Patch "net: ethernet: ti: cpsw_ale: Fix cpsw_ale_get_field()/cpsw_ale_set_field()" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: ethernet: ti: cpsw_ale: Fix cpsw_ale_get_field()/cpsw_ale_set_field()

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ethernet-ti-cpsw_ale-fix-cpsw_ale_get_field-cpsw.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4b1ceed57aa791f16d3264dae3b1a75703df6675
Author: Tanmay Patil <t-patil@xxxxxx>
Date:   Wed Jul 12 16:36:57 2023 +0530

    net: ethernet: ti: cpsw_ale: Fix cpsw_ale_get_field()/cpsw_ale_set_field()
    
    [ Upstream commit b685f1a58956fa36cc01123f253351b25bfacfda ]
    
    CPSW ALE has 75 bit ALE entries which are stored within three 32 bit words.
    The cpsw_ale_get_field() and cpsw_ale_set_field() functions assume that the
    field will be strictly contained within one word. However, this is not
    guaranteed to be the case and it is possible for ALE field entries to span
    across up to two words at the most.
    
    Fix the methods to handle getting/setting fields spanning up to two words.
    
    Fixes: db82173f23c5 ("netdev: driver: ethernet: add cpsw address lookup engine support")
    Signed-off-by: Tanmay Patil <t-patil@xxxxxx>
    [s-vadapalli@xxxxxx: rephrased commit message and added Fixes tag]
    Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/ti/cpsw_ale.c b/drivers/net/ethernet/ti/cpsw_ale.c
index c245629a38c76..6cb98760bc84e 100644
--- a/drivers/net/ethernet/ti/cpsw_ale.c
+++ b/drivers/net/ethernet/ti/cpsw_ale.c
@@ -67,23 +67,37 @@
 
 static inline int cpsw_ale_get_field(u32 *ale_entry, u32 start, u32 bits)
 {
-	int idx;
+	int idx, idx2;
+	u32 hi_val = 0;
 
 	idx    = start / 32;
+	idx2 = (start + bits - 1) / 32;
+	/* Check if bits to be fetched exceed a word */
+	if (idx != idx2) {
+		idx2 = 2 - idx2; /* flip */
+		hi_val = ale_entry[idx2] << ((idx2 * 32) - start);
+	}
 	start -= idx * 32;
 	idx    = 2 - idx; /* flip */
-	return (ale_entry[idx] >> start) & BITMASK(bits);
+	return (hi_val + (ale_entry[idx] >> start)) & BITMASK(bits);
 }
 
 static inline void cpsw_ale_set_field(u32 *ale_entry, u32 start, u32 bits,
 				      u32 value)
 {
-	int idx;
+	int idx, idx2;
 
 	value &= BITMASK(bits);
-	idx    = start / 32;
+	idx = start / 32;
+	idx2 = (start + bits - 1) / 32;
+	/* Check if bits to be set exceed a word */
+	if (idx != idx2) {
+		idx2 = 2 - idx2; /* flip */
+		ale_entry[idx2] &= ~(BITMASK(bits + start - (idx2 * 32)));
+		ale_entry[idx2] |= (value >> ((idx2 * 32) - start));
+	}
 	start -= idx * 32;
-	idx    = 2 - idx; /* flip */
+	idx = 2 - idx; /* flip */
 	ale_entry[idx] &= ~(BITMASK(bits) << start);
 	ale_entry[idx] |=  (value << start);
 }