Hi!
> This patch adds the codes for generating random number array as the
> HMAC key that will used by later EFI stub codes.
>
> The original codes in efi_random copied from aslr and add the codes
> to accept input entropy and EFI debugging. In later patch will add
> the codes to get random number by EFI protocol. The separate codes
> can avoid impacting aslr function.
>
> Signed-off-by: Lee, Chun-Yi <jlee@xxxxxxxx>
> +#define X86_FEATURE_EDX_TSC (1 << 4)
> +#define X86_FEATURE_ECX_RDRAND (1 << 30)
Can you pull it from existing includes somewhere?
> +static bool rdrand_feature(void)
> +{
> + return (cpuid_ecx(0x1) & X86_FEATURE_ECX_RDRAND);
> +}
> +
> +static bool rdtsc_feature(void)
> +{
> + return (cpuid_edx(0x1) & X86_FEATURE_EDX_TSC);
> +}
Are these helpers neccessary?
> + if (rdrand_feature()) {
> + efi_printk(sys_table, " RDRAND");
> + if (rdrand_long(&raw)) {
> + random ^= raw;
> + use_i8254 = false;
> + }
> + }
> +
> + if (rdtsc_feature()) {
> + efi_printk(sys_table, " RDTSC");
> + rdtscll(raw);
> +
> + random ^= raw;
> + use_i8254 = false;
> + }
You'll do two (expensive) cpuids calls here.
--
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