On Mon, Jul 6, 2020 at 6:12 PM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > Hi Guo, > > On Sat, 4 Jul 2020 03:34:18 +0000 > guoren@xxxxxxxxxx wrote: > > > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > > This patch enables "kprobe & kretprobe" to work with ftrace > > interface. It utilized software breakpoint as single-step > > mechanism. > > > > Some instructions which can't be single-step executed must be > > simulated in kernel execution slot, such as: branch, jal, auipc, > > la ... > > > > Some instructions should be rejected for probing and we use a > > blacklist to filter, such as: ecall, ebreak, ... > > > > We use ebreak & c.ebreak to replace origin instruction and the > > kprobe handler prepares an executable memory slot for out-of-line > > execution with a copy of the original instruction being probed. > > In execution slot we add ebreak behind original instruction to > > simulate a single-setp mechanism. > > > > The patch is based on packi's work [1] and csky's work [2]. > > - The kprobes_trampoline.S is all from packi's patch > > - The single-step mechanism is new designed for riscv without hw > > single-step trap > > - The simulation codes are from csky > > - Frankly, all codes refer to other archs' implementation > > > > [1] https://lore.kernel.org/linux-riscv/20181113195804.22825-1-me@xxxxxxxx/ > > [2] https://lore.kernel.org/linux-csky/20200403044150.20562-9-guoren@xxxxxxxxxx/ > > > > This looks good to me. Thanks for updating ! > > Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > > Thank you, > It works to me. Thanks! Tested-by: Zong Li <zong.li@xxxxxxxxxx> > > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > Co-Developed-by: Patrick Stählin <me@xxxxxxxx> > > Cc: Patrick Stählin <me@xxxxxxxx> > > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > > Cc: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx> > > Cc: Björn Töpel <bjorn.topel@xxxxxxxxx> > > --- > > arch/riscv/Kconfig | 2 + > > arch/riscv/include/asm/kprobes.h | 40 +++ > > arch/riscv/include/asm/probes.h | 24 ++ > > arch/riscv/kernel/Makefile | 1 + > > arch/riscv/kernel/probes/Makefile | 4 + > > arch/riscv/kernel/probes/decode-insn.c | 48 +++ > > arch/riscv/kernel/probes/decode-insn.h | 18 + > > arch/riscv/kernel/probes/kprobes.c | 471 ++++++++++++++++++++++++++ > > arch/riscv/kernel/probes/kprobes_trampoline.S | 93 +++++ > > arch/riscv/kernel/probes/simulate-insn.c | 85 +++++ > > arch/riscv/kernel/probes/simulate-insn.h | 47 +++ > > arch/riscv/kernel/traps.c | 9 + > > arch/riscv/mm/fault.c | 4 + > > 13 files changed, 846 insertions(+) > > create mode 100644 arch/riscv/include/asm/probes.h > > create mode 100644 arch/riscv/kernel/probes/Makefile > > create mode 100644 arch/riscv/kernel/probes/decode-insn.c > > create mode 100644 arch/riscv/kernel/probes/decode-insn.h > > create mode 100644 arch/riscv/kernel/probes/kprobes.c > > create mode 100644 arch/riscv/kernel/probes/kprobes_trampoline.S > > create mode 100644 arch/riscv/kernel/probes/simulate-insn.c > > create mode 100644 arch/riscv/kernel/probes/simulate-insn.h > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index 58d6f66..a295f0b 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -57,6 +57,8 @@ config RISCV > > select HAVE_EBPF_JIT if MMU > > select HAVE_FUTEX_CMPXCHG if FUTEX > > select HAVE_GENERIC_VDSO if MMU && 64BIT > > + select HAVE_KPROBES > > + select HAVE_KRETPROBES > > select HAVE_PCI > > select HAVE_PERF_EVENTS > > select HAVE_PERF_REGS > > diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h > > index 56a98ea3..4647d38 100644 > > --- a/arch/riscv/include/asm/kprobes.h > > +++ b/arch/riscv/include/asm/kprobes.h > > @@ -11,4 +11,44 @@ > > > > #include <asm-generic/kprobes.h> > > > > +#ifdef