linux-kernel - Re: [PATCH v4 perf,bpf 07/15] perf, bpf: save bpf_prog

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Date:   Wed, 27 Feb 2019 14:21:55 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     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 v4 perf,bpf 07/15] perf, bpf: save bpf_prog_info
 information as headers to perf.data

On Mon, Feb 25, 2019 at 04:20:11PM -0800, Song Liu wrote:

SNIP

> +		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 */

so there's no way we can swap the data? why?

jirka

> +		if (ff->ph->needs_swap) {
> +			free(info_linear);
> +			continue;
> +		}

SNIP