/* * sigreturn_codes.S - code sinpets for sigreturn syscalls * * Created by:	Victor Kamensky, 2013-08-13 * Copyright:	(C) 2013  Linaro Limited * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. */ #include <asm/unistd.h> /* * For ARM syscalls, we encode the syscall number into the instruction. * With EABI, the syscall number has to be loaded into r7. As result * ARM syscall sequence snippet will have move and svc in .arm encoding * * For Thumb syscalls, we pass the syscall number via r7.  We therefore * need two 16-bit instructions in .thumb encoding * * Please note sigreturn_codes code are not executed in place. Instead * they just copied by kernel into appropriate places. Code inside of * arch/arm/kernel/signal.c is very sensitive to layout of these code * snippets. */ /* * In CPU_THUMBONLY case kernel arm opcodes are not allowed. * Note in this case codes skips those instructions but it uses .org * directive to keep correct layout of sigreturn_codes array. */#ifndef CONFIG_CPU_THUMBONLY#define ARM_OK(code...)	code#else#define ARM_OK(code...)#endif 	.macro arm_slot n	.org	sigreturn_codes + 12 * (\n)ARM_OK(	.arm	)	.endm 	.macro thumb_slot n	.org	sigreturn_codes + 12 * (\n) + 8	.thumb	.endm #if __LINUX_ARM_ARCH__ <= 4	/*	 * Note we manually set minimally required arch that supports	 * required thumb opcodes for early arch versions. It is OK	 * for this file to be used in combination with other	 * lower arch variants, since these code snippets are only	 * used as input data.	 */	.arch armv4t#endif 	.section .rodata	.global sigreturn_codes	.type	sigreturn_codes, #object 	.align sigreturn_codes: 	/* ARM sigreturn syscall code snippet */	arm_slot 0ARM_OK(	mov	r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)	)ARM_OK(	swi	#(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)	) 	/* Thumb sigreturn syscall code snippet */	thumb_slot 0	movs	r7, #(__NR_sigreturn - __NR_SYSCALL_BASE)	swi	#0 	/* ARM sigreturn_rt syscall code snippet */	arm_slot 1ARM_OK(	mov	r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)	)ARM_OK(	swi	#(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)	) 	/* Thumb sigreturn_rt syscall code snippet */	thumb_slot 1	movs	r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE)	swi	#0 	/*	 * Note on addtional space: setup_return in signal.c	 * algorithm uses two words copy regardless whether	 * it is thumb case or not, so we need additional	 * word after real last entry.	 */	arm_slot 2	.space	4 	.size	sigreturn_codes, . - sigreturn_codes