CONFIG_KPROBES > > +#include <linux/types.h> > > +#include <linux/ptrace.h> > > +#include <linux/percpu.h> > > + > > +#define __ARCH_WANT_KPROBES_INSN_SLOT > > +#define MAX_INSN_SIZE 2 > > + > > +#define flush_insn_slot(p) do { } while (0) > > +#define kretprobe_blacklist_size 0 > > + > > +#include <asm/probes.h> > > + > > +struct prev_kprobe { > > + struct kprobe *kp; > > + unsigned int status; > > +}; > > + > > +/* Single step context for kprobe */ > > +struct kprobe_step_ctx { > > + unsigned long ss_pending; > > + unsigned long match_addr; > > +}; > > + > > +/* per-cpu kprobe control block */ > > +struct kprobe_ctlblk { > > + unsigned int kprobe_status; > > + unsigned long saved_status; > > + struct prev_kprobe prev_kprobe; > > + struct kprobe_step_ctx ss_ctx; > > +}; > > + > > +void arch_remove_kprobe(struct kprobe *p); > > +int kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr); > > +bool kprobe_breakpoint_handler(struct pt_regs *regs); > > +bool kprobe_single_step_handler(struct pt_regs *regs); > > +void kretprobe_trampoline(void); > > +void __kprobes *trampoline_probe_handler(struct pt_regs *regs); > > + > > +#endif /* CONFIG_KPROBES */ > > #endif /* _ASM_RISCV_KPROBES_H */ > > diff --git a/arch/riscv/include/asm/probes.h b/arch/riscv/include/asm/probes.h > > new file mode 100644 > > index 00000000..a787e6d > > --- /dev/null > > +++ b/arch/riscv/include/asm/probes.h > > @@ -0,0 +1,24 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > + > > +#ifndef _ASM_RISCV_PROBES_H > > +#define _ASM_RISCV_PROBES_H > > + > > +typedef u32 probe_opcode_t; > > +typedef bool (probes_handler_t) (u32 opcode, unsigned long addr, struct pt_regs *); > > + > > +/* architecture specific copy of original instruction */ > > +struct arch_probe_insn { > > + probe_opcode_t *insn; > > + probes_handler_t *handler; > > + /* restore address after simulation */ > > + unsigned long restore; > > +}; > > + > > +#ifdef CONFIG_KPROBES > > +typedef u32 kprobe_opcode_t; > > +struct arch_specific_insn { > > + struct arch_probe_insn api; > > +}; > > +#endif > > + > > +#endif /* _ASM_RISCV_PROBES_H */ > > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > > index b355cf4..c3fff3e 100644 > > --- a/arch/riscv/kernel/Makefile > > +++ b/arch/riscv/kernel/Makefile > > @@ -29,6 +29,7 @@ obj-y += riscv_ksyms.o > > obj-y += stacktrace.o > > obj-y += cacheinfo.o > > obj-y += patch.o > > +obj-y += probes/ > > obj-$(CONFIG_MMU) += vdso.o vdso/ > > > > obj-$(CONFIG_RISCV_M_MODE) += clint.o traps_misaligned.o > > diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile > > new file mode 100644 > > index 00000000..8a39507 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/Makefile > > @@ -0,0 +1,4 @@ > > +# SPDX-License-Identifier: GPL-2.0 > > +obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o simulate-insn.o > > +obj-$(CONFIG_KPROBES) += kprobes_trampoline.o > > +CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE) > > diff --git a/arch/riscv/kernel/probes/decode-insn.c b/arch/riscv/kernel/probes/decode-insn.c > > new file mode 100644 > > index 00000000..0876c30 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/decode-insn.c > > @@ -0,0 +1,48 @@ > > +// SPDX-License-Identifier: GPL-2.0+ > > + > > +#include <linux/kernel.h> > > +#include <linux/kprobes.h> > > +#include <linux/module.h> > > +#include <linux/kallsyms.h> > > +#include <asm/sections.h> > > + > > +#include "decode-insn.h" > > +#include "simulate-insn.h" > > + > > +/* Return: > > + * INSN_REJECTED If instruction is one not allowed to kprobe, > > + * INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot. > > + */ > > +enum probe_insn __kprobes > > +riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *api) > > +{ > > + probe_opcode_t