brief Validate an ELF program header.
*
* @param phdr Pointer to the ELF program header to validate.
* @return RT_EOK if valid, -RT_ERROR if invalid.
*/
static int elf_check_phdr(const Elf_Phdr *phdr)
{
if (phdr->p_filesz > FILE_LENGTH_MAX)
{
LOG_E("%s : phdr p_filesz 0x%x error", __func__, phdr->p_filesz);
return -RT_ERROR;
}
if (phdr->p_offset > FILE_LENGTH_MAX)
{
LOG_E("%s : phdr p_offset 0x%x error", __func__, phdr->p_offset);
return -RT_ERROR;
}
if (phdr->p_memsz > MEM_SIZE_MAX)
{
LOG_E("%s[%d], phdr p_memsz 0x%x error", __func__, phdr->p_memsz);
return -RT_ERROR;
}
LOG_D("%s : phdr p_vaddr : 0x%x", __func__, phdr->p_vaddr);
return RT_EOK;
}
/**
* @brief Load and validate the ELF header from a file.
*
* This function opens the ELF file, reads its elf header, and performs basic validation
* to ensure it's a valid ELF file. It also retrieves the file size and stores the
* file descriptor for subsequent operations.
*
* @param elf_info Pointer to the ELF file information structure.
* @return RT_EOK on success, -RT_ERROR on failure.
*/
static int elf_load_ehdr(elf_info_t *elf_info)
{
int ret;
ret = elf_file_open(elf_info->filename);
if (ret < 0)
{
LOG_E("%s : elf_file_open %s failed", __func__, elf_info->filename);
return ret;
}
elf_info->fd = ret;
ret = elf_file_length(elf_info->filename, &elf_info->file_len);
if (ret != RT_EOK)
{
return -RT_ERROR;
}
ret = elf_file_read(elf_info->fd, (rt_uint8_t *)&elf_info->ehdr, sizeof(Elf_Ehdr), 0);
if (ret != RT_EOK)
{
LOG_E("%s : elf_file_read failed, ret : %d", __func__, ret);
return -RT_ERROR;
}
ret = elf_check_ehdr(&elf_info->ehdr, elf_info->file_len);
if (ret != RT_EOK)
{
LOG_E("%s : elf_check_ehdr failed, ret : %d", __func__, ret);
return -RT_ERROR;
}
return RT_EOK;
}
/**
* @brief Load the program header table from an ELF file.
*
* This function reads and validates the program header table from the ELF file.
* It ensures the program header table is properly aligned and within the file bounds.
*
* @param elf_info Pointer to the ELF file information structure.
* @return RT_EOK on success, -RT_ERROR on failure.
*/
static int elf_load_phdr(elf_info_t *elf_info)
{
Elf_Ehdr *ehdr = &elf_info->ehdr;
uint32_t size;
int ret;
if (ehdr->e_phnum < 1)
{
return -RT_ERROR;
}
if (ehdr->e_phentsize != sizeof(Elf_Phdr))
{
return -RT_ERROR;
}
size = sizeof(Elf_Phdr) * ehdr->e_phnum;
if ((ehdr->e_phoff + size) > elf_info->file_len)
{
return -RT_ERROR;
}
elf_info->phdr = rt_malloc(size);
if (elf_info->phdr == RT_NULL)
{
LOG_E("%s : alloc phdr failed", __func__);
return -RT_ENOMEM;
}
ret = elf_file_read(elf_info->fd, (rt_uint8_t *)elf_info->phdr, size, ehdr->e_phoff);
if (ret != RT_EOK)
{
rt_free(elf_info->phdr);
elf_info->phdr = RT_NULL;
LOG_E("%s : elf_file_read failed, ret = %d", __func__, ret);
return -RT_ERROR;
}
return RT_EOK;
}
/**
* @brief Load the ELF interpreter specified in the program header.
*
* This function searches for the PT_INTERP segment in the program headers,
* validates its properties, and loads the interpreter's filename and
* associated ELF information.
*
* @param load_info Pointer to the ELF loading context structure.
* @return RT_EOK on success, -RT_ERROR on failure.
