arch/arc/lib/relocate.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2013-2014 Synopsys, Inc. All rights reserved.
   4  */
   5
   6 #include <common.h>
   7 #include <elf.h>
   8 #include <asm-generic/sections.h>
   9
  10 extern ulong __image_copy_start;
  11 extern ulong __ivt_start;
  12 extern ulong __ivt_end;
  13 extern ulong __text_end;
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 int copy_uboot_to_ram(void)
  18 {
  19         size_t len = (size_t)&__image_copy_end - (size_t)&__image_copy_start;
  20
  21         if (gd->flags & GD_FLG_SKIP_RELOC)
  22                 return 0;
  23
  24         memcpy((void *)gd->relocaddr, (void *)&__image_copy_start, len);
  25
  26         return 0;
  27 }
  28
  29 int clear_bss(void)
  30 {
  31         ulong dst_addr = (ulong)&__bss_start + gd->reloc_off;
  32         size_t len = (size_t)&__bss_end - (size_t)&__bss_start;
  33
  34         memset((void *)dst_addr, 0x00, len);
  35
  36         return 0;
  37 }
  38
  39 /*
  40  * Base functionality is taken from x86 version with added ARC-specifics
  41  */
  42 int do_elf_reloc_fixups(void)
  43 {
  44         Elf32_Rela *re_src = (Elf32_Rela *)(&__rel_dyn_start);
  45         Elf32_Rela *re_end = (Elf32_Rela *)(&__rel_dyn_end);
  46
  47         if (gd->flags & GD_FLG_SKIP_RELOC)
  48                 return 0;
  49
  50         debug("Section .rela.dyn is located at %08x-%08x\n",
  51               (unsigned int)re_src, (unsigned int)re_end);
  52
  53         Elf32_Addr *offset_ptr_rom;
  54         Elf32_Addr *offset_ptr_ram;
  55
  56         do {
  57                 /* Get the location from the relocation entry */
  58                 offset_ptr_rom = (Elf32_Addr *)re_src->r_offset;
  59
  60                 /* Check that the location of the relocation is in .text */
  61                 if (offset_ptr_rom >= (Elf32_Addr *)&__image_copy_start &&
  62                     offset_ptr_rom < (Elf32_Addr *)&__image_copy_end) {
  63                         unsigned int val, do_swap = 0;
  64                         /* Switch to the in-RAM version */
  65                         offset_ptr_ram = (Elf32_Addr *)((ulong)offset_ptr_rom +
  66                                                         gd->reloc_off);
  67
  68 #ifdef __LITTLE_ENDIAN__
  69                         /* If location in ".text" section swap value */
  70                         if (((u32)offset_ptr_rom >= (u32)&__text_start &&
  71                              (u32)offset_ptr_rom <= (u32)&__text_end)
  72 #if defined(__ARC700__) || defined(__ARC600__)
  73                             || ((u32)offset_ptr_rom >= (u32)&__ivt_start &&
  74                                 (u32)offset_ptr_rom <= (u32)&__ivt_end)
  75 #endif
  76                            )
  77                                 do_swap = 1;
  78 #endif
  79
  80                         debug("Patching value @ %08x (relocated to %08x)%s\n",
  81                               (unsigned int)offset_ptr_rom,
  82                               (unsigned int)offset_ptr_ram,
  83                               do_swap ? ", middle-endian encoded" : "");
  84
  85                         /*
  86                          * Use "memcpy" because target location might be
  87                          * 16-bit aligned on ARC so we may need to read
  88                          * byte-by-byte. On attempt to read entire word by
  89                          * CPU throws an exception
  90                          */
  91                         memcpy(&val, offset_ptr_ram, sizeof(int));
  92
  93                         if (do_swap)
  94                                 val = (val << 16) | (val >> 16);
  95
  96                         /* Check that the target points into executable */
  97                         if (val < (unsigned int)&__image_copy_start ||
  98                             val > (unsigned int)&__image_copy_end) {
  99                                 /* TODO: Use panic() instead of debug()
 100                                  *
 101                                  * For some reason GCC might generate
 102                                  * fake relocation even for LD/SC of constant
 103                                  * inderectly. See an example below:
 104                                  * ----------------------->8--------------------
 105                                  * static int setup_mon_len(void)
 106                                  * {
 107                                  *         gd->mon_len = (ulong)&__bss_end - CONFIG_SYS_MONITOR_BASE;
 108                                  *         return 0;
 109                                  * }
 110                                  * ----------------------->8--------------------
 111                                  *
 112                                  * And that's what we get in the binary:
 113                                  * ----------------------->8--------------------
 114                                  * 10005cb4 <setup_mon_len>:
 115                                  * 10005cb4:       193c 3f80 0003 2f80     st      0x32f80,[r25,60]
 116                                  *                         10005cb8: R_ARC_RELATIVE        *ABS*-0x10000000
 117                                  * 10005cbc:       7fe0                    j_s.d   [blink]
 118                                  * 10005cbe:       700c                    mov_s   r0,0
 119                                  * ----------------------->8--------------------
 120                                  */
 121                                 debug("Relocation target %08x points outside of image\n",
 122                                       val);
 123                         }
 124
 125                         val += gd->reloc_off;
 126
 127                         if (do_swap)
 128                                 val = (val << 16) | (val >> 16);
 129
 130                         memcpy(offset_ptr_ram, &val, sizeof(int));
 131                 }
 132         } while (++re_src < re_end);
 133
 134         return 0;
 135 }