From 83803d97dae1eaf6850a45ef8ee179cc66e147dc Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 5 Jan 2015 19:29:18 +0800 Subject: ARM: kprobes: introduces checker This patch introdces 'checker' to decoding phase, and calls checkers when instruction decoding. This allows further decoding for specific instructions. This patch introduces a stub call of checkers in kprobe arch_prepare_kprobe() as an example and for further expansion. Signed-off-by: Wang Nan Reviewed-by: Jon Medhurst Reviewed-by: Masami Hiramatsu Signed-off-by: Jon Medhurst --- arch/arm/probes/decode.c | 60 +++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 54 insertions(+), 6 deletions(-) (limited to 'arch/arm/probes/decode.c') diff --git a/arch/arm/probes/decode.c b/arch/arm/probes/decode.c index 3b05d5742359..c7d442018902 100644 --- a/arch/arm/probes/decode.c +++ b/arch/arm/probes/decode.c @@ -342,6 +342,31 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = { [DECODE_TYPE_REJECT] = sizeof(struct decode_reject) }; +static int run_checkers(const struct decode_checker *checkers[], + int action, probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + const struct decode_checker **p; + + if (!checkers) + return INSN_GOOD; + + p = checkers; + while (*p != NULL) { + int retval; + probes_check_t *checker_func = (*p)[action].checker; + + retval = INSN_GOOD; + if (checker_func) + retval = checker_func(insn, asi, h); + if (retval == INSN_REJECTED) + return retval; + p++; + } + return INSN_GOOD; +} + /* * probes_decode_insn operates on data tables in order to decode an ARM * architecture instruction onto which a kprobe has been placed. @@ -388,11 +413,17 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = { int __kprobes probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, const union decode_item *table, bool thumb, - bool emulate, const union decode_action *actions) + bool emulate, const union decode_action *actions, + const struct decode_checker *checkers[]) { const struct decode_header *h = (struct decode_header *)table; const struct decode_header *next; bool matched = false; + /* + * @insn can be modified by decode_regs. Save its original + * value for checkers. + */ + probes_opcode_t origin_insn = insn; if (emulate) insn = prepare_emulated_insn(insn, asi, thumb); @@ -422,24 +453,41 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, } case DECODE_TYPE_CUSTOM: { + int err; struct decode_custom *d = (struct decode_custom *)h; - return actions[d->decoder.action].decoder(insn, asi, h); + int action = d->decoder.action; + + err = run_checkers(checkers, action, origin_insn, asi, h); + if (err == INSN_REJECTED) + return INSN_REJECTED; + return actions[action].decoder(insn, asi, h); } case DECODE_TYPE_SIMULATE: { + int err; struct decode_simulate *d = (struct decode_simulate *)h; - asi->insn_handler = actions[d->handler.action].handler; + int action = d->handler.action; + + err = run_checkers(checkers, action, origin_insn, asi, h); + if (err == INSN_REJECTED) + return INSN_REJECTED; + asi->insn_handler = actions[action].handler; return INSN_GOOD_NO_SLOT; } case DECODE_TYPE_EMULATE: { + int err; struct decode_emulate *d = (struct decode_emulate *)h; + int action = d->handler.action; + + err = run_checkers(checkers, action, origin_insn, asi, h); + if (err == INSN_REJECTED) + return INSN_REJECTED; if (!emulate) - return actions[d->handler.action].decoder(insn, - asi, h); + return actions[action].decoder(insn, asi, h); - asi->insn_handler = actions[d->handler.action].handler; + asi->insn_handler = actions[action].handler; set_emulated_insn(insn, asi, thumb); return INSN_GOOD; } -- cgit v1.2.3