*/
static int elf_load_interp(elf_load_info_t *load_info)
{
Elf_Phdr *phdr = load_info->exec_info.phdr;
int ret;
int i;
for (i = 0; i < load_info->exec_info.ehdr.e_phnum; ++i, ++phdr)
{
if (phdr->p_type != PT_INTERP)
{
continue;
}
if (elf_check_phdr(phdr) != RT_EOK)
{
return -RT_ERROR;
}
if ((phdr->p_filesz > ELF_PATH_MAX) || (phdr->p_filesz < FLF_PATH_MIN))
{
LOG_E("%s : phdr p_filesz error", __func__, phdr->p_filesz);
return -RT_ERROR;
}
if (phdr->p_offset + phdr->p_filesz > load_info->exec_info.file_len)
{
LOG_E("%s : phdr p_offset error", __func__, phdr->p_offset);
return -RT_ERROR;
}
load_info->interp_info.filename = rt_malloc(phdr->p_filesz);
if (load_info->interp_info.filename == RT_NULL)
{
LOG_E("%s : alloc elf interpreter failed", __func__);
return -RT_ENOMEM;
}
ret = elf_file_read(load_info->exec_info.fd, (rt_uint8_t *)load_info->interp_info.filename,
phdr->p_filesz, phdr->p_offset);
if (ret != RT_EOK)
{
LOG_E("%s : elf_file_read failed, ret = %d", __func__, ret);
ret = -RT_ERROR;
goto error_exit;
}
if (load_info->interp_info.filename[phdr->p_filesz - 1] != '\0')
{
LOG_E("%s : elf interpreter is invalid", __func__);
ret = -RT_ERROR;
goto error_exit;
}
LOG_D("%s : elf interpreter : %s", __func__, load_info->interp_info.filename);
ret = elf_load_ehdr(&load_info->interp_info);
if (ret != RT_EOK)
{
LOG_E("%s : elf_load_ehdr failed, ret = %d", __func__, ret);
goto error_exit;
}
ret = elf_load_phdr(&load_info->interp_info);
if (ret != RT_EOK)
{
LOG_E("%s : elf_load_phdr failed, ret = %d", __func__, ret);
goto error_exit;
}
break;
}
return RT_EOK;
error_exit:
return ret;
}
/**
* @brief Calculate the total size required to map all loadable ELF segments.
*
* @param elf_info Pointer to the ELF file information structure.
* @return 0 on success, -1 if no loadable segments are found.
*/
static int total_mapping_size(elf_info_t *elf_info)
{
int i;
int first_idx = -1;
int last_idx = -1;
for (i = 0; i < elf_info->ehdr.e_phnum; i++)
{
if (elf_info->phdr[i].p_type == PT_LOAD)
{
last_idx = i;
if (first_idx == -1)
first_idx = i;
}
}
if (first_idx == -1)
return -1;
elf_info->map_size = elf_info->phdr[last_idx].p_vaddr + elf_info->phdr[last_idx].p_memsz -
ELF_PAGESTART(elf_info->phdr[first_idx].p_vaddr);
return 0;
}
/**
* @brief Map an ELF segment into the process's address space.
*
* This function maps a specific ELF segment into the process's virtual memory space.
* It handles page alignment, calculates the correct offset, and performs the actual
* memory mapping operation.
*
* @param lwp Pointer to the Light Weight Process (LWP) structure.
* @param elf_phdr Pointer to the ELF program header describing the segment.
* @param fd File descriptor of the ELF file.
* @param addr Desired virtual address for mapping.
* @param prot Memory protection flags (e.g., PROT_READ, PROT_WRITE).
* @param flags Mapping flags (e.g., MAP_FIXED, MAP_PRIVATE).
* @param map_size Size of the memory mapping (0 for automatic calculation).
*
* @return Virtual address where the segment is mapped on success.
* @return 0 on failure.
*/
static rt_ubase_t elf_map(struct rt_lwp *lwp, const Elf_Phdr *elf_phdr, int fd, rt_ubase_t addr, size_t prot, size_t flags, rt_ubase_t map_size)
{
rt_ubase_t map_va = 0;
rt_ubase_t va_offset;
addr = ELF_PAGESTART(addr);
va_offset = elf_phdr->p_offset - ELF_PAGEOFFSET(elf_phdr->p_vaddr);
rt_ubase_t size;
if (map_size != 0)
{
size = map_size;
}
else
{
size = elf_phdr->p_memsz + ELF_PAGEOFFSET(elf_phdr->p_vaddr);
if (size == 0)
{
return addr;
}
}
map_va = (rt_ubase_t)file_mmap(lwp, fd, addr, size, prot, flags, va_offset);
return map_va;
}
static int elf_zero_bss(struct rt_lwp *lwp, int fd, const Elf_Phdr *phdr, rt_ubase_t bss_start,
rt_ubase_t bss_end)
{
lwp_data_set(lwp, (void *)bss_start, 0, bss_end - bss_start);
return RT_EOK;
}
/**
* @brief Map ELF segments into memory.
