diff options
| author | Dave Martin <dave.martin@linaro.org> | 2011-05-23 12:22:10 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-05-26 10:31:06 +0100 |
| commit | dc2eb928a1bcf6a48f40c1f2ff21b66bdbf91a3c (patch) | |
| tree | 3f877569ca481ad79378ed0e5932006434a1cc1e /arch/arm/kernel/fiqasm.S | |
| parent | 4db70f73e56961b9bcdfd0c36c62847a18b7dbb5 (diff) | |
ARM: 6938/1: fiq: Refactor {get,set}_fiq_regs() for Thumb-2
* To remove the risk of inconvenient register allocation decisions
by the compiler, these functions are separated out as pure
assembler.
* The apcs frame manipulation code is not applicable for Thumb-2
(and also not easily compatible). Since it's not essential to
have a full frame on these leaf assembler functions, the frame
manipulation is removed, in the interests of simplicity.
* Split up ldm/stm instructions to be compatible with Thumb-2,
as well as avoiding instruction forms deprecated on >= ARMv7.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/fiqasm.S')
| -rw-r--r-- | arch/arm/kernel/fiqasm.S | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/arch/arm/kernel/fiqasm.S b/arch/arm/kernel/fiqasm.S new file mode 100644 index 000000000000..207f9d652010 --- /dev/null +++ b/arch/arm/kernel/fiqasm.S @@ -0,0 +1,49 @@ +/* + * linux/arch/arm/kernel/fiqasm.S + * + * Derived from code originally in linux/arch/arm/kernel/fiq.c: + * + * Copyright (C) 1998 Russell King + * Copyright (C) 1998, 1999 Phil Blundell + * Copyright (C) 2011, Linaro Limited + * + * FIQ support written by Philip Blundell <philb@gnu.org>, 1998. + * + * FIQ support re-written by Russell King to be more generic + * + * v7/Thumb-2 compatibility modifications by Linaro Limited, 2011. + */ + +#include <linux/linkage.h> +#include <asm/assembler.h> + +/* + * Taking an interrupt in FIQ mode is death, so both these functions + * disable irqs for the duration. + */ + +ENTRY(__set_fiq_regs) + mov r2, #PSR_I_BIT | PSR_F_BIT | FIQ_MODE + mrs r1, cpsr + msr cpsr_c, r2 @ select FIQ mode + mov r0, r0 @ avoid hazard prior to ARMv4 + ldmia r0!, {r8 - r12} + ldr sp, [r0], #4 + ldr lr, [r0] + msr cpsr_c, r1 @ return to SVC mode + mov r0, r0 @ avoid hazard prior to ARMv4 + mov pc, lr +ENDPROC(__set_fiq_regs) + +ENTRY(__get_fiq_regs) + mov r2, #PSR_I_BIT | PSR_F_BIT | FIQ_MODE + mrs r1, cpsr + msr cpsr_c, r2 @ select FIQ mode + mov r0, r0 @ avoid hazard prior to ARMv4 + stmia r0!, {r8 - r12} + str sp, [r0], #4 + str lr, [r0] + msr cpsr_c, r1 @ return to SVC mode + mov r0, r0 @ avoid hazard prior to ARMv4 + mov pc, lr +ENDPROC(__get_fiq_regs) |