1 // SPDX-License-Identifier: GPL-2.0+
5 * Copyright (c) 2017 Imagination Technologies Ltd.
7 * Relocation data, found in the .rel section, is generated by the mips-relocs
8 * tool & contains a record of all locations in the U-Boot binary that need to
9 * be fixed up during relocation.
11 * The data is a sequence of unsigned integers, which are of somewhat arbitrary
12 * size. This is achieved by encoding integers as a sequence of bytes, each of
13 * which contains 7 bits of data with the most significant bit indicating
14 * whether any further bytes need to be read. The least significant bits of the
15 * integer are found in the first byte - ie. it somewhat resembles little
18 * Each pair of two integers represents a relocation that must be applied. The
19 * first integer represents the type of relocation as a standard ELF relocation
20 * type (ie. R_MIPS_*). The second integer represents the offset at which to
21 * apply the relocation, relative to the previous relocation or for the first
22 * relocation the start of the relocated .text section.
24 * The end of the relocation data is indicated when type R_MIPS_NONE (0) is
25 * read, at which point no further integers should be read. That is, the
26 * terminating R_MIPS_NONE reloc includes no offset.
32 #include <asm/relocs.h>
33 #include <asm/sections.h>
34 #include <linux/bitops.h>
37 * read_uint() - Read an unsigned integer from the buffer
38 * @buf: pointer to a pointer to the reloc buffer
40 * Read one whole unsigned integer from the relocation data pointed to by @buf,
41 * advancing @buf past the bytes encoding the integer.
43 * Returns: the integer read from @buf
45 static unsigned long read_uint(uint8_t **buf)
47 unsigned long val = 0;
48 unsigned int shift = 0;
53 val |= (new & 0x7f) << shift;
61 * apply_reloc() - Apply a single relocation
62 * @type: the type of reloc (R_MIPS_*)
63 * @addr: the address that the reloc should be applied to
64 * @off: the relocation offset, ie. number of bytes we're moving U-Boot by
66 * Apply a single relocation of type @type at @addr. This function is
67 * intentionally simple, and does the bare minimum needed to fixup the
68 * relocated U-Boot - in particular, it does not check for overflows.
70 static void apply_reloc(unsigned int type, void *addr, long off)
76 u32 = *(uint32_t *)addr;
77 u32 = (u32 & GENMASK(31, 26)) |
78 ((u32 + (off >> 2)) & GENMASK(25, 0));
79 *(uint32_t *)addr = u32;
83 *(uint32_t *)addr += off;
87 *(uint64_t *)addr += off;
91 *(uint32_t *)addr += off >> 16;
95 panic("Unhandled reloc type %u\n", type);
100 * relocate_code() - Relocate U-Boot, generally from flash to DDR
101 * @start_addr_sp: new stack pointer
102 * @new_gd: pointer to relocated global data
103 * @relocaddr: the address to relocate to
105 * Relocate U-Boot from its current location (generally in flash) to a new one
106 * (generally in DDR). This function will copy the U-Boot binary & apply
107 * relocations as necessary, then jump to board_init_r in the new build of
108 * U-Boot. As such, this function does not return.
110 void relocate_code(ulong start_addr_sp, gd_t *new_gd, ulong relocaddr)
112 unsigned long addr, length, bss_len;
113 uint8_t *buf, *bss_start;
118 * Ensure that we're relocating by an offset which is a multiple of
119 * 64KiB, ie. doesn't change the least significant 16 bits of any
120 * addresses. This allows us to discard R_MIPS_LO16 relocs, saving
121 * space in the U-Boot binary & complexity in handling them.
123 off = relocaddr - (unsigned long)__text_start;
125 panic("Mis-aligned relocation\n");
127 /* Copy U-Boot to RAM */
128 length = __image_copy_end - __text_start;
129 memcpy((void *)relocaddr, __text_start, length);
131 /* Now apply relocations to the copy in RAM */
135 type = read_uint(&buf);
136 if (type == R_MIPS_NONE)
139 addr += read_uint(&buf) << 2;
140 apply_reloc(type, (void *)addr, off);
143 /* Ensure the icache is coherent */
144 flush_cache(relocaddr, length);
146 /* Clear the .bss section */
147 bss_start = (uint8_t *)((unsigned long)__bss_start + off);
148 bss_len = (unsigned long)&__bss_end - (unsigned long)__bss_start;
149 memset(bss_start, 0, bss_len);
151 /* Jump to the relocated U-Boot */
159 : "r"(start_addr_sp),
162 "r"((unsigned long)board_init_r + off));
164 /* Since we jumped to the new U-Boot above, we won't get here */