linux/arch/arm64/kernel/entry32.S
Mark Rutland ad2daa85bd arm64: entry32: remove pointless register assignment
We currently set x27 in compat_sys_sigreturn_wrapper and
compat_sys_rt_sigreturn_wrapper, similarly to what we do with r8/why on
32-bit ARM, in an attempt to prevent sigreturns from being restarted.

However, on arm64 we have always used pt_regs::syscallno for syscall
restarting (for both native and compat tasks), and x27 is never
inspected again before being overwritten in kernel_exit.

This patch removes the pointless register assignments.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2015-07-10 16:47:13 +01:00

122 lines
3.0 KiB
ArmAsm

/*
* Compat system call wrappers
*
* Copyright (C) 2012 ARM Ltd.
* Authors: Will Deacon <will.deacon@arm.com>
* Catalin Marinas <catalin.marinas@arm.com>
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/linkage.h>
#include <linux/const.h>
#include <asm/assembler.h>
#include <asm/asm-offsets.h>
#include <asm/errno.h>
#include <asm/page.h>
/*
* System call wrappers for the AArch32 compatibility layer.
*/
ENTRY(compat_sys_sigreturn_wrapper)
mov x0, sp
b compat_sys_sigreturn
ENDPROC(compat_sys_sigreturn_wrapper)
ENTRY(compat_sys_rt_sigreturn_wrapper)
mov x0, sp
b compat_sys_rt_sigreturn
ENDPROC(compat_sys_rt_sigreturn_wrapper)
ENTRY(compat_sys_statfs64_wrapper)
mov w3, #84
cmp w1, #88
csel w1, w3, w1, eq
b compat_sys_statfs64
ENDPROC(compat_sys_statfs64_wrapper)
ENTRY(compat_sys_fstatfs64_wrapper)
mov w3, #84
cmp w1, #88
csel w1, w3, w1, eq
b compat_sys_fstatfs64
ENDPROC(compat_sys_fstatfs64_wrapper)
/*
* Note: off_4k (w5) is always in units of 4K. If we can't do the
* requested offset because it is not page-aligned, we return -EINVAL.
*/
ENTRY(compat_sys_mmap2_wrapper)
#if PAGE_SHIFT > 12
tst w5, #~PAGE_MASK >> 12
b.ne 1f
lsr w5, w5, #PAGE_SHIFT - 12
#endif
b sys_mmap_pgoff
1: mov x0, #-EINVAL
ret
ENDPROC(compat_sys_mmap2_wrapper)
/*
* Wrappers for AArch32 syscalls that either take 64-bit parameters
* in registers or that take 32-bit parameters which require sign
* extension.
*/
ENTRY(compat_sys_pread64_wrapper)
regs_to_64 x3, x4, x5
b sys_pread64
ENDPROC(compat_sys_pread64_wrapper)
ENTRY(compat_sys_pwrite64_wrapper)
regs_to_64 x3, x4, x5
b sys_pwrite64
ENDPROC(compat_sys_pwrite64_wrapper)
ENTRY(compat_sys_truncate64_wrapper)
regs_to_64 x1, x2, x3
b sys_truncate
ENDPROC(compat_sys_truncate64_wrapper)
ENTRY(compat_sys_ftruncate64_wrapper)
regs_to_64 x1, x2, x3
b sys_ftruncate
ENDPROC(compat_sys_ftruncate64_wrapper)
ENTRY(compat_sys_readahead_wrapper)
regs_to_64 x1, x2, x3
mov w2, w4
b sys_readahead
ENDPROC(compat_sys_readahead_wrapper)
ENTRY(compat_sys_fadvise64_64_wrapper)
mov w6, w1
regs_to_64 x1, x2, x3
regs_to_64 x2, x4, x5
mov w3, w6
b sys_fadvise64_64
ENDPROC(compat_sys_fadvise64_64_wrapper)
ENTRY(compat_sys_sync_file_range2_wrapper)
regs_to_64 x2, x2, x3
regs_to_64 x3, x4, x5
b sys_sync_file_range2
ENDPROC(compat_sys_sync_file_range2_wrapper)
ENTRY(compat_sys_fallocate_wrapper)
regs_to_64 x2, x2, x3
regs_to_64 x3, x4, x5
b sys_fallocate
ENDPROC(compat_sys_fallocate_wrapper)