On Wed, Jan 05, 2022 at 06:25:33PM -0800, Song Liu wrote:
> From: Song Liu <songliubraving@xxxxxx>
>
> Use bpf_prog_pack allocator in x86_64 jit.
>
> The program header from bpf_prog_pack is read only during the jit process.
> Therefore, the binary is first written to a temporary buffer, and later
> copied to final location with text_poke_jit().
>
> Similarly, jit_fill_hole() is updated to fill the hole with 0xcc using
> text_poke_jit().
>
> Signed-off-by: Song Liu <songliubraving@xxxxxx>
> ---
> arch/x86/net/bpf_jit_comp.c | 131 +++++++++++++++++++++++++++---------
> 1 file changed, 100 insertions(+), 31 deletions(-)
>
> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> index fe4f08e25a1d..ad69a64ee4fe 100644
> --- a/arch/x86/net/bpf_jit_comp.c
> +++ b/arch/x86/net/bpf_jit_comp.c
> @@ -216,11 +216,33 @@ static u8 simple_alu_opcodes[] = {
> [BPF_ARSH] = 0xF8,
> };
>
> +static char jit_hole_buffer[PAGE_SIZE] = {};
> +
> static void jit_fill_hole(void *area, unsigned int size)
> +{
> + struct bpf_binary_header *hdr = area;
> + int i;
> +
> + for (i = 0; i < roundup(size, PAGE_SIZE); i += PAGE_SIZE) {
> + int s;
> +
> + s = min_t(int, PAGE_SIZE, size - i);
> + text_poke_jit(area + i, jit_hole_buffer, s);
> + }
> +
> + /* bpf_jit_binary_alloc_pack cannot write size directly to the ro
> + * mapping. Write it here with text_poke_jit().
> + */
Could we move this file towards regular comment style please? It's
already mixed style, let's take the opportunity and not add more
net-style comments.
> + text_poke_jit(&hdr->size, &size, sizeof(size));
> +}