insn = le32_to_cpu(*addr); > > + > > + /* > > + * Reject instructions list: > > + */ > > + RISCV_INSN_REJECTED(system, insn); > > + RISCV_INSN_REJECTED(fence, insn); > > + > > + /* > > + * Simulate instructions list: > > + * TODO: the REJECTED ones below need to be implemented > > + */ > > +#ifdef CONFIG_RISCV_ISA_C > > + RISCV_INSN_REJECTED(c_j, insn); > > + RISCV_INSN_REJECTED(c_jr, insn); > > + RISCV_INSN_REJECTED(c_jal, insn); > > + RISCV_INSN_REJECTED(c_jalr, insn); > > + RISCV_INSN_REJECTED(c_beqz, insn); > > + RISCV_INSN_REJECTED(c_bnez, insn); > > + RISCV_INSN_REJECTED(c_ebreak, insn); > > +#endif > > + > > + RISCV_INSN_REJECTED(auipc, insn); > > + RISCV_INSN_REJECTED(branch, insn); > > + > > + RISCV_INSN_SET_SIMULATE(jal, insn); > > + RISCV_INSN_SET_SIMULATE(jalr, insn); > > + > > + return INSN_GOOD; > > +} > > diff --git a/arch/riscv/kernel/probes/decode-insn.h b/arch/riscv/kernel/probes/decode-insn.h > > new file mode 100644 > > index 00000000..42269a7 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/decode-insn.h > > @@ -0,0 +1,18 @@ > > +/* SPDX-License-Identifier: GPL-2.0+ */ > > + > > +#ifndef _RISCV_KERNEL_KPROBES_DECODE_INSN_H > > +#define _RISCV_KERNEL_KPROBES_DECODE_INSN_H > > + > > +#include <asm/sections.h> > > +#include <asm/kprobes.h> > > + > > +enum probe_insn { > > + INSN_REJECTED, > > + INSN_GOOD_NO_SLOT, > > + INSN_GOOD, > > +}; > > + > > +enum probe_insn __kprobes > > +riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *asi); > > + > > +#endif /* _RISCV_KERNEL_KPROBES_DECODE_INSN_H */ > > diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c > > new file mode 100644 > > index 00000000..31b6196 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/kprobes.c > > @@ -0,0 +1,471 @@ > > +// SPDX-License-Identifier: GPL-2.0+ > > + > > +#include <linux/kprobes.h> > > +#include <linux/extable.h> > > +#include <linux/slab.h> > > +#include <linux/stop_machine.h> > > +#include <asm/ptrace.h> > > +#include <linux/uaccess.h> > > +#include <asm/sections.h> > > +#include <asm/cacheflush.h> > > +#include <asm/bug.h> > > +#include <asm/patch.h> > > + > > +#include "decode-insn.h" > > + > > +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; > > +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); > > + > > +static void __kprobes > > +post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); > > + > > +static void __kprobes arch_prepare_ss_slot(struct kprobe *p) > > +{ > > + unsigned long offset = GET_INSN_LENGTH(p->opcode); > > + > > + p->ainsn.api.restore = (unsigned long)p->addr + offset; > > + > > + patch_text(p->ainsn.api.insn, p->opcode); > > + patch_text((void *)((unsigned long)(p->ainsn.api.insn) + offset), > > + __BUG_INSN_32); > > +} > > + > > +static void __kprobes arch_prepare_simulate(struct kprobe *p) > > +{ > > + p->ainsn.api.restore = 0; > > +} > > + > > +static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) > > +{ > > + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); > > + > > + if (p->ainsn.api.handler) > > + p->ainsn.api.handler((u32)p->opcode, > > + (unsigned long)p->addr, regs); > > + > > + post_kprobe_handler(kcb, regs); > > +} > > + > > +int __kprobes arch_prepare_kprobe(struct kprobe *p) > > +{ > > + unsigned long probe_addr = (unsigned long)p->addr; > > + > > + if (probe_addr & 0x1) { > > + pr_warn("Address not aligned.