From nobody Thu Sep 18 10:09:08 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0741C04FDE for ; Fri, 9 Dec 2022 08:53:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229841AbiLIIxY (ORCPT ); Fri, 9 Dec 2022 03:53:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229879AbiLIIxM (ORCPT ); Fri, 9 Dec 2022 03:53:12 -0500 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 39C6E17044 for ; Fri, 9 Dec 2022 00:53:10 -0800 (PST) Received: from loongson.cn (unknown [113.200.148.30]) by gateway (Coremail) with SMTP id _____8Dxfet095JjF2AEAA--.10264S3; Fri, 09 Dec 2022 16:53:08 +0800 (CST) Received: from linux.localdomain (unknown [113.200.148.30]) by localhost.localdomain (Coremail) with SMTP id AQAAf8BxV1dt95Jj7xUpAA--.16661S4; Fri, 09 Dec 2022 16:53:07 +0800 (CST) From: Tiezhu Yang To: Huacai Chen , WANG Xuerui , Masami Hiramatsu Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v10 2/4] LoongArch: Add kprobe support Date: Fri, 9 Dec 2022 16:52:59 +0800 Message-Id: <1670575981-14389-3-git-send-email-yangtiezhu@loongson.cn> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1670575981-14389-1-git-send-email-yangtiezhu@loongson.cn> References: <1670575981-14389-1-git-send-email-yangtiezhu@loongson.cn> X-CM-TRANSID: AQAAf8BxV1dt95Jj7xUpAA--.16661S4 X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ X-Coremail-Antispam: 1Uk129KBjvAXoW3Kr4DuFy3KryUKFy7KrWUCFg_yoW8XF1fCo WSvF4DWw48KrW7uF45Ar1kXFWUu3W8KFZ5Aryayanxur1DAr18Xr1UCrWrJ3W2qrsYg3yf u345ua4fGFW3Crnxn29KB7ZKAUJUUUU8529EdanIXcx71UUUUU7KY7ZEXasCq-sGcSsGvf J3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU0xBIdaVrnRJU UUkYb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2IYs7xG6rWj6s 0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1l84 ACjcxK6I8E87Iv67AKxVWxJr0_GcWl84ACjcxK6I8E87Iv6xkF7I0E14v26F4UJVW0owAS 0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI0UMc02F40EFcxC0V AKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUtVWrXwAv7VC2z280aVAFwI0_Gr0_Cr1l Ox8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JMxAIw28IcxkI7VAKI48JMxC20s 026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_ JrI_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14 v26r1I6r4UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xva j40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8JV W8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU84xRDUUUUU== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Kprobes allows you to trap at almost any kernel address and execute a callback function, this commit adds kprobe support for LoongArch. Signed-off-by: Tiezhu Yang --- arch/loongarch/Kconfig | 1 + arch/loongarch/include/asm/inst.h | 15 ++ arch/loongarch/include/asm/kprobes.h | 59 ++++++ arch/loongarch/kernel/Makefile | 2 + arch/loongarch/kernel/kprobes.c | 340 +++++++++++++++++++++++++++++++= ++++ arch/loongarch/kernel/traps.c | 13 +- arch/loongarch/mm/fault.c | 3 + 7 files changed, 429 insertions(+), 4 deletions(-) create mode 100644 arch/loongarch/include/asm/kprobes.h create mode 100644 arch/loongarch/kernel/kprobes.c diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 16bf1b6..f6fc156 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -102,6 +102,7 @@ config LOONGARCH select HAVE_IOREMAP_PROT select HAVE_IRQ_EXIT_ON_IRQ_STACK select HAVE_IRQ_TIME_ACCOUNTING + select HAVE_KPROBES select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI select HAVE_PCI diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm= /inst.h index e25fd54..a7c85df 100644 --- a/arch/loongarch/include/asm/inst.h +++ b/arch/loongarch/include/asm/inst.h @@ -24,6 +24,10 @@ =20 #define ADDR_IMM(addr, INSN) ((addr & ADDR_IMMMASK_##INSN) >> ADDR_IMMSHIF= T_##INSN) =20 +enum reg0i15_op { + break_op =3D 0x54, +}; + enum reg0i26_op { b_op =3D 0x14, bl_op =3D 0x15, @@ -180,6 +184,11 @@ enum reg3sa2_op { alsld_op =3D 0x16, }; =20 +struct reg0i15_format { + unsigned int immediate : 15; + unsigned int opcode : 17; +}; + struct reg0i26_format { unsigned int immediate_h : 10; unsigned int immediate_l : 16; @@ -265,6 +274,7 @@ struct reg3sa2_format { =20 union loongarch_instruction { unsigned int word; + struct reg0i15_format reg0i15_format; struct reg0i26_format reg0i26_format; struct reg1i20_format reg1i20_format; struct reg1i21_format reg1i21_format; @@ -335,6 +345,11 @@ static inline bool is_branch_ins(union loongarch_instr= uction *ip) ip->reg1i21_format.opcode <=3D bgeu_op; } =20 +static inline bool is_break_ins(union loongarch_instruction *ip) +{ + return ip->reg0i15_format.opcode =3D=3D break_op; +} + static inline bool is_ra_save_ins(union loongarch_instruction *ip) { /* st.d $ra, $sp, offset */ diff --git a/arch/loongarch/include/asm/kprobes.h b/arch/loongarch/include/= asm/kprobes.h new file mode 100644 index 0000000..d3903f3 --- /dev/null +++ b/arch/loongarch/include/asm/kprobes.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_LOONGARCH_KPROBES_H +#define __ASM_LOONGARCH_KPROBES_H + +#include +#include + +#ifdef CONFIG_KPROBES + +#include + +#define __ARCH_WANT_KPROBES_INSN_SLOT +#define MAX_INSN_SIZE 2 + +#define flush_insn_slot(p) \ +do { \ + if (p->addr) \ + flush_icache_range((unsigned long)p->addr, \ + (unsigned long)p->addr + \ + (MAX_INSN_SIZE * sizeof(kprobe_opcode_t))); \ +} while (0) + +#define kretprobe_blacklist_size 0 + +typedef union loongarch_instruction kprobe_opcode_t; + +/* Architecture specific copy of original instruction */ +struct arch_specific_insn { + /* copy of the original instruction */ + kprobe_opcode_t *insn; +}; + +struct prev_kprobe { + struct kprobe *kp; + unsigned long status; + unsigned long saved_irq; + unsigned long saved_era; +}; + +/* per-cpu kprobe control block */ +struct kprobe_ctlblk { + unsigned long kprobe_status; + unsigned long kprobe_saved_irq; + unsigned long kprobe_saved_era; + struct prev_kprobe prev_kprobe; +}; + +void arch_remove_kprobe(struct kprobe *p); +bool kprobe_fault_handler(struct pt_regs *regs, int trapnr); +bool kprobe_breakpoint_handler(struct pt_regs *regs); +bool kprobe_singlestep_handler(struct pt_regs *regs); + +#else /* !CONFIG_KPROBES */ + +static inline bool kprobe_breakpoint_handler(struct pt_regs *regs) { retur= n 0; } +static inline bool kprobe_singlestep_handler(struct pt_regs *regs) { retur= n 0; } + +#endif /* CONFIG_KPROBES */ +#endif /* __ASM_LOONGARCH_KPROBES_H */ diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile index fcaa024..6fe4a4e 100644 --- a/arch/loongarch/kernel/Makefile +++ b/arch/loongarch/kernel/Makefile @@ -47,4 +47,6 @@ obj-$(CONFIG_UNWINDER_PROLOGUE) +=3D unwind_prologue.o =20 obj-$(CONFIG_PERF_EVENTS) +=3D perf_event.o perf_regs.o =20 +obj-$(CONFIG_KPROBES) +=3D kprobes.o + CPPFLAGS_vmlinux.lds :=3D $(KBUILD_CFLAGS) diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobe= s.c new file mode 100644 index 0000000..546a3c3 --- /dev/null +++ b/arch/loongarch/kernel/kprobes.c @@ -0,0 +1,340 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include + +static const union loongarch_instruction breakpoint_insn =3D { + .reg0i15_format =3D { + .opcode =3D break_op, + .immediate =3D BRK_KPROBE_BP, + } +}; + +static const union loongarch_instruction singlestep_insn =3D { + .reg0i15_format =3D { + .opcode =3D break_op, + .immediate =3D BRK_KPROBE_SSTEPBP, + } +}; + +DEFINE_PER_CPU(struct kprobe *, current_kprobe); +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static bool insns_not_supported(union loongarch_instruction insn) +{ + switch (insn.reg2i14_format.opcode) { + case llw_op: + case lld_op: + case scw_op: + case scd_op: + pr_notice("kprobe: ll and sc instructions are not supported\n"); + return true; + } + + switch (insn.reg1i21_format.opcode) { + case bceqz_op: + pr_notice("kprobe: bceqz and bcnez instructions are not supported\n"); + return true; + } + + return false; +} +NOKPROBE_SYMBOL(insns_not_supported); + +int arch_prepare_kprobe(struct kprobe *p) +{ + union loongarch_instruction insn; + + insn =3D p->addr[0]; + if (insns_not_supported(insn)) + return -EINVAL; + + p->ainsn.insn =3D get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + + p->ainsn.insn[0] =3D *p->addr; + p->ainsn.insn[1] =3D singlestep_insn; + + p->opcode =3D *p->addr; + + return 0; +} +NOKPROBE_SYMBOL(arch_prepare_kprobe); + +/* Install breakpoint in text */ +void arch_arm_kprobe(struct kprobe *p) +{ + *p->addr =3D breakpoint_insn; + flush_insn_slot(p); +} +NOKPROBE_SYMBOL(arch_arm_kprobe); + +/* Remove breakpoint from text */ +void arch_disarm_kprobe(struct kprobe *p) +{ + *p->addr =3D p->opcode; + flush_insn_slot(p); +} +NOKPROBE_SYMBOL(arch_disarm_kprobe); + +void arch_remove_kprobe(struct kprobe *p) +{ + if (p->ainsn.insn) { + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn =3D NULL; + } +} +NOKPROBE_SYMBOL(arch_remove_kprobe); + +static void save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp =3D kprobe_running(); + kcb->prev_kprobe.status =3D kcb->kprobe_status; + kcb->prev_kprobe.saved_irq =3D kcb->kprobe_saved_irq; + kcb->prev_kprobe.saved_era =3D kcb->kprobe_saved_era; +} +NOKPROBE_SYMBOL(save_previous_kprobe); + +static void restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); + kcb->kprobe_status =3D kcb->prev_kprobe.status; + kcb->kprobe_saved_irq =3D kcb->prev_kprobe.saved_irq; + kcb->kprobe_saved_era =3D kcb->prev_kprobe.saved_era; +} +NOKPROBE_SYMBOL(restore_previous_kprobe); + +static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, p); + kcb->kprobe_saved_irq =3D regs->csr_prmd & CSR_PRMD_PIE; + kcb->kprobe_saved_era =3D regs->csr_era; +} +NOKPROBE_SYMBOL(set_current_kprobe); + +static bool insns_not_simulated(struct kprobe *p, struct pt_regs *regs) +{ + if (is_branch_ins(&p->opcode)) { + simu_branch(regs, p->opcode); + return false; + } else if (is_pc_ins(&p->opcode)) { + simu_pc(regs, p->opcode); + return false; + } else { + return true; + } +} +NOKPROBE_SYMBOL(insns_not_simulated); + +static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb, int reenter) +{ + if (reenter) { + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status =3D KPROBE_REENTER; + } else { + kcb->kprobe_status =3D KPROBE_HIT_SS; + } + + regs->csr_prmd &=3D ~CSR_PRMD_PIE; + + if (p->ainsn.insn->word =3D=3D breakpoint_insn.word) { + regs->csr_prmd |=3D kcb->kprobe_saved_irq; + preempt_enable_no_resched(); + return; + } + + if (insns_not_simulated(p, regs)) { + kcb->kprobe_status =3D KPROBE_HIT_SS; + regs->csr_era =3D (unsigned long)&p->ainsn.insn[0]; + } else { + kcb->kprobe_status =3D KPROBE_HIT_SSDONE; + if (p->post_handler) + p->post_handler(p, regs, 0); + reset_current_kprobe(); + preempt_enable_no_resched(); + } +} +NOKPROBE_SYMBOL(setup_singlestep); + +static bool reenter_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: + case KPROBE_HIT_ACTIVE: + kprobes_inc_nmissed_count(p); + setup_singlestep(p, regs, kcb, 1); + break; + case KPROBE_HIT_SS: + case KPROBE_REENTER: + pr_warn("Failed to recover from reentered kprobes.\n"); + dump_kprobe(p); + BUG(); + break; + default: + WARN_ON(1); + return false; + } + + return true; +} +NOKPROBE_SYMBOL(reenter_kprobe); + +bool kprobe_breakpoint_handler(struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb; + struct kprobe *p, *cur_kprobe; + kprobe_opcode_t *addr =3D (kprobe_opcode_t *)regs->csr_era; + + /* + * We don't want to be preempted for the entire + * duration of kprobe processing. + */ + preempt_disable(); + kcb =3D get_kprobe_ctlblk(); + cur_kprobe =3D kprobe_running(); + + p =3D get_kprobe(addr); + if (p) { + if (cur_kprobe) { + if (reenter_kprobe(p, regs, kcb)) + return true; + } else { + /* Probe hit */ + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status =3D KPROBE_HIT_ACTIVE; + + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it will + * modify the execution path and no need to single + * stepping. Let's just reset current kprobe and exit. + * + * pre_handler can hit a breakpoint and can step thru + * before return. