From mboxrd@z Thu Jan 1 00:00:00 1970 From: tony@atomide.com (Tony Lindgren) Date: Wed, 2 Jul 2014 02:02:18 -0700 Subject: [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ In-Reply-To: References: Message-ID: <20140702090218.GV28884@atomide.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Russell King [140701 09:01]: > ARMv6 and greater introduced a new instruction ("bx") which can be used > to return from function calls. Recent CPUs perform better when the > "bx lr" instruction is used rather than the "mov pc, lr" instruction, > and this sequence is strongly recommended to be used by the ARM > architecture manual (section A.4.1.1). > > We provide a new macro "ret" with all its variants for the condition > code which will resolve to the appropriate instruction. > > Rather than doing this piecemeal, and miss some instances, change all > the "mov pc" instances to use the new macro, with the exception of > the "movs" instruction and the kprobes code. This allows us to detect > the "mov pc, lr" case and fix it up - and also gives us the possibility > of deploying this for other registers depending on the CPU selection. > > Signed-off-by: Russell King Seems to boot fine for omaps: Tested-by: Tony Lindgren