*
* This function maps the loadable segments of an ELF file into the process's address space.
* It handles both executable and shared library files, manages BSS sections, and sets up
* the load address and base address for dynamic libraries.
*
* @param load_info Pointer to the structure containing ELF loading context.
* @param elf_info Pointer to the structure containing ELF file information.
* @param elfload_addr Pointer to store the final load address of the ELF file.
* @param map_size Size of the memory mapping (0 for automatic calculation).
* @param load_base Base address for loading (used for position-independent code).
*
* @return RT_EOK on success.
* @return -RT_ERROR if memory mapping fails.
* @return -ENOMEM if memory allocation fails.
*/
static int elf_file_mmap(elf_load_info_t *load_info, elf_info_t *elf_info, rt_ubase_t *elfload_addr,
rt_uint32_t map_size, rt_ubase_t *load_base)
{
int ret, i;
rt_ubase_t map_va, bss_start, bss_end;
Elf_Ehdr *ehdr = &elf_info->ehdr; /* ELF header */
Elf_Phdr *phdr = elf_info->phdr; /* Program header array */
const Elf_Phdr *tmp_phdr = phdr; /* Current program header */
int fd = elf_info->fd; /* File descriptor for ELF file */
rt_ubase_t load_addr; /* Calculated load address */
size_t prot = PROT_READ | PROT_WRITE; /* Memory protection flags */
size_t flags = MAP_FIXED | MAP_PRIVATE; /* Memory mapping flags */
/* Iterate through all program headers */
for (i = 0; i < ehdr->e_phnum; ++i, ++tmp_phdr)
{
/* Only process PT_LOAD segments (loadable segments) */
if (tmp_phdr->p_type != PT_LOAD)
{
continue;
}
/* For executable files, validate the program header */
if (ehdr->e_type == ET_EXEC)
{
if (elf_check_phdr(tmp_phdr) != RT_EOK)
{
LOG_E("%s : elf_check_phdr failed", __func__);
return -RT_ERROR;
}
}
load_addr = tmp_phdr->p_vaddr + *load_base;
LOG_D("%s : p_vaddr : 0x%x, load_addr : 0x%x", __func__, tmp_phdr->p_vaddr, load_addr);
/* When both the segment's virtual address and the load base are 0, the segment is loaded at any available
address rather than a fixed one. This behavior is particularly useful for Position-Independent Code (PIC)
or shared libraries. */
if ((tmp_phdr->p_vaddr == 0) && (*load_base == 0))
{
flags &= ~MAP_FIXED;
}
/* Map the segment into memory */
map_va = elf_map(load_info->lwp, tmp_phdr, fd, load_addr, prot, flags, map_size);
if (!map_va)
{
LOG_E("%s : elf_map failed", __func__);
return -ENOMEM;
}
map_size = 0;
elf_user_dump(load_info->lwp, (void *)load_addr, 64);
/* Handle BSS section (zero-initialized data) */
if ((tmp_phdr->p_memsz > tmp_phdr->p_filesz) && (tmp_phdr->p_flags & PF_W))
{
bss_start = load_addr + tmp_phdr->p_filesz;
bss_end = load_addr + tmp_phdr->p_memsz;
ret = elf_zero_bss(load_info->lwp, fd, tmp_phdr, bss_start, bss_end);
if (ret)
{
LOG_E("%s : elf_zero_bss error", __func__);
return ret;
}
}
if (*elfload_addr == 0)
{
*elfload_addr = map_va + ELF_PAGEOFFSET(tmp_phdr->p_vaddr);
LOG_D("%s elf_load_addr : %p, vAddr : %p, load_base : %p, map_va : %p", __func__,
*elfload_addr, tmp_phdr->p_vaddr, *load_base, map_va);
}
if ((*load_base == 0) && (ehdr->e_type == ET_DYN))
{
*load_base = map_va;
}
}
return RT_EOK;
}
/**
* @brief Load the ELF interpreter into memory.
