[dpdk-dev] [PATCH] net/ice/base: added union to avoid ptr dereference

[dpdk-dev] [PATCH] net/ice/base: added union to avoid ptr dereference

[Aman Singh]

Code changes done to avoid build issue as seen in
Bug 817 - net/ice build failure with gcc 4.8.5
error: dereferencing type-punned pointer will
break strict-aliasing rules.

Signed-off-by: Aman Singh <aman.deep.singh@intel.com>
---
 drivers/net/ice/base/ice_parser_rt.c | 36 +++++++++++++++-------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ice/base/ice_parser_rt.c b/drivers/net/ice/base/ice_parser_rt.c
index 7a44675737..bcbc0b5e15 100644
--- a/drivers/net/ice/base/ice_parser_rt.c
+++ b/drivers/net/ice/base/ice_parser_rt.c
@@ -187,21 +187,23 @@ static u32 _bit_rev_u32(u32 v, int len)
 
 static u32 _hv_bit_sel(struct ice_parser_rt *rt, int start, int len)
 {
-	u64 d64, msk;
-	u8 b[8];
+	u64 msk;
+	union {
+	   u64 d64;
+	   u8 b[8];
+	} bit_sel;
 	int i;
 
 	int offset = GPR_HB_IDX + start / 16;
 
-	ice_memcpy(b, &rt->gpr[offset], 8, ICE_NONDMA_TO_NONDMA);
+	ice_memcpy(bit_sel.b, &rt->gpr[offset], 8, ICE_NONDMA_TO_NONDMA);
 
 	for (i = 0; i < 8; i++)
-		b[i] = _bit_rev_u8(b[i]);
+		bit_sel.b[i] = _bit_rev_u8(bit_sel.b[i]);
 
-	d64 = *(u64 *)&b[0];
 	msk = (1ul << len) - 1;
 
-	return _bit_rev_u32((u32)((d64 >> (start % 16)) & msk), len);
+	return _bit_rev_u32((u32)((bit_sel.d64 >> (start % 16)) & msk), len);
 }
 
 static u32 _pk_build(struct ice_parser_rt *rt, struct ice_np_keybuilder *kb)
@@ -444,21 +446,23 @@ static void _po_update(struct ice_parser_rt *rt, struct ice_alu *alu)
 static u16 _reg_bit_sel(struct ice_parser_rt *rt, int reg_idx,
 			int start, int len)
 {
-	u32 d32, msk;
-	u8 b[4];
-	u8 v[4];
+	u32 msk;
+	union {
+	   u32 d32;
+	   u8 b[4];
+	} bit_sel;
 
-	ice_memcpy(b, &rt->gpr[reg_idx + start / 16], 4, ICE_NONDMA_TO_NONDMA);
+	ice_memcpy(bit_sel.b, &rt->gpr[reg_idx + start / 16], 4,
+		   ICE_NONDMA_TO_NONDMA);
 
-	v[0] = _bit_rev_u8(b[0]);
-	v[1] = _bit_rev_u8(b[1]);
-	v[2] = _bit_rev_u8(b[2]);
-	v[3] = _bit_rev_u8(b[3]);
+	bit_sel.b[0] = _bit_rev_u8(bit_sel.b[0]);
+	bit_sel.b[1] = _bit_rev_u8(bit_sel.b[1]);
+	bit_sel.b[2] = _bit_rev_u8(bit_sel.b[2]);
+	bit_sel.b[3] = _bit_rev_u8(bit_sel.b[3]);
 
-	d32 = *(u32 *)&v[0];
 	msk = (1u << len) - 1;
 
-	return _bit_rev_u16((u16)((d32 >> (start % 16)) & msk), len);
+	return _bit_rev_u16((u16)((bit_sel.d32 >> (start % 16)) & msk), len);
 }
 
 static void _err_add(struct ice_parser_rt *rt, int idx, bool val)
-- 
2.17.1

Re: [dpdk-dev] [PATCH] net/ice/base: added union to avoid ptr dereference

[Ferruh Yigit]

On 10/5/2021 11:57 AM, Aman Singh wrote:
> Code changes done to avoid build issue as seen in
> Bug 817 - net/ice build failure with gcc 4.8.5
> error: dereferencing type-punned pointer will
> break strict-aliasing rules.
> 
> Signed-off-by: Aman Singh <aman.deep.singh@intel.com>

superseded by 'net/ice/base: fix build error for GCC 4.8.5'
https://patches.dpdk.org/project/dpdk/patch/20211005115754.34117-1-aman.deep.singh@intel.com/