arch/x86/include/asm/syscall_wrapper.h - linux/torvalds/linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * syscall_wrapper.h - x86 specific wrappers to syscall definitions
  */

 #ifndef _ASM_X86_SYSCALL_WRAPPER_H
 #define _ASM_X86_SYSCALL_WRAPPER_H

 struct pt_regs;

 /* Mapping of registers to parameters for syscalls on x86-64 and x32 */
 #define SC_X86_64_REGS_TO_ARGS(x, ...)					\
 	__MAP(x,__SC_ARGS						\
 		,,regs->di,,regs->si,,regs->dx				\
 		,,regs->r10,,regs->r8,,regs->r9)			\

 /* Mapping of registers to parameters for syscalls on i386 */
 #define SC_IA32_REGS_TO_ARGS(x, ...)					\
 	__MAP(x,__SC_ARGS						\
 	      ,,(unsigned int)regs->bx,,(unsigned int)regs->cx		\
 	      ,,(unsigned int)regs->dx,,(unsigned int)regs->si		\
 	      ,,(unsigned int)regs->di,,(unsigned int)regs->bp)

 #ifdef CONFIG_IA32_EMULATION
 /*
  * For IA32 emulation, we need to handle "compat" syscalls *and* create
  * additional wrappers (aptly named __ia32_sys_xyzzy) which decode the
  * ia32 regs in the proper order for shared or "common" syscalls. As some
  * syscalls may not be implemented, we need to expand COND_SYSCALL in
  * kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this
  * case as well.
  */
 #define __IA32_COMPAT_SYS_STUB0(x, name)				\
 	asmlinkage long __ia32_compat_sys_##name(const struct pt_regs *regs);\
 	ALLOW_ERROR_INJECTION(__ia32_compat_sys_##name, ERRNO);		\
 	asmlinkage long __ia32_compat_sys_##name(const struct pt_regs *regs)\
 	{								\
 		return __se_compat_sys_##name();			\
 	}

 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)				\
 	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\
 	ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO);		\
 	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\
 	{								\
 		return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
 	}

 #define __IA32_SYS_STUBx(x, name, ...)					\
 	asmlinkage long __ia32_sys##name(const struct pt_regs *regs);	\
 	ALLOW_ERROR_INJECTION(__ia32_sys##name, ERRNO);			\
 	asmlinkage long __ia32_sys##name(const struct pt_regs *regs)	\
 	{								\
 		return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
 	}

 /*
  * To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias
  * named __ia32_sys_*()
  */

 #define SYSCALL_DEFINE0(sname)						\
 	SYSCALL_METADATA(_##sname, 0);					\
 	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused);\
 	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO);		\
 	SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname);		\
 	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)

 #define COND_SYSCALL(name)							\
 	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused)	\
 	{									\
 		return sys_ni_syscall();					\
 	}									\
 	asmlinkage __weak long __ia32_sys_##name(const struct pt_regs *__unused)\
 	{									\
 		return sys_ni_syscall();					\
 	}

 #define SYS_NI(name)							\
 	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);		\
 	SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers)

 #else /* CONFIG_IA32_EMULATION */
 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)
 #define __IA32_SYS_STUBx(x, fullname, name, ...)
 #endif /* CONFIG_IA32_EMULATION */


 #ifdef CONFIG_X86_X32
 /*
  * For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
  * of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
  * with x86_64 obviously do not need such care.
  */
 #define __X32_COMPAT_SYS_STUB0(x, name, ...)				\
 	asmlinkage long __x32_compat_sys_##name(const struct pt_regs *regs);\
 	ALLOW_ERROR_INJECTION(__x32_compat_sys_##name, ERRNO);		\
 	asmlinkage long __x32_compat_sys_##name(const struct pt_regs *regs)\
 	{								\
 		return __se_compat_sys_##name();\
 	}

 #define __X32_COMPAT_SYS_STUBx(x, name, ...)				\
 	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\
 	ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO);		\
 	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\
 	{								\
 		return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
 	}

 #else /* CONFIG_X86_X32 */
 #define __X32_COMPAT_SYS_STUB0(x, name)
 #define __X32_COMPAT_SYS_STUBx(x, name, ...)
 #endif /* CONFIG_X86_X32 */


