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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>
40 lines
697 B
ArmAsm
40 lines
697 B
ArmAsm
#include <asm/assembler.h>
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/*
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* Interrupt handling. Preserves r7, r8, r9
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*/
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.macro arch_irq_handler_default
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get_irqnr_preamble r6, lr
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1: get_irqnr_and_base r0, r2, r6, lr
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movne r1, sp
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@
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@ routine called with r0 = irq number, r1 = struct pt_regs *
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@
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adrne lr, BSYM(1b)
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bne asm_do_IRQ
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#ifdef CONFIG_SMP
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/*
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* XXX
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*
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* this macro assumes that irqstat (r2) and base (r6) are
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* preserved from get_irqnr_and_base above
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*/
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ALT_SMP(test_for_ipi r0, r2, r6, lr)
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ALT_UP_B(9997f)
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movne r1, sp
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adrne lr, BSYM(1b)
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bne do_IPI
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#endif
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9997:
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.endm
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.macro arch_irq_handler, symbol_name
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.align 5
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.global \symbol_name
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\symbol_name:
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mov r8, lr
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arch_irq_handler_default
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ret r8
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.endm
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