From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Sun, 8 Oct 2017 21:04:08 -0700
Subject: nfp: bpf: remove register rename
Patch-mainline: v4.15-rc1
Git-commit: 226e0e94ce3575bd9ca85f90957516ac1dff5bf3
References: bsc#1109837

Remove the register renumbering optimization.  To implement calling
map and other helpers we need more strict register layout.  We can't
freely reassign register numbers.

This will have the effect of running in 4 context/thread mode, which
should be OK since we are moving towards integrating the BPF closer
with FW app datapath anyway, and the target datapath itself runs in
4 context mode.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c |   46 +--------------------------
 1 file changed, 3 insertions(+), 43 deletions(-)

--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -1621,38 +1621,6 @@ static void nfp_bpf_opt_reg_init(struct
 	}
 }
 
-/* Try to rename registers so that program uses only low ones */
-static int nfp_bpf_opt_reg_rename(struct nfp_prog *nfp_prog)
-{
-	bool reg_used[MAX_BPF_REG] = {};
-	u8 tgt_reg[MAX_BPF_REG] = {};
-	struct nfp_insn_meta *meta;
-	unsigned int i, j;
-
-	list_for_each_entry(meta, &nfp_prog->insns, l) {
-		if (meta->skip)
-			continue;
-
-		reg_used[meta->insn.src_reg] = true;
-		reg_used[meta->insn.dst_reg] = true;
-	}
-
-	for (i = 0, j = 0; i < ARRAY_SIZE(tgt_reg); i++) {
-		if (!reg_used[i])
-			continue;
-
-		tgt_reg[i] = j++;
-	}
-	nfp_prog->num_regs = j;
-
-	list_for_each_entry(meta, &nfp_prog->insns, l) {
-		meta->insn.src_reg = tgt_reg[meta->insn.src_reg];
-		meta->insn.dst_reg = tgt_reg[meta->insn.dst_reg];
-	}
-
-	return 0;
-}
-
 /* Remove masking after load since our load guarantees this is not needed */
 static void nfp_bpf_opt_ld_mask(struct nfp_prog *nfp_prog)
 {
@@ -1729,14 +1697,8 @@ static void nfp_bpf_opt_ld_shift(struct
 
 static int nfp_bpf_optimize(struct nfp_prog *nfp_prog)
 {
-	int ret;
-
 	nfp_bpf_opt_reg_init(nfp_prog);
 
-	ret = nfp_bpf_opt_reg_rename(nfp_prog);
-	if (ret)
-		return ret;
-
 	nfp_bpf_opt_ld_mask(nfp_prog);
 	nfp_bpf_opt_ld_shift(nfp_prog);
 
@@ -1783,10 +1745,8 @@ nfp_bpf_jit(struct bpf_prog *filter, voi
 	if (ret)
 		goto out;
 
-	if (nfp_prog->num_regs <= 7)
-		nfp_prog->regs_per_thread = 16;
-	else
-		nfp_prog->regs_per_thread = 32;
+	nfp_prog->num_regs = MAX_BPF_REG;
+	nfp_prog->regs_per_thread = 32;
 
 	nfp_prog->prog = prog_mem;
 	nfp_prog->__prog_alloc_len = prog_sz;
@@ -1799,7 +1759,7 @@ nfp_bpf_jit(struct bpf_prog *filter, voi
 	}
 
 	res->n_instr = nfp_prog->prog_len;
-	res->dense_mode = nfp_prog->num_regs <= 7;
+	res->dense_mode = false;
 out:
 	nfp_prog_free(nfp_prog);