/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* syscall_wrapper.h - x86 specific wrappers to syscall definitions
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*/
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#ifndef _ASM_X86_SYSCALL_WRAPPER_H
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#define _ASM_X86_SYSCALL_WRAPPER_H
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struct pt_regs;
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extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
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extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
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/*
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* Instead of the generic __SYSCALL_DEFINEx() definition, the x86 version takes
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* struct pt_regs *regs as the only argument of the syscall stub(s) named as:
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* __x64_sys_*() - 64-bit native syscall
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* __ia32_sys_*() - 32-bit native syscall or common compat syscall
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* __ia32_compat_sys_*() - 32-bit compat syscall
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* __x32_compat_sys_*() - 64-bit X32 compat syscall
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*
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* The registers are decoded according to the ABI:
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* 64-bit: RDI, RSI, RDX, R10, R8, R9
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* 32-bit: EBX, ECX, EDX, ESI, EDI, EBP
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*
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* The stub then passes the decoded arguments to the __se_sys_*() wrapper to
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* perform sign-extension (omitted for zero-argument syscalls). Finally the
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* arguments are passed to the __do_sys_*() function which is the actual
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* syscall. These wrappers are marked as inline so the compiler can optimize
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* the functions where appropriate.
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*
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* Example assembly (slightly re-ordered for better readability):
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*
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* <__x64_sys_recv>: <-- syscall with 4 parameters
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* callq <__fentry__>
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*
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* mov 0x70(%rdi),%rdi <-- decode regs->di
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* mov 0x68(%rdi),%rsi <-- decode regs->si
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* mov 0x60(%rdi),%rdx <-- decode regs->dx
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* mov 0x38(%rdi),%rcx <-- decode regs->r10
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*
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* xor %r9d,%r9d <-- clear %r9
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* xor %r8d,%r8d <-- clear %r8
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*
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* callq __sys_recvfrom <-- do the actual work in __sys_recvfrom()
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* which takes 6 arguments
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*
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* cltq <-- extend return value to 64-bit
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* retq <-- return
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*
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* This approach avoids leaking random user-provided register content down
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* the call chain.
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*/
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/* Mapping of registers to parameters for syscalls on x86-64 and x32 */
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#define SC_X86_64_REGS_TO_ARGS(x, ...) \
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__MAP(x,__SC_ARGS \
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,,regs->di,,regs->si,,regs->dx \
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,,regs->r10,,regs->r8,,regs->r9) \
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/* Mapping of registers to parameters for syscalls on i386 */
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#define SC_IA32_REGS_TO_ARGS(x, ...) \
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__MAP(x,__SC_ARGS \
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,,(unsigned int)regs->bx,,(unsigned int)regs->cx \
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,,(unsigned int)regs->dx,,(unsigned int)regs->si \
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,,(unsigned int)regs->di,,(unsigned int)regs->bp)
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#define __SYS_STUB0(abi, name) \
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long __##abi##_##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \
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long __##abi##_##name(const struct pt_regs *regs) \
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__alias(__do_##name);
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#define __SYS_STUBx(abi, name, ...) \
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long __##abi##_##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \
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long __##abi##_##name(const struct pt_regs *regs) \
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{ \
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return __se_##name(__VA_ARGS__); \
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}
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#define __COND_SYSCALL(abi, name) \
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__weak long __##abi##_##name(const struct pt_regs *__unused) \
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{ \
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return sys_ni_syscall(); \
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}
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#define __SYS_NI(abi, name) \
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SYSCALL_ALIAS(__##abi##_##name, sys_ni_posix_timers);
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#ifdef CONFIG_X86_64
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#define __X64_SYS_STUB0(name) \
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__SYS_STUB0(x64, sys_##name)
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#define __X64_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(x64, sys##name, \
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SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __X64_COND_SYSCALL(name) \
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__COND_SYSCALL(x64, sys_##name)
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#define __X64_SYS_NI(name) \
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__SYS_NI(x64, sys_##name)
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#else /* CONFIG_X86_64 */
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#define __X64_SYS_STUB0(name)
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#define __X64_SYS_STUBx(x, name, ...)
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#define __X64_COND_SYSCALL(name)
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#define __X64_SYS_NI(name)
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#endif /* CONFIG_X86_64 */
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#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
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#define __IA32_SYS_STUB0(name) \
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__SYS_STUB0(ia32, sys_##name)
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#define __IA32_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(ia32, sys##name, \
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SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __IA32_COND_SYSCALL(name) \
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__COND_SYSCALL(ia32, sys_##name)
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#define __IA32_SYS_NI(name) \
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__SYS_NI(ia32, sys_##name)
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#else /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
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#define __IA32_SYS_STUB0(name)
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#define __IA32_SYS_STUBx(x, name, ...)
