Hi Pingfan,
On Tue, 19 Aug 2025 09:24:22 +0800
Pingfan Liu <piliu@xxxxxxxxxx> wrote:
> This patch does two things:
> First, register as a listener on bpf_copy_to_kernel()
> Second, in order that the hooked bpf-prog can call the sleepable kfuncs,
> bpf_handle_pefile and bpf_post_handle_pefile are marked as
> KF_SLEEPABLE.
>
> Signed-off-by: Pingfan Liu <piliu@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Philipp Rudo <prudo@xxxxxxxxxx>
> Cc: Baoquan He <bhe@xxxxxxxxxx>
> Cc: Dave Young <dyoung@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: bpf@xxxxxxxxxxxxxxx
> To: kexec@xxxxxxxxxxxxxxxxxxx
> ---
> kernel/kexec_pe_image.c | 67 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 67 insertions(+)
>
> diff --git a/kernel/kexec_pe_image.c b/kernel/kexec_pe_image.c
> index b0cf9942e68d2..f8debcde6b516 100644
> --- a/kernel/kexec_pe_image.c
> +++ b/kernel/kexec_pe_image.c
> @@ -38,6 +38,51 @@ static struct kexec_res parsed_resource[3] = {
> { KEXEC_RES_CMDLINE_NAME, },
> };
>
> +/*
> + * @name should be one of : kernel, initrd, cmdline
> + */
> +static int bpf_kexec_carrier(const char *name, struct mem_range_result *r)
> +{
> + struct kexec_res *res;
> + int i;
> +
> + if (!r || !name)
> + return -EINVAL;
> +
> + for (i = 0; i < 3; i++) {
> + if (!strcmp(parsed_resource[i].name, name))
> + break;
> + }
> + if (i >= 3)
> + return -EINVAL;
Can you please replace the magic '3' by ARRAY_SIZE, just like you did
below when (un-)registering the listener.
Thanks
Philipp
> +
> + res = &parsed_resource[i];
> + /*
> + * Replace the intermediate resource generated by the previous step.
> + */
> + if (!!res->r)
> + mem_range_result_put(res->r);
> + mem_range_result_get(r);
> + res->r = r;
> + return 0;
> +}
> +
> +static struct carrier_listener kexec_res_listener[3] = {
> + { .name = KEXEC_RES_KERNEL_NAME,
> + .alloc_type = 1,
> + .handler = bpf_kexec_carrier,
> + },
> + { .name = KEXEC_RES_INITRD_NAME,
> + .alloc_type = 1,
> + .handler = bpf_kexec_carrier,
> + },
> + { .name = KEXEC_RES_CMDLINE_NAME,
> + /* kmalloc-ed */
> + .alloc_type = 0,
> + .handler = bpf_kexec_carrier,
> + },
> +};
> +
> static bool pe_has_bpf_section(const char *file_buf, unsigned long pe_sz);
>
> static bool is_valid_pe(const char *kernel_buf, unsigned long kernel_len)
> @@ -159,6 +204,22 @@ __attribute__((used, optimize("O0"))) void bpf_post_handle_pefile(struct kexec_c
> dummy += 2;
> }
>
> +BTF_KFUNCS_START(kexec_modify_return_ids)
> +BTF_ID_FLAGS(func, bpf_handle_pefile, KF_SLEEPABLE)
> +BTF_ID_FLAGS(func, bpf_post_handle_pefile, KF_SLEEPABLE)
> +BTF_KFUNCS_END(kexec_modify_return_ids)
> +
> +static const struct btf_kfunc_id_set kexec_modify_return_set = {
> + .owner = THIS_MODULE,
> + .set = &kexec_modify_return_ids,
> +};
> +
> +static int __init kexec_bpf_prog_run_init(void)
> +{
> + return register_btf_fmodret_id_set(&kexec_modify_return_set);
> +}
> +late_initcall(kexec_bpf_prog_run_init);
> +
> /*
> * PE file may be nested and should be unfold one by one.
> * Query 'kernel', 'initrd', 'cmdline' in cur_phase, as they are inputs for the
> @@ -213,6 +274,9 @@ static void *pe_image_load(struct kimage *image,
> cmdline_start = cmdline;
> cmdline_sz = cmdline_len;
>
> + for (int i = 0; i < ARRAY_SIZE(kexec_res_listener); i++)
> + register_carrier_listener(&kexec_res_listener[i]);
> +
> while (is_valid_format(linux_start, linux_sz) &&
> pe_has_bpf_section(linux_start, linux_sz)) {
> struct kexec_context context;
> @@ -250,6 +314,9 @@ static void *pe_image_load(struct kimage *image,
> disarm_bpf_prog();
> }
>
> + for (int i = 0; i < ARRAY_SIZE(kexec_res_listener); i++)
> + unregister_carrier_listener(kexec_res_listener[i].name);
> +
> /*
> * image's kernel_buf, initrd_buf, cmdline_buf are set. Now they should
> * be updated to the new content.