\n"); > > + > > + return -EINVAL; > > + } > > + > > + /* copy instruction */ > > + p->opcode = le32_to_cpu(*p->addr); > > + > > + /* decode instruction */ > > + switch (riscv_probe_decode_insn(p->addr, &p->ainsn.api)) { > > + case INSN_REJECTED: /* insn not supported */ > > + return -EINVAL; > > + > > + case INSN_GOOD_NO_SLOT: /* insn need simulation */ > > + p->ainsn.api.insn = NULL; > > + break; > > + > > + case INSN_GOOD: /* instruction uses slot */ > > + p->ainsn.api.insn = get_insn_slot(); > > + if (!p->ainsn.api.insn) > > + return -ENOMEM; > > + break; > > + } > > + > > + /* prepare the instruction */ > > + if (p->ainsn.api.insn) > > + arch_prepare_ss_slot(p); > > + else > > + arch_prepare_simulate(p); > > + > > + return 0; > > +} > > + > > +/* install breakpoint in text */ > > +void __kprobes arch_arm_kprobe(struct kprobe *p) > > +{ > > + if ((p->opcode & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) > > + patch_text(p->addr, __BUG_INSN_32); > > + else > > + patch_text(p->addr, __BUG_INSN_16); > > +} > > + > > +/* remove breakpoint from text */ > > +void __kprobes arch_disarm_kprobe(struct kprobe *p) > > +{ > > + patch_text(p->addr, p->opcode); > > +} > > + > > +void __kprobes arch_remove_kprobe(struct kprobe *p) > > +{ > > +} > > + > > +static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) > > +{ > > + kcb->prev_kprobe.kp = kprobe_running(); > > + kcb->prev_kprobe.status = kcb->kprobe_status; > > +} > > + > > +static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) > > +{ > > + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); > > + kcb->kprobe_status = kcb->prev_kprobe.status; > > +} > > + > > +static void __kprobes set_current_kprobe(struct kprobe *p) > > +{ > > + __this_cpu_write(current_kprobe, p); > > +} > > + > > +/* > > + * Interrupts need to be disabled before single-step mode is set, and not > > + * reenabled until after single-step mode ends. > > + * Without disabling interrupt on local CPU, there is a chance of > > + * interrupt occurrence in the period of exception return and start of > > + * out-of-line single-step, that result in wrongly single stepping > > + * into the interrupt handler. > > + */ > > +static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb, > > + struct pt_regs *regs) > > +{ > > + kcb->saved_status = regs->status; > > + regs->status &= ~SR_SPIE; > > +} > > + > > +static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, > > + struct pt_regs *regs) > > +{ > > + regs->status = kcb->saved_status; > > +} > > + > > +static void __kprobes > > +set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr, struct kprobe *p) > > +{ > > + unsigned long offset = GET_INSN_LENGTH(p->opcode); > > + > > + kcb->ss_ctx.ss_pending = true; > > + kcb->ss_ctx.match_addr = addr + offset; > > +} > > + > > +static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) > > +{ > > + kcb->ss_ctx.ss_pending = false; > > + kcb->ss_ctx.match_addr = 0; > > +} > > + > > +static void __kprobes setup_singlestep(struct kprobe *p, > > + struct pt_regs *regs, > > + struct kprobe_ctlblk *kcb, int reenter) > > +{ > > + unsigned long slot; > > + > > + if (reenter) { > > + save_previous_kprobe(kcb); > > + set_current_kprobe(p); > > + kcb->kprobe_status = KPROBE_REENTER; > > + } else { > > + kcb->kprobe_status = KPROBE_HIT_SS; > > + } > > + > > + if (p->ainsn.api.insn) { > > + /* prepare for single stepping */ > > + slot = (unsigned long)p->ainsn.api.insn; > > + > > + set_ss_context(kcb, slot, p); /* mark pending ss */ > > + > > + /* IRQs and single stepping do not mix well. */ > > + kprobes_save_local_irqflag(kcb, regs); > > + > > + instruction_pointer_set(regs, slot); > > + } else { > > + /* insn simulation */ > > + arch_simulate_insn(p, regs); > > + } > > +} > > + > > +static int __kprobes 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("Unrecoverable kprobe detected.