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sortix--sortix/sortix/x64/syscall.s
2011-12-01 14:29:49 +01:00

159 lines
3.1 KiB
ArmAsm

/******************************************************************************
COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix 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 Sortix. If not, see <http://www.gnu.org/licenses/>.
syscall.s
An assembly stub that acts as glue for system calls.
******************************************************************************/
.global syscall_handler
.global resume_syscall
.section .text
.type syscall_handler, @function
syscall_handler:
cli
# Compabillity with InterruptRegisters.
pushq $0x0
pushq $0x80
pushq %r15
pushq %r14
pushq %r13
pushq %r12
pushq %r11
pushq %r10
pushq %r9
pushq %r8
pushq %rax
pushq %rcx
pushq %rdx
pushq %rbx
pushq %rsp
pushq %rbp
pushq %rsi
pushq %rdi
# Push the user-space data segment.
movl %ds, %ebp
pushq %rbp
# Load the kernel data segment.
movw $0x10, %bp
movl %ebp, %ds
movl %ebp, %es
movl %ebp, %fs
movl %ebp, %gs
# Compabillity with InterruptRegisters.
movq %cr2, %rbp
pushq %rbp
# Store the state structure's pointer so the call can modify it if needed.
movq %rsp, syscall_state_ptr
# By default, assume the system call was complete.
movl $0, system_was_incomplete
# Reset the kernel errno.
movl $0, errno
# Make sure the requested system call is valid.
cmp SYSCALL_MAX, %rax
jb valid_rax
xorq %rax, %rax
valid_rax:
# Read a system call function pointer.
xorq %rbp, %rbp
movq syscall_list(%rbp,%rax,8), %rax
# Oh how nice, user-space put the parameters in: rdi, rsi, rdx, rcx, r8, r9
# Call the system call.
callq *%rax
# Test if the system call was incomplete
movl system_was_incomplete, %ebx
testl %ebx, %ebx
# If the system call was incomplete, the value in %eax is meaningless.
jg return_to_userspace
# The system call was completed, so store the return value.
movq %rax, 72(%rsp)
# Don't forget to update userspace's errno value.
call update_userspace_errno
return_to_userspace:
# Compabillity with InterruptRegisters.
addq $8, %rsp
# Restore the user-space data segment.
popq %rbp
movl %ebp, %ds
movl %ebp, %es
movl %ebp, %fs
movl %ebp, %gs
popq %rdi
popq %rsi
popq %rbp
popq %rsp
popq %rbx
popq %rdx
popq %rcx
popq %rax
popq %r8
popq %r9
popq %r10
popq %r11
popq %r12
popq %r13
popq %r14
popq %r15
# Compabillity with InterruptRegisters.
addq $16, %rsp
# Return to user-space.
iretq
.type resume_syscall, @function
resume_syscall:
pushq %rbp
movq %rsp, %rbp
movq %rdi, %rax
movq %rdx, %r11
movq 0(%r11), %rdi
movq 8(%r11), %rsi
movq 16(%r11), %rdx
movq 24(%r11), %rcx
movq 32(%r11), %r8
movq 40(%r11), %r9
callq *%rax
leaveq
retq