diff options
| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-06-30 16:29:12 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-07-18 12:29:04 +0100 |
| commit | 6ebbf2ce437b33022d30badd49dc94d33ecfa498 (patch) | |
| tree | bc015e35b456a28bb0e501803a454dc0c0d3291a /arch/arm/kernel/iwmmxt.S | |
| parent | af040ffc9ba1e079ee4c0748aff64fa3d4716fa5 (diff) | |
ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
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.
Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/iwmmxt.S')
| -rw-r--r-- | arch/arm/kernel/iwmmxt.S | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/arm/kernel/iwmmxt.S b/arch/arm/kernel/iwmmxt.S index a5599cfc43cb..0960be7953f0 100644 --- a/arch/arm/kernel/iwmmxt.S +++ b/arch/arm/kernel/iwmmxt.S @@ -179,7 +179,7 @@ concan_load: get_thread_info r10 #endif 4: dec_preempt_count r10, r3 - mov pc, lr + ret lr /* * Back up Concan regs to save area and disable access to them @@ -265,7 +265,7 @@ ENTRY(iwmmxt_task_copy) mov r3, lr @ preserve return address bl concan_dump msr cpsr_c, ip @ restore interrupt mode - mov pc, r3 + ret r3 /* * Restore Concan state from given memory address @@ -301,7 +301,7 @@ ENTRY(iwmmxt_task_restore) mov r3, lr @ preserve return address bl concan_load msr cpsr_c, ip @ restore interrupt mode - mov pc, r3 + ret r3 /* * Concan handling on task switch @@ -323,7 +323,7 @@ ENTRY(iwmmxt_task_switch) add r3, r0, #TI_IWMMXT_STATE @ get next task Concan save area ldr r2, [r2] @ get current Concan owner teq r2, r3 @ next task owns it? - movne pc, lr @ no: leave Concan disabled + retne lr @ no: leave Concan disabled 1: @ flip Concan access XSC(eor r1, r1, #0x3) @@ -350,7 +350,7 @@ ENTRY(iwmmxt_task_release) eors r0, r0, r1 @ if equal... streq r0, [r3] @ then clear ownership msr cpsr_c, r2 @ restore interrupts - mov pc, lr + ret lr .data concan_owner: |