\n"); > > + dump_kprobe(p); > > + BUG(); > > + break; > > + default: > > + WARN_ON(1); > > + return 0; > > + } > > + > > + return 1; > > +} > > + > > +static void __kprobes > > +post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) > > +{ > > + struct kprobe *cur = kprobe_running(); > > + > > + if (!cur) > > + return; > > + > > + /* return addr restore if non-branching insn */ > > + if (cur->ainsn.api.restore != 0) > > + regs->epc = cur->ainsn.api.restore; > > + > > + /* restore back original saved kprobe variables and continue */ > > + if (kcb->kprobe_status == KPROBE_REENTER) { > > + restore_previous_kprobe(kcb); > > + return; > > + } > > + > > + /* call post handler */ > > + kcb->kprobe_status = KPROBE_HIT_SSDONE; > > + if (cur->post_handler) { > > + /* post_handler can hit breakpoint and single step > > + * again, so we enable D-flag for recursive exception. > > + */ > > + cur->post_handler(cur, regs, 0); > > + } > > + > > + reset_current_kprobe(); > > +} > > + > > +int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr) > > +{ > > + struct kprobe *cur = kprobe_running(); > > + struct kprobe_ctlblk *kcb = 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->epc = (unsigned long) cur->addr; > > + if (!instruction_pointer(regs)) > > + BUG(); > > + > > + if (kcb->kprobe_status == KPROBE_REENTER) > > + restore_previous_kprobe(kcb); > > + else > > + reset_current_kprobe(); > > + > > + break; > > + case KPROBE_HIT_ACTIVE: > > + case KPROBE_HIT_SSDONE: > > + /* > > + * We increment the nmissed count for accounting, > > + * we can also use npre/npostfault count for accounting > > + * these specific fault cases. > > + */ > > + kprobes_inc_nmissed_count(cur); > > + > > + /* > > + * We come here because instructions in the pre/post > > + * handler caused the page_fault, this could happen > > + * if handler tries to access user space by > > + * copy_from_user(), get_user() etc. Let the > > + * user-specified handler try to fix it first. > > + */ > > + if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) > > + return 1; > > + > > + /* > > + * In case the user-specified fault handler returned > > + * zero, try to fix up. > > + */ > > + if (fixup_exception(regs)) > > + return 1; > > + } > > + return 0; > > +} > > + > > +bool __kprobes > > +kprobe_breakpoint_handler(struct pt_regs *regs) > > +{ > > + struct kprobe *p, *cur_kprobe; > > + struct kprobe_ctlblk *kcb; > > + unsigned long addr = instruction_pointer(regs); > > + > > + kcb = get_kprobe_ctlblk(); > > + cur_kprobe = kprobe_running(); > > + > > + p = get_kprobe((kprobe_opcode_t *) addr); > > + > > + if (p) { > > + if (cur_kprobe) { > > + if (reenter_kprobe(p, regs, kcb)) > > + return true; > > + } else { > > + /* Probe hit */ > > + set_current_kprobe(p); > > + kcb->kprobe_status = 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(); > > + } > > + return true; > > + } > > + > > + /* > > + * 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. > > + */ > > + return false; > > +} > > + > > +bool __kprobes > > +kprobe_single_step_handler(struct pt_regs *regs) > > +{ > > + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); > > + > > + if ((kcb->ss_ctx.ss_pending) > > + && (kcb->ss_ctx.match_addr == instruction_pointer(regs))) { > > + clear_ss_context(kcb); /* clear pending ss */ > > + > > + kprobes_restore_local_irqflag(kcb, regs); > > + > > + post_kprobe_handler(kcb, regs); > > + return true; > > + } > > + return false; > > +} > > + > > +/* > > + * Provide a blacklist of symbols identifying ranges which cannot be kprobed. > > + * This blacklist is exposed to userspace via debugfs (kprobes/blacklist). > > + */ > > +int __init arch_populate_kprobe_blacklist(void) > > +{ > > + int ret; > > + > > + ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start, > > + (unsigned long)__irqentry_text_end); > > + return ret; > > +} > > + > > +void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) > > +{ > > + struct kretprobe_instance *ri = NULL; > > + struct hlist_head *head, empty_rp; > > + struct hlist_node *tmp; > > + unsigned long flags, orig_ret_address = 0; > > + unsigned long trampoline_address = > > + (unsigned long)&kretprobe_trampoline; > > + kprobe_opcode_t *correct_ret_addr = NULL; > > + > > + INIT_HLIST_HEAD(&empty_rp); > > + kretprobe_hash_lock(current, &head, &flags); > > + > > + /* > > + * It is possible to have multiple instances associated with a given > > + * task either because multiple functions in the call path have > > + * return probes installed on them, and/or more than one > > + * return probe was registered for a target function. > > + * > > + * We can handle this because: > > + * - instances are always pushed into the head of the list > > + * - when multiple return probes are registered for the same > > + * function, the (chronologically) first instance's ret_addr > > + * will be the real return address, and all the rest will > > + * point to kretprobe_trampoline. > > + */ > > + hlist_for_each_entry_safe(ri, tmp, head, hlist) { > > + if (ri->task != current) > > + /* another task is sharing our hash bucket */ > > + continue; > > + > > + orig_ret_address = (unsigned long)ri->ret_addr; > > + > > + if (orig_ret_address != trampoline_address) > > + /* > > + * This is the real return address. Any other > > + * instances associated with this task are for > > + * other calls deeper on the call stack > > + */ > > + break; > > + } > > + > > + kretprobe_assert(ri, orig_ret_address, trampoline_address); > > + > > + correct_ret_addr = ri->ret_addr; > > + hlist_for_each_entry_safe(ri, tmp, head, hlist) { > > + if (ri->task != current) > > + /* another task is sharing our hash bucket */ > > + continue; > > + > > + orig_ret_address = (unsigned long)ri->ret_addr; > > + if (ri->rp && ri->rp->handler) { > > + __this_cpu_write(current_kprobe, &ri->rp->kp); > > + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; > > + ri->ret_addr = correct_ret_addr; > > + ri->rp->handler(ri, regs); > > + __this_cpu_write(current_kprobe, NULL); > > + } > > + > > + recycle_rp_inst(ri, &empty_rp); > > + > > + if (orig_ret_address != trampoline_address) > > + /* > > + * This is the real return address. Any other > > + * instances associated with this task are for > > + * other calls deeper on the call stack > > + */ > > + break; > > + } > > + > > + kretprobe_hash_unlock(current, &flags); > > + > > + hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { > > + hlist_del(&ri->hlist); > > + kfree(ri); > > + } > > + return (void *)orig_ret_address; > > +} > > + > > +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, > > + struct pt_regs *regs) > > +{ > > + ri->ret_addr = (kprobe_opcode_t *)regs->ra; > > + regs->ra = (unsigned long) &kretprobe_trampoline; > > +} > > + > > +int __kprobes arch_trampoline_kprobe(struct kprobe *p) > > +{ > > + return 0; > > +} > > + > > +int __init arch_init_kprobes(void) > > +{ > > + return 0; > > +} > > diff --git a/arch/riscv/kernel/probes/kprobes_trampoline.S b/arch/riscv/kernel/probes/kprobes_trampoline.S > > new file mode 100644 > > index 00000000..6e85d02 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/kprobes_trampoline.S > > @@ -0,0 +1,93 @@ > > +/* SPDX-License-Identifier: GPL-2.0+ */ > > +/* > > + * Author: Patrick Stählin <me@xxxxxxxx> > > + */ > > +#include <linux/linkage.h> > > + > > +#include <asm/asm.h> > > +#include <asm/asm-offsets.h> > > + > > + .text > > + .altmacro > > + > > + .macro save_all_base_regs > > + REG_S x1, PT_RA(sp) > > + REG_S x3, PT_GP(sp) > > + REG_S x4, PT_TP(sp) > > + REG_S x5, PT_T0(sp) > > + REG_S x6, PT_T1(sp) > > + REG_S x7, PT_T2(sp) > > + REG_S x8, PT_S0(sp) > > + REG_S x9, PT_S1(sp) > > + REG_S x10, PT_A0(sp) > > + REG_S x11, PT_A1(sp) > > + REG_S x12, PT_A2(sp) > > + REG_S