source: trunk/softs/tsar_boot/src/reset_elf_loader.c

Last change on this file was 992, checked in by alain, 9 years ago

Introduce a new driver for SD Card using the 4bits wide SD bus.
THere is now 5 supported block device peripherals, and the driver names
have been re-organised: reset_ioc_xxx with xxx in (bdv, hba, rdk, spi, sdc)

File size: 4.2 KB
Line 
1/**
2 * \file    : reset_elf_loader.c
3 * \date    : August 2012
4 * \author  : Cesar Fuguet
5 *
6 * This file defines an elf file loader which reads an executable .elf file
7 * starting at a sector passed as argument on a disk and copy the different
8 * ELF program segments in the appropriate memory address using as information
9 * the virtual address read from the .elf file.
10 */
11
12#include <reset_ioc.h>
13#include <elf-types.h>
14#include <reset_tty.h>
15#include <reset_utils.h>
16#include <defs.h>
17
18extern int blk_buf_idx;
19extern int dtb_start, dtb_end;
20
21addr_t dtb_addr;
22
23///////////////////////////////////////////////////////////////////////////////
24void * reset_elf_loader(size_t lba)
25///////////////////////////////////////////////////////////////////////////////
26{
27    size_t file_offset = lba * BLOCK_SIZE;
28
29    reset_puts("\n[RESET] Start reset_elf_loader at cycle ");
30    reset_putd( proctime() );
31    reset_puts("\n");
32
33    /*
34     * Init the cache block index
35     */
36    blk_buf_idx = -1;
37
38    /*
39     * Load ELF HEADER
40     */
41    Elf32_Ehdr elf_header;
42    if (pread(file_offset, (void*)&elf_header, sizeof(Elf32_Ehdr), 0) < 0) {
43        goto error;
44    }
45
46#if (RESET_DEBUG > 1)
47    reset_display_block( (char*)&elf_header );
48#endif
49
50    check_elf_header(&elf_header);
51
52    /*
53     * Load ELF PROGRAM HEADER TABLE
54     */
55    Elf32_Phdr elf_pht[RESET_PHDR_ARRAY_SIZE];
56    size_t phdr_nbyte = sizeof(Elf32_Phdr) * elf_header.e_phnum;
57    size_t phdr_off = elf_header.e_phoff;
58    if (pread(file_offset, (void*)&elf_pht, phdr_nbyte, phdr_off) < 0) {
59        goto error;
60    }
61
62    /*
63     * Search for loadable segments in the ELF file
64     */
65    int pseg;
66    for (pseg = 0; pseg < elf_header.e_phnum; pseg++) {
67        if(elf_pht[pseg].p_type != PT_LOAD) continue;
68
69#if (RESET_DEBUG == 1)
70        reset_puts("\n[RESET DEBUG] Loadable segment found:\n");
71        reset_print_elf_phdr(&elf_pht[pseg]);
72#endif
73
74        addr_t p_paddr = elf_pht[pseg].p_paddr;
75        size_t p_filesz = elf_pht[pseg].p_filesz;
76        size_t p_memsz = elf_pht[pseg].p_memsz;
77        size_t p_offset = elf_pht[pseg].p_offset;
78
79        /*
80         * Copy program segment from ELF executable into corresponding physical
81         * address
82         */
83        if (pread(file_offset, (void*)p_paddr, p_filesz, p_offset) < 0) {
84            goto error;
85        }
86
87        /*
88         * Fill remaining bytes with zero (filesz < memsz)
89         */
90        char* pseg_ptr = (char*)p_paddr;
91        memset((void*)&pseg_ptr[p_filesz], 0, (p_memsz - p_filesz));
92
93        reset_puts("\n[RESET] Segment loaded : address = ");
94        reset_putx(p_paddr);
95        reset_puts(" / size = ");
96        reset_putx(p_filesz);
97        reset_puts("\n");
98    }
99
100    if (pseg == 0) {
101        reset_puts("\n[RESET ERROR] No loadable segments");
102        goto error;
103    }
104
105    /* By default, the used device tree is the one in the ROM */
106    dtb_addr = (addr_t)&dtb_start;
107
108#if OS_LINUX
109    /* When loading a Linux kernel, the device tree should be located in low
110     * memory addresses before the kernel itself.
111     * - When the ROM-contained DTB is located before the kernel no need to copy
112     *   the DTB elsewhere.
113     * - When the ROM-contained DTB is located after the kernel the DTB is
114     *   copied before the kernel. */
115    const int copy_dtb = ((addr_t)&dtb_start > elf_pht[0].p_paddr);
116    if (copy_dtb) {
117        size_t dtb_size = (size_t)&dtb_end - (size_t)&dtb_start;
118        dtb_addr = SEG_RAM_BASE;
119        if ((dtb_addr + (addr_t)dtb_size) >= elf_pht[0].p_paddr) {
120            reset_puts("\n[RESET ERROR] Insufficient space to copy the DTB");
121            goto error;
122        }
123
124        memcpy((void*)dtb_addr, (void*)&dtb_start, dtb_size);
125        reset_puts("\n[RESET] Device tree blob copied / address = ");
126        reset_putx(dtb_addr);
127        reset_puts(" / size = ");
128        reset_putx(dtb_size);
129    }
130#endif
131
132    reset_puts("\n[RESET] Complete reset_elf_loader at cycle ");
133    reset_putd(proctime());
134    reset_puts(" / boot entry = ");
135    reset_putx((addr_t)elf_header.e_entry);
136    reset_puts("\n");
137
138    return ((void*)elf_header.e_entry);
139
140error:
141    reset_puts("\n[RESET ERROR] Error while loading ELF file");
142    reset_exit();
143    return 0;
144}
145
146// vim: tabstop=4 : softtabstop=4 : shiftwidth=4 : expandtab
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