160 lines
3.1 KiB
ArmAsm
160 lines
3.1 KiB
ArmAsm
/******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along
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with Sortix. If not, see <http://www.gnu.org/licenses/>.
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syscall.s
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An assembly stub that acts as glue for system calls.
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******************************************************************************/
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.global syscall_handler
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.global resume_syscall
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.section .text
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.type syscall_handler, @function
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syscall_handler:
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cli
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# Compabillity with InterruptRegisters.
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pushq $0x0
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pushq $0x80
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pushq %r15
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pushq %r14
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pushq %r13
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pushq %r12
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pushq %r11
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pushq %r10
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pushq %r9
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pushq %r8
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pushq %rax
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pushq %rcx
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pushq %rdx
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pushq %rbx
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pushq %rsp
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pushq %rbp
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pushq %rsi
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pushq %rdi
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# Push the user-space data segment.
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movl %ds, %ebp
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pushq %rbp
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# Load the kernel data segment.
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movw $0x10, %bp
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movl %ebp, %ds
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movl %ebp, %es
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movl %ebp, %fs
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movl %ebp, %gs
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# Compabillity with InterruptRegisters.
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movq %cr2, %rbp
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pushq %rbp
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# Store the state structure's pointer so the call can modify it if needed.
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movq %rsp, syscall_state_ptr
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# By default, assume the system call was complete.
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movl $0, system_was_incomplete
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# Reset the kernel errno.
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movl $0, errno
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# Make sure the requested system call is valid.
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cmp SYSCALL_MAX, %rax
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jb valid_rax
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xorq %rax, %rax
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valid_rax:
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# Read a system call function pointer.
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xorq %rbp, %rbp
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movq syscall_list(%rbp,%rax,8), %rax
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# Oh how nice, user-space put the parameters in: rdi, rsi, rdx, rcx, r8, r9
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# Call the system call.
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callq *%rax
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# Test if the system call was incomplete
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movl system_was_incomplete, %ebx
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testl %ebx, %ebx
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# If the system call was incomplete, the value in %eax is meaningless.
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jg return_to_userspace
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# The system call was completed, so store the return value.
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movq %rax, 72(%rsp)
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# Don't forget to update userspace's errno value.
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call update_userspace_errno
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return_to_userspace:
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# Compabillity with InterruptRegisters.
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addq $8, %rsp
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# Restore the user-space data segment.
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popq %rbp
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movl %ebp, %ds
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movl %ebp, %es
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movl %ebp, %fs
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movl %ebp, %gs
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popq %rdi
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popq %rsi
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popq %rbp
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popq %rsp
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popq %rbx
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popq %rdx
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popq %rcx
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popq %rax
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popq %r8
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popq %r9
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popq %r10
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popq %r11
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popq %r12
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popq %r13
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popq %r14
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popq %r15
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# Compabillity with InterruptRegisters.
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addq $16, %rsp
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# Return to user-space.
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iretq
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.type resume_syscall, @function
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resume_syscall:
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pushq %rbp
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movq %rsp, %rbp
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movq %rdi, %rax
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movq %rdx, %r11
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movq 0(%r11), %rdi
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movq 8(%r11), %rsi
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movq 16(%r11), %rdx
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movq 24(%r11), %rcx
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movq 32(%r11), %r8
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movq 40(%r11), %r9
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callq *%rax
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leaveq
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retq
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