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e83b07dc8c
All MIPS ISAs before r6 use the 'lo' and 'hi' special registers. These are clobbered by system calls and need to be marked as such to avoid miscompilations. Currently nolibc ties the clobbers to the ABI. But this is wrong and leads to ISA<->ABI combinations which are not handled correctly, leading to compiler errors or miscompilations. Handle all different combinations of ABI and ISA. Fixes:a6a2a8a429("tools/nolibc: MIPS: add support for N64 and N32 ABIs") Fixes:66b6f755ad("rcutorture: Import a copy of nolibc") Suggested-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.2603141744240.55200@angie.orcam.me.uk/ Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Link: https://patch.msgid.link/20260317-nolibc-mips-clobber-v2-1-5b9a97761a9e@linutronix.de Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
282 lines
14 KiB
C
282 lines
14 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* MIPS specific definitions for NOLIBC
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* Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
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*/
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#ifndef _NOLIBC_ARCH_MIPS_H
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#define _NOLIBC_ARCH_MIPS_H
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#include "compiler.h"
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#include "crt.h"
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#if !defined(_ABIO32) && !defined(_ABIN32) && !defined(_ABI64)
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#error Unsupported MIPS ABI
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#endif
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/* Syscalls for MIPS ABI O32 :
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* - WARNING! there's always a delayed slot!
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* - WARNING again, the syntax is different, registers take a '$' and numbers
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* do not.
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* - registers are 32-bit
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* - stack is 8-byte aligned
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* - syscall number is passed in v0 (starts at 0xfa0).
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* - arguments are in a0, a1, a2, a3, then the stack. The caller needs to
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* leave some room in the stack for the callee to save a0..a3 if needed.
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* - Many registers are clobbered, in fact only a0..a2 and s0..s8 are
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* preserved. See: https://www.linux-mips.org/wiki/Syscall as well as
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* scall32-o32.S in the kernel sources.
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* - the system call is performed by calling "syscall"
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* - syscall return comes in v0, and register a3 needs to be checked to know
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* if an error occurred, in which case errno is in v0.
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* - the arguments are cast to long and assigned into the target registers
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* which are then simply passed as registers to the asm code, so that we
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* don't have to experience issues with register constraints.
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*
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* Syscalls for MIPS ABI N32, same as ABI O32 with the following differences :
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* - arguments are in a0, a1, a2, a3, t0, t1, t2, t3.
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* t0..t3 are also known as a4..a7.
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* - stack is 16-byte aligned
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*/
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#if !defined(__mips_isa_rev) || __mips_isa_rev < 6
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#define _NOLIBC_SYSCALL_CLOBBER_HI_LO "hi", "lo"
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#else
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#define _NOLIBC_SYSCALL_CLOBBER_HI_LO "$0"
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#endif
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#if defined(_ABIO32)
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#define _NOLIBC_SYSCALL_CLOBBERLIST \
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"memory", "cc", "at", "v1", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9", \
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_NOLIBC_SYSCALL_CLOBBER_HI_LO
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#define _NOLIBC_SYSCALL_STACK_RESERVE "addiu $sp, $sp, -32\n"
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#define _NOLIBC_SYSCALL_STACK_UNRESERVE "addiu $sp, $sp, 32\n"
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#else /* _ABIN32 || _ABI64 */
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/* binutils, GCC and clang disagree about register aliases, use numbers instead. */
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#define _NOLIBC_SYSCALL_CLOBBERLIST \
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"memory", "cc", "at", "v1", \
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"10", "11", "12", "13", "14", "15", "24", "25", \
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_NOLIBC_SYSCALL_CLOBBER_HI_LO
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#define _NOLIBC_SYSCALL_STACK_RESERVE
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#define _NOLIBC_SYSCALL_STACK_UNRESERVE
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#endif /* _ABIO32 */
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#define __nolibc_syscall0(num) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r"(_num), "=r"(_arg4) \
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: "r"(_num) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define __nolibc_syscall1(num, arg1) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r"(_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define __nolibc_syscall2(num, arg1, arg2) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r"(_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define __nolibc_syscall3(num, arg1, arg2, arg3) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r"(_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define __nolibc_syscall4(num, arg1, arg2, arg3, arg4) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#if defined(_ABIO32)
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#define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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register long _arg5 = (long)(arg5); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"sw %7, 16($sp)\n" \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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register long _arg5 = (long)(arg5); \
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register long _arg6 = (long)(arg6); \
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\
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__asm__ volatile ( \
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_NOLIBC_SYSCALL_STACK_RESERVE \
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"sw %7, 16($sp)\n" \
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"sw %8, 20($sp)\n" \
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"syscall\n" \
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_NOLIBC_SYSCALL_STACK_UNRESERVE \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
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"r"(_arg6) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#else /* _ABIN32 || _ABI64 */
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#define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("$4") = (long)(arg1); \
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register long _arg2 __asm__ ("$5") = (long)(arg2); \
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register long _arg3 __asm__ ("$6") = (long)(arg3); \
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register long _arg4 __asm__ ("$7") = (long)(arg4); \
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register long _arg5 __asm__ ("$8") = (long)(arg5); \
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\
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__asm__ volatile ( \
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"syscall\n" \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("$4") = (long)(arg1); \
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register long _arg2 __asm__ ("$5") = (long)(arg2); \
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register long _arg3 __asm__ ("$6") = (long)(arg3); \
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register long _arg4 __asm__ ("$7") = (long)(arg4); \
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register long _arg5 __asm__ ("$8") = (long)(arg5); \
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register long _arg6 __asm__ ("$9") = (long)(arg6); \
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\
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__asm__ volatile ( \
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"syscall\n" \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
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"r"(_arg6) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#endif /* _ABIO32 */
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#ifndef NOLIBC_NO_RUNTIME
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/* startup code, note that it's called __start on MIPS */
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void __start(void);
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void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector __start(void)
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{
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__asm__ volatile (
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"move $a0, $sp\n" /* save stack pointer to $a0, as arg1 of _start_c */
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#if defined(_ABIO32)
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"addiu $sp, $sp, -16\n" /* the callee expects to save a0..a3 there */
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#endif /* _ABIO32 */
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"lui $t9, %hi(_start_c)\n" /* ABI requires current function address in $t9 */
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"ori $t9, %lo(_start_c)\n"
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#if defined(_ABI64)
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"lui $t0, %highest(_start_c)\n"
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"ori $t0, %higher(_start_c)\n"
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"dsll $t0, 0x20\n"
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"or $t9, $t0\n"
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#endif /* _ABI64 */
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"jalr $t9\n" /* transfer to c runtime */
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);
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__nolibc_entrypoint_epilogue();
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}
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#endif /* NOLIBC_NO_RUNTIME */
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#endif /* _NOLIBC_ARCH_MIPS_H */
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