diff mbox series

[4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass

Message ID 20191115093209.26434-5-yanaijie@huawei.com (mailing list archive)
State Superseded
Headers show
Series implement KASLR for powerpc/fsl_booke/64 | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/merge (3b4852888d3f7e0cde65b29af9c518f4019e145f)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/next (565f9bc05e2dad6c7fdfc7c2e641be580aa599cd)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch linus/master (96b95eff4a591dbac582c2590d067e356a18aacb)
snowpatch_ozlabs/apply_patch warning Failed to apply on branch powerpc/fixes (7d6475051fb3d9339c5c760ed9883bc0a9048b21)
snowpatch_ozlabs/apply_patch success Successfully applied on branch linux-next (5a6fcbeabe3e20459ed8504690b2515dacc5246f)
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 13 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Jason Yan Nov. 15, 2019, 9:32 a.m. UTC 
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 mbox series

Patch

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index ad79fddb974d..76d8cdeddc69 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -907,6 +907,13 @@  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