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From: Mark Brown <broonie@kernel.org>
To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Mark Brown <broonie@kernel.org>,
	Richard Henderson <richard.henderson@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: [PATCH v10 3/3] arm64: Use v8.5-RNG entropy for KASLR seed
Date: Fri, 10 Jan 2020 12:23:41 +0000	[thread overview]
Message-ID: <20200110122341.8445-4-broonie@kernel.org> (raw)
In-Reply-To: <20200110122341.8445-1-broonie@kernel.org>

When seeding KALSR on a system where we have architecture level random
number generation make use of that entropy, mixing it in with the seed
passed by the bootloader. Since this is run very early in init before
feature detection is complete we open code rather than use archrandom.h.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/kaslr.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 2a11a962e571..53b8a4ee64ff 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -120,6 +120,17 @@ u64 __init kaslr_early_init(u64 dt_phys)
 		return 0;
 	}
 
+	/*
+	 * Mix in any entropy obtainable architecturally, open coded
+	 * since this runs extremely early.
+	 */
+	if (__early_cpu_has_rndr()) {
+		unsigned long raw;
+
+		if (__arm64_rndr(&raw))
+			seed ^= raw;
+	}
+
 	if (!seed) {
 		kaslr_status = KASLR_DISABLED_NO_SEED;
 		return 0;
-- 
2.20.1


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  parent reply	other threads:[~2020-01-10 12:24 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 12:23 [PATCH v10 0/3] ARMv8.5-RNG support Mark Brown
2020-01-10 12:23 ` [PATCH v10 1/3] arm64: Implement archrandom.h for ARMv8.5-RNG Mark Brown
2020-01-14 17:44   ` Will Deacon
2020-01-15  7:40     ` Ard Biesheuvel
2020-01-15  9:16       ` Will Deacon
2020-01-15  9:24         ` Ard Biesheuvel
2020-01-15 11:07           ` Mark Brown
2020-01-15 11:16             ` Will Deacon
2020-01-15 14:26             ` Catalin Marinas
2020-01-16  0:23               ` Richard Henderson
2020-01-16 11:02                 ` Catalin Marinas
2020-01-16 11:10                   ` Ard Biesheuvel
2020-01-16 11:40                     ` Catalin Marinas
2020-01-10 12:23 ` [PATCH v10 2/3] arm64: random: Add data to pool from setup_arch() Mark Brown
2020-01-10 12:35   ` Mark Rutland
2020-01-13 19:09   ` Richard Henderson
2020-01-15  7:48   ` Ard Biesheuvel
2020-01-15  9:16     ` Will Deacon
2020-01-15  9:22       ` Ard Biesheuvel
2020-01-15 10:11         ` Mark Rutland
2020-01-15 14:01           ` Mark Brown
2020-01-15 12:07       ` Mark Brown
2020-01-15 12:42         ` Will Deacon
2020-01-15 13:36           ` Ard Biesheuvel
2020-01-15 17:04             ` Mark Brown
2020-01-16 11:33               ` Will Deacon
2020-01-15 15:40           ` Mark Brown
2020-01-10 12:23 ` Mark Brown [this message]
2020-01-10 12:35   ` [PATCH v10 3/3] arm64: Use v8.5-RNG entropy for KASLR seed Mark Rutland
2020-01-13 19:09   ` Richard Henderson

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