[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+ (part1)
Hi Russell, On 01.07.2014 18:19, Russell King wrote: > 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 <rmk+kernel@xxxxxxxxxxxxxxxx> Build- and boot-tested on mach-s3c64xx. Tested-by: Tomasz Figa <tomasz.figa@xxxxxxxxx> Best regards, Tomasz _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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