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Diffstat (limited to 'arch/mips/lib/reloc.c')
-rw-r--r-- | arch/mips/lib/reloc.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/arch/mips/lib/reloc.c b/arch/mips/lib/reloc.c new file mode 100644 index 00000000000..d0c52c9674f --- /dev/null +++ b/arch/mips/lib/reloc.c @@ -0,0 +1,164 @@ +/* + * MIPS Relocation + * + * Copyright (c) 2017 Imagination Technologies Ltd. + * + * SPDX-License-Identifier: GPL-2.0+ + * + * Relocation data, found in the .rel section, is generated by the mips-relocs + * tool & contains a record of all locations in the U-Boot binary that need to + * be fixed up during relocation. + * + * The data is a sequence of unsigned integers, which are of somewhat arbitrary + * size. This is achieved by encoding integers as a sequence of bytes, each of + * which contains 7 bits of data with the most significant bit indicating + * whether any further bytes need to be read. The least significant bits of the + * integer are found in the first byte - ie. it somewhat resembles little + * endian. + * + * Each pair of two integers represents a relocation that must be applied. The + * first integer represents the type of relocation as a standard ELF relocation + * type (ie. R_MIPS_*). The second integer represents the offset at which to + * apply the relocation, relative to the previous relocation or for the first + * relocation the start of the relocated .text section. + * + * The end of the relocation data is indicated when type R_MIPS_NONE (0) is + * read, at which point no further integers should be read. That is, the + * terminating R_MIPS_NONE reloc includes no offset. + */ + +#include <common.h> +#include <asm/relocs.h> +#include <asm/sections.h> + +/** + * read_uint() - Read an unsigned integer from the buffer + * @buf: pointer to a pointer to the reloc buffer + * + * Read one whole unsigned integer from the relocation data pointed to by @buf, + * advancing @buf past the bytes encoding the integer. + * + * Returns: the integer read from @buf + */ +static unsigned long read_uint(uint8_t **buf) +{ + unsigned long val = 0; + unsigned int shift = 0; + uint8_t new; + + do { + new = *(*buf)++; + val |= (new & 0x7f) << shift; + shift += 7; + } while (new & 0x80); + + return val; +} + +/** + * apply_reloc() - Apply a single relocation + * @type: the type of reloc (R_MIPS_*) + * @addr: the address that the reloc should be applied to + * @off: the relocation offset, ie. number of bytes we're moving U-Boot by + * + * Apply a single relocation of type @type at @addr. This function is + * intentionally simple, and does the bare minimum needed to fixup the + * relocated U-Boot - in particular, it does not check for overflows. + */ +static void apply_reloc(unsigned int type, void *addr, long off) +{ + uint32_t u32; + + switch (type) { + case R_MIPS_26: + u32 = *(uint32_t *)addr; + u32 = (u32 & GENMASK(31, 26)) | + ((u32 + (off >> 2)) & GENMASK(25, 0)); + *(uint32_t *)addr = u32; + break; + + case R_MIPS_32: + *(uint32_t *)addr += off; + break; + + case R_MIPS_64: + *(uint64_t *)addr += off; + break; + + case R_MIPS_HI16: + *(uint32_t *)addr += off >> 16; + break; + + default: + panic("Unhandled reloc type %u\n", type); + } +} + +/** + * relocate_code() - Relocate U-Boot, generally from flash to DDR + * @start_addr_sp: new stack pointer + * @new_gd: pointer to relocated global data + * @relocaddr: the address to relocate to + * + * Relocate U-Boot from its current location (generally in flash) to a new one + * (generally in DDR). This function will copy the U-Boot binary & apply + * relocations as necessary, then jump to board_init_r in the new build of + * U-Boot. As such, this function does not return. + */ +void relocate_code(ulong start_addr_sp, gd_t *new_gd, ulong relocaddr) +{ + unsigned long addr, length, bss_len; + uint8_t *buf, *bss_start; + unsigned int type; + long off; + + /* + * Ensure that we're relocating by an offset which is a multiple of + * 64KiB, ie. doesn't change the least significant 16 bits of any + * addresses. This allows us to discard R_MIPS_LO16 relocs, saving + * space in the U-Boot binary & complexity in handling them. + */ + off = relocaddr - (unsigned long)__text_start; + if (off & 0xffff) + panic("Mis-aligned relocation\n"); + + /* Copy U-Boot to RAM */ + length = __image_copy_end - __text_start; + memcpy((void *)relocaddr, __text_start, length); + + /* Now apply relocations to the copy in RAM */ + buf = __rel_start; + addr = relocaddr; + while (true) { + type = read_uint(&buf); + if (type == R_MIPS_NONE) + break; + + addr += read_uint(&buf) << 2; + apply_reloc(type, (void *)addr, off); + } + + /* Ensure the icache is coherent */ + flush_cache(relocaddr, length); + + /* Clear the .bss section */ + bss_start = (uint8_t *)((unsigned long)__bss_start + off); + bss_len = (unsigned long)&__bss_end - (unsigned long)__bss_start; + memset(bss_start, 0, bss_len); + + /* Jump to the relocated U-Boot */ + asm volatile( + "move $29, %0\n" + " move $4, %1\n" + " move $5, %2\n" + " move $31, $0\n" + " jr %3" + : /* no outputs */ + : "r"(start_addr_sp), + "r"(new_gd), + "r"(relocaddr), + "r"((unsigned long)board_init_r + off)); + + /* Since we jumped to the new U-Boot above, we won't get here */ + unreachable(); +} |