 #ifdef CONFIG_COMPAT
 /*
  * Compat means IA32_EMULATION and/or X86_X32. As they use a different
  * mapping of registers to parameters, we need to generate stubs for each
  * of them.
  */
 #define COMPAT_SYSCALL_DEFINE0(name)					\
 	static long __se_compat_sys_##name(void);			\
 	static inline long __do_compat_sys_##name(void);		\
 	__IA32_COMPAT_SYS_STUB0(x, name)				\
 	__X32_COMPAT_SYS_STUB0(x, name)					\
 	static long __se_compat_sys_##name(void)			\
 	{								\
 		return __do_compat_sys_##name();			\
 	}								\
 	static inline long __do_compat_sys_##name(void)

 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)					\
 	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
 	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
 	__IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__)				\
 	__X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__)				\
 	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))	\
 	{									\
 		return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
 	}									\
 	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))

 /*
  * As some compat syscalls may not be implemented, we need to expand
  * COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in
  * kernel/time/posix-stubs.c to cover this case as well.
  */
 #define COND_SYSCALL_COMPAT(name) 					\
 	cond_syscall(__ia32_compat_sys_##name);				\
 	cond_syscall(__x32_compat_sys_##name)

 #define COMPAT_SYS_NI(name)						\
 	SYSCALL_ALIAS(__ia32_compat_sys_##name, sys_ni_posix_timers);	\
 	SYSCALL_ALIAS(__x32_compat_sys_##name, sys_ni_posix_timers)

 #endif /* CONFIG_COMPAT */


 /*
  * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes
  * struct pt_regs *regs as the only argument of the syscall stub named
  * __x64_sys_*(). It decodes just the registers it needs and passes them on to
  * the __se_sys_*() wrapper performing sign extension and then to the
  * __do_sys_*() function doing the actual job. These wrappers and functions
  * are inlined (at least in very most cases), meaning that the assembly looks
  * as follows (slightly re-ordered for better readability):
  *
  * <__x64_sys_recv>:		<-- syscall with 4 parameters
  *	callq	<__fentry__>
  *
  *	mov	0x70(%rdi),%rdi	<-- decode regs->di
  *	mov	0x68(%rdi),%rsi	<-- decode regs->si
  *	mov	0x60(%rdi),%rdx	<-- decode regs->dx
  *	mov	0x38(%rdi),%rcx	<-- decode regs->r10
  *
  *	xor	%r9d,%r9d	<-- clear %r9
  *	xor	%r8d,%r8d	<-- clear %r8
  *
  *	callq	__sys_recvfrom	<-- do the actual work in __sys_recvfrom()
  *				    which takes 6 arguments
  *
  *	cltq			<-- extend return value to 64-bit
  *	retq			<-- return
  *
  * This approach avoids leaking random user-provided register content down
  * the call chain.
  *
  * If IA32_EMULATION is enabled, this macro generates an additional wrapper
  * named __ia32_sys_*() which decodes the struct pt_regs *regs according
  * to the i386 calling convention (bx, cx, dx, si, di, bp).
  */
 #define __SYSCALL_DEFINEx(x, name, ...)					\
 	asmlinkage long __x64_sys##name(const struct pt_regs *regs);	\
 	ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO);			\
 	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
 	asmlinkage long __x64_sys##name(const struct pt_regs *regs)	\
 	{								\
 		return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
 	}								\
 	__IA32_SYS_STUBx(x, name, __VA_ARGS__)				\
 	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))	\
 	{								\
 		long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
 		__MAP(x,__SC_TEST,__VA_ARGS__);				\
 		__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__));	\
 		return ret;						\
 	}								\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))

 /*
  * As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
  * obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
  * hurt, we only need to re-define it here to keep the naming congruent to
  * SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI()
  * macros to work correctly.
  */
 #ifndef SYSCALL_DEFINE0
 #define SYSCALL_DEFINE0(sname)						\
 	SYSCALL_METADATA(_##sname, 0);					\
 	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused);\
 	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO);		\
 	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)
 #endif

 #ifndef COND_SYSCALL
 #define COND_SYSCALL(name) 							\
 	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused)	\
 	{									\
 		return sys_ni_syscall();					\
 	}
 #endif

 #ifndef SYS_NI
 #define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);
 #endif


