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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>,
	Theodore Ts'o <tytso@mit.edu>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	"David S . Miller" <davem@davemloft.net>,
	Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Chris Zankel <chris@zankel.net>,
	Max Filippov <jcmvbkbc@gmail.com>,
	John Stultz <john.stultz@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Dinh Nguyen <dinguyen@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org,
	linux-um@lists.infradead.org, x86@kernel.org,
	linux-xtensa@linux-xtensa.org
Subject: [PATCH v4 06/11] nios2: use fallback for random_get_entropy() instead of zero
Date: Wed, 13 Apr 2022 13:54:06 +0200	[thread overview]
Message-ID: <20220413115411.21489-7-Jason@zx2c4.com> (raw)
In-Reply-To: <20220413115411.21489-1-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.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/nios2/include/asm/timex.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/nios2/include/asm/timex.h b/arch/nios2/include/asm/timex.h
index a769f871b28d..d9a3f426cdda 100644
--- a/arch/nios2/include/asm/timex.h
+++ b/arch/nios2/include/asm/timex.h
@@ -9,4 +9,6 @@ typedef unsigned long cycles_t;
 
 extern cycles_t get_cycles(void);
 
+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
+
 #endif
-- 
2.35.1


WARNING: multiple messages have this Message-ID (diff)
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>,
	Theodore Ts'o <tytso@mit.edu>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	"David S . Miller" <davem@davemloft.net>,
	Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Chris Zankel <chris@zankel.net>,
	Max Filippov <jcmvbkbc@gmail.com>,
	John Stultz <john.stultz@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Dinh Nguyen <dinguyen@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org,
	linux-um@lists.infradead.org, x86@kernel.org,
	linux-xtensa@linux-xtensa.org
Subject: [PATCH v4 06/11] nios2: use fallback for random_get_entropy() instead of zero
Date: Wed, 13 Apr 2022 13:54:06 +0200	[thread overview]
Message-ID: <20220413115411.21489-7-Jason@zx2c4.com> (raw)
In-Reply-To: <20220413115411.21489-1-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.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/nios2/include/asm/timex.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/nios2/include/asm/timex.h b/arch/nios2/include/asm/timex.h
index a769f871b28d..d9a3f426cdda 100644
--- a/arch/nios2/include/asm/timex.h
+++ b/arch/nios2/include/asm/timex.h
@@ -9,4 +9,6 @@ typedef unsigned long cycles_t;
 
 extern cycles_t get_cycles(void);
 
+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
+
 #endif
-- 
2.35.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

WARNING: multiple messages have this Message-ID (diff)
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>,
	Theodore Ts'o <tytso@mit.edu>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	"David S . Miller" <davem@davemloft.net>,
	Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Chris Zankel <chris@zankel.net>,
	Max Filippov <jcmvbkbc@gmail.com>,
	John Stultz <john.stultz@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Dinh Nguyen <dinguyen@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org,
	linux-um@lists.infradead.org, x86@kernel.org,
	linux-xtensa@linux-xtensa.org
Subject: [PATCH v4 06/11] nios2: use fallback for random_get_entropy() instead of zero
Date: Wed, 13 Apr 2022 13:54:06 +0200	[thread overview]
Message-ID: <20220413115411.21489-7-Jason@zx2c4.com> (raw)
In-Reply-To: <20220413115411.21489-1-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.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/nios2/include/asm/timex.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/nios2/include/asm/timex.h b/arch/nios2/include/asm/timex.h
index a769f871b28d..d9a3f426cdda 100644
--- a/arch/nios2/include/asm/timex.h
+++ b/arch/nios2/include/asm/timex.h
@@ -9,4 +9,6 @@ typedef unsigned long cycles_t;
 
 extern cycles_t get_cycles(void);
 
+#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
+
 #endif
-- 
2.35.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-04-13 11:55 UTC|newest]

