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* 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
* 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.
#define ARM_OK(code...) code
#define ARM_OK(code...)
.macro arm_slot n
.org sigreturn_codes + 12 * (\n)
ARM_OK( .arm )
.macro thumb_slot n
.org sigreturn_codes + 12 * (\n) + 8
#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
.section .rodata
.global sigreturn_codes
.type sigreturn_codes, #object
/* ARM sigreturn syscall code snippet */
arm_slot 0
ARM_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 1
ARM_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