*
* @param load_info Pointer to the ELF loading context.
* @param interp_base Pointer to store the interpreter's base address.
*
* @return RT_EOK on success, -RT_ERROR on failure.
*/
static int load_elf_interp(elf_load_info_t *load_info, rt_ubase_t *interp_base)
{
int ret;
rt_ubase_t load_base = ELF_INTERP_LOAD_ADDR + elf_random_offset();
ret = total_mapping_size(&load_info->interp_info);
if (ret)
{
LOG_E("%s : total_mapping_size failed", __func__);
return -RT_ERROR;
}
LOG_D("%s : total_mapping_size 0x%x", __func__, load_info->interp_info.map_size);
return elf_file_mmap(load_info, &load_info->interp_info, interp_base,
load_info->interp_info.map_size, &load_base);
}
/**
* @brief Populate the auxiliary vector for an ELF-loaded process.
*
* This function sets up the auxiliary vector that provides essential information
* to the ELF executable about the runtime environment. It includes information
* about page size, program headers, entry point, and other system-specific details.
*
* @param load_info Pointer to the structure containing ELF loading information.
*
* @return 0 on success, -1 if the auxiliary structure is invalid, or -RT_ERROR
* if memory mapping fails.
*
* @note The auxiliary vector is crucial for proper initialization of the ELF
* executable and its interaction with the runtime environment.
*/
static int elf_aux_fill(elf_load_info_t *load_info)
{
uint8_t *random;
struct process_aux *aux = load_info->aux;
elf_addr_t *aux_info;
uint32_t random_value = rt_tick_get();
size_t prot = PROT_READ | PROT_WRITE;
size_t flags = MAP_FIXED | MAP_PRIVATE;
rt_lwp_t lwp = load_info->lwp;
void *va;
if (!aux)
{
LOG_E("%s : aux is null", __func__);
return -1;
}
aux_info = (elf_addr_t *)aux->item;
ELF_AUX_ENT(aux_info, AT_PAGESZ, ARCH_PAGE_SIZE);
va = lwp_mmap2(lwp, (void *)(USER_VADDR_TOP - ARCH_PAGE_SIZE * 2), ARCH_PAGE_SIZE, prot, flags, -1, 0);
if (!va)
{
LOG_E("lwp map user failed!");
return -RT_ERROR;
}
random = (uint8_t *)(USER_VADDR_TOP - ARCH_PAGE_SIZE - sizeof(char[16]));
lwp_data_put(load_info->lwp, random, &random_value, sizeof(random_value));
ELF_AUX_ENT(aux_info, AT_RANDOM, (size_t)random);
ELF_AUX_ENT(aux_info, AT_PHDR, (size_t)load_info->load_addr + load_info->exec_info.ehdr.e_phoff);
ELF_AUX_ENT(aux_info, AT_PHNUM, (size_t)load_info->exec_info.ehdr.e_phnum);
ELF_AUX_ENT(aux_info, AT_PHENT, sizeof(Elf_Phdr));
ELF_AUX_ENT(aux_info, AT_BASE, load_info->interp_base);
ELF_AUX_ENT(aux_info, AT_FLAGS, 0);
ELF_AUX_ENT(aux_info, AT_ENTRY, load_info->exec_info.ehdr.e_entry);
ELF_AUX_ENT(aux_info, AT_UID, 0);
ELF_AUX_ENT(aux_info, AT_EUID, 0);
ELF_AUX_ENT(aux_info, AT_GID, 0);
ELF_AUX_ENT(aux_info, AT_EGID, 0);
ELF_AUX_ENT(aux_info, AT_HWCAP, 0);
ELF_AUX_ENT(aux_info, AT_CLKTCK, 0);
ELF_AUX_ENT(aux_info, AT_SECURE, 0);
#ifdef RT_USING_VDSO
if(RT_EOK == arch_setup_additional_pages(load_info->lwp))
{
ELF_AUX_ENT(aux_info, AT_SYSINFO_EHDR, (size_t)load_info->lwp->vdso_vbase);
}
else
{
LOG_W("vdso map error,VDSO currently only supports aarch64 architecture!");
}
#endif
return 0;
}
/**
* @brief Load the segments of an ELF file into memory.
