Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751968AbaL0Hkm (ORCPT ); Sat, 27 Dec 2014 02:40:42 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:21284 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751929AbaL0Hki (ORCPT ); Sat, 27 Dec 2014 02:40:38 -0500 From: Wang Nan To: , , CC: , , Subject: [PATCH v17 10/11] ARM: kprobes: check register usage for probed instruction. Date: Sat, 27 Dec 2014 15:35:54 +0800 Message-ID: <1419665754-13283-1-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.4 In-Reply-To: <1419665637-12744-1-git-send-email-wangnan0@huawei.com> References: <1419665637-12744-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.247] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020205.549E6275.0119,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 1ebb210be439f2a1c969a619bfe4de64 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch utilizes previous introduced checker to check register usage for probed ARM instruction and saves it in a mask. Futher patch will use such information to avoid simuation or emulation. Signed-off-by: Wang Nan --- arch/arm/include/asm/probes.h | 9 +++ arch/arm/probes/decode.c | 7 ++ arch/arm/probes/kprobes/actions-arm.c | 2 +- arch/arm/probes/kprobes/checkers-arm.c | 124 +++++++++++++++++++++++++++++++++ arch/arm/probes/kprobes/checkers.h | 1 + 5 files changed, 142 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/probes.h b/arch/arm/include/asm/probes.h index f0a1ee8..ee8725c 100644 --- a/arch/arm/include/asm/probes.h +++ b/arch/arm/include/asm/probes.h @@ -41,6 +41,15 @@ struct arch_probes_insn { probes_insn_singlestep_t *insn_singlestep; probes_insn_fn_t *insn_fn; int stack_space; + + /* Use 2 bits for a register. One more bit for extension */ +#define REG_NO_USE (0) +#define REG_USE (1) +#define __set_register_flag(m, n, f) do {(m) = (m) | ((f) << ((n) * 2));} while(0) +#define __clear_register_flag(m, n, f) do {(m) = (m) & (~((f) << ((n) * 2)));} while(0) +#define set_register_nouse(m, n) __clear_register_flag(m, n, REG_NO_USE) +#define set_register_use(m, n) __set_register_flag(m, n, REG_USE) + int register_usage_mask; }; #endif /* __ASSEMBLY__ */ diff --git a/arch/arm/probes/decode.c b/arch/arm/probes/decode.c index f9d7c42..d60a1b2 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; + /* + * Similay to stack_space, register_usage_mask 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_mask = ~(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 4fedd4c..26e435b 100644 --- a/arch/arm/probes/kprobes/actions-arm.c +++ b/arch/arm/probes/kprobes/actions-arm.c @@ -340,4 +340,4 @@ 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..df1d77b 100644 --- a/arch/arm/probes/kprobes/checkers-arm.c +++ b/arch/arm/probes/kprobes/checkers-arm.c @@ -97,3 +97,127 @@ 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_mask = 0; + return INSN_GOOD; +} + +static void __arm_check_regs(probes_opcode_t insn, + const struct decode_header *h, + int *quintuple) +{ + int i; + u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS; + probes_opcode_t mask, shifted; + + memset(quintuple, 0xff, sizeof(int) * 5); + for (i = 0, shifted = insn, mask = 0xf; regs != 0; + regs >>= 4, mask <<= 4, shifted >>= 4, i++) + if (regs & 0xf) + quintuple[i] = shifted & 0xf; +} + +static enum probes_insn arm_check_regs_normal(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int quintuple[5], i; + asi->register_usage_mask = 0; + __arm_check_regs(insn, h, quintuple); + for (i = 0; i < 5; i++) { + int r = quintuple[i]; + if (r < 0) + continue; + set_register_use(asi->register_usage_mask, r); + } + + 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; + int i; + + set_register_use(asi->register_usage_mask, rn); + for (i = 0; reglist > 0; i++, reglist >>= 1) + if (reglist & 1) + set_register_use(asi->register_usage_mask, i); + 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) +{ + /* should be 'mov ip, sp' */ + set_register_use(asi->register_usage_mask, 12); + set_register_use(asi->register_usage_mask, 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 for Rt/d and Rt2/d2. + */ +static enum probes_insn arm_check_regs_ldrdstrd(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int quintuple[5], rn, rdt, rm; + asi->register_usage_mask = 0; + __arm_check_regs(insn, h, quintuple); + + rn = quintuple[4]; + rdt = quintuple[3]; + rm = quintuple[0]; + set_register_use(asi->register_usage_mask, rn); + set_register_use(asi->register_usage_mask, rdt); + set_register_use(asi->register_usage_mask, rdt + 1); + if (rm >= 0) + set_register_use(asi->register_usage_mask, rm); + + return INSN_GOOD; +} + + +const struct decode_checker arm_regs_checker[NUM_PROBES_ARM_ACTIONS] = { + [PROBES_EMULATE_NONE] = {.checker = arm_check_regs_nouse}, + [PROBES_SIMULATE_NOP] = {.checker = arm_check_regs_nouse}, + [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_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[]; -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/