On Tue, Jan 25, 2022 at 06:57:07PM +0800, Hou Tao wrote:
> insn_to_jit_off passed to bpf_prog_fill_jited_linfo() is calculated
> in instruction granularity instead of bytes granularity, but bpf
> line info requires byte offset, so fixing it by calculating offset
> as byte-offset.
>
> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
> ---
> arch/arm64/net/bpf_jit_comp.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
> index 6a83f3070985..7b94e0c5e134 100644
> --- a/arch/arm64/net/bpf_jit_comp.c
> +++ b/arch/arm64/net/bpf_jit_comp.c
> @@ -152,10 +152,12 @@ static inline int bpf2a64_offset(int bpf_insn, int off,
> bpf_insn++;
> /*
> * Whereas arm64 branch instructions encode the offset
> - * from the branch itself, so we must subtract 1 from the
> + * from the branch itself, so we must subtract 4 from the
> * instruction offset.
> */
> - return ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1);
> + return (ctx->offset[bpf_insn + off] -
> + (ctx->offset[bpf_insn] - AARCH64_INSN_SIZE)) /
> + AARCH64_INSN_SIZE;
Is it another bug fix? It does not seem to be related
to the change described in the commit message.
> }
>
> static void jit_fill_hole(void *area, unsigned int size)
> @@ -946,13 +948,14 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass)
> const struct bpf_insn *insn = &prog->insnsi[i];
> int ret;
>
> + /* BPF line info needs byte-offset instead of insn-offset */
> if (ctx->image == NULL)
> - ctx->offset[i] = ctx->idx;
> + ctx->offset[i] = ctx->idx * AARCH64_INSN_SIZE;
> ret = build_insn(insn, ctx, extra_pass);
> if (ret > 0) {
> i++;
> if (ctx->image == NULL)
> - ctx->offset[i] = ctx->idx;
> + ctx->offset[i] = ctx->idx * AARCH64_INSN_SIZE;
> continue;
> }
> if (ret)
> @@ -964,7 +967,7 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass)
> * instruction (end of program)
> */
> if (ctx->image == NULL)
> - ctx->offset[i] = ctx->idx;
> + ctx->offset[i] = ctx->idx * AARCH64_INSN_SIZE;
Changes in this function makes sense.
