diff options
Diffstat (limited to 'arch/x86/boot/compressed/misc.c')
-rw-r--r-- | arch/x86/boot/compressed/misc.c | 77 |
1 files changed, 76 insertions, 1 deletions
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 0319c88290a5..434f077d2c4d 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -271,6 +271,79 @@ static void error(char *x) asm("hlt"); } +#if CONFIG_X86_NEED_RELOCS +static void handle_relocations(void *output, unsigned long output_len) +{ + int *reloc; + unsigned long delta, map, ptr; + unsigned long min_addr = (unsigned long)output; + unsigned long max_addr = min_addr + output_len; + + /* + * Calculate the delta between where vmlinux was linked to load + * and where it was actually loaded. + */ + delta = min_addr - LOAD_PHYSICAL_ADDR; + if (!delta) { + debug_putstr("No relocation needed... "); + return; + } + debug_putstr("Performing relocations... "); + + /* + * The kernel contains a table of relocation addresses. Those + * addresses have the final load address of the kernel in virtual + * memory. We are currently working in the self map. So we need to + * create an adjustment for kernel memory addresses to the self map. + * This will involve subtracting out the base address of the kernel. + */ + map = delta - __START_KERNEL_map; + + /* + * Process relocations: 32 bit relocations first then 64 bit after. + * Two sets of binary relocations are added to the end of the kernel + * before compression. Each relocation table entry is the kernel + * address of the location which needs to be updated stored as a + * 32-bit value which is sign extended to 64 bits. + * + * Format is: + * + * kernel bits... + * 0 - zero terminator for 64 bit relocations + * 64 bit relocation repeated + * 0 - zero terminator for 32 bit relocations + * 32 bit relocation repeated + * + * So we work backwards from the end of the decompressed image. + */ + for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { + int extended = *reloc; + extended += map; + + ptr = (unsigned long)extended; + if (ptr < min_addr || ptr > max_addr) + error("32-bit relocation outside of kernel!\n"); + + *(uint32_t *)ptr += delta; + } +#ifdef CONFIG_X86_64 + for (reloc--; *reloc; reloc--) { + long extended = *reloc; + extended += map; + + ptr = (unsigned long)extended; + if (ptr < min_addr || ptr > max_addr) + error("64-bit relocation outside of kernel!\n"); + + *(uint64_t *)ptr += delta; + } +#endif +} +#else +static inline void handle_relocations(void *output, unsigned long output_len) +{ } +#endif + static void parse_elf(void *output) { #ifdef CONFIG_X86_64 @@ -325,7 +398,8 @@ static void parse_elf(void *output) asmlinkage void decompress_kernel(void *rmode, memptr heap, unsigned char *input_data, unsigned long input_len, - unsigned char *output) + unsigned char *output, + unsigned long output_len) { real_mode = rmode; @@ -365,6 +439,7 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap, debug_putstr("\nDecompressing Linux... "); decompress(input_data, input_len, NULL, NULL, output, NULL, error); parse_elf(output); + handle_relocations(output, output_len); debug_putstr("done.\nBooting the kernel.\n"); return; } |