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[209.132.180.67]) by mx.google.com with ESMTP id kt6si7779455pbc.47.2015.01.13.08.13.59; Tue, 13 Jan 2015 08:14:00 -0800 (PST) Received-SPF: none (google.com: linux-kernel-owner@vger.kernel.org does not designate permitted sender hosts) client-ip=209.132.180.67; Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752870AbbAMQN4 (ORCPT + 27 others); Tue, 13 Jan 2015 11:13:56 -0500 Received: from smarthost01c.mail.zen.net.uk ([212.23.1.5]:45611 "EHLO smarthost01c.mail.zen.net.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751452AbbAMQNy (ORCPT ); Tue, 13 Jan 2015 11:13:54 -0500 Received: from [82.69.122.217] (helo=linaro1) by smarthost01c.mail.zen.net.uk with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1YB46H-0001QG-1h; Tue, 13 Jan 2015 16:13:49 +0000 Message-ID: <1421165628.4215.63.camel@linaro.org> Subject: [PATCH] ARM: kprobes: check register usage for probed instruction From: "Jon Medhurst (Tixy)" To: Wang Nan Cc: masami.hiramatsu.pt@hitachi.com, lizefan@huawei.com, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Date: Tue, 13 Jan 2015 16:13:48 +0000 In-Reply-To: <1421161268.4215.56.camel@linaro.org> References: <1420457284-76923-1-git-send-email-wangnan0@huawei.com> <1420457384-77449-1-git-send-email-wangnan0@huawei.com> <1421161268.4215.56.camel@linaro.org> X-Mailer: Evolution 3.12.9-1+b1 Mime-Version: 1.0 X-Originating-smarthost01c-IP: [82.69.122.217] Sender: linux-kernel-owner@vger.kernel.org Precedence: list List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: tixy@linaro.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.217.176 as permitted sender) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , This patch utilizes the previously introduced checker to check register usage for probed ARM instruction and saves it in a mask. A further patch will use such information to avoid simulation or emulation. Signed-off-by: Wang Nan Reviewed-by: Jon Medhurst Signed-off-by: Jon Medhurst --- This patch applies my review comments on "[PATCH v19 10/11] ARM: kprobes: check register usage for probed instruction." It is also rebased on top of the kprobes-opt branch at git://git.linaro.org/people/tixy/kernel.git arch/arm/include/asm/probes.h | 1 + arch/arm/probes/decode.c | 7 +++ arch/arm/probes/kprobes/actions-arm.c | 2 +- arch/arm/probes/kprobes/checkers-arm.c | 93 ++++++++++++++++++++++++++++++++++ arch/arm/probes/kprobes/checkers.h | 1 + 5 files changed, 103 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/probes.h b/arch/arm/include/asm/probes.h index cd9e815..b668e60 100644 --- a/arch/arm/include/asm/probes.h +++ b/arch/arm/include/asm/probes.h @@ -41,6 +41,7 @@ struct arch_probes_insn { probes_insn_singlestep_t *insn_singlestep; probes_insn_fn_t *insn_fn; int stack_space; + unsigned long register_usage_flags; }; #endif /* __ASSEMBLY__ */ diff --git a/arch/arm/probes/decode.c b/arch/arm/probes/decode.c index f9d7c42..880ebe0 100644 --- a/arch/arm/probes/decode.c +++ b/arch/arm/probes/decode.c @@ -435,6 +435,13 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, */ asi->stack_space = 0; + /* + * Similarly to stack_space, register_usage_flags is filled by + * checkers. Its default value is set to ~0, which is 'all + * registers are used', to prevent any potential optimization. + */ + asi->register_usage_flags = ~0UL; + if (emulate) insn = prepare_emulated_insn(insn, asi, thumb); diff --git a/arch/arm/probes/kprobes/actions-arm.c b/arch/arm/probes/kprobes/actions-arm.c index 06988ef..b9056d6 100644 --- a/arch/arm/probes/kprobes/actions-arm.c +++ b/arch/arm/probes/kprobes/actions-arm.c @@ -341,4 +341,4 @@ const union decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = { [PROBES_LDMSTM] = {.decoder = kprobe_decode_ldmstm} }; -const struct decode_checker *kprobes_arm_checkers[] = {arm_stack_checker, NULL}; +const struct decode_checker *kprobes_arm_checkers[] = {arm_stack_checker, arm_regs_checker, NULL}; diff --git a/arch/arm/probes/kprobes/checkers-arm.c