diff options
Diffstat (limited to 'arch/i386/kernel/kprobes.c')
| -rw-r--r-- | arch/i386/kernel/kprobes.c | 97 |
1 files changed, 71 insertions, 26 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index 38806f42784..727e419ad78 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -57,34 +57,85 @@ static __always_inline void set_jmp_op(void *from, void *to) /* * returns non-zero if opcodes can be boosted. */ -static __always_inline int can_boost(kprobe_opcode_t opcode) +static __always_inline int can_boost(kprobe_opcode_t *opcodes) { - switch (opcode & 0xf0 ) { +#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ + (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ + (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ + (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ + (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ + << (row % 32)) + /* + * Undefined/reserved opcodes, conditional jump, Opcode Extension + * Groups, and some special opcodes can not be boost. + */ + static const unsigned long twobyte_is_boostable[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ------------------------------- */ + W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */ + W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */ + W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */ + W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */ + W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */ + W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */ + W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */ + W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */ + W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */ + W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */ + W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */ + W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */ + W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */ + W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */ + W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */ + W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */ + /* ------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + }; +#undef W + kprobe_opcode_t opcode; + kprobe_opcode_t *orig_opcodes = opcodes; +retry: + if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) + return 0; + opcode = *(opcodes++); + + /* 2nd-byte opcode */ + if (opcode == 0x0f) { + if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) + return 0; + return test_bit(*opcodes, twobyte_is_boostable); + } + + switch (opcode & 0xf0) { + case 0x60: + if (0x63 < opcode && opcode < 0x67) + goto retry; /* prefixes */ + /* can't boost Address-size override and bound */ + return (opcode != 0x62 && opcode != 0x67); case 0x70: return 0; /* can't boost conditional jump */ - case 0x90: - /* can't boost call and pushf */ - return opcode != 0x9a && opcode != 0x9c; case 0xc0: - /* can't boost undefined opcodes and soft-interruptions */ - return (0xc1 < opcode && opcode < 0xc6) || - (0xc7 < opcode && opcode < 0xcc) || opcode == 0xcf; + /* can't boost software-interruptions */ + return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; case 0xd0: /* can boost AA* and XLAT */ return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); case 0xe0: - /* can boost in/out and (may be) jmps */ - return (0xe3 < opcode && opcode != 0xe8); + /* can boost in/out and absolute jmps */ + return ((opcode & 0x04) || opcode == 0xea); case 0xf0: + if ((opcode & 0x0c) == 0 && opcode != 0xf1) + goto retry; /* lock/rep(ne) prefix */ /* clear and set flags can be boost */ return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); default: - /* currently, can't boost 2 bytes opcodes */ - return opcode != 0x0f; + if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) + goto retry; /* prefixes */ + /* can't boost CS override and call */ + return (opcode != 0x2e && opcode != 0x9a); } } - /* * returns non-zero if opcode modifies the interrupt flag. */ @@ -109,7 +160,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); p->opcode = *p->addr; - if (can_boost(p->opcode)) { + if (can_boost(p->addr)) { p->ainsn.boostable = 0; } else { p->ainsn.boostable = -1; @@ -208,7 +259,9 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) struct kprobe_ctlblk *kcb; #ifdef CONFIG_PREEMPT unsigned pre_preempt_count = preempt_count(); -#endif /* CONFIG_PREEMPT */ +#else + unsigned pre_preempt_count = 1; +#endif addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t)); @@ -285,22 +338,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) /* handler has already set things up, so skip ss setup */ return 1; - if (p->ainsn.boostable == 1 && -#ifdef CONFIG_PREEMPT - !(pre_preempt_count) && /* - * This enables booster when the direct - * execution path aren't preempted. - */ -#endif /* CONFIG_PREEMPT */ - !p->post_handler && !p->break_handler ) { +ss_probe: + if (pre_preempt_count && p->ainsn.boostable == 1 && !p->post_handler){ /* Boost up -- we can execute copied instructions directly */ reset_current_kprobe(); regs->eip = (unsigned long)p->ainsn.insn; preempt_enable_no_resched(); return 1; } - -ss_probe: prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_HIT_SS; return 1; @@ -607,7 +652,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, struct die_args *args = (struct die_args *)data; int ret = NOTIFY_DONE; - if (args->regs && user_mode(args->regs)) + if (args->regs && user_mode_vm(args->regs)) return ret; switch (val) { |