Messages in this thread | | | Subject | Re: [PATCH 2/2] arm64: Add support for SMCCC TRNG firmware interface | From | James Morse <> | Date | Wed, 7 Oct 2020 15:16:07 +0100 |
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Hi Andre,
On 06/10/2020 21:18, Andre Przywara wrote: > The ARM architected TRNG firmware interface, described in ARM spec > DEN0098[1], defines an ARM SMCCC based interface to a true random number > generator, provided by firmware. > This can be discovered via the SMCCC >=v1.1 interface, and provides > up to 192 bits of entropy per call. > > Hook this SMC call into arm64's arch_get_random_*() implementation, > coming to the rescue when the CPU does not implement the ARM v8.5 RNG > system registers. > > For the detection, we piggy back on the PSCI/SMCCC discovery (which gives > us the conduit to use: hvc or smc), then try to call the > ARM_SMCCC_TRNG_VERSION function, which returns -1 if this interface is > not implemented.
> arch/arm64/include/asm/archrandom.h | 83 +++++++++++++++++++++++++---- > 1 file changed, 73 insertions(+), 10 deletions(-)
> diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h > index ffb1a40d5475..b6c291c42a48 100644 > --- a/arch/arm64/include/asm/archrandom.h > +++ b/arch/arm64/include/asm/archrandom.h > @@ -7,6 +7,13 @@ > #include <linux/bug.h> > #include <linux/kernel.h> > #include <asm/cpufeature.h> > +#include <linux/arm-smccc.h> > + > +static enum smc_trng_status { > + SMC_TRNG_UNKNOWN, > + SMC_TRNG_NOT_SUPPORTED, > + SMC_TRNG_SUPPORTED > +} smc_trng_status = SMC_TRNG_UNKNOWN;
Doesn't this static variable in a header file mean each file that includes this has its own copy? Is that intentional?
Thanks,
James
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