x13, PT_A3(sp) > > + REG_S x14, PT_A4(sp) > > + REG_S x15, PT_A5(sp) > > + REG_S x16, PT_A6(sp) > > + REG_S x17, PT_A7(sp) > > + REG_S x18, PT_S2(sp) > > + REG_S x19, PT_S3(sp) > > + REG_S x20, PT_S4(sp) > > + REG_S x21, PT_S5(sp) > > + REG_S x22, PT_S6(sp) > > + REG_S x23, PT_S7(sp) > > + REG_S x24, PT_S8(sp) > > + REG_S x25, PT_S9(sp) > > + REG_S x26, PT_S10(sp) > > + REG_S x27, PT_S11(sp) > > + REG_S x28, PT_T3(sp) > > + REG_S x29, PT_T4(sp) > > + REG_S x30, PT_T5(sp) > > + REG_S x31, PT_T6(sp) > > + .endm > > + > > + .macro restore_all_base_regs > > + REG_L x3, PT_GP(sp) > > + REG_L x4, PT_TP(sp) > > + REG_L x5, PT_T0(sp) > > + REG_L x6, PT_T1(sp) > > + REG_L x7, PT_T2(sp) > > + REG_L x8, PT_S0(sp) > > + REG_L x9, PT_S1(sp) > > + REG_L x10, PT_A0(sp) > > + REG_L x11, PT_A1(sp) > > + REG_L x12, PT_A2(sp) > > + REG_L x13, PT_A3(sp) > > + REG_L x14, PT_A4(sp) > > + REG_L x15, PT_A5(sp) > > + REG_L x16, PT_A6(sp) > > + REG_L x17, PT_A7(sp) > > + REG_L x18, PT_S2(sp) > > + REG_L x19, PT_S3(sp) > > + REG_L x20, PT_S4(sp) > > + REG_L x21, PT_S5(sp) > > + REG_L x22, PT_S6(sp) > > + REG_L x23, PT_S7(sp) > > + REG_L x24, PT_S8(sp) > > + REG_L x25, PT_S9(sp) > > + REG_L x26, PT_S10(sp) > > + REG_L x27, PT_S11(sp) > > + REG_L x28, PT_T3(sp) > > + REG_L x29, PT_T4(sp) > > + REG_L x30, PT_T5(sp) > > + REG_L x31, PT_T6(sp) > > + .endm > > + > > +ENTRY(kretprobe_trampoline) > > + addi sp, sp, -(PT_SIZE_ON_STACK) > > + save_all_base_regs > > + > > + move a0, sp /* pt_regs */ > > + > > + call trampoline_probe_handler > > + > > + /* use the result as the return-address */ > > + move ra, a0 > > + > > + restore_all_base_regs > > + addi sp, sp, PT_SIZE_ON_STACK > > + > > + ret > > +ENDPROC(kretprobe_trampoline) > > diff --git a/arch/riscv/kernel/probes/simulate-insn.c b/arch/riscv/kernel/probes/simulate-insn.c > > new file mode 100644 > > index 00000000..2519ce2 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/simulate-insn.c > > @@ -0,0 +1,85 @@ > > +// SPDX-License-Identifier: GPL-2.0+ > > + > > +#include <linux/bitops.h> > > +#include <linux/kernel.h> > > +#include <linux/kprobes.h> > > + > > +#include "decode-insn.h" > > +#include "simulate-insn.h" > > + > > +static inline bool rv_insn_reg_get_val(struct pt_regs *regs, u32 index, > > + unsigned long *ptr) > > +{ > > + if (index == 0) > > + *ptr = 0; > > + else if (index <= 31) > > + *ptr = *((unsigned long *)regs + index); > > + else > > + return false; > > + > > + return true; > > +} > > + > > +static inline bool rv_insn_reg_set_val(struct pt_regs *regs, u32 index, > > + unsigned long val) > > +{ > > + if (index == 0) > > + return false; > > + else if (index <= 31) > > + *((unsigned long *)regs + index) = val; > > + else > > + return false; > > + > > + return true; > > +} > > + > > +bool __kprobes simulate_jal(u32 opcode, unsigned long addr, struct pt_regs *regs) > > +{ > > + /* > > + * 31 30 21 20 19 12 11 7 6 0 > > + * imm [20] | imm[10:1] | imm[11] | imm[19:12] | rd | opcode > > + * 1 10 1 8 5 JAL/J > > + */ > > + bool ret; > > + u32 imm; > > + u32 index = (opcode >> 7) & 0x1f; > > + > > + ret = rv_insn_reg_set_val(regs, index, addr + 4); > > + if (!ret) > > + return ret; > > + > > + imm = ((opcode >> 21) & 0x3ff) << 1; > > + imm |= ((opcode >> 20) & 0x1) << 11; > > + imm |= ((opcode >> 12) & 0xff) << 12; > > + imm |= ((opcode >> 31) & 0x1) << 20; > > + > > + instruction_pointer_set(regs, addr + sign_extend32((imm), 20)); > > + > > + return ret; > > +} > > + > > +bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *regs) > > +{ > > + /* > > + * 31 20 19 15 14 12 11 7 6 0 > > + * offset[11:0] | rs1 | 010 | rd | opcode > > + * 12 5 3 5 JALR/JR > > + */ > > + bool ret; > > + unsigned long base_addr; > > + u32 imm = (opcode >> 20) & 