linux-kernel - Re: [PATCH bpf-next 1/3] bpf: make bpf_prog

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Message-ID: <CAPhsuW5+ija4umxAhOMk5mVGGCGV=iPBNm-QbhkVz99WHzrmsQ@mail.gmail.com>
Date:   Mon, 5 Jun 2023 09:30:10 -0700
From:   Song Liu <song@...nel.org>
To:     Puranjay Mohan <puranjay12@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        martin.lau@...ux.dev, catalin.marinas@....com,
        mark.rutland@....com, bpf@...r.kernel.org, kpsingh@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next 1/3] bpf: make bpf_prog_pack allocator portable

On Mon, Jun 5, 2023 at 12:40 AM Puranjay Mohan <puranjay12@...il.com> wrote:
>
> The bpf_prog_pack allocator currently uses module_alloc() and
> module_memfree() to allocate and free memory. This is not portable
> because different architectures use different methods for allocating
> memory for BPF programs. Like ARM64 uses vmalloc()/vfree().
>
> Use bpf_jit_alloc_exec() and bpf_jit_free_exec() for memory management
> in bpf_prog_pack allocator. Other architectures can override these with
> their implementation and will be able to use bpf_prog_pack directly.
>
> Signed-off-by: Puranjay Mohan <puranjay12@...il.com>

Acked-by: Song Liu <song@...nel.org>

> ---
>  kernel/bpf/core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 7421487422d4..2bc9092bf9be 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -860,7 +860,7 @@ static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_ins
>                        GFP_KERNEL);
>         if (!pack)
>                 return NULL;
> -       pack->ptr = module_alloc(BPF_PROG_PACK_SIZE);
> +       pack->ptr = bpf_jit_alloc_exec(BPF_PROG_PACK_SIZE);
>         if (!pack->ptr) {
>                 kfree(pack);
>                 return NULL;
> @@ -884,7 +884,7 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns)
>         mutex_lock(&pack_mutex);
>         if (size > BPF_PROG_PACK_SIZE) {
>                 size = round_up(size, PAGE_SIZE);
> -               ptr = module_alloc(size);
> +               ptr = bpf_jit_alloc_exec(size);
>                 if (ptr) {
>                         bpf_fill_ill_insns(ptr, size);
>                         set_vm_flush_reset_perms(ptr);
> @@ -922,7 +922,7 @@ void bpf_prog_pack_free(struct bpf_binary_header *hdr)
>
>         mutex_lock(&pack_mutex);
>         if (hdr->size > BPF_PROG_PACK_SIZE) {
> -               module_memfree(hdr);
> +               bpf_jit_free_exec(hdr);
>                 goto out;
>         }
>
> @@ -946,7 +946,7 @@ void bpf_prog_pack_free(struct bpf_binary_header *hdr)
>         if (bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0,
>                                        BPF_PROG_CHUNK_COUNT, 0) == 0) {
>                 list_del(&pack->list);
> -               module_memfree(pack->ptr);
> +               bpf_jit_free_exec(pack->ptr);
>                 kfree(pack);
>         }
>  out:
> --
> 2.39.2
>