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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-06-30 17:29:12 +0200 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-07-18 13:29:04 +0200 |
| commit | 6ebbf2ce437b33022d30badd49dc94d33ecfa498 (patch) | |
| tree | bc015e35b456a28bb0e501803a454dc0c0d3291a /arch/arm/vfp/vfphw.S | |
| parent | ARM: make it easier to check the CPU part number correctly (diff) | |
| download | linux-6ebbf2ce437b33022d30badd49dc94d33ecfa498.tar.xz linux-6ebbf2ce437b33022d30badd49dc94d33ecfa498.zip | |
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/vfp/vfphw.S')
| -rw-r--r-- | arch/arm/vfp/vfphw.S | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index be807625ed8c..cda654cbf2c2 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -183,7 +183,7 @@ vfp_hw_state_valid: @ always subtract 4 from the following @ instruction address. dec_preempt_count_ti r10, r4 - mov pc, r9 @ we think we have handled things + ret r9 @ we think we have handled things look_for_VFP_exceptions: @@ -202,7 +202,7 @@ look_for_VFP_exceptions: DBGSTR "not VFP" dec_preempt_count_ti r10, r4 - mov pc, lr + ret lr process_exception: DBGSTR "bounce" @@ -234,7 +234,7 @@ ENTRY(vfp_save_state) VFPFMRX r12, FPINST2 @ FPINST2 if needed (and present) 1: stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2 - mov pc, lr + ret lr ENDPROC(vfp_save_state) .align @@ -245,7 +245,7 @@ vfp_current_hw_state_address: #ifdef CONFIG_THUMB2_KERNEL adr \tmp, 1f add \tmp, \tmp, \base, lsl \shift - mov pc, \tmp + ret \tmp #else add pc, pc, \base, lsl \shift mov r0, r0 @@ -257,10 +257,10 @@ ENTRY(vfp_get_float) tbl_branch r0, r3, #3 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 1: mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0 - mov pc, lr + ret lr .org 1b + 8 1: mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1 - mov pc, lr + ret lr .org 1b + 8 .endr ENDPROC(vfp_get_float) @@ -269,10 +269,10 @@ ENTRY(vfp_put_float) tbl_branch r1, r3, #3 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 1: mcr p10, 0, r0, c\dr, c0, 0 @ fmsr r0, s0 - mov pc, lr + ret lr .org 1b + 8 1: mcr p10, 0, r0, c\dr, c0, 4 @ fmsr r0, s1 - mov pc, lr + ret lr .org 1b + 8 .endr ENDPROC(vfp_put_float) @@ -281,14 +281,14 @@ ENTRY(vfp_get_double) tbl_branch r0, r3, #3 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 1: fmrrd r0, r1, d\dr - mov pc, lr + ret lr .org 1b + 8 .endr #ifdef CONFIG_VFPv3 @ d16 - d31 registers .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 1: mrrc p11, 3, r0, r1, c\dr @ fmrrd r0, r1, d\dr - mov pc, lr + ret lr .org 1b + 8 .endr #endif @@ -296,21 +296,21 @@ ENTRY(vfp_get_double) @ virtual register 16 (or 32 if VFPv3) for compare with zero mov r0, #0 mov r1, #0 - mov pc, lr + ret lr ENDPROC(vfp_get_double) ENTRY(vfp_put_double) tbl_branch r2, r3, #3 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 1: fmdrr d\dr, r0, r1 - mov pc, lr + ret lr .org 1b + 8 .endr #ifdef CONFIG_VFPv3 @ d16 - d31 registers .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 1: mcrr p11, 3, r0, r1, c\dr @ fmdrr r0, r1, d\dr - mov pc, lr + ret lr .org 1b + 8 .endr #endif |