*
* This function is responsible for loading the segments of an ELF file into memory,
* including handling dynamic libraries and setting up the entry point for execution.
*
* @param load_info Pointer to the structure containing ELF loading information.
* @return RT_EOK if the segments are successfully loaded and prepared for execution.
* @return -RT_ERROR if any error occurs during the loading process, including:
* - Memory allocation failure
* - File mapping errors
* - Interpreter loading errors
*/
static int elf_load_segment(elf_load_info_t *load_info)
{
int ret;
rt_ubase_t app_load_base = 0; /* Base address for loading the application. */
load_info->load_addr = 0; /* Load address for the ELF file. */
load_info->interp_base = 0; /* Base address for loading the interpreter. */
load_info->exec_info.map_size = 0; /* Total size of the mapped segments. */
if (load_info->exec_info.ehdr.e_type == ET_DYN)
{
ret = total_mapping_size(&load_info->exec_info);
if (ret)
{
LOG_E("%s : total_mapping_size failed", __func__);
return -RT_ERROR;
}
LOG_D("%s : map_size : 0x%x", __func__, load_info->exec_info.map_size);
/* Calculate the base address for loading the ELF file by adding a random offset to the default load address.
This randomization enhances security by making it harder for attackers to predict the memory layout. */
app_load_base = ELF_EXEC_LOAD_ADDR + elf_random_offset();
}
/* Map the segments of the ELF file into memory */
ret = elf_file_mmap(load_info, &load_info->exec_info, &load_info->load_addr,
load_info->exec_info.map_size, &app_load_base);
elf_file_close(load_info->exec_info.fd);
if (ret != RT_EOK)
{
LOG_W("%s : elf_file_close exec failed", __func__);
}
load_info->exec_info.fd = ELF_INVALID_FD;
if (load_info->interp_info.fd != ELF_INVALID_FD)
{
ret = load_elf_interp(load_info, &load_info->interp_base); /* load the interpreter */
if (ret)
{
LOG_E("%s : load_elf_interp failed, ret = %d", __func__, ret);
return ret;
}
elf_file_close(load_info->interp_info.fd);
if (ret != RT_EOK)
{
LOG_W("%s : elf_file_close interp failed, ret = %d", __func__, ret);
}
load_info->interp_info.fd = ELF_INVALID_FD;
/* if a interpreter exist, first jump to the interpreter's entry to handle dynamic libs' loading. */
load_info->e_entry = load_info->interp_info.ehdr.e_entry + load_info->interp_base;
load_info->exec_info.ehdr.e_entry = load_info->exec_info.ehdr.e_entry + app_load_base; /* Update the ELF file's entry address by adding the base address. */
}
else
{
/* If there is no interpreter, use the ELF file's entry address directly. */
load_info->e_entry = load_info->exec_info.ehdr.e_entry;
}
load_info->lwp->text_entry = (void *)load_info->e_entry;
LOG_D("%s : lwp->text_entry : %p loadaddr : %p", __func__, load_info->lwp->text_entry, app_load_base);
/* Debug information: dump user space data. */
elf_user_dump(load_info->lwp, load_info->lwp->text_entry, 64);
/* Fill auxiliary information. */
ret = elf_aux_fill(load_info);
if (ret)
{
LOG_E("%s : elf_aux_fill failed", __func__);
return ret;
}
return RT_EOK;
}
/**
* @brief Clean up resources allocated during ELF loading.
*
* This function releases all resources (file descriptors, memory, etc.) that were
* allocated during the ELF loading process. It ensures that no memory leaks occur
* and all file descriptors are properly closed.
*
* @param load_info Pointer to the structure containing ELF loading information.
*/
static void elf_load_deinit(elf_load_info_t *load_info)
{
if (load_info->exec_info.fd != ELF_INVALID_FD)
{
elf_file_close(load_info->exec_info.fd);
}
if (load_info->interp_info.fd != ELF_INVALID_FD)
{
elf_file_close(load_info->interp_info.fd);
}
if (load_info->exec_info.phdr != RT_NULL)
{
rt_free(load_info->exec_info.phdr);
}
if (load_info->exec_info.filename != RT_NULL)
{
rt_free(load_info->exec_info.filename);
}
if (load_info->interp_info.phdr != RT_NULL)
{
rt_free(load_info->interp_info.phdr);
}
if (load_info->interp_info.filename != RT_NULL)
{
rt_free(load_info->interp_info.filename);
}
}
/**
* @brief Load the ELF header and program header information.
