freebsd-dev/sys/arm64/linux/linux_locore.asm
Dmitry Chagin c56480a832 linux(4): Implement signal trampoline for arm64 in a FreeBSD-way
The implemenation differs from others Linuxulators.
For unwinders Linux ucontext_t is stored, however native machine context
is used to store/restore process state to avoid code duplication.

As DWARF Aarch64 does not define a register number for PC and provides no
direct way to encode the PC of the previous frame, CFI cannot describe a
signal trampoline frame. So, modified the vdso linker script to discard
unused sections.

Extensions are not implemented.

MFC after:		2 weeks
2022-05-15 21:10:50 +03:00

60 lines
1.9 KiB
NASM

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (C) 2018 Turing Robotic Industries Inc.
* Copyright (C) 2020 Andrew Turner <andrew@FreeBSD.org>
* Copyright (C) 2022 Dmitry Chagin <dchagin@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* arm64 Linux VDSO signal trampoline.
*/
#include <machine/asm.h>
#include <arm64/linux/linux_syscall.h>
.data
.globl linux_platform
linux_platform:
.asciz "aarch64"
.text
nop /* This is what Linux calls a "Mysterious NOP". */
EENTRY(__kernel_rt_sigreturn)
mov x8, #LINUX_SYS_linux_rt_sigreturn
svc #0
EEND(__kernel_rt_sigreturn)
EENTRY(linux_vdso_sigcode)
blr x8
mov x8, #LINUX_SYS_linux_rt_sigreturn
svc #0
EEND(linux_vdso_sigcode)