Re: [PATCH v5 3/9] riscv/kprobe: Prepare the skeleton to prepare optimized kprobe

Björn Töpel
2023-01-02T18:04:45Z

Chen Guokai <chenguokai17@mails.ucas.ac.cn> writes:

> From: Liao Chang <liaochang1@huawei.com>

> arch/riscv/kernel/probes/opt.c | 107 ++++++++++++++++++++++++++++++++-
>
> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c
> index 56c8a227c857..a4271e6033ba 100644
> --- a/arch/riscv/kernel/probes/opt.c
> +++ b/arch/riscv/kernel/probes/opt.c

> @@ -24,7 +72,64 @@ int arch_check_optimized_kprobe(struct optimized_kprobe *op)
> int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
> struct kprobe *orig)
> {
> - return 0;
> + long rel;
> + int rd, ra, ret;
> + kprobe_opcode_t *code = NULL, *slot = NULL;
> +
> + if (!can_optimize((unsigned long)orig->addr, op))
> + return -EILSEQ;
> +
> + code = kzalloc(MAX_OPTINSN_SIZE, GFP_KERNEL);
> + slot = get_optinsn_slot();
> + if (!code || !slot) {
> + ret = -ENOMEM;
> + goto on_error;
> + }
> +
> + /*
> + * Verify if the address gap is within 4GB range, because this uses
> + * a auipc+jalr pair.

Try to be consistent. You're mixing "AUIPC/JALR" with "auipc+jalr".

> + */
> + rel = (unsigned long)slot - (unsigned long)orig->addr;
> + if (!in_auipc_jalr_range(rel)) {
> + /*
> + * Different from x86, we free code buf directly instead
> of

Reword for readers that are not familiar with x86.

Björn