On Thu, Apr 9, 2026 at 7:24 PM Wathsala Vithanage <[email protected]> wrote: > > Hi Christophe, > > Thanks for doing this work. I saw that you intend to submit a v3 due to > failure in Ubuntu. Please, see my comment regarding emit_b below. > > >> + /* A64_R(0) = mbuf->buf_addr */ > >> + emit_mov_imm(ctx, 1, tmp1, offsetof(struct rte_mbuf, buf_addr)); > >> + emit_ldr(ctx, EBPF_DW, A64_R(0), r6, tmp1); > >> + /* tmp2 = * mbuf->data_off */ > >> + emit_mov_imm(ctx, 1, tmp2, offsetof(struct rte_mbuf, data_off)); > >> + emit_ldr(ctx, BPF_H, tmp2, r6, tmp2); > >> + > >> + /* A64_R(0) += data_off + off */ > >> + emit_add(ctx, 1, A64_R(0), tmp2); > >> + emit_add(ctx, 1, A64_R(0), A64_R(1)); > >> + > >> + /* End of Fast Path, skip slow path */ > >> + emit_b(ctx, 4); > >> + > Followed by emit_b() above there is an emit_call(). It invokes > emit_mov_imm() which could possibly generate different number of movk > instructions depending on the address of the __rte_pktmbuf_read. So, > emit_b(ctx, 4), may not necessarily land at the intended location > because there could be more than 4 instructions emitted by emit_call.
Hi Very good point, this was probably the cause of the error on Ubuntu. Sorry for the delay in responding to this patch, but I'm about to send a new version, fixing (hopefully!) all the previous comments. I'll add you in CC for the new version as well. Christophe > >> + /* slow path, call __rte_pktmbuf_read */ > >> + emit_call(ctx, tmp1, __rte_pktmbuf_read); > >> + /* check return value of __rte_pktmbuf_read */ > >> + emit_return_zero_if_src_zero(ctx, 1, A64_R(0)); > >> + > >> + /* A64_R(0) points to the data, load 1/2/4 bytes into r0*/ > >> + emit_ldr(ctx, opsz, r0, A64_R(0), A64_ZR); > >> + if (sz != sizeof(uint8_t)) > >> + emit_be(ctx, r0, sz * CHAR_BIT); > >> +} > >> + > >> > > --wathsala > >
