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Groups > linux.kernel > #1712192
| From | Borislav Petkov <bp@alien8.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: early x86 unseeded randomness |
| Date | 2017-08-15 15:50 +0200 |
| Message-ID | <ueKoh-1VC-3@gated-at.bofh.it> (permalink) |
| References | (4 earlier) <uesUp-83a-11@gated-at.bofh.it> <ueyZR-3cJ-31@gated-at.bofh.it> <ueDPQ-6jk-7@gated-at.bofh.it> <ueELT-6RV-1@gated-at.bofh.it> <ueHA6-bQ-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Aug 15, 2017 at 12:47:36PM +0200, Thomas Gleixner wrote:
> 8<-------------------
>
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -1360,3 +1360,19 @@ unsigned long calibrate_delay_is_known(v
> return 0;
> }
> #endif
> +
> +u64 __init tsc_early_random(void)
> +{
> + u64 uninitialized_var(res);
> + int i;
> +
> + if (!boot_cpu_has(X86_FEATURE_TSC))
> + return res;
> +
> + res ^= rdtsc();
> + for (i = 0; i < BITS_PER_LONG; i++) {
> + res ^= ((rdtsc() & 0x04) >> 2) << i;
> + udelay(2);
> + }
> + return res;
> +}
Something like this is exactly what I was aiming at with my dumb patch.
We could use this for early boot randomness on x86.
Should I turn it into proper patches or you want to?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-14 19:40 +0200
Re: early x86 unseeded randomness Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-14 19:50 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-14 20:10 +0200
Re: early x86 unseeded randomness Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-14 20:20 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-14 21:10 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-15 03:40 +0200
Re: early x86 unseeded randomness Willy Tarreau <w@1wt.eu> - 2017-08-15 08:50 +0200
Re: early x86 unseeded randomness Ingo Molnar <mingo@kernel.org> - 2017-08-15 09:50 +0200
Re: early x86 unseeded randomness Willy Tarreau <w@1wt.eu> - 2017-08-15 10:10 +0200
Re: early x86 unseeded randomness Ingo Molnar <mingo@kernel.org> - 2017-08-15 10:10 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-15 14:20 +0200
Re: early x86 unseeded randomness Willy Tarreau <w@1wt.eu> - 2017-08-15 15:30 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 12:50 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-15 15:50 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 15:50 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-15 16:30 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 16:50 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-15 17:30 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 19:40 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-16 05:40 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-16 11:20 +0200
Re: early x86 unseeded randomness Will Deacon <will.deacon@arm.com> - 2017-08-16 12:00 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-16 05:30 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-15 17:30 +0200
Re: early x86 unseeded randomness Michael Ellerman <mpe@ellerman.id.au> - 2017-08-15 14:50 +0200
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