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Rao" CC: Thomas Gleixner , Peter Zijlstra , Steven Rostedt , Mark Rutland , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: [PATCH v5] arm64: implement KPROBES_ON_FTRACE Thread-Topic: [PATCH v5] arm64: implement KPROBES_ON_FTRACE Thread-Index: AQHVWNw8B9jpjP9XI02aOFdGy0xKpw== Date: Thu, 22 Aug 2019 11:25:00 +0000 Message-ID: <20190822191351.3796aca8@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: TYAPR01CA0001.jpnprd01.prod.outlook.com (2603:1096:404::13) 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: dfa4a9a0-8708-4dc3-5a44-08d726f35e9c x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(5600166)(711020)(4605104)(1401327)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(2017052603328)(7193020);SRVR:BYAPR03MB3895; x-ms-traffictypediagnostic: BYAPR03MB3895: 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)(346002)(39860400002)(376002)(396003)(54534003)(189003)(199004)(50226002)(305945005)(6436002)(99286004)(110136005)(102836004)(316002)(386003)(54906003)(14454004)(5660300002)(478600001)(7416002)(6506007)(256004)(66066001)(6486002)(966005)(8936002)(476003)(53936002)(14444005)(3846002)(6116002)(1076003)(6306002)(9686003)(6512007)(81166006)(71200400001)(81156014)(71190400001)(486006)(186003)(26005)(7736002)(8676002)(25786009)(4326008)(66476007)(66556008)(66446008)(66946007)(64756008)(86362001)(52116002)(2906002)(39210200001);DIR:OUT;SFP:1101;SCL:1;SRVR:BYAPR03MB3895;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: Mq4RkuDdwASWxp1ognYDuftlQnyC5TU3U12FewHKmlbztnqrxdMzo1bVjoSufMU1kaOxjSGFD79imBE3WF0f4KWkRijxOyARs6EPVqb/jptLPNBV5/HVuK4/H9cF0OxRQ0JfdeTJVbQPl8mCa+CTp0xsqxcw1Ll+DeRHnedv0FV+hIocHUTsg+UfSOvLTwuQnIhm9Z3uP3WrrvmF9MnkP6E/Fp6KLUKCdueGaU1JZTjw77fKrpdB2RkR430wd5HHnhtW4oQefy4PaTAApTdVopsBlcJTUa1jXuLeFny9669gL7bp29/ggMoGKxvDgEvRZ6/HXyGKbaom/MjbaJQD67DhhDEtgkz4jcZuzv3+PoOcn4mznNwNRsjJ59Izw81t+964tcAMifSTvFCcdGeM8CgJB2XCjCynn2kxNDELCwo= x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-ID: <538610905093B748B9C9D95A36273D2E@namprd03.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: synaptics.com X-MS-Exchange-CrossTenant-Network-Message-Id: dfa4a9a0-8708-4dc3-5a44-08d726f35e9c X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Aug 2019 11:25:00.5116 (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: H0BqU98EQeq+bKT3l97RaMTJaRP6k9iNX9c197gQ7+c/KJK7vWzBH8w+wdPKKg3HcNP0MgLudLtLHdIrRXrBag== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR03MB3895 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 --- 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.ht= ml Changes since v4: - correct reg->pc: probed on foo, then pre_handler see foo+0x4, while post_handler see foo+0x8 Changes since v3: - move kprobe_lookup_name() and arch_kprobe_on_func_entry to ftrace.c sin= ce 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 in= stead of patching the common kprobes code Changes since v1: - make the kprobes/x86: use instruction_pointer and instruction_pointer_s= et 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 | 83 +++++++++++++++++++ 4 files changed, 86 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/probes/ftrace.c diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.tx= t 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/M= akefile index 8e4be92e25b1..4020cfc66564 100644 --- a/arch/arm64/kernel/probes/Makefile +++ b/arch/arm64/kernel/probes/Makefile @@ -4,3 +4,4 @@ obj-$(CONFIG_KPROBES) +=3D kprobes.o decode-insn.o \ simulate-insn.o obj-$(CONFIG_UPROBES) +=3D uprobes.o decode-insn.o \ simulate-insn.o +obj-$(CONFIG_KPROBES_ON_FTRACE) +=3D ftrace.o diff --git a/arch/arm64/kernel/probes/ftrace.c b/arch/arm64/kernel/probes/f= trace.c new file mode 100644 index 000000000000..9f80905f02fa --- /dev/null +++ b/arch/arm64/kernel/probes/ftrace.c @@ -0,0 +1,83 @@ +// 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 =3D get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(!p) || kprobe_disabled(p)) + return; + + kcb =3D get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_ip =3D instruction_pointer(regs); + + instruction_pointer_set(regs, ip); + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status =3D 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 =3D 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 =3D kallsyms_lookup_name(name); + + if (addr && !offset) { + unsigned long faddr; + /* + * with -fpatchable-function-entry=3D2, 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 =3D 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 <=3D AARCH64_INSN_SIZE; +} + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn =3D NULL; + return 0; +} --=20 2.23.0.rc1