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Message-ID: <20200205025527.28640-5-yanaijie@huawei.com>
Date: Wed, 5 Feb 2020 10:55:25 +0800
From: Jason Yan <yanaijie@...wei.com>
To: <mpe@...erman.id.au>, <linuxppc-dev@...ts.ozlabs.org>,
<diana.craciun@....com>, <christophe.leroy@....fr>,
<benh@...nel.crashing.org>, <paulus@...ba.org>, <npiggin@...il.com>,
<keescook@...omium.org>, <kernel-hardening@...ts.openwall.com>,
<oss@...error.net>
CC: <linux-kernel@...r.kernel.org>, <zhaohongjiang@...wei.com>, Jason Yan
<yanaijie@...wei.com>
Subject: [PATCH v2 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass
The BSS section has already cleared out in the first pass. No need to
clear it again. This can save some time when booting with KASLR
enabled.
Signed-off-by: Jason Yan <yanaijie@...wei.com>
Cc: Scott Wood <oss@...error.net>
Cc: Diana Craciun <diana.craciun@....com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Christophe Leroy <christophe.leroy@....fr>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Kees Cook <keescook@...omium.org>
---
arch/powerpc/kernel/head_64.S | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index b4ececc4323d..9ae7fd8bbf7c 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -914,6 +914,13 @@ start_here_multiplatform:
bl relative_toc
tovirt(r2,r2)
+ /* Do not clear the BSS for the second pass if randomized */
+ LOAD_REG_ADDR(r3, kernstart_virt_addr)
+ lwz r3,0(r3)
+ LOAD_REG_IMMEDIATE(r4, KERNELBASE)
+ cmpw r3,r4
+ bne 4f
+
/* Clear out the BSS. It may have been done in prom_init,
* already but that's irrelevant since prom_init will soon
* be detached from the kernel completely. Besides, we need
--
2.17.2
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