Messages in this thread |  | | Subject | Re: [PATCH v2 1/3] arm64: crypto/aes-ce-ccm: Cleanup hwcap check | From | Suzuki K Poulose <> | Date | Tue, 1 Nov 2016 14:18:12 +0000 |
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On 01/11/16 14:03, Ard Biesheuvel wrote: > Hi Suzuki, > > On 31 October 2016 at 16:03, Suzuki K Poulose <suzuki.poulose@arm.com> wrote: >> Use the module_cpu_feature_match to make sure the system has >> HWCAP_AES to use the module. >> >> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >> --- >> 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
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