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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
	tglx@linutronix.de, arnd@arndb.de
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
	Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Johannes Berg <johannes@sipsolutions.net>
Subject: [PATCH v6 14/17] um: use fallback for random_get_entropy() instead of zero
Date: Sat, 23 Apr 2022 23:26:20 +0200	[thread overview]
Message-ID: <20220423212623.1957011-15-Jason@zx2c4.com> (raw)
In-Reply-To: <20220423212623.1957011-1-Jason@zx2c4.com>

In the event that random_get_entropy() can't access a cycle counter or
similar, falling back to returning 0 is really not the best we can do.
Instead, at least calling random_get_entropy_fallback() would be
preferable, because that always needs to return _something_, even
falling back to jiffies eventually. It's not as though
random_get_entropy_fallback() is super high precision or guaranteed to
be entropic, but basically anything that's not zero all the time is
better than returning zero all the time.

This is accomplished by just including the asm-generic code like on
other architectures, which means we can get rid of the empty stub
function here.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/um/include/asm/timex.h | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/um/include/asm/timex.h b/arch/um/include/asm/timex.h
index e392a9a5bc9b..9f27176adb26 100644
--- a/arch/um/include/asm/timex.h
+++ b/arch/um/include/asm/timex.h
@@ -2,13 +2,8 @@
 #ifndef __UM_TIMEX_H
 #define __UM_TIMEX_H
 
-typedef unsigned long cycles_t;
-
-static inline cycles_t get_cycles (void)
-{
-	return 0;
-}
-
 #define CLOCK_TICK_RATE (HZ)
 
+#include <asm-generic/timex.h>
+
 #endif
-- 
2.35.1


  parent reply	other threads:[~2022-04-23 21:27 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-23 21:26 [PATCH v6 00/17] archs/random: fallback to best raw ktime when no cycle counter Jason A. Donenfeld
2022-04-23 21:26 ` Jason A. Donenfeld
2022-04-23 21:26 ` [OpenRISC] " Jason A. Donenfeld
2022-04-23 21:26 ` Jason A. Donenfeld
2022-04-23 21:26 ` Jason A. Donenfeld
2022-04-23 21:26 ` [PATCH v6 01/17] ia64: define get_cycles macro for arch-override Jason A. Donenfeld
2022-04-23 21:26 ` [PATCH v6 02/17] s390: " Jason A. Donenfeld
2022-04-25  9:43   ` Heiko Carstens
2022-04-25  9:48     ` Jason A. Donenfeld
2022-04-25 10:21       ` Heiko Carstens
2022-04-23 21:26 ` [PATCH v6 03/17] parisc: " Jason A. Donenfeld
2022-04-24 18:35   ` Helge Deller
2022-04-23 21:26 ` [PATCH v6 04/17] alpha: " Jason A. Donenfeld
2022-04-26 20:31   ` Matt Turner
2022-04-23 21:26 ` [PATCH v6 05/17] powerpc: " Jason A. Donenfeld
2022-04-23 21:26   ` Jason A. Donenfeld
2022-04-28  5:19   ` Michael Ellerman
2022-04-23 21:26 ` [PATCH v6 06/17] timekeeping: add raw clock fallback for random_get_entropy() Jason A. Donenfeld
2022-04-25 12:37   ` Thomas Gleixner
2022-04-25 13:22     ` Jason A. Donenfeld
2022-05-02  9:37       ` Thomas Gleixner
2022-05-05  0:19         ` [PATCH v7] timekeeping: Add " Jason A. Donenfeld
2022-05-05  0:29           ` Jason A. Donenfeld
2022-05-06  3:20           ` [timekeeping] 3aeaac747d: PANIC:early_exception kernel test robot
2022-05-06  3:20             ` kernel test robot
2022-05-06  7:59             ` Thomas Gleixner
2022-05-06  7:59               ` Thomas Gleixner
2022-05-06 10:12               ` Jason A. Donenfeld
2022-05-06 10:12                 ` Jason A. Donenfeld
2022-05-06 16:01                 ` Thomas Gleixner
2022-05-06 16:01                   ` Thomas Gleixner
2022-05-06 10:21         ` [PATCH v8] timekeeping: Add raw clock fallback for random_get_entropy() Jason A. Donenfeld
2022-04-23 21:26 ` [PATCH v6 07/17] m68k: use fallback for random_get_entropy() instead of zero Jason A. Donenfeld
2022-04-23 21:26 ` [PATCH v6 08/17] riscv: " Jason A. Donenfeld
2022-04-25 14:55   ` Palmer Dabbelt
2022-04-25 15:02     ` Jason A. Donenfeld
2022-04-25 15:20       ` Palmer Dabbelt
2022-04-23 21:26 ` [PATCH v6 09/17] mips: use fallback for random_get_entropy() instead of just c0 random Jason A. Donenfeld
2022-04-26 20:28   ` Maciej W. Rozycki
2022-04-27  1:29     ` Jason A. Donenfeld
2022-06-24 13:04       ` Jason A. Donenfeld
2022-06-24 13:25         ` Maciej W. Rozycki
2022-09-25 10:00           ` Jason A. Donenfeld
2022-09-25 14:17             ` Maciej W. Rozycki
2022-04-23 21:26 ` [PATCH v6 10/17] arm: use fallback for random_get_entropy() instead of zero Jason A. Donenfeld
2022-04-25 14:30   ` Russell King (Oracle)
2022-04-23 21:26 ` [PATCH v6 11/17] openrisc: " Jason A. Donenfeld
2022-04-27 21:42   ` Stafford Horne
2022-04-27 23:26     ` Jason A. Donenfeld
2022-04-29  0:16   ` [PATCH v7 11/17] openrisc: account for 0 starting value in random_get_entropy() Jason A. Donenfeld
2022-04-30  1:19     ` Stafford Horne
2022-04-30  1:29       ` Jason A. Donenfeld
2022-04-30 22:11         ` Stafford Horne
2022-04-30 22:34           ` Jason A. Donenfeld
2022-04-30 22:44             ` Stafford Horne
2022-04-23 21:26 ` [PATCH v6 12/17] nios2: use fallback for random_get_entropy() instead of zero Jason A. Donenfeld
2022-05-23 13:56   ` Dinh Nguyen
2022-04-23 21:26 ` [PATCH v6 13/17] x86: " Jason A. Donenfeld
2022-04-25 12:35   ` Thomas Gleixner
2022-04-25 13:41     ` Jason A. Donenfeld
2022-04-25 13:51       ` Jason A. Donenfeld
2022-04-25 17:03       ` Thomas Gleixner
2022-04-25 17:24         ` Jason A. Donenfeld
2022-04-26  8:33           ` [PATCH v7 13/17] x86/asm: " Jason A. Donenfeld
2022-05-02  9:40             ` Thomas Gleixner
2022-04-23 21:26 ` Jason A. Donenfeld [this message]
2022-04-23 21:26 ` [PATCH v6 15/17] sparc: " Jason A. Donenfeld
2022-04-23 21:26 ` [PATCH v6 16/17] xtensa: " Jason A. Donenfeld
2022-04-23 21:26 ` [PATCH v6 17/17] random: insist on random_get_entropy() existing in order to simplify Jason A. Donenfeld

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