Thread overview: 103+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-13 11:54 [PATCH v4 00/11] archs/random: fallback to best raw ktime when no cycle counter Jason A. Donenfeld
2022-04-13 11:54 ` Jason A. Donenfeld
2022-04-13 11:54 ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 01/11] timekeeping: add raw clock fallback for random_get_entropy() Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 14:32   ` Rob Herring
2022-04-13 14:32     ` Rob Herring
2022-04-13 14:32     ` Rob Herring
2022-04-13 22:38     ` Jason A. Donenfeld
2022-04-13 22:38       ` Jason A. Donenfeld
2022-04-13 22:38       ` Jason A. Donenfeld
2022-04-14 20:41       ` Rob Herring
2022-04-14 20:41         ` Rob Herring
2022-04-14 20:41         ` Rob Herring
2022-04-14 21:49         ` H. Peter Anvin
2022-04-14 21:49           ` H. Peter Anvin
2022-04-14 21:49           ` H. Peter Anvin
2022-04-14 10:12   ` Russell King (Oracle)
2022-04-14 10:12     ` Russell King (Oracle)
2022-04-14 10:12     ` Russell King (Oracle)
2022-04-14 11:56     ` Jason A. Donenfeld
2022-04-14 11:56       ` Jason A. Donenfeld
2022-04-14 11:56       ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 02/11] m68k: use fallback for random_get_entropy() instead of zero Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 03/11] riscv: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 14:40   ` Rob Herring
2022-04-13 14:40     ` Rob Herring
2022-04-13 14:40     ` Rob Herring
2022-04-13 22:40     ` Jason A. Donenfeld
2022-04-13 22:40       ` Jason A. Donenfeld
2022-04-13 22:40       ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 04/11] mips: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 12:25   ` Thomas Bogendoerfer
2022-04-13 12:25     ` Thomas Bogendoerfer
2022-04-13 12:25     ` Thomas Bogendoerfer
2022-04-13 12:46     ` Maciej W. Rozycki
2022-04-13 12:46       ` Maciej W. Rozycki
2022-04-13 12:46       ` Maciej W. Rozycki
2022-04-13 22:35       ` Jason A. Donenfeld
2022-04-13 22:35         ` Jason A. Donenfeld
2022-04-13 22:35         ` Jason A. Donenfeld
2022-04-14  1:16         ` Maciej W. Rozycki
2022-04-14  1:16           ` Maciej W. Rozycki
2022-04-14  1:16           ` Maciej W. Rozycki
2022-04-14  9:27           ` Jason A. Donenfeld
2022-04-14  9:27             ` Jason A. Donenfeld
2022-04-14  9:27             ` Jason A. Donenfeld
2022-04-15 12:26             ` Maciej W. Rozycki
2022-04-15 12:26               ` Maciej W. Rozycki
2022-04-15 12:26               ` Maciej W. Rozycki
2022-04-16 11:09               ` Jason A. Donenfeld
2022-04-16 11:09                 ` Jason A. Donenfeld
2022-04-16 11:09                 ` Jason A. Donenfeld
2022-04-16 14:44                 ` Maciej W. Rozycki
2022-04-16 14:44                   ` Maciej W. Rozycki
2022-04-16 14:44                   ` Maciej W. Rozycki
2022-04-16 22:54                   ` Jason A. Donenfeld
2022-04-16 22:54                     ` Jason A. Donenfeld
2022-04-16 22:54                     ` Jason A. Donenfeld
2022-04-18  7:10               ` Thomas Bogendoerfer
2022-04-18  7:10                 ` Thomas Bogendoerfer
2022-04-18  7:10                 ` Thomas Bogendoerfer
2022-04-18  7:10                 ` Thomas Bogendoerfer
2022-04-23 23:33                 ` Maciej W. Rozycki
2022-04-23 23:33                   ` Maciej W. Rozycki
2022-04-23 23:33                   ` Maciej W. Rozycki
2022-04-24  8:15                   ` Jason A. Donenfeld
2022-04-24  8:15                     ` Jason A. Donenfeld
2022-04-24  8:15                     ` Jason A. Donenfeld
2022-04-24 10:51                     ` Maciej W. Rozycki
2022-04-24 10:51                       ` Maciej W. Rozycki
2022-04-24 10:51                       ` Maciej W. Rozycki
2022-04-13 11:54 ` [PATCH v4 05/11] arm: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54 ` Jason A. Donenfeld [this message]
2022-04-13 11:54   ` [PATCH v4 06/11] nios2: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-05-23 13:58   ` Dinh Nguyen
2022-05-23 13:58     ` Dinh Nguyen
2022-05-23 13:58     ` Dinh Nguyen
2022-04-13 11:54 ` [PATCH v4 07/11] x86: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 08/11] um: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 09/11] sparc: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 10/11] xtensa: " Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54 ` [PATCH v4 11/11] random: insist on random_get_entropy() existing in order to simplify Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld
2022-04-13 11:54   ` Jason A. Donenfeld

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