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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>,
	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 v5 02/11] m68k: use fallback for random_get_entropy() instead of zero
Date: Tue, 19 Apr 2022 13:16:41 +0200	[thread overview]
Message-ID: <20220419111650.1582274-3-Jason@zx2c4.com> (raw)
In-Reply-To: <20220419111650.1582274-1-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>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/m68k/include/asm/timex.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
index 6a21d9358280..f4a7a340f4ca 100644
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -35,7 +35,7 @@ static inline unsigned long random_get_entropy(void)
 {
 	if (mach_random_get_entropy)
 		return mach_random_get_entropy();
-	return 0;
+	return random_get_entropy_fallback();
 }
 #define random_get_entropy	random_get_entropy
 
-- 
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>,
	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 v5 02/11] m68k: use fallback for random_get_entropy() instead of zero
Date: Tue, 19 Apr 2022 13:16:41 +0200	[thread overview]
Message-ID: <20220419111650.1582274-3-Jason@zx2c4.com> (raw)
In-Reply-To: <20220419111650.1582274-1-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>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/m68k/include/asm/timex.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
index 6a21d9358280..f4a7a340f4ca 100644
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -35,7 +35,7 @@ static inline unsigned long random_get_entropy(void)
 {
 	if (mach_random_get_entropy)
 		return mach_random_get_entropy();
-	return 0;
+	return random_get_entropy_fallback();
 }
 #define random_get_entropy	random_get_entropy
 
-- 
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>,
	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 v5 02/11] m68k: use fallback for random_get_entropy() instead of zero
Date: Tue, 19 Apr 2022 13:16:41 +0200	[thread overview]
Message-ID: <20220419111650.1582274-3-Jason@zx2c4.com> (raw)
In-Reply-To: <20220419111650.1582274-1-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>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/m68k/include/asm/timex.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
index 6a21d9358280..f4a7a340f4ca 100644
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -35,7 +35,7 @@ static inline unsigned long random_get_entropy(void)
 {
 	if (mach_random_get_entropy)
 		return mach_random_get_entropy();
-	return 0;
+	return random_get_entropy_fallback();
 }
 #define random_get_entropy	random_get_entropy
 
-- 
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:[~2022-04-19 11:17 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-19 11:16 [PATCH v5 00/11] archs/random: fallback to best raw ktime when no cycle counter Jason A. Donenfeld
2022-04-19 11:16 ` Jason A. Donenfeld
2022-04-19 11:16 ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 01/11] timekeeping: add raw clock fallback for random_get_entropy() Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16 ` Jason A. Donenfeld [this message]
2022-04-19 11:16   ` [PATCH v5 02/11] m68k: use fallback for random_get_entropy() instead of zero Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 03/11] riscv: " Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 04/11] mips: use fallback for random_get_entropy() instead of just c0 random Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-21 19:25   ` Maciej W. Rozycki
2022-04-21 19:25     ` Maciej W. Rozycki
2022-04-21 19:25     ` Maciej W. Rozycki
2022-04-21 20:01     ` Jason A. Donenfeld
2022-04-21 20:01       ` Jason A. Donenfeld
2022-04-21 20:01       ` Jason A. Donenfeld
2022-04-21 21:05   ` Thomas Bogendoerfer
2022-04-21 21:05     ` Thomas Bogendoerfer
2022-04-21 21:05     ` Thomas Bogendoerfer
2022-04-19 11:16 ` [PATCH v5 05/11] arm: use fallback for random_get_entropy() instead of zero Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 06/11] nios2: " Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-05-02 21:01   ` Dinh Nguyen
2022-05-02 21:01     ` Dinh Nguyen
2022-05-02 21:01     ` Dinh Nguyen
2022-04-19 11:16 ` [PATCH v5 07/11] x86: " Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 18:16   ` Borislav Petkov
2022-04-19 18:16     ` Borislav Petkov
2022-04-19 18:16     ` Borislav Petkov
2022-04-19 18:38     ` Jason A. Donenfeld
2022-04-19 18:38       ` Jason A. Donenfeld
2022-04-19 18:38       ` Jason A. Donenfeld
2022-04-19 18:59       ` Borislav Petkov
2022-04-19 18:59         ` Borislav Petkov
2022-04-19 18:59         ` Borislav Petkov
2022-04-19 19:00         ` Jason A. Donenfeld
2022-04-19 19:00           ` Jason A. Donenfeld
2022-04-19 19:00           ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 08/11] um: " Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:33   ` Johannes Berg
2022-04-19 11:33     ` Johannes Berg
2022-04-19 11:33     ` Johannes Berg
2022-04-19 11:37     ` Jason A. Donenfeld
2022-04-19 11:37       ` Jason A. Donenfeld
2022-04-19 11:37       ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 09/11] sparc: " Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16 ` [PATCH v5 10/11] xtensa: " Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-21  8:00   ` Max Filippov
2022-04-21  8:00     ` Max Filippov
2022-04-21  8:00     ` Max Filippov
2022-04-19 11:16 ` [PATCH v5 11/11] random: insist on random_get_entropy() existing in order to simplify Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-19 11:16   ` Jason A. Donenfeld
2022-04-23  2:24   ` Sandy Harris
2022-04-23  2:24     ` Sandy Harris
2022-04-23  2:24     ` Sandy Harris
2022-04-23 10:00     ` Jason A. Donenfeld
2022-04-23 10:00       ` Jason A. Donenfeld
2022-04-23 10:00       ` Jason A. Donenfeld

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