elfloader-arm.c

00001 #include <stdlib.h>
00002 #include <malloc.h>
00003 #include <loader/elfloader-arch-otf.h>
00004 
00005 #if 0
00006 #include <stdio.h>
00007 #define PRINTF(...) printf(__VA_ARGS__)
00008 #else
00009 #define PRINTF(...) do {} while (0)
00010 #endif
00011 
00012 #define ELF32_R_TYPE(info)      ((unsigned char)(info))
00013 
00014 /* Supported relocations */
00015 
00016 #define R_ARM_ABS32     2
00017 #define R_ARM_THM_CALL  10
00018 
00019 /* Adapted from elfloader-avr.c */
00020 
00021 int
00022 elfloader_arch_relocate(int input_fd,
00023                         struct elfloader_output *output,
00024                         unsigned int sectionoffset,
00025                         char *sectionaddr,
00026                         struct elf32_rela *rela, char *addr)
00027 {
00028   unsigned int type;
00029 
00030   type = ELF32_R_TYPE(rela->r_info);
00031 
00032   cfs_seek(input_fd, sectionoffset + rela->r_offset, CFS_SEEK_SET);
00033 
00034 /*   PRINTF("elfloader_arch_relocate: type %d\n", type); */
00035 /*   PRINTF("Addr: %p, Addend: %ld\n",   addr, rela->r_addend); */
00036   switch(type) {
00037   case R_ARM_ABS32:
00038     {
00039       int32_t addend;
00040       cfs_read(input_fd, (char*)&addend, 4);
00041       addr += addend;
00042       elfloader_output_write_segment(output,(char*) &addr, 4);
00043       PRINTF("%p: addr: %p\n", sectionaddr +rela->r_offset,
00044              addr);
00045     }
00046     break;
00047   case R_ARM_THM_CALL:
00048     {
00049       uint16_t instr[2];
00050       int32_t offset;
00051       char *base;
00052       cfs_read(input_fd, (char*)instr, 4);
00053       /* Ignore the addend since it will be zero for calls to symbols,
00054          and I can't think of a case when doing a relative call to
00055          a non-symbol position */
00056       base = sectionaddr + (rela->r_offset + 4);
00057 
00058       if (((instr[1]) & 0xe800) == 0xe800) {
00059         /* BL or BLX */
00060         if (((uint32_t)addr) & 0x1) {
00061           /* BL */
00062           instr[1] |= 0x1800;
00063         } else {
00064 #if defined(__ARM_ARCH_4T__)
00065           return ELFLOADER_UNHANDLED_RELOC;
00066 #else
00067           /* BLX */
00068           instr[1] &= ~0x1800;
00069           instr[1] |= 0x0800;
00070 #endif
00071         }
00072       }
00073       /* Adjust address for BLX */
00074       if ((instr[1] & 0x1800) == 0x0800) {
00075         addr = (char*)((((uint32_t)addr) & 0xfffffffd)
00076                        | (((uint32_t)base) & 0x00000002));
00077       }
00078       offset = addr -  (sectionaddr + (rela->r_offset + 4));
00079       if (offset < -(1<<22) || offset >= (1<<22)) {
00080         PRINTF("elfloader-arm.c: offset %d too large for relative call\n",
00081                (int)offset);
00082       }
00083     /*   PRINTF("%p: %04x %04x  offset: %d addr: %p\n", sectionaddr +rela->r_offset, instr[0], instr[1], (int)offset, addr);  */
00084       instr[0] = (instr[0] & 0xf800) | ((offset>>12)&0x07ff);
00085       instr[1] = (instr[1] & 0xf800) | ((offset>>1)&0x07ff);
00086       elfloader_output_write_segment(output, (char*)instr, 4);
00087   /*     PRINTF("cfs_write: %04x %04x\n",instr[0], instr[1]);  */
00088     }
00089     break;
00090     
00091   default:
00092     PRINTF("elfloader-arm.c: unsupported relocation type %d\n", type);
00093     return ELFLOADER_UNHANDLED_RELOC;
00094   }
00095   return ELFLOADER_OK;
00096 }

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