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Rao" Subject: [PATCH v4] arm64: implement KPROBES_ON_FTRACE Thread-Topic: [PATCH v4] arm64: implement KPROBES_ON_FTRACE Thread-Index: AQHVWJwQA6oCa6sgREe9v4FYsERl0w== Date: Thu, 22 Aug 2019 03:45:38 +0000 Message-ID: <20190822113421.52920377@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: TYAPR01CA0039.jpnprd01.prod.outlook.com (2603:1096:404:28::27) To DM6PR03MB4778.namprd03.prod.outlook.com (2603:10b6:5:184::26) 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: a576ac20-4f76-4e9a-468a-08d726b3329e x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020); SRVR:DM6PR03MB5036; x-ms-traffictypediagnostic: DM6PR03MB5036: x-ms-exchange-purlcount: 1 x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8273; x-forefront-prvs: 01371B902F x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(366004)(136003)(376002)(39850400004)(396003)(346002)(189003)(199004)(54534003)(70486001)(6306002)(6512007)(9686003)(8936002)(66066001)(117636001)(86362001)(478600001)(6436002)(6486002)(7416002)(8266002)(2906002)(6116002)(3846002)(81166006)(50226002)(8676002)(81156014)(316002)(4326008)(1076003)(14444005)(256004)(71200400001)(99286004)(52116002)(476003)(486006)(110136005)(54906003)(7736002)(305945005)(25786009)(66446008)(64756008)(66556008)(97876018)(26005)(386003)(6506007)(186003)(102836004)(66476007)(66946007)(966005)(53936002)(14454004)(71190400001)(5660300002)(39210200001); DIR:OUT; SFP:1101; SCL:1; SRVR:DM6PR03MB5036; H:DM6PR03MB4778.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: zbkARI8DZa8D+GPXXm/YHcuw6AjlKe0qx5WQGe4OWTHQ+nK31GpqkRGx0vKIFstiLFiMr/oElLZzu0jHrqJPIVXk3nZn9IlY2t4lRpB99hCJz7A9pZ+zB+/rpjf3Au543czNAPMMgfaRGBYcOE6CDkjltZeoSlsUsFs4gERINgRwx0ieEy03sKATobQ9D3Tg7sw0ecw3eMYGnPnKbBhDxaJZVyNDj7CiWB3nNodsOGgrQqRAZDFJTmEWMZ8Ym/RV1HJ+ZzVveKakTUfkLVmFZ39QonoADEAO+kFpP3eyr0VMuzvsCnHF8FgXvpAF6Aiqyow/w9r46NjyWhHUMKwGG20hd1rFVtvpOptNYjtlZFkYBZ2vn4YYaKRAXzONUgnHZ0vLEKnQl7I6grqqtkNMDri4OUofrEQhMCT0WTgTR9Y= x-ms-exchange-transport-forked: True Content-ID: <3C6EDF32F9D3EE49B3B4F56DC9A91833@namprd03.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: synaptics.com X-MS-Exchange-CrossTenant-Network-Message-Id: a576ac20-4f76-4e9a-468a-08d726b3329e X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Aug 2019 03:45:38.9847 (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: hrT4hLLiwrhDf6hugZ02bNMrZJkR84ApAfp25i2dk/ZtTbCrHWgQWP9FJN62Af5sX1vrZqMcyRvZPk1CqiZ/tA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR03MB5036 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190821_204604_602520_BE82FC19 X-CRM114-Status: GOOD ( 20.24 ) 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 [40.107.81.75 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_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 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: Mark Rutland , "linux-doc@vger.kernel.org" , Peter Zijlstra , "linux-kernel@vger.kernel.org" , Steven Rostedt , Ingo Molnar , Thomas Gleixner , "linux-arm-kernel@lists.infradead.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. 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 Reviewed-by: Naveen N. Rao --- 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. Applied after arm64 FTRACE_WITH_REGS: http://lists.infradead.org/pipermail/linux-arm-kernel/2019-August/674404.html Changes since v3: - move kprobe_lookup_name() and arch_kprobe_on_func_entry to ftrace.c since we only want to choose the ftrace entry for KPROBES_ON_FTRACE. - only choose ftrace entry if (addr && !offset) Changes since v2: - remove patch1, make it a single cleanup patch - remove "This patch" in the change log - implement arm64's kprobe_lookup_name() and arch_kprobe_on_func_entry instead of patching the common kprobes code Changes since v1: - make the kprobes/x86: use instruction_pointer and instruction_pointer_set as patch1 - add Masami's ACK to patch1 - add some description about KPROBES_ON_FTRACE and why we need it on arm64 - correct the log before the patch - remove the consolidation patch, make it as TODO - only adjust kprobe's addr when KPROBE_FLAG_FTRACE is set - if KPROBES_ON_FTRACE, ftrace_call_adjust() the kprobe's addr before calling ftrace_location() - update the kprobes-on-ftrace/arch-support.txt in doc .../debug/kprobes-on-ftrace/arch-support.txt | 2 +- arch/arm64/Kconfig | 1 + arch/arm64/kernel/probes/Makefile | 1 + arch/arm64/kernel/probes/ftrace.c | 84 +++++++++++++++++++ 4 files changed, 87 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..5989c57660f3 --- /dev/null +++ b/arch/arm64/kernel/probes/ftrace.c @@ -0,0 +1,84 @@ +// 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 + 4 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); + +kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) +{ + unsigned long addr = kallsyms_lookup_name(name); + + if (addr && !offset) { + unsigned long faddr; + /* + * with -fpatchable-function-entry=2, the first 4 bytes is the + * LR saver, then the actual call insn. So ftrace location is + * always on the first 4 bytes offset. + */ + faddr = ftrace_location_range(addr, + addr + AARCH64_INSN_SIZE); + if (faddr) + return (kprobe_opcode_t *)faddr; + } + return (kprobe_opcode_t *)addr; +} + +bool arch_kprobe_on_func_entry(unsigned long offset) +{ + return offset <= AARCH64_INSN_SIZE; +} + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn = NULL; + return 0; +}