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Peter Anvin" , "x86@kernel.org" , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Masami Hiramatsu Subject: [PATCH v2 3/3] arm64: implement KPROBES_ON_FTRACE Thread-Topic: [PATCH v2 3/3] arm64: implement KPROBES_ON_FTRACE Thread-Index: AQHVVwryjSNW9eV9u0mDAvz7yXMGOw== Date: Tue, 20 Aug 2019 03:54:20 +0000 Message-ID: <20190820114314.685a3239@xhacker.debian> References: <20190820113928.1971900c@xhacker.debian> In-Reply-To: <20190820113928.1971900c@xhacker.debian> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [124.74.246.114] x-clientproxiedby: TY2PR06CA0027.apcprd06.prod.outlook.com (2603:1096:404:2e::15) To BYAPR03MB4773.namprd03.prod.outlook.com (2603:10b6:a03:134::24) authentication-results: spf=none (sender IP is ) smtp.mailfrom=Jisheng.Zhang@synaptics.com; x-ms-exchange-messagesentrepresentingtype: 1 x-mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 4cf07ffa-c85f-46fb-5508-08d72522145e x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020); SRVR:BYAPR03MB4870; x-ms-traffictypediagnostic: BYAPR03MB4870: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:7219; x-forefront-prvs: 013568035E x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(136003)(346002)(39860400002)(376002)(366004)(396003)(189003)(199004)(6116002)(6486002)(3846002)(53936002)(76176011)(2906002)(6436002)(86362001)(1076003)(64756008)(71190400001)(6512007)(110136005)(9686003)(6506007)(71200400001)(54906003)(66066001)(5660300002)(4326008)(14454004)(316002)(52116002)(66556008)(476003)(7736002)(99286004)(446003)(2501003)(486006)(386003)(8676002)(14444005)(81166006)(66946007)(256004)(478600001)(50226002)(102836004)(8936002)(26005)(305945005)(66446008)(66476007)(7416002)(186003)(11346002)(25786009)(81156014)(921003)(39210200001)(1121003); DIR:OUT; SFP:1101; SCL:1; SRVR:BYAPR03MB4870; H:BYAPR03MB4773.namprd03.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; MX:1; A:0; received-spf: None (protection.outlook.com: synaptics.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: aCiZWPwy8Jwdi/+8CSI+xJM9idFvTBdYY4HlzBQTf8HwUnS/c4nJpic5UAvYidiJ6dtg4XAdC2K7Gd0LNqQFfQ4jgQS+31sJxp23Qva49gPylD2dTWoSPr2gg5qUlQcMR97ECGzM22nQnXyUrc+aDYK+DHrkaOl03hY29WpfiwtLc1F83yU30RzioHt75JvaXN5ADv9p/N+iNCT5VOAi23KHLuszvh8qaJdq+ALd/Z7zs37vSRzqTYUPP8H9eHB8rtAN+sJORY/TRKvdkmUlSIyjwp/qdjgMUvtHrmEweSNP3qR7PJJPsWidlwPWScegHfwDUYqZyMkB5QSWMN/muCpZCpBnmzS5RUJkqOJgrymiivETL8HyKWkjXvOTvGxZJwMiMG5HP2FkYNnkljePAj0JMgLz9pydgcVDsKhYAto= x-ms-exchange-transport-forked: True Content-ID: <758C392CCF526742B344A76B55289EB3@namprd03.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: synaptics.com X-MS-Exchange-CrossTenant-Network-Message-Id: 4cf07ffa-c85f-46fb-5508-08d72522145e X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Aug 2019 03:54:20.0344 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 335d1fbc-2124-4173-9863-17e7051a2a0e X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: CAcL2sqKhRE5cmCP02pDSD1yfO3F+kGxqmameVtbPHlnLTImORFfR/k7vWwSSIv5o1KHH5PMynr1R/LnJg29iA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR03MB4870 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190819_205420_944317_C8A60B7B X-CRM114-Status: GOOD ( 16.07 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [40.107.71.56 listed in list.dnswl.org] 0.0 SPF_NONE SPF: sender does not publish an SPF Record -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-doc@vger.kernel.org" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org KPROBES_ON_FTRACE avoids much of the overhead with regular kprobes as it eliminates the need for a trap, as well as the need to emulate or single-step instructions. This patch implements KPROBES_ON_FTRACE for arm64. Tested on berlin arm64 platform. ~ # mount -t debugfs debugfs /sys/kernel/debug/ ~ # cd /sys/kernel/debug/ /sys/kernel/debug # echo 'p _do_fork' > tracing/kprobe_events before the patch: /sys/kernel/debug # cat kprobes/list ffffff801009fe28 k _do_fork+0x0 [DISABLED] after the patch: /sys/kernel/debug # cat kprobes/list ffffff801009ff54 k _do_fork+0x4 [DISABLED][FTRACE] Signed-off-by: Jisheng Zhang --- .../debug/kprobes-on-ftrace/arch-support.txt | 2 +- arch/arm64/Kconfig | 1 + arch/arm64/kernel/probes/Makefile | 1 + arch/arm64/kernel/probes/ftrace.c | 60 +++++++++++++++++++ 4 files changed, 63 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/probes/ftrace.c diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt index 68f266944d5f..e8358a38981c 100644 --- a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt +++ b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt @@ -9,7 +9,7 @@ | alpha: | TODO | | arc: | TODO | | arm: | TODO | - | arm64: | TODO | + | arm64: | ok | | c6x: | TODO | | csky: | TODO | | h8300: | TODO | diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 663392d1eae2..928700f15e23 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -167,6 +167,7 @@ config ARM64 select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES + select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES select HAVE_GENERIC_VDSO select IOMMU_DMA if IOMMU_SUPPORT diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile index 8e4be92e25b1..4020cfc66564 100644 --- a/arch/arm64/kernel/probes/Makefile +++ b/arch/arm64/kernel/probes/Makefile @@ -4,3 +4,4 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \ simulate-insn.o obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \ simulate-insn.o +obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o diff --git a/arch/arm64/kernel/probes/ftrace.c b/arch/arm64/kernel/probes/ftrace.c new file mode 100644 index 000000000000..52901ffff570 --- /dev/null +++ b/arch/arm64/kernel/probes/ftrace.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Dynamic Ftrace based Kprobes Optimization + * + * Copyright (C) Hitachi Ltd., 2012 + * Copyright (C) 2019 Jisheng Zhang + * Synaptics Incorporated + */ + +#include + +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + /* Preempt is disabled by ftrace */ + p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(!p) || kprobe_disabled(p)) + return; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_ip = instruction_pointer(regs); + /* Kprobe handler expects regs->pc = pc + 1 as breakpoint hit */ + instruction_pointer_set(regs, ip + sizeof(kprobe_opcode_t)); + + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (!p->pre_handler || !p->pre_handler(p, regs)) { + /* + * Emulate singlestep (and also recover regs->pc) + * as if there is a nop + */ + instruction_pointer_set(regs, + (unsigned long)p->addr + MCOUNT_INSN_SIZE); + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + instruction_pointer_set(regs, orig_ip); + } + /* + * If pre_handler returns !0, it changes regs->pc. We have to + * skip emulating post_handler. + */ + __this_cpu_write(current_kprobe, NULL); + } +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn = NULL; + return 0; +}