From adca6dc23bc620ea95392659625200a252b97be3 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 24 Jul 2009 12:32:59 +0100 Subject: Thumb-2: Add support for loadable modules Modules compiled to Thumb-2 have two additional relocations needing to be resolved at load time, R_ARM_THM_CALL and R_ARM_THM_JUMP24, for BL and B.W instructions. The maximum Thumb-2 addressing range is +/-2^24 (+/-16MB) therefore the MODULES_VADDR macro in asm/memory.h is set to (MODULES_END - 8MB) for the Thumb-2 compiled kernel. Signed-off-by: Catalin Marinas --- arch/arm/kernel/module.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) (limited to 'arch/arm/kernel/module.c') diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c index bac03c81489d..f28c5e9c51ea 100644 --- a/arch/arm/kernel/module.c +++ b/arch/arm/kernel/module.c @@ -102,6 +102,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned long loc; Elf32_Sym *sym; s32 offset; + u32 upper, lower, sign, j1, j2; offset = ELF32_R_SYM(rel->r_info); if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) { @@ -184,6 +185,58 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, (offset & 0x0fff); break; + case R_ARM_THM_CALL: + case R_ARM_THM_JUMP24: + upper = *(u16 *)loc; + lower = *(u16 *)(loc + 2); + + /* + * 25 bit signed address range (Thumb-2 BL and B.W + * instructions): + * S:I1:I2:imm10:imm11:0 + * where: + * S = upper[10] = offset[24] + * I1 = ~(J1 ^ S) = offset[23] + * I2 = ~(J2 ^ S) = offset[22] + * imm10 = upper[9:0] = offset[21:12] + * imm11 = lower[10:0] = offset[11:1] + * J1 = lower[13] + * J2 = lower[11] + */ + sign = (upper >> 10) & 1; + j1 = (lower >> 13) & 1; + j2 = (lower >> 11) & 1; + offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) | + ((~(j2 ^ sign) & 1) << 22) | + ((upper & 0x03ff) << 12) | + ((lower & 0x07ff) << 1); + if (offset & 0x01000000) + offset -= 0x02000000; + offset += sym->st_value - loc; + + /* only Thumb addresses allowed (no interworking) */ + if (!(offset & 1) || + offset <= (s32)0xff000000 || + offset >= (s32)0x01000000) { + printk(KERN_ERR + "%s: relocation out of range, section " + "%d reloc %d sym '%s'\n", module->name, + relindex, i, strtab + sym->st_name); + return -ENOEXEC; + } + + sign = (offset >> 24) & 1; + j1 = sign ^ (~(offset >> 23) & 1); + j2 = sign ^ (~(offset >> 22) & 1); + *(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) | + ((offset >> 12) & 0x03ff)); + *(u16 *)(loc + 2) = (u16)((lower & 0xd000) | + (j1 << 13) | (j2 << 11) | + ((offset >> 1) & 0x07ff)); + upper = *(u16 *)loc; + lower = *(u16 *)(loc + 2); + break; + default: printk(KERN_ERR "%s: unknown relocation: %u\n", module->name, ELF32_R_TYPE(rel->r_info)); -- cgit v1.2.3