diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 944a3f73c2efce442bde8cce7b5e9c120dc9646c..45d747e92afd61f508675dba9bd50d1bd0b7f543 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1193,10 +1193,13 @@ void text_poke_sync(void) } struct text_poke_loc { - s32 rel_addr; /* addr := _stext + rel_addr */ - s32 rel32; + /* addr := _stext + rel_addr */ + s32 rel_addr; + s32 disp; + u8 len; u8 opcode; const u8 text[POKE_MAX_OPCODE_SIZE]; + /* see text_poke_bp_batch() */ u8 old; }; @@ -1211,7 +1214,8 @@ static struct bp_patching_desc *bp_desc; static __always_inline struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp) { - struct bp_patching_desc *desc = __READ_ONCE(*descp); /* rcu_dereference */ + /* rcu_dereference */ + struct bp_patching_desc *desc = __READ_ONCE(*descp); if (!desc || !arch_atomic_inc_not_zero(&desc->refs)) return NULL; @@ -1245,7 +1249,7 @@ noinstr int poke_int3_handler(struct pt_regs *regs) { struct bp_patching_desc *desc; struct text_poke_loc *tp; - int len, ret = 0; + int ret = 0; void *ip; if (user_mode(regs)) @@ -1285,8 +1289,7 @@ noinstr int poke_int3_handler(struct pt_regs *regs) goto out_put; } - len = text_opcode_size(tp->opcode); - ip += len; + ip += tp->len; switch (tp->opcode) { case INT3_INSN_OPCODE: @@ -1301,12 +1304,12 @@ noinstr int poke_int3_handler(struct pt_regs *regs) break; case CALL_INSN_OPCODE: - int3_emulate_call(regs, (long)ip + tp->rel32); + int3_emulate_call(regs, (long)ip + tp->disp); break; case JMP32_INSN_OPCODE: case JMP8_INSN_OPCODE: - int3_emulate_jmp(regs, (long)ip + tp->rel32); + int3_emulate_jmp(regs, (long)ip + tp->disp); break; default: @@ -1381,7 +1384,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries */ for (do_sync = 0, i = 0; i < nr_entries; i++) { u8 old[POKE_MAX_OPCODE_SIZE] = { tp[i].old, }; - int len = text_opcode_size(tp[i].opcode); + int len = tp[i].len; if (len - INT3_INSN_SIZE > 0) { memcpy(old + INT3_INSN_SIZE, @@ -1458,20 +1461,36 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr, const void *opcode, size_t len, const void *emulate) { struct insn insn; - int ret; + int ret, i; memcpy((void *)tp->text, opcode, len); if (!emulate) emulate = opcode; ret = insn_decode_kernel(&insn, emulate); - BUG_ON(ret < 0); - BUG_ON(len != insn.length); tp->rel_addr = addr - (void *)_stext; + tp->len = len; tp->opcode = insn.opcode.bytes[0]; + switch (tp->opcode) { + case RET_INSN_OPCODE: + case JMP32_INSN_OPCODE: + case JMP8_INSN_OPCODE: + /* + * Control flow instructions without implied execution of the + * next instruction can be padded with INT3. + */ + for (i = insn.length; i < len; i++) + BUG_ON(tp->text[i] != INT3_INSN_OPCODE); + break; + + default: + BUG_ON(len != insn.length); + }; + + switch (tp->opcode) { case INT3_INSN_OPCODE: case RET_INSN_OPCODE: @@ -1480,7 +1499,7 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr, case CALL_INSN_OPCODE: case JMP32_INSN_OPCODE: case JMP8_INSN_OPCODE: - tp->rel32 = insn.immediate.value; + tp->disp = insn.immediate.value; break; default: /* assume NOP */ @@ -1488,13 +1507,13 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr, case 2: /* NOP2 -- emulate as JMP8+0 */ BUG_ON(memcmp(emulate, ideal_nops[len], len)); tp->opcode = JMP8_INSN_OPCODE; - tp->rel32 = 0; + tp->disp = 0; break; case 5: /* NOP5 -- emulate as JMP32+0 */ BUG_ON(memcmp(emulate, ideal_nops[NOP_ATOMIC5], len)); tp->opcode = JMP32_INSN_OPCODE; - tp->rel32 = 0; + tp->disp = 0; break; default: /* unknown instruction */