*
* @param exec_info Pointer to the elf_info_t structure containing elf file information.
*
* @return RT_EOK if the ELF header and program header information are successfully loaded.
* @return -RT_ERROR if any error occurs during the loading process.
*/
static int elf_load_app(elf_info_t *exec_info)
{
int ret;
/* load elf header */
ret = elf_load_ehdr(exec_info);
if (ret != RT_EOK)
{
return ret;
}
/* load the ELF program header */
ret = elf_load_phdr(exec_info);
if (ret != RT_EOK)
{
return ret;
}
return ret;
}
/**
* @brief Load an ELF file into memory.
*
* @param load_info Pointer to the elf_load_info_t structure containing information about the ELF file.
*
* @return RT_EOK if the ELF file is successfully loaded.
* @return -RT_ERROR if any error occurs during the loading process.
*/
static int elf_file_load(elf_load_info_t *load_info)
{
int ret;
/* Load basic information of the ELF application (ELF header and program header) */
ret = elf_load_app(&load_info->exec_info);
if (ret != RT_EOK)
{
goto OUT;
}
/* Load the interpreter (if any) */
ret = elf_load_interp(load_info);
if (ret != RT_EOK)
{
goto OUT;
}
/* Load each segment of the ELF file into memory */
ret = elf_load_segment(load_info);
if (ret != RT_EOK)
{
goto OUT;
}
OUT:
/* Perform resource cleanup regardless of success or failure */
elf_load_deinit(load_info);
return ret;
}
/**
* @brief Load an ELF executable file into memory and prepare it for execution.
*
* This function is responsible for loading an ELF format executable file into memory,
* setting up the necessary process structures, and preparing it for execution.
*
* @param filename The path to the ELF file to be loaded.
* @param lwp Pointer to the Light Weight Process (LWP) structure that will execute the program.
* @param load_addr The memory address where the ELF should be loaded.
* @param addr_size The size of the memory area available for loading.
* @param aux_ua Pointer to the auxiliary information structure for process initialization.
*
* @return RT_EOK if the ELF file is successfully loaded and prepared for execution.
* @return -RT_ERROR if any error occurs during the loading process, including:
* - Invalid filename or path
* - Memory allocation failure
* - ELF file format errors
*
* @see dfs_normalize_path, elf_file_load
*/
int lwp_load(const char *filename, struct rt_lwp *lwp, uint8_t *load_addr, size_t addr_size,
struct process_aux *aux_ua)
{
elf_load_info_t load_info = { 0 };
int len;
int ret;
/* Validate input filename */
if (filename == RT_NULL)
{
LOG_E("%s : file is NULL", __func__);
return -RT_ERROR;
}
/* Check filename length constraints */
len = rt_strlen(filename);
if (len < FLF_PATH_MIN || len > ELF_PATH_MAX)
{
LOG_E("%s : file length (%d) invalid", __func__, len);
return -RT_ERROR;
}
/* Allocate memory for filename and copy it */
load_info.exec_info.filename = rt_malloc(len + 1);
if (!load_info.exec_info.filename)
{
LOG_E("%s : alloc filename failed", __func__, len);
return -RT_ERROR;
}
else
{
rt_memset(load_info.exec_info.filename, 0, len + 1);
rt_strncpy(load_info.exec_info.filename, filename, len);
}
/* Initialize load information structure */
load_info.lwp = lwp;
load_info.aux = aux_ua;
load_info.exec_info.fd = ELF_INVALID_FD;
load_info.interp_info.fd = ELF_INVALID_FD;
load_info.load_addr = (rt_ubase_t)load_addr;
/* copy file name to process name */
rt_strncpy(lwp->cmd, filename, RT_NAME_MAX);
lwp->exe_file = dfs_normalize_path(NULL, filename); /* malloc */
/* Load and process the ELF file */
ret = elf_file_load(&load_info);
if (ret != RT_EOK)
{
LOG_E("%s : elf_file_load error, ret : %d", __func__, ret);
return ret;
}
return RT_EOK;
}
#endif
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