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#define __IA32_COND_SYSCALL(name)
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#define __IA32_SYS_NI(name)
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#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
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#ifdef CONFIG_IA32_EMULATION
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/*
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* For IA32 emulation, we need to handle "compat" syscalls *and* create
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* additional wrappers (aptly named __ia32_sys_xyzzy) which decode the
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* ia32 regs in the proper order for shared or "common" syscalls. As some
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* syscalls may not be implemented, we need to expand COND_SYSCALL in
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* kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this
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* case as well.
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*/
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#define __IA32_COMPAT_SYS_STUB0(name) \
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__SYS_STUB0(ia32, compat_sys_##name)
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#define __IA32_COMPAT_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(ia32, compat_sys##name, \
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SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __IA32_COMPAT_COND_SYSCALL(name) \
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__COND_SYSCALL(ia32, compat_sys_##name)
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#define __IA32_COMPAT_SYS_NI(name) \
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__SYS_NI(ia32, compat_sys_##name)
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#else /* CONFIG_IA32_EMULATION */
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#define __IA32_COMPAT_SYS_STUB0(name)
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#define __IA32_COMPAT_SYS_STUBx(x, name, ...)
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#define __IA32_COMPAT_COND_SYSCALL(name)
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#define __IA32_COMPAT_SYS_NI(name)
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#endif /* CONFIG_IA32_EMULATION */
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#ifdef CONFIG_X86_X32
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/*
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* For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
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* of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
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* with x86_64 obviously do not need such care.
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*/
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#define __X32_COMPAT_SYS_STUB0(name) \
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__SYS_STUB0(x32, compat_sys_##name)
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#define __X32_COMPAT_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(x32, compat_sys##name, \
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SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __X32_COMPAT_COND_SYSCALL(name) \
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__COND_SYSCALL(x32, compat_sys_##name)
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#define __X32_COMPAT_SYS_NI(name) \
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__SYS_NI(x32, compat_sys_##name)
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#else /* CONFIG_X86_X32 */
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#define __X32_COMPAT_SYS_STUB0(name)
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#define __X32_COMPAT_SYS_STUBx(x, name, ...)
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#define __X32_COMPAT_COND_SYSCALL(name)
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#define __X32_COMPAT_SYS_NI(name)
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#endif /* CONFIG_X86_X32 */
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#ifdef CONFIG_COMPAT
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/*
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* Compat means IA32_EMULATION and/or X86_X32. As they use a different
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* mapping of registers to parameters, we need to generate stubs for each
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* of them.
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*/
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#define COMPAT_SYSCALL_DEFINE0(name) \
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static long \
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__do_compat_sys_##name(const struct pt_regs *__unused); \
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__IA32_COMPAT_SYS_STUB0(name) \
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__X32_COMPAT_SYS_STUB0(name) \
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static long \
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__do_compat_sys_##name(const struct pt_regs *__unused)
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#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
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static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
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static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
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__IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
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__X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
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static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
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{ \
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return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
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} \
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static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
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/*
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* As some compat syscalls may not be implemented, we need to expand
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* COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in
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* kernel/time/posix-stubs.c to cover this case as well.
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*/
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#define COND_SYSCALL_COMPAT(name) \
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__IA32_COMPAT_COND_SYSCALL(name) \
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__X32_COMPAT_COND_SYSCALL(name)
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#define COMPAT_SYS_NI(name) \
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__IA32_COMPAT_SYS_NI(name) \
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__X32_COMPAT_SYS_NI(name)
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#endif /* CONFIG_COMPAT */
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#define __SYSCALL_DEFINEx(x, name, ...) \
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static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
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static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
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__X64_SYS_STUBx(x, name, __VA_ARGS__) \
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__IA32_SYS_STUBx(x, name, __VA_ARGS__) \
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static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
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{ \
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long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
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__MAP(x,__SC_TEST,__VA_ARGS__); \
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__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
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return ret; \
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} \
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static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
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/*
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* As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
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* obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
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* hurt, we only need to re-define it here to keep the naming congruent to
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* SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI()
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* macros to work correctly.
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*/
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#define SYSCALL_DEFINE0(sname) \
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SYSCALL_METADATA(_##sname, 0); \
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static long __do_sys_##sname(const struct pt_regs *__unused); \
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__X64_SYS_STUB0(sname) \
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__IA32_SYS_STUB0(sname) \
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static long __do_sys_##sname(const struct pt_regs *__unused)
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#define COND_SYSCALL(name) \
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__X64_COND_SYSCALL(name) \
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__IA32_COND_SYSCALL(name)
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#define SYS_NI(name) \
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__X64_SYS_NI(name) \
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__IA32_SYS_NI(name)
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/*
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* For VSYSCALLS, we need to declare these three syscalls with the new
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* pt_regs-based calling convention for in-kernel use.
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*/
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long __x64_sys_getcpu(const struct pt_regs *regs);
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long __x64_sys_gettimeofday(const struct pt_regs *regs);
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long __x64_sys_time(const struct pt_regs *regs);
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#endif /* _ASM_X86_SYSCALL_WRAPPER_H */
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