netdev - [PATCH net-next 07/13] nfp: bpf: relax source operands check

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Date:   Thu, 30 Nov 2017 21:32:54 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     netdev@...r.kernel.org
Cc:     oss-drivers@...ronome.com, Jiong Wang <jiong.wang@...ronome.com>
Subject: [PATCH net-next 07/13] nfp: bpf: relax source operands check

From: Jiong Wang <jiong.wang@...ronome.com>

The NFP normally requires the source operands to be difference addressing
modes, but we should rule out the very special NN_REG_NONE type.

There are instruction that ignores both A/B operands, for example:

  local_csr_rd

For these instructions, we might pass the same operand type, NN_REG_NONE,
for both A/B operands.

NOTE: in current NFP ISA, it is only possible for instructions with
unrestricted operands to take none operands, but in case there is new and
similar instructoin in restricted form, they would follow similar rules,
so swreg_to_restricted is updated as well.

Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
 drivers/net/ethernet/netronome/nfp/nfp_asm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.c b/drivers/net/ethernet/netronome/nfp/nfp_asm.c
index 830f6de25f47..da277386077c 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_asm.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.c
@@ -120,7 +120,8 @@ int swreg_to_unrestricted(swreg dst, swreg lreg, swreg rreg,
 	reg->dst = nfp_swreg_to_unreg(dst, true);
 
 	/* Decode source operands */
-	if (swreg_type(lreg) == swreg_type(rreg))
+	if (swreg_type(lreg) == swreg_type(rreg) &&
+	    swreg_type(lreg) != NN_REG_NONE)
 		return -EFAULT;
 
 	if (swreg_type(lreg) == NN_REG_GPR_B ||
@@ -200,7 +201,8 @@ int swreg_to_restricted(swreg dst, swreg lreg, swreg rreg,
 	reg->dst = nfp_swreg_to_rereg(dst, true, false, NULL);
 
 	/* Decode source operands */
-	if (swreg_type(lreg) == swreg_type(rreg))
+	if (swreg_type(lreg) == swreg_type(rreg) &&
+	    swreg_type(lreg) != NN_REG_NONE)
 		return -EFAULT;
 
 	if (swreg_type(lreg) == NN_REG_GPR_B ||
-- 
2.15.0