b/arch/arm/probes/kprobes/checkers-arm.c index f817663..7b98173 100644 --- a/arch/arm/probes/kprobes/checkers-arm.c +++ b/arch/arm/probes/kprobes/checkers-arm.c @@ -97,3 +97,96 @@ const struct decode_checker arm_stack_checker[NUM_PROBES_ARM_ACTIONS] = { [PROBES_STORE] = {.checker = arm_check_stack}, [PROBES_LDMSTM] = {.checker = arm_check_stack}, }; + +static enum probes_insn __kprobes arm_check_regs_nouse(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + asi->register_usage_flags = 0; + return INSN_GOOD; +} + +static enum probes_insn arm_check_regs_normal(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS; + int i; + + asi->register_usage_flags = 0; + for (i = 0; i < 5; regs >>= 4, insn >>= 4, i++) + if (regs & 0xf) + asi->register_usage_flags |= 1 << (insn & 0xf); + + return INSN_GOOD; +} + + +static enum probes_insn arm_check_regs_ldmstm(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + unsigned int reglist = insn & 0xffff; + unsigned int rn = (insn >> 16) & 0xf; + asi->register_usage_flags = reglist | (1 << rn); + return INSN_GOOD; +} + +static enum probes_insn arm_check_regs_mov_ip_sp(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + /* Instruction is 'mov ip, sp' i.e. 'mov r12, r13' */ + asi->register_usage_flags = (1 << 12) | (1<< 13); + return INSN_GOOD; +} + +/* + * | Rn |Rt/d| | Rm | + * LDRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1101 xxxx + * STRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1111 xxxx + * | Rn |Rt/d| |imm4L| + * LDRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1101 xxxx + * STRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1111 xxxx + * + * Such instructions access Rt/d and its next register, so different + * from others, a specific checker is required to handle this extra + * implicit register usage. + */ +static enum probes_insn arm_check_regs_ldrdstrd(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int rdt = (insn >> 12) & 0xf; + arm_check_regs_normal(insn, asi, h); + asi->register_usage_flags |= 1 << (rdt + 1); + return INSN_GOOD; +} + + +const struct decode_checker arm_regs_checker[NUM_PROBES_ARM_ACTIONS] = { + [PROBES_MRS] = {.checker = arm_check_regs_normal}, + [PROBES_SATURATING_ARITHMETIC] = {.checker = arm_check_regs_normal}, + [PROBES_MUL1] = {.checker = arm_check_regs_normal}, + [PROBES_MUL2] = {.checker = arm_check_regs_normal}, + [PROBES_MUL_ADD_LONG] = {.checker = arm_check_regs_normal}, + [PROBES_MUL_ADD] = {.checker = arm_check_regs_normal}, + [PROBES_LOAD] = {.checker = arm_check_regs_normal}, + [PROBES_LOAD_EXTRA] = {.checker = arm_check_regs_normal}, + [PROBES_STORE] = {.checker = arm_check_regs_normal}, + [PROBES_STORE_EXTRA] = {.checker = arm_check_regs_normal}, + [PROBES_DATA_PROCESSING_REG] = {.checker = arm_check_regs_normal}, + [PROBES_DATA_PROCESSING_IMM] = {.checker = arm_check_regs_normal}, + [PROBES_SEV] = {.checker = arm_check_regs_nouse}, + [PROBES_WFE] = {.checker = arm_check_regs_nouse}, + [PROBES_SATURATE] = {.checker = arm_check_regs_normal}, + [PROBES_REV] = {.checker = arm_check_regs_normal}, + [PROBES_MMI] = {.checker = arm_check_regs_normal}, + [PROBES_PACK] = {.checker = arm_check_regs_normal}, + [PROBES_EXTEND] = {.checker = arm_check_regs_normal}, + [PROBES_EXTEND_ADD] = {.checker = arm_check_regs_normal}, + [PROBES_BITFIELD] = {.checker = arm_check_regs_normal}, + [PROBES_LDMSTM] = {.checker = arm_check_regs_ldmstm}, + [PROBES_MOV_IP_SP] = {.checker = arm_check_regs_mov_ip_sp}, + [PROBES_LDRSTRD] = {.checker = arm_check_regs_ldrdstrd}, +}; diff --git a/arch/arm/probes/kprobes/checkers.h b/arch/arm/probes/kprobes/checkers.h index bddfa0e..cf6c9e7 100644 --- a/arch/arm/probes/kprobes/checkers.h +++ b/arch/arm/probes/kprobes/checkers.h @@ -47,6 +47,7 @@ extern const union decode_action stack_check_actions[]; #ifndef CONFIG_THUMB2_KERNEL extern const struct decode_checker arm_stack_checker[]; +extern const struct decode_checker arm_regs_checker[]; #else #endif extern const struct decode_checker t32_stack_checker[];