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net: bcmgenet: fix 64-bit RTNL stats reading in ethtool on 32-bit systems

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When bcmgenet was converted to 64-bit statistics, STAT_RTNL members were
switched to point into struct rtnl_link_stats64, whose fields are 64-bit
(__u64) regardless of architecture.

However, bcmgenet_get_ethtool_stats() retained a legacy check:
  if (sizeof(unsigned long) != sizeof(u32) &&
      s->stat_sizeof == sizeof(unsigned long))

On 32-bit systems, sizeof(unsigned long) == sizeof(u32), causing this
condition to evaluate to false. As a result, 64-bit RTNL stats fields were
read via *(u32 *)p. On 32-bit Big-Endian systems (such as MIPS BE), this
reads the high 32 bits and returns 0 until the counter exceeds 4GB; on
32-bit Little-Endian systems (such as 32-bit ARM), the value is truncated
to 32 bits.

Fix this by checking if s->stat_sizeof == sizeof(u64) so 64-bit fields are
always read as 64-bit values.

Fixes: 59aa6e3072 ("net: bcmgenet: switch to use 64bit statistics")
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20260921220021.281418-2-florian.fainelli@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Florian Fainelli 2026-09-21 15:00:17 -07:00 committed by Jakub Kicinski
parent 87cd6b717e
commit 0e2bec77ea
1 changed files with 2 additions and 3 deletions
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5
drivers/net/ethernet/broadcom/genet/bcmgenet.c
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@ -1346,9 +1346,8 @@ static void bcmgenet_get_ethtool_stats(struct net_device *dev,
p = (char *)&stats64;
p += s->stat_offset;
if (sizeof(unsigned long) != sizeof(u32) &&
s->stat_sizeof == sizeof(unsigned long))
data[i] = *(unsigned long *)p;
if (s->stat_sizeof == sizeof(u64))
data[i] = *(u64 *)p;
else
data[i] = *(u32 *)p;
}