From: Will Deacon <will.deacon@arm.com>
Date: Mon, 29 Sep 2014 10:44:01 +0000 (+0100)
Subject: arm64: entry: avoid writing lr explicitly for constructing return paths
X-Git-Tag: omap-for-v3.19/fixes-for-merge-window~18^2~49
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d54e81f9af1d106e47ae8594903c43a80dae1a99;p=pandora-kernel.git

arm64: entry: avoid writing lr explicitly for constructing return paths

Using an explicit adr instruction to set the link register to point at
ret_fast_syscall/ret_to_user can defeat branch and return stack predictors.

Instead, use the standard calling instructions (bl, blr) and have an
unconditional branch as the following instruction.

Signed-off-by: Will Deacon <will.deacon@arm.com>
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