From 62f7970a5a063991a00fb426704bfcf7c9dc9c11 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Thu, 28 Feb 2013 19:26:16 +0000 Subject: [PATCH] x86: Add error checking to x86 relocation code This does not actually change normal behaviour, but adds a check that should detect corruption of relocation data (e.g. by using BSS data prior to relocation). Also add additional debugging output when enabled. During this investigation, two situations have been seen: 1. calculate_relocation_address(): uintptr_t size = (uintptr_t)&__bss_end - (uintptr_t)&__text_start; turns into 111166f: b8 83 c4 17 01 mov $0x117c483,%eax whih is beyond the end of bss: 0117b484 g .bss 00000000 __bss_end Somehow the __bss_end here is 255 bytes ahead. 2. do_elf_reloc_fixups(): uintptr_t size = (uintptr_t)&__bss_end - (uintptr_t)&__text_start; Here the __text_start is 0 in the file: 1111d9f: bb a0 e0 13 01 mov $0x113e0a0,%ebx 1111da4: 81 ef 00 00 00 00 sub $0x0,%edi As it happens, both of these are in pre-relocation code. For these reasons we silent check and ignore bad relocations. Signed-off-by: Simon Glass --- arch/x86/lib/relocate.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/x86/lib/relocate.c b/arch/x86/lib/relocate.c index 3a38e52ac9..3e370f2906 100644 --- a/arch/x86/lib/relocate.c +++ b/arch/x86/lib/relocate.c @@ -73,12 +73,16 @@ int clear_bss(void) return 0; } +/* + * This function has more error checking than you might expect. Please see + * the commit message for more informaiton. + */ int do_elf_reloc_fixups(void) { Elf32_Rel *re_src = (Elf32_Rel *)(&__rel_dyn_start); Elf32_Rel *re_end = (Elf32_Rel *)(&__rel_dyn_end); - Elf32_Addr *offset_ptr_rom; + Elf32_Addr *offset_ptr_rom, *last_offset = NULL; Elf32_Addr *offset_ptr_ram; /* The size of the region of u-boot that runs out of RAM. */ @@ -89,7 +93,8 @@ int do_elf_reloc_fixups(void) offset_ptr_rom = (Elf32_Addr *)re_src->r_offset; /* Check that the location of the relocation is in .text */ - if (offset_ptr_rom >= (Elf32_Addr *)CONFIG_SYS_TEXT_BASE) { + if (offset_ptr_rom >= (Elf32_Addr *)CONFIG_SYS_TEXT_BASE && + offset_ptr_rom > last_offset) { /* Switch to the in-RAM version */ offset_ptr_ram = (Elf32_Addr *)((ulong)offset_ptr_rom + @@ -100,8 +105,19 @@ int do_elf_reloc_fixups(void) *offset_ptr_ram <= (CONFIG_SYS_TEXT_BASE + size)) { *offset_ptr_ram += gd->reloc_off; + } else { + debug(" %p: rom reloc %x, ram %p, value %x," + " limit %lx\n", re_src, + re_src->r_offset, offset_ptr_ram, + *offset_ptr_ram, + CONFIG_SYS_TEXT_BASE + size); } + } else { + debug(" %p: rom reloc %x, last %p\n", re_src, + re_src->r_offset, last_offset); } + last_offset = offset_ptr_rom; + } while (++re_src < re_end); return 0; -- 2.39.5