226 lines
8.2 KiB
C
226 lines
8.2 KiB
C
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/* 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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/* 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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#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_STUBx(x, name, ...) \
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asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\
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ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO); \
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asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\
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{ \
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return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
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} \
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#define __IA32_SYS_STUBx(x, name, ...) \
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asmlinkage long __ia32_sys##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__ia32_sys##name, ERRNO); \
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asmlinkage long __ia32_sys##name(const struct pt_regs *regs) \
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{ \
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return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
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}
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/*
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* To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias
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* named __ia32_sys_*()
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*/
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#define SYSCALL_DEFINE0(sname) \
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SYSCALL_METADATA(_##sname, 0); \
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asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused);\
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ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \
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SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname); \
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asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)
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#define COND_SYSCALL(name) \
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asmlinkage __weak long __x64_sys_##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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asmlinkage __weak long __ia32_sys_##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(name) \
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SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers); \
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SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers)
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#else /* CONFIG_IA32_EMULATION */
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#define __IA32_COMPAT_SYS_STUBx(x, name, ...)
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#define __IA32_SYS_STUBx(x, fullname, 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_STUBx(x, name, ...) \
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asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\
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ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO); \
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asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\
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{ \
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return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
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} \
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#else /* CONFIG_X86_X32 */
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#define __X32_COMPAT_SYS_STUBx(x, 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_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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asmlinkage __weak long __ia32_compat_sys_##name( \
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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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cond_syscall(__x32_compat_sys_##name)
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#define COMPAT_SYS_NI(name) \
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SYSCALL_ALIAS(__ia32_compat_sys_##name, sys_ni_posix_timers); \
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SYSCALL_ALIAS(__x32_compat_sys_##name, sys_ni_posix_timers)
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#endif /* CONFIG_COMPAT */
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/*
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* Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes
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* struct pt_regs *regs as the only argument of the syscall stub named
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* __x64_sys_*(). It decodes just the registers it needs and passes them on to
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* the __se_sys_*() wrapper performing sign extension and then to the
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* __do_sys_*() function doing the actual job. These wrappers and functions
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* are inlined (at least in very most cases), meaning that the assembly looks
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* as follows (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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* If IA32_EMULATION is enabled, this macro generates an additional wrapper
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* named __ia32_sys_*() which decodes the struct pt_regs *regs according
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* to the i386 calling convention (bx, cx, dx, si, di, bp).
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*/
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#define __SYSCALL_DEFINEx(x, name, ...) \
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asmlinkage long __x64_sys##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO); \
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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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asmlinkage long __x64_sys##name(const struct pt_regs *regs) \
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{ \
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return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
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} \
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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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#ifndef SYSCALL_DEFINE0
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#define SYSCALL_DEFINE0(sname) \
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SYSCALL_METADATA(_##sname, 0); \
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asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused);\
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ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \
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asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)
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#endif
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#ifndef COND_SYSCALL
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#define COND_SYSCALL(name) \
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asmlinkage __weak long __x64_sys_##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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#endif
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#ifndef SYS_NI
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#define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);
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#endif
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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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asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
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asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
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asmlinkage long __x64_sys_time(const struct pt_regs *regs);
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#endif /* _ASM_X86_SYSCALL_WRAPPER_H */
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