/* SPDX-License-Identifier: GPL-2.0-only */
|
/*
|
* sigreturn_codes.S - code sinpets for sigreturn syscalls
|
*
|
* Created by: Victor Kamensky, 2013-08-13
|
* Copyright: (C) 2013 Linaro Limited
|
*/
|
|
#include <asm/assembler.h>
|
#include <asm/asm-offsets.h>
|
#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
|
|
.macro arm_fdpic_slot n
|
.org sigreturn_codes + 24 + 20 * (\n)
|
ARM_OK( .arm )
|
.endm
|
|
.macro thumb_fdpic_slot n
|
.org sigreturn_codes + 24 + 20 * (\n) + 12
|
.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 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
|
|
/* ARM sigreturn restorer FDPIC bounce code snippet */
|
arm_fdpic_slot 0
|
ARM_OK( ldr r3, [sp, #SIGFRAME_RC3_OFFSET] )
|
ARM_OK( ldmia r3, {r3, r9} )
|
#ifdef CONFIG_ARM_THUMB
|
ARM_OK( bx r3 )
|
#else
|
ARM_OK( ret r3 )
|
#endif
|
|
/* Thumb sigreturn restorer FDPIC bounce code snippet */
|
thumb_fdpic_slot 0
|
ldr r3, [sp, #SIGFRAME_RC3_OFFSET]
|
ldmia r3, {r2, r3}
|
mov r9, r3
|
bx r2
|
|
/* ARM sigreturn_rt restorer FDPIC bounce code snippet */
|
arm_fdpic_slot 1
|
ARM_OK( ldr r3, [sp, #RT_SIGFRAME_RC3_OFFSET] )
|
ARM_OK( ldmia r3, {r3, r9} )
|
#ifdef CONFIG_ARM_THUMB
|
ARM_OK( bx r3 )
|
#else
|
ARM_OK( ret r3 )
|
#endif
|
|
/* Thumb sigreturn_rt restorer FDPIC bounce code snippet */
|
thumb_fdpic_slot 1
|
ldr r3, [sp, #RT_SIGFRAME_RC3_OFFSET]
|
ldmia r3, {r2, r3}
|
mov r9, r3
|
bx r2
|
|
/*
|
* Note on additional space: setup_return in signal.c
|
* always copies the same number of words regardless whether
|
* it is thumb case or not, so we need one additional padding
|
* word after the last entry.
|
*/
|
.space 4
|
|
.size sigreturn_codes, . - sigreturn_codes
|
