60 lines
1.8 KiB
ArmAsm
60 lines
1.8 KiB
ArmAsm
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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x64/syscall.s
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Function for performing system calls.
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*******************************************************************************/
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# x86_64 system call conventions:
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# interrupt 128
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# system call number: %rax
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# parameters: %rdi, %rsi, %rdx, %rcx, %r8, %r9
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# return value: %rax, %rdx
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# return errno: %rcx
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# clobbered: %rdi, %rsi, %r8, %r9, %r10, %r11
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# preserved: %rbx, %rsp, %rbp, %r12, %r13, %r14, %r15
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.global asm_syscall
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asm_syscall: /* syscall num in %rax. */
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push %rbp
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mov %rsp, %rbp
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int $0x80
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test %ecx, %ecx
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jnz 1f
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pop %rbp
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ret
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1:
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push %rbx
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push %r12
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push %r13
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mov %ecx, %ebx # preserve: ret_errno
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mov %rax, %r12 # preserve: ret_low
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mov %rdx, %r13 # preserve: ret_high
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call get_errno_location # get_errno_location()
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mov %ebx, (%rax) # *get_errno_location() = ret_errno
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mov %r12, %rax # restore: ret_low
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mov %r13, %rdx # restore: ret_high
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pop %r13
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pop %r12
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pop %rbx
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pop %rbp
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ret
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.size asm_syscall, .-asm_syscall
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