diff options
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 66 |
1 files changed, 52 insertions, 14 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index b4e576600969..d374cb3cf024 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -115,6 +115,7 @@ static void __init_or_module add_nops(void *insns, unsigned int len) } extern s32 __retpoline_sites[], __retpoline_sites_end[]; +extern s32 __ibt_endbr_seal[], __ibt_endbr_seal_end[]; extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; extern s32 __smp_locks[], __smp_locks_end[]; void text_poke_early(void *addr, const void *opcode, size_t len); @@ -512,6 +513,42 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end) { } #endif /* CONFIG_RETPOLINE && CONFIG_STACK_VALIDATION */ +#ifdef CONFIG_X86_KERNEL_IBT + +/* + * Generated by: objtool --ibt + */ +void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end) +{ + s32 *s; + + for (s = start; s < end; s++) { + u32 endbr, poison = gen_endbr_poison(); + void *addr = (void *)s + *s; + + if (WARN_ON_ONCE(get_kernel_nofault(endbr, addr))) + continue; + + if (WARN_ON_ONCE(!is_endbr(endbr))) + continue; + + DPRINTK("ENDBR at: %pS (%px)", addr, addr); + + /* + * When we have IBT, the lack of ENDBR will trigger #CP + */ + DUMP_BYTES(((u8*)addr), 4, "%px: orig: ", addr); + DUMP_BYTES(((u8*)&poison), 4, "%px: repl: ", addr); + text_poke_early(addr, &poison, 4); + } +} + +#else + +void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end) { } + +#endif /* CONFIG_X86_KERNEL_IBT */ + #ifdef CONFIG_SMP static void alternatives_smp_lock(const s32 *start, const s32 *end, u8 *text, u8 *text_end) @@ -713,34 +750,39 @@ asm ( " .pushsection .init.text, \"ax\", @progbits\n" " .type int3_magic, @function\n" "int3_magic:\n" + ANNOTATE_NOENDBR " movl $1, (%" _ASM_ARG1 ")\n" ASM_RET " .size int3_magic, .-int3_magic\n" " .popsection\n" ); -extern __initdata unsigned long int3_selftest_ip; /* defined in asm below */ +extern void int3_selftest_ip(void); /* defined in asm below */ static int __init int3_exception_notify(struct notifier_block *self, unsigned long val, void *data) { + unsigned long selftest = (unsigned long)&int3_selftest_ip; struct die_args *args = data; struct pt_regs *regs = args->regs; + OPTIMIZER_HIDE_VAR(selftest); + if (!regs || user_mode(regs)) return NOTIFY_DONE; if (val != DIE_INT3) return NOTIFY_DONE; - if (regs->ip - INT3_INSN_SIZE != int3_selftest_ip) + if (regs->ip - INT3_INSN_SIZE != selftest) return NOTIFY_DONE; int3_emulate_call(regs, (unsigned long)&int3_magic); return NOTIFY_STOP; } -static void __init int3_selftest(void) +/* Must be noinline to ensure uniqueness of int3_selftest_ip. */ +static noinline void __init int3_selftest(void) { static __initdata struct notifier_block int3_exception_nb = { .notifier_call = int3_exception_notify, @@ -753,18 +795,12 @@ static void __init int3_selftest(void) /* * Basically: int3_magic(&val); but really complicated :-) * - * Stick the address of the INT3 instruction into int3_selftest_ip, - * then trigger the INT3, padded with NOPs to match a CALL instruction - * length. + * INT3 padded with NOP to CALL_INSN_SIZE. The int3_exception_nb + * notifier above will emulate CALL for us. */ - asm volatile ("1: int3; nop; nop; nop; nop\n\t" - ".pushsection .init.data,\"aw\"\n\t" - ".align " __ASM_SEL(4, 8) "\n\t" - ".type int3_selftest_ip, @object\n\t" - ".size int3_selftest_ip, " __ASM_SEL(4, 8) "\n\t" - "int3_selftest_ip:\n\t" - __ASM_SEL(.long, .quad) " 1b\n\t" - ".popsection\n\t" + asm volatile ("int3_selftest_ip:\n\t" + ANNOTATE_NOENDBR + " int3; nop; nop; nop; nop\n\t" : ASM_CALL_CONSTRAINT : __ASM_SEL_RAW(a, D) (&val) : "memory"); @@ -831,6 +867,8 @@ void __init alternative_instructions(void) */ apply_alternatives(__alt_instructions, __alt_instructions_end); + apply_ibt_endbr(__ibt_endbr_seal, __ibt_endbr_seal_end); + #ifdef CONFIG_SMP /* Patch to UP if other cpus not imminent. */ if (!noreplace_smp && (num_present_cpus() == 1 || setup_max_cpus <= 1)) { |