All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jason Yan <yanaijie@huawei.com>
To: <mpe@ellerman.id.au>, <linuxppc-dev@lists.ozlabs.org>,
	<diana.craciun@nxp.com>, <christophe.leroy@c-s.fr>,
	<benh@kernel.crashing.org>, <paulus@samba.org>,
	<npiggin@gmail.com>, <keescook@chromium.org>,
	<kernel-hardening@lists.openwall.com>, <oss@buserror.net>
Cc: <linux-kernel@vger.kernel.org>, <zhaohongjiang@huawei.com>,
	Jason Yan <yanaijie@huawei.com>
Subject: [PATCH v2 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass
Date: Wed, 5 Feb 2020 10:55:25 +0800	[thread overview]
Message-ID: <20200205025527.28640-5-yanaijie@huawei.com> (raw)
In-Reply-To: <20200205025527.28640-1-yanaijie@huawei.com>

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@huawei.com>
Cc: Scott Wood <oss@buserror.net>
Cc: Diana Craciun <diana.craciun@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <keescook@chromium.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


WARNING: multiple messages have this Message-ID (diff)
From: Jason Yan <yanaijie@huawei.com>
To: <mpe@ellerman.id.au>, <linuxppc-dev@lists.ozlabs.org>,
	<diana.craciun@nxp.com>, <christophe.leroy@c-s.fr>,
	<benh@kernel.crashing.org>, <paulus@samba.org>,
	<npiggin@gmail.com>, <keescook@chromium.org>,
	<kernel-hardening@lists.openwall.com>, <oss@buserror.net>
Cc: Jason Yan <yanaijie@huawei.com>,
	linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com
Subject: [PATCH v2 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass
Date: Wed, 5 Feb 2020 10:55:25 +0800	[thread overview]
Message-ID: <20200205025527.28640-5-yanaijie@huawei.com> (raw)
In-Reply-To: <20200205025527.28640-1-yanaijie@huawei.com>

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@huawei.com>
Cc: Scott Wood <oss@buserror.net>
Cc: Diana Craciun <diana.craciun@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <keescook@chromium.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


  parent reply	other threads:[~2020-02-05  2:56 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05  2:55 [PATCH v2 0/6] implement KASLR for powerpc/fsl_booke/64 Jason Yan
2020-02-05  2:55 ` Jason Yan
2020-02-05  2:55 ` [PATCH v2 1/6] powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and kaslr_early_init() Jason Yan
2020-02-05  2:55   ` Jason Yan
2020-02-05  2:55 ` [PATCH v2 2/6] powerpc/fsl_booke/64: introduce reloc_kernel_entry() helper Jason Yan
2020-02-05  2:55   ` Jason Yan
2020-02-05  2:55 ` [PATCH v2 3/6] powerpc/fsl_booke/64: implement KASLR for fsl_booke64 Jason Yan
2020-02-05  2:55   ` Jason Yan
2020-02-05  5:13   ` kbuild test robot
2020-02-05  5:13     ` kbuild test robot
2020-02-05  5:13     ` kbuild test robot
2020-02-05  2:55 ` Jason Yan [this message]
2020-02-05  2:55   ` [PATCH v2 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass Jason Yan
2020-02-05  2:55 ` [PATCH v2 5/6] powerpc/fsl_booke/64: clear the original kernel if randomized Jason Yan
2020-02-05  2:55   ` Jason Yan
2020-02-05  2:55 ` [PATCH v2 6/6] powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst and add 64bit part Jason Yan
2020-02-05  2:55   ` Jason Yan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200205025527.28640-5-yanaijie@huawei.com \
    --to=yanaijie@huawei.com \
    --cc=benh@kernel.crashing.org \
    --cc=christophe.leroy@c-s.fr \
    --cc=diana.craciun@nxp.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=npiggin@gmail.com \
    --cc=oss@buserror.net \
    --cc=paulus@samba.org \
    --cc=zhaohongjiang@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.