 /*
  * For VSYSCALLS, we need to declare these three syscalls with the new
  * pt_regs-based calling convention for in-kernel use.
  */
 asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
 asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
 asmlinkage long __x64_sys_time(const struct pt_regs *regs);

 #endif /* _ASM_X86_SYSCALL_WRAPPER_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* syscall_wrapper.h - x86 specific wrappers to syscall definitions
	*/

	#ifndef _ASM_X86_SYSCALL_WRAPPER_H
	#define _ASM_X86_SYSCALL_WRAPPER_H

	struct pt_regs;

	/* Mapping of registers to parameters for syscalls on x86-64 and x32 */
	#define SC_X86_64_REGS_TO_ARGS(x, ...) \
	__MAP(x,__SC_ARGS \
	,,regs->di,,regs->si,,regs->dx \
	,,regs->r10,,regs->r8,,regs->r9) \

	/* Mapping of registers to parameters for syscalls on i386 */
	#define SC_IA32_REGS_TO_ARGS(x, ...) \
	__MAP(x,__SC_ARGS \
	,,(unsigned int)regs->bx,,(unsigned int)regs->cx \
	,,(unsigned int)regs->dx,,(unsigned int)regs->si \
	,,(unsigned int)regs->di,,(unsigned int)regs->bp)

	#ifdef CONFIG_IA32_EMULATION
	/*
	* For IA32 emulation, we need to handle "compat" syscalls and create
	* additional wrappers (aptly named __ia32_sys_xyzzy) which decode the
	* ia32 regs in the proper order for shared or "common" syscalls. As some
	* syscalls may not be implemented, we need to expand COND_SYSCALL in
	* kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this
	* case as well.
	*/
	#define __IA32_COMPAT_SYS_STUB0(x, name) \
	asmlinkage long __ia32_compat_sys_##name(const struct pt_regs *regs);\
	ALLOW_ERROR_INJECTION(__ia32_compat_sys_##name, ERRNO); \
	asmlinkage long __ia32_compat_sys_##name(const struct pt_regs *regs)\
	{ \
	return __se_compat_sys_##name(); \
	}

	#define __IA32_COMPAT_SYS_STUBx(x, name, ...) \
	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\
	ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO); \
	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\
	{ \
	return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
	}

	#define __IA32_SYS_STUBx(x, name, ...) \
	asmlinkage long __ia32_sys##name(const struct pt_regs *regs); \
	ALLOW_ERROR_INJECTION(__ia32_sys##name, ERRNO); \
	asmlinkage long __ia32_sys##name(const struct pt_regs *regs) \
	{ \
	return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
	}

	/*
	* To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias
	* named __ia32_sys_*()
	*/

	#define SYSCALL_DEFINE0(sname) \
	SYSCALL_METADATA(_##sname, 0); \
	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused);\
	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \
	SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname); \
	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)

	#define COND_SYSCALL(name) \
	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused) \
	{ \
	return sys_ni_syscall(); \
	} \
	asmlinkage __weak long __ia32_sys_##name(const struct pt_regs *__unused)\
	{ \
	return sys_ni_syscall(); \
	}

	#define SYS_NI(name) \
	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers); \
	SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers)

	#else /* CONFIG_IA32_EMULATION */
	#define __IA32_COMPAT_SYS_STUBx(x, name, ...)
	#define __IA32_SYS_STUBx(x, fullname, name, ...)
	#endif /* CONFIG_IA32_EMULATION */


	#ifdef CONFIG_X86_X32
	/*
	* For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
	* of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
	* with x86_64 obviously do not need such care.
	*/
	#define __X32_COMPAT_SYS_STUB0(x, name, ...) \
	asmlinkage long __x32_compat_sys_##name(const struct pt_regs *regs);\
	ALLOW_ERROR_INJECTION(__x32_compat_sys_##name, ERRNO); \
	asmlinkage long __x32_compat_sys_##name(const struct pt_regs *regs)\
	{ \
	return __se_compat_sys_##name();\
	}

	#define __X32_COMPAT_SYS_STUBx(x, name, ...) \
	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\
	ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO); \
	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\
	{ \
	return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
	}

	#else /* CONFIG_X86_X32 */
	#define __X32_COMPAT_SYS_STUB0(x, name)
	#define __X32_COMPAT_SYS_STUBx(x, name, ...)
	#endif /* CONFIG_X86_X32 */


