Messages in this thread | | | Date | Wed, 4 Jan 2023 16:35:15 +0800 | Subject | Re: [PATCH v5 6/9] riscv/kprobe: Add code to check if kprobe can be optimized | From | "liaochang (A)" <> |
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在 2023/1/3 2:04, Björn Töpel 写道: > Chen Guokai <chenguokai17@mails.ucas.ac.cn> writes: > >> From: Liao Chang <liaochang1@huawei.com> > >> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c >> index a0d2ab39e3fa..258a283c906d 100644 >> --- a/arch/riscv/kernel/probes/opt.c >> +++ b/arch/riscv/kernel/probes/opt.c >> @@ -271,15 +271,103 @@ static void find_free_registers(struct kprobe *kp, struct optimized_kprobe *op, >> *ra = (kw == 1UL) ? 0 : __builtin_ctzl(kw & ~1UL); >> } >> >> +static bool insn_jump_into_range(unsigned long addr, unsigned long start, >> + unsigned long end) >> +{ >> + kprobe_opcode_t insn = *(kprobe_opcode_t *)addr; >> + unsigned long target, offset = GET_INSN_LENGTH(insn); >> + >> +#ifdef CONFIG_RISCV_ISA_C >> + if (offset == RVC_INSN_LEN) { >> + if (riscv_insn_is_c_beqz(insn) || riscv_insn_is_c_bnez(insn)) >> + target = addr + rvc_branch_imme(insn); >> + else if (riscv_insn_is_c_jal(insn) || riscv_insn_is_c_j(insn)) >> + target = addr + rvc_jal_imme(insn); >> + else >> + target = 0; >> + return (target >= start) && (target < end); >> + } >> +#endif >> + >> + if (riscv_insn_is_branch(insn)) >> + target = addr + rvi_branch_imme(insn); >> + else if (riscv_insn_is_jal(insn)) >> + target = addr + rvi_jal_imme(insn); >> + else >> + target = 0; >> + return (target >= start) && (target < end); >> +} >> + >> +static int search_copied_insn(unsigned long paddr, struct optimized_kprobe *op) >> +{ >> + int i = 1; >> + unsigned long offset = GET_INSN_LENGTH(*(kprobe_opcode_t *)paddr); >> + >> + while ((i++ < MAX_COPIED_INSN) && (offset < 2 * RVI_INSN_LEN)) { >> + if (riscv_probe_decode_insn((probe_opcode_t *)paddr + offset, >> + NULL) != INSN_GOOD) > > If the second argument is NULL, and the insn is auipc, we'll splat with > NULL-ptr exception.
Good catch, it is my fault to ignore the access to second argument in macro RISCV_INSN_SET_SIMULATE.
> > Hmm, probe_opcode_t is u32, right? And GET_INSN_LENGTH() returns 4 or 2 > ...then the pointer arithmetic will be a mess?
Hmm, This pointer arithemtic does make no sense here, i had debugged this function on QEMU step by step, and it work well. Anyway, i will go through this function again, thanks.
> > > Björn
-- BR, Liao, Chang
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