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) { + setup_singlestep(p, regs, kcb, 0); + } else { + reset_current_kprobe(); + preempt_enable_no_resched(); + } + } + return true; + } + + if (!is_break_ins(addr)) { + /* + * The breakpoint instruction was removed right + * after we hit it. Another cpu has removed + * either a probepoint or a debugger breakpoint + * at this address. In either case, no further + * handling of this interrupt is appropriate. + * Return back to original instruction, and continue. + */ + preempt_enable_no_resched(); + return true; + } + + preempt_enable_no_resched(); + return false; +} +NOKPROBE_SYMBOL(kprobe_breakpoint_handler); + +bool kprobe_singlestep_handler(struct pt_regs *regs) +{ + struct kprobe *cur =3D kprobe_running(); + struct kprobe_ctlblk *kcb =3D get_kprobe_ctlblk(); + + if (!cur) + return false; + + /* Restore back the original saved kprobes variables and continue */ + if (kcb->kprobe_status =3D=3D KPROBE_REENTER) { + restore_previous_kprobe(kcb); + goto out; + } + + /* Call post handler */ + if (cur->post_handler) { + kcb->kprobe_status =3D KPROBE_HIT_SSDONE; + cur->post_handler(cur, regs, 0); + } + + regs->csr_era =3D kcb->kprobe_saved_era + LOONGARCH_INSN_SIZE; + regs->csr_prmd |=3D kcb->kprobe_saved_irq; + + reset_current_kprobe(); +out: + preempt_enable_no_resched(); + return true; +} +NOKPROBE_SYMBOL(kprobe_singlestep_handler); + +bool kprobe_fault_handler(struct pt_regs *regs, int trapnr) +{ + struct kprobe *cur =3D kprobe_running(); + struct kprobe_ctlblk *kcb =3D get_kprobe_ctlblk(); + + switch (kcb->kprobe_status) { + case KPROBE_HIT_SS: + case KPROBE_REENTER: + /* + * We are here because the instruction being single + * stepped caused a page fault. We reset the current + * kprobe and the ip points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + regs->csr_era =3D (unsigned long) cur->addr; + BUG_ON(!instruction_pointer(regs)); + + if (kcb->kprobe_status =3D=3D KPROBE_REENTER) { + restore_previous_kprobe(kcb); + } else { + regs->csr_prmd |=3D kcb->kprobe_saved_irq; + reset_current_kprobe(); + } + preempt_enable_no_resched(); + break; + case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SSDONE: + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + if (fixup_exception(regs)) + return true; + + /* + * If fixup_exception() could not handle it, + * let do_page_fault() fix it. + */ + break; + default: + break; + } + return false; +} +NOKPROBE_SYMBOL(kprobe_fault_handler); + +/* + * Provide a blacklist of symbols identifying ranges which cannot be kprob= ed. + * This blacklist is exposed to userspace via debugfs (kprobes/blacklist). + */ +int __init arch_populate_kprobe_blacklist(void) +{ + return kprobe_add_area_blacklist((unsigned long)__irqentry_text_start, + (unsigned long)__irqentry_text_end); +} + +int __init arch_init_kprobes(void) +{ + return 0; +} diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c index a19bb32..4d9f775 100644 --- a/arch/loongarch/kernel/traps.c +++ b/arch/loongarch/kernel/traps.c @@ -448,14 +448,12 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs) */ switch (bcode) { case BRK_KPROBE_BP: - if (notify_die(DIE_BREAK, "Kprobe", regs, bcode, - current->thread.trap_nr, SIGTRAP) =3D=3D NOTIFY_STOP) + if (kprobe_breakpoint_handler(regs)) goto out; else break; case BRK_KPROBE_SSTEPBP: - if (notify_die(DIE_SSTEPBP, "Kprobe_SingleStep", regs, bcode, - current->thread.trap_nr, SIGTRAP) =3D=3D NOTIFY_STOP) + if (kprobe_singlestep_handler(regs)) goto out; else break; @@ -479,6 +477,13 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs) break; } =20 + if (bcode =3D=3D BRK_KPROBE_BP) { + if (__get_inst(&opcode, (u32 *)era, user)) + goto out_sigsegv; + + bcode =3D (opcode & 0x7fff); + } + switch (bcode) { case BRK_BUG: bug_handler(regs); diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c index 1ccd536..449087b 100644 --- a/arch/loongarch/mm/fault.c +++ b/arch/loongarch/mm/fault.c @@ -135,6 +135,9 @@ static void __kprobes __do_page_fault(struct pt_regs *r= egs, struct vm_area_struct *vma =3D NULL; vm_fault_t fault; =20 + if (kprobe_page_fault(regs, current->thread.trap_nr)) + return; + /* * We fault-in kernel-space virtual memory on-demand. The * 'reference' page table is init_mm.pgd. --=20 2.1.0