Commit 91ff69e8 authored by Jiong Wang's avatar Jiong Wang Committed by Alexei Starovoitov
Browse files

nfp: bpf: support unaligned read offset 



This patch add the support for unaligned read offset, i.e. the read offset
to the start of packet cache area is not aligned to REG_WIDTH. In this
case, the read area might across maximum three transfer-in registers.

Signed-off-by: default avatarJiong Wang <jiong.wang@netronome.com>
Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent be759237

drivers/net/ethernet/netronome/nfp/bpf/jit.c

+70 −3
Original line number Diff line number Diff line
@@ -553,6 +553,19 @@ wrp_reg_subpart(struct nfp_prog *nfp_prog, swreg dst, swreg src, u8 field_len, 
	emit_ld_field_any(nfp_prog, dst, mask, src, sc, offset * 8, true);

}



/* wrp_reg_or_subpart() - load @field_len bytes from low end of @src, or the

 * result to @dst from offset, there is no change on the other bits of @dst.

 */

static void

wrp_reg_or_subpart(struct nfp_prog *nfp_prog, swreg dst, swreg src,

		   u8 field_len, u8 offset)

{

	enum shf_sc sc = offset ? SHF_SC_L_SHF : SHF_SC_NONE;

	u8 mask = ((1 << field_len) - 1) << offset;



	emit_ld_field(nfp_prog, dst, mask, src, sc, 32 - offset * 8);

}



static void

addr40_offset(struct nfp_prog *nfp_prog, u8 src_gpr, swreg offset,

	      swreg *rega, swreg *regb)
@@ -1864,6 +1877,60 @@ mem_ldx_data_init_pktcache(struct nfp_prog *nfp_prog, 
		     off, xfer_num - 1, true, indir);

}



static int

mem_ldx_data_from_pktcache_unaligned(struct nfp_prog *nfp_prog,

				     struct nfp_insn_meta *meta,

				     unsigned int size)

{

	s16 range_start = meta->pkt_cache.range_start;

	s16 insn_off = meta->insn.off - range_start;

	swreg dst_lo, dst_hi, src_lo, src_mid;

	u8 dst_gpr = meta->insn.dst_reg * 2;

	u8 len_lo = size, len_mid = 0;

	u8 idx = insn_off / REG_WIDTH;

	u8 off = insn_off % REG_WIDTH;



	dst_hi = reg_both(dst_gpr + 1);

	dst_lo = reg_both(dst_gpr);

	src_lo = reg_xfer(idx);



	/* The read length could involve as many as three registers. */

	if (size > REG_WIDTH - off) {

		/* Calculate the part in the second register. */

		len_lo = REG_WIDTH - off;

		len_mid = size - len_lo;



		/* Calculate the part in the third register. */

		if (size > 2 * REG_WIDTH - off)

			len_mid = REG_WIDTH;

	}



	wrp_reg_subpart(nfp_prog, dst_lo, src_lo, len_lo, off);



	if (!len_mid) {

		wrp_immed(nfp_prog, dst_hi, 0);

		return 0;

	}



	src_mid = reg_xfer(idx + 1);



	if (size <= REG_WIDTH) {

		wrp_reg_or_subpart(nfp_prog, dst_lo, src_mid, len_mid, len_lo);

		wrp_immed(nfp_prog, dst_hi, 0);

	} else {

		swreg src_hi = reg_xfer(idx + 2);



		wrp_reg_or_subpart(nfp_prog, dst_lo, src_mid,

				   REG_WIDTH - len_lo, len_lo);

		wrp_reg_subpart(nfp_prog, dst_hi, src_mid, len_lo,

				REG_WIDTH - len_lo);

		wrp_reg_or_subpart(nfp_prog, dst_hi, src_hi, REG_WIDTH - len_lo,

				   len_lo);

	}



	return 0;

}



static int

mem_ldx_data_from_pktcache_aligned(struct nfp_prog *nfp_prog,

				   struct nfp_insn_meta *meta,
@@ -1900,10 +1967,10 @@ mem_ldx_data_from_pktcache(struct nfp_prog *nfp_prog, 
{

	u8 off = meta->insn.off - meta->pkt_cache.range_start;



	if (WARN_ON_ONCE(!IS_ALIGNED(off, REG_WIDTH)))

		return -EOPNOTSUPP;



	if (IS_ALIGNED(off, REG_WIDTH))

		return mem_ldx_data_from_pktcache_aligned(nfp_prog, meta, size);



	return mem_ldx_data_from_pktcache_unaligned(nfp_prog, meta, size);

}



static int

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