On 12/21/2017 05:28 PM, David Miller wrote:
> From: David Miller <da...@davemloft.net>
> Date: Wed, 20 Dec 2017 16:16:44 -0500 (EST)
>
>> I think I understand how this new stuff works, I'll take a stab at
>> doing the sparc64 JIT bits.
>
> This patch should do it, please queue up for bpf-next.
>
> But this is really overkill on sparc64.
>
> No matter where you relocate the call destination to, the size of the
> program and the code output will be identical except for the call
> instruction PC relative offset field.
>
> So at some point as a follow-up I should change this code to simply
> scan the insns for the function calls and fixup the offsets, rather
> than do a full set of code generation passes.
>
> Thanks.
>
> ====================
> bpf: sparc64: Add JIT support for multi-function programs.
>
> Modelled strongly upon the arm64 implementation.
>
> Signed-off-by: David S. Miller <da...@davemloft.net>
>
> diff --git a/arch/sparc/net/bpf_jit_comp_64.c
> b/arch/sparc/net/bpf_jit_comp_64.c
> index a2f1b5e..4ee417f 100644
> --- a/arch/sparc/net/bpf_jit_comp_64.c
> +++ b/arch/sparc/net/bpf_jit_comp_64.c
> @@ -1507,11 +1507,19 @@ static void jit_fill_hole(void *area, unsigned int
> size)
> *ptr++ = 0x91d02005; /* ta 5 */
> }
>
> +struct sparc64_jit_data {
> + struct bpf_binary_header *header;
> + u8 *image;
> + struct jit_ctx ctx;
> +};
> +
> struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
> {
> struct bpf_prog *tmp, *orig_prog = prog;
> + struct sparc64_jit_data *jit_data;
> struct bpf_binary_header *header;
> bool tmp_blinded = false;
> + bool extra_pass = false;
> struct jit_ctx ctx;
> u32 image_size;
> u8 *image_ptr;
> @@ -1531,13 +1539,30 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog
> *prog)
> prog = tmp;
> }
>
> + jit_data = prog->aux->jit_data;
> + if (!jit_data) {
> + jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
> + if (!jit_data) {
> + prog = orig_prog;
> + goto out;
> + }
Looks good, one thing: If I spot this correctly, isn't here a ...
prog->aux->jit_data = jit_data;
... missing? Otherwise the context from the initial pass is neither
saved for the extra pass nor freed.
> + }
> + if (jit_data->ctx.offset) {
> + ctx = jit_data->ctx;
> + image_ptr = jit_data->image;
> + header = jit_data->header;
> + extra_pass = true;
> + image_size = sizeof(u32) * ctx.idx;
> + goto skip_init_ctx;
> + }
> +
> memset(&ctx, 0, sizeof(ctx));
> ctx.prog = prog;
>
> ctx.offset = kcalloc(prog->len, sizeof(unsigned int), GFP_KERNEL);
> if (ctx.offset == NULL) {
> prog = orig_prog;
> - goto out;
> + goto out_off;
> }
>
> /* Fake pass to detect features used, and get an accurate assessment
> @@ -1560,7 +1585,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog
> *prog)
> }
>
> ctx.image = (u32 *)image_ptr;
> -
> +skip_init_ctx:
> for (pass = 1; pass < 3; pass++) {
> ctx.idx = 0;
>
> @@ -1591,14 +1616,24 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog
> *prog)
>
> bpf_flush_icache(header, (u8 *)header + (header->pages * PAGE_SIZE));
>
> - bpf_jit_binary_lock_ro(header);
> + if (!prog->is_func || extra_pass) {
> + bpf_jit_binary_lock_ro(header);
> + } else {
> + jit_data->ctx = ctx;
> + jit_data->image = image_ptr;
> + jit_data->header = header;
> + }
>
> prog->bpf_func = (void *)ctx.image;
> prog->jited = 1;
> prog->jited_len = image_size;
>
> + if (!prog->is_func || extra_pass) {
> out_off:
> - kfree(ctx.offset);
> + kfree(ctx.offset);
> + kfree(jit_data);
> + prog->aux->jit_data = NULL;
> + }
> out:
> if (tmp_blinded)
> bpf_jit_prog_release_other(prog, prog == orig_prog ?
>
