linux-kernel - Re: [PATCH v6 perf,bpf 07/15] perf, bpf: save bpf_prog

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Message-ID: <20190307140555.GD7233@krava>
Date:   Thu, 7 Mar 2019 15:05:55 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        kernel-team@...com, peterz@...radead.org, acme@...hat.com,
        jolsa@...nel.org, namhyung@...nel.org
Subject: Re: [PATCH v6 perf,bpf 07/15] perf, bpf: save bpf_prog_info
 information as headers to perf.data

On Tue, Mar 05, 2019 at 11:13:51PM -0800, Song Liu wrote:

SNIP

> +static int process_bpf_prog_info(struct feat_fd *ff,
> +				 void *data __maybe_unused)
> +{
> +	struct bpf_prog_info_linear *info_linear;
> +	struct bpf_prog_info_node *info_node;
> +	struct perf_env *env = &ff->ph->env;
> +	u32 count, i;
> +	int err = -1;
> +
> +	if (do_read_u32(ff, &count))
> +		return -1;
> +
> +	if (ff->ph->needs_swap)
> +		pr_warning("interpreting bpf_prog_info from systems with endianity is not yet supported\n");

		return 0; ?

what's here to process?

jirka

> +
> +	down_write(&env->bpf_progs.lock);
> +
> +	for (i = 0; i < count; ++i) {
> +		u32 info_len, data_len;
> +
> +		info_linear = NULL;
> +		info_node = NULL;
> +		if (do_read_u32(ff, &info_len))
> +			goto out;
> +		if (do_read_u32(ff, &data_len))
> +			goto out;
> +
> +		if (info_len > sizeof(struct bpf_prog_info)) {
> +			pr_warning("detected invalid bpf_prog_info\n");
> +			goto out;
> +		}
> +
> +		info_linear = malloc(sizeof(struct bpf_prog_info_linear) +
> +				     data_len);
> +		if (!info_linear)
> +			goto out;
> +		info_linear->info_len = sizeof(struct bpf_prog_info);
> +		info_linear->data_len = data_len;
> +		if (do_read_u64(ff, (u64 *)(&info_linear->arrays)))
> +			goto out;
> +		if (__do_read(ff, &info_linear->info, info_len))
> +			goto out;
> +		if (info_len < sizeof(struct bpf_prog_info))
> +			memset(((void *)(&info_linear->info)) + info_len, 0,
> +			       sizeof(struct bpf_prog_info) - info_len);
> +
> +		if (__do_read(ff, info_linear->data, data_len))
> +			goto out;
> +
> +		/* endian mismatch, drop the info, continue */
> +		if (ff->ph->needs_swap) {
> +			free(info_linear);
> +			continue;
> +		}
> +
> +		info_node = malloc(sizeof(struct bpf_prog_info_node));
> +		if (!info_node)
> +			goto out;
> +
> +		/* after reading from file, translate offset to address */
> +		bpf_program__bpil_offs_to_addr(info_linear);
> +		info_node->info_linear = info_linear;
> +		perf_env__insert_bpf_prog_info(env, info_node);
> +	}
> +
> +	return 0;
> +out:
> +	free(info_linear);
> +	free(info_node);
> +	up_write(&env->bpf_progs.lock);
> +	return err;
> +}

SNIP