	#ifdef CONFIG_COMPAT
	/*
	* Compat means IA32_EMULATION and/or X86_X32. As they use a different
	* mapping of registers to parameters, we need to generate stubs for each
	* of them.
	*/
	#define COMPAT_SYSCALL_DEFINE0(name) \
	static long __se_compat_sys_##name(void); \
	static inline long __do_compat_sys_##name(void); \
	__IA32_COMPAT_SYS_STUB0(x, name) \
	__X32_COMPAT_SYS_STUB0(x, name) \
	static long __se_compat_sys_##name(void) \
	{ \
	return __do_compat_sys_##name(); \
	} \
	static inline long __do_compat_sys_##name(void)

	#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
	__IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
	__X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
	{ \
	return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
	} \
	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))

	/*
	* As some compat syscalls may not be implemented, we need to expand
	* COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in
	* kernel/time/posix-stubs.c to cover this case as well.
	*/
	#define COND_SYSCALL_COMPAT(name) \
	cond_syscall(__ia32_compat_sys_##name); \
	cond_syscall(__x32_compat_sys_##name)

	#define COMPAT_SYS_NI(name) \
	SYSCALL_ALIAS(__ia32_compat_sys_##name, sys_ni_posix_timers); \
	SYSCALL_ALIAS(__x32_compat_sys_##name, sys_ni_posix_timers)

	#endif /* CONFIG_COMPAT */


	/*
	* Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes
	* struct pt_regs *regs as the only argument of the syscall stub named
	* __x64_sys_*(). It decodes just the registers it needs and passes them on to
	* the __se_sys_*() wrapper performing sign extension and then to the
	* __do_sys_*() function doing the actual job. These wrappers and functions
	* are inlined (at least in very most cases), meaning that the assembly looks
	* as follows (slightly re-ordered for better readability):
	*
	* <__x64_sys_recv>: <-- syscall with 4 parameters
	* callq <__fentry__>
	*
	* mov 0x70(%rdi),%rdi <-- decode regs->di
	* mov 0x68(%rdi),%rsi <-- decode regs->si
	* mov 0x60(%rdi),%rdx <-- decode regs->dx
	* mov 0x38(%rdi),%rcx <-- decode regs->r10
	*
	* xor %r9d,%r9d <-- clear %r9
	* xor %r8d,%r8d <-- clear %r8
	*
	* callq __sys_recvfrom <-- do the actual work in __sys_recvfrom()
	* which takes 6 arguments
	*
	* cltq <-- extend return value to 64-bit
	* retq <-- return
	*
	* This approach avoids leaking random user-provided register content down
	* the call chain.
	*
	* If IA32_EMULATION is enabled, this macro generates an additional wrapper
	* named __ia32_sys_() which decodes the struct pt_regs regs according
	* to the i386 calling convention (bx, cx, dx, si, di, bp).
	*/
	#define __SYSCALL_DEFINEx(x, name, ...) \
	asmlinkage long __x64_sys##name(const struct pt_regs *regs); \
	ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO); \
	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
	asmlinkage long __x64_sys##name(const struct pt_regs *regs) \
	{ \
	return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
	} \
	__IA32_SYS_STUBx(x, name, __VA_ARGS__) \
	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
	{ \
	long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
	__MAP(x,__SC_TEST,__VA_ARGS__); \
	__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
	return ret; \
	} \
	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))

	/*
	* As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
	* obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
	* hurt, we only need to re-define it here to keep the naming congruent to
	* SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI()
	* macros to work correctly.
	*/
	#ifndef SYSCALL_DEFINE0
	#define SYSCALL_DEFINE0(sname) \
	SYSCALL_METADATA(_##sname, 0); \
	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused);\
	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \
	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)
	#endif

	#ifndef COND_SYSCALL
	#define COND_SYSCALL(name) \
	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused) \
	{ \
	return sys_ni_syscall(); \
	}
	#endif

	#ifndef SYS_NI
	#define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);
	#endif


	/*
	* For VSYSCALLS, we need to declare these three syscalls with the new
	* pt_regs-based calling convention for in-kernel use.
	*/
	asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
	asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
	asmlinkage long __x64_sys_time(const struct pt_regs *regs);

	#endif /* _ASM_X86_SYSCALL_WRAPPER_H */