0xfff; > > + u32 rd_index = (opcode >> 7) & 0x1f; > > + u32 rs1_index = (opcode >> 15) & 0x1f; > > + > > + ret = rv_insn_reg_set_val(regs, rd_index, addr + 4); > > + if (!ret) > > + return ret; > > + > > + ret = rv_insn_reg_get_val(regs, rs1_index, &base_addr); > > + if (!ret) > > + return ret; > > + > > + instruction_pointer_set(regs, (base_addr + sign_extend32((imm), 11))&~1); > > + > > + return ret; > > +} > > diff --git a/arch/riscv/kernel/probes/simulate-insn.h b/arch/riscv/kernel/probes/simulate-insn.h > > new file mode 100644 > > index 00000000..a62d784 > > --- /dev/null > > +++ b/arch/riscv/kernel/probes/simulate-insn.h > > @@ -0,0 +1,47 @@ > > +/* SPDX-License-Identifier: GPL-2.0+ */ > > + > > +#ifndef _RISCV_KERNEL_PROBES_SIMULATE_INSN_H > > +#define _RISCV_KERNEL_PROBES_SIMULATE_INSN_H > > + > > +#define __RISCV_INSN_FUNCS(name, mask, val) \ > > +static __always_inline bool riscv_insn_is_##name(probe_opcode_t code) \ > > +{ \ > > + BUILD_BUG_ON(~(mask) & (val)); \ > > + return (code & (mask)) == (val); \ > > +} \ > > +bool simulate_##name(u32 opcode, unsigned long addr, \ > > + struct pt_regs *regs); > > + > > +#define RISCV_INSN_REJECTED(name, code) \ > > + do { \ > > + if (riscv_insn_is_##name(code)) { \ > > + return INSN_REJECTED; \ > > + } \ > > + } while (0) > > + > > +__RISCV_INSN_FUNCS(system, 0x7f, 0x73) > > +__RISCV_INSN_FUNCS(fence, 0x7f, 0x0f) > > + > > +#define RISCV_INSN_SET_SIMULATE(name, code) \ > > + do { \ > > + if (riscv_insn_is_##name(code)) { \ > > + api->handler = simulate_##name; \ > > + return INSN_GOOD_NO_SLOT; \ > > + } \ > > + } while (0) > > + > > +__RISCV_INSN_FUNCS(c_j, 0xe003, 0xa001) > > +__RISCV_INSN_FUNCS(c_jr, 0xf007, 0x8002) > > +__RISCV_INSN_FUNCS(c_jal, 0xe003, 0x2001) > > +__RISCV_INSN_FUNCS(c_jalr, 0xf007, 0x9002) > > +__RISCV_INSN_FUNCS(c_beqz, 0xe003, 0xc001) > > +__RISCV_INSN_FUNCS(c_bnez, 0xe003, 0xe001) > > +__RISCV_INSN_FUNCS(c_ebreak, 0xffff, 0x9002) > > + > > +__RISCV_INSN_FUNCS(auipc, 0x7f, 0x17) > > +__RISCV_INSN_FUNCS(branch, 0x7f, 0x63) > > + > > +__RISCV_INSN_FUNCS(jal, 0x7f, 0x6f) > > +__RISCV_INSN_FUNCS(jalr, 0x707f, 0x67) > > + > > +#endif /* _RISCV_KERNEL_PROBES_SIMULATE_INSN_H */ > > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > > index ecec177..ac2e786 100644 > > --- a/arch/riscv/kernel/traps.c > > +++ b/arch/riscv/kernel/traps.c > > @@ -12,6 +12,7 @@ > > #include <linux/signal.h> > > #include <linux/kdebug.h> > > #include <linux/uaccess.h> > > +#include <linux/kprobes.h> > > #include <linux/mm.h> > > #include <linux/module.h> > > #include <linux/irq.h> > > @@ -145,6 +146,14 @@ static inline unsigned long get_break_insn_length(unsigned long pc) > > > > asmlinkage __visible void do_trap_break(struct pt_regs *regs) > > { > > +#ifdef CONFIG_KPROBES > > + if (kprobe_single_step_handler(regs)) > > + return; > > + > > + if (kprobe_breakpoint_handler(regs)) > > + return; > > +#endif > > + > > if (user_mode(regs)) > > force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc); > > #ifdef CONFIG_KGDB > > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c > > index ae7b7fe..da0c08c 100644 > > --- a/arch/riscv/mm/fault.c > > +++ b/arch/riscv/mm/fault.c > > @@ -13,6 +13,7 @@ > > #include <linux/perf_event.h> > > #include <linux/signal.h> > > #include <linux/uaccess.h> > > +#include <linux/kprobes.h> > > > > #include <asm/pgalloc.h> > > #include <asm/ptrace.h> > > @@ -40,6 +41,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs) > > tsk = current; > > mm = tsk->mm; > > > > + if (kprobe_page_fault(regs, cause)) > > + return; > > + > > /* > > * Fault-in kernel-space virtual memory on-demand. > > * The 'reference' page table is init_mm.pgd. > > -- > > 2.7.4 > > > > > -- > Masami Hiramatsu <mhiramat@xxxxxxxxxx>
