From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki.Poulose@arm.com (Suzuki K Poulose) Date: Tue, 1 Nov 2016 14:18:12 +0000 Subject: [PATCH v2 1/3] arm64: crypto/aes-ce-ccm: Cleanup hwcap check In-Reply-To: References: <1477929825-5907-1-git-send-email-suzuki.poulose@arm.com> <1477929825-5907-2-git-send-email-suzuki.poulose@arm.com> Message-ID: <42a11fce-d231-2317-3c8e-a9044bbe5f62@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/11/16 14:03, Ard Biesheuvel wrote: > Hi Suzuki, > > On 31 October 2016 at 16:03, Suzuki K Poulose wrote: >> Use the module_cpu_feature_match to make sure the system has >> HWCAP_AES to use the module. >> >> Cc: Ard Biesheuvel >> Signed-off-by: Suzuki K Poulose >> --- >> arch/arm64/crypto/aes-ce-ccm-glue.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/crypto/aes-ce-ccm-glue.c b/arch/arm64/crypto/aes-ce-ccm-glue.c >> index f4bf2f2..fa82eaa 100644 >> --- a/arch/arm64/crypto/aes-ce-ccm-glue.c >> +++ b/arch/arm64/crypto/aes-ce-ccm-glue.c ... >> -module_init(aes_mod_init); >> +module_cpu_feature_match(AES, aes_mod_init); > > I don't think this change is correct. This will result in the AES > instruction dependency to be exposed via the module alias, causing the > module to be loaded automatically as soon as udev detects that the CPU > implements those instructions. For plain AES, that makes sense, but > AES in CCM mode is specific to CCMP (WPA2) on mac80211 controllers > that have no hardware AES support, and to IPsec VPN. For this reason, > the algo type is exposed via the module alias instead (i.e, > 'ccm(aes)'), which will result in the module being loaded as soon as > the crypto algo manager instantiates the transform. On CPUs that don't > implement the AES instructions, this will fail, and it will fall back > to the generic CCM driver instead. Ah, thanks for the explanation. I will drop it. Cheers Suzuki