[mirror_ubuntu-disco-kernel.git] / arch / x86 / include / asm / 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

/* 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_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(void);		\
	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO);	\
	SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname);	\
	asmlinkage long __x64_sys_##sname(void)

#define COND_SYSCALL(name)						\
	cond_syscall(__x64_sys_##name);					\
	cond_syscall(__ia32_sys_##name)

#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_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_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_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(void);		\
	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO);	\
	asmlinkage long __x64_sys_##sname(void)
#endif

#ifndef COND_SYSCALL
#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name)
#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.
 */
struct pt_regs;
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 */
Commit	Line	Data
fa697140 DB	1	/* SPDX-License-Identifier: GPL-2.0 */
	2	/*
	3	* syscall_wrapper.h - x86 specific wrappers to syscall definitions
	4	*/
	5
	6	#ifndef _ASM_X86_SYSCALL_WRAPPER_H
	7	#define _ASM_X86_SYSCALL_WRAPPER_H
	8
ebeb8c82 DB	9	/* Mapping of registers to parameters for syscalls on x86-64 and x32 */
	10	#define SC_X86_64_REGS_TO_ARGS(x, ...) \
	11	__MAP(x,__SC_ARGS \
	12	,,regs->di,,regs->si,,regs->dx \
	13	,,regs->r10,,regs->r8,,regs->r9) \
	14
	15	/* Mapping of registers to parameters for syscalls on i386 */
	16	#define SC_IA32_REGS_TO_ARGS(x, ...) \
	17	__MAP(x,__SC_ARGS \
	18	,,(unsigned int)regs->bx,,(unsigned int)regs->cx \
	19	,,(unsigned int)regs->dx,,(unsigned int)regs->si \
	20	,,(unsigned int)regs->di,,(unsigned int)regs->bp)
	21
	22	#ifdef CONFIG_IA32_EMULATION
	23	/*
	24	* For IA32 emulation, we need to handle "compat" syscalls and create
e145242e	25	* additional wrappers (aptly named __ia32_sys_xyzzy) which decode the
ebeb8c82 DB	26	* ia32 regs in the proper order for shared or "common" syscalls. As some
	27	* syscalls may not be implemented, we need to expand COND_SYSCALL in
	28	* kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this
	29	* case as well.
	30	*/
c76fc982	31	#define __IA32_COMPAT_SYS_STUBx(x, name, ...) \
5ac9efa3 DB	32	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\
	33	ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO); \
	34	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\
ebeb8c82	35	{ \
5ac9efa3	36	return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
ebeb8c82 DB	37	} \
ebeb8c82 DB	38
c76fc982	39	#define __IA32_SYS_STUBx(x, name, ...) \
e145242e DB	40	asmlinkage long __ia32_sys##name(const struct pt_regs *regs); \
	41	ALLOW_ERROR_INJECTION(__ia32_sys##name, ERRNO); \
	42	asmlinkage long __ia32_sys##name(const struct pt_regs *regs) \
ebeb8c82	43	{ \
e145242e	44	return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
ebeb8c82 DB	45	}
ebeb8c82 DB	46
d5a00528 DB	47	/*
	48	* To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias
	49	* named __ia32_sys_*()
	50	*/
	51	#define SYSCALL_DEFINE0(sname) \
	52	SYSCALL_METADATA(_##sname, 0); \
	53	asmlinkage long __x64_sys_##sname(void); \
	54	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \
	55	SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname); \
	56	asmlinkage long __x64_sys_##sname(void)
	57
ebeb8c82	58	#define COND_SYSCALL(name) \
d5a00528	59	cond_syscall(__x64_sys_##name); \
e145242e	60	cond_syscall(__ia32_sys_##name)
ebeb8c82 DB	61
ebeb8c82 DB	62	#define SYS_NI(name) \
d5a00528	63	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers); \
e145242e	64	SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers)
ebeb8c82 DB	65
ebeb8c82 DB	66	#else /* CONFIG_IA32_EMULATION */
c76fc982 DB	67	#define __IA32_COMPAT_SYS_STUBx(x, name, ...)
c76fc982 DB	68	#define __IA32_SYS_STUBx(x, fullname, name, ...)
ebeb8c82 DB	69	#endif /* CONFIG_IA32_EMULATION */
	70
	71
	72	#ifdef CONFIG_X86_X32
	73	/*
	74	* For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
	75	* of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
	76	* with x86_64 obviously do not need such care.
	77	*/
c76fc982	78	#define __X32_COMPAT_SYS_STUBx(x, name, ...) \
5ac9efa3 DB	79	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\
	80	ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO); \
	81	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\
ebeb8c82	82	{ \
5ac9efa3	83	return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
ebeb8c82 DB	84	} \
	85
	86	#else /* CONFIG_X86_X32 */
c76fc982	87	#define __X32_COMPAT_SYS_STUBx(x, name, ...)
ebeb8c82 DB	88	#endif /* CONFIG_X86_X32 */
	89
	90
	91	#ifdef CONFIG_COMPAT
	92	/*
	93	* Compat means IA32_EMULATION and/or X86_X32. As they use a different
	94	* mapping of registers to parameters, we need to generate stubs for each
d5a00528	95	* of them.
ebeb8c82	96	*/
5ac9efa3 DB	97	#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
	98	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
	99	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
c76fc982 DB	100	__IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
c76fc982 DB	101	__X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
5ac9efa3 DB	102	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
	103	{ \
	104	return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
	105	} \
	106	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
ebeb8c82 DB	107
	108	/*
	109	* As some compat syscalls may not be implemented, we need to expand
	110	* COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in
	111	* kernel/time/posix-stubs.c to cover this case as well.
	112	*/
	113	#define COND_SYSCALL_COMPAT(name) \
5ac9efa3 DB	114	cond_syscall(__ia32_compat_sys_##name); \
5ac9efa3 DB	115	cond_syscall(__x32_compat_sys_##name)
ebeb8c82 DB	116
ebeb8c82 DB	117	#define COMPAT_SYS_NI(name) \
5ac9efa3 DB	118	SYSCALL_ALIAS(__ia32_compat_sys_##name, sys_ni_posix_timers); \
5ac9efa3 DB	119	SYSCALL_ALIAS(__x32_compat_sys_##name, sys_ni_posix_timers)
ebeb8c82 DB	120
	121	#endif /* CONFIG_COMPAT */
	122
	123
fa697140 DB	124	/*
	125	* Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes
	126	* struct pt_regs *regs as the only argument of the syscall stub named
d5a00528	127	* __x64_sys_*(). It decodes just the registers it needs and passes them on to
e145242e DB	128	* the __se_sys_*() wrapper performing sign extension and then to the
	129	* __do_sys_*() function doing the actual job. These wrappers and functions
	130	* are inlined (at least in very most cases), meaning that the assembly looks
	131	* as follows (slightly re-ordered for better readability):
fa697140	132	*
d5a00528	133	* <__x64_sys_recv>: <-- syscall with 4 parameters
fa697140 DB	134	* callq <__fentry__>
	135	*
	136	* mov 0x70(%rdi),%rdi <-- decode regs->di
	137	* mov 0x68(%rdi),%rsi <-- decode regs->si
	138	* mov 0x60(%rdi),%rdx <-- decode regs->dx
	139	* mov 0x38(%rdi),%rcx <-- decode regs->r10
	140	*
	141	* xor %r9d,%r9d <-- clear %r9
	142	* xor %r8d,%r8d <-- clear %r8
	143	*
	144	* callq __sys_recvfrom <-- do the actual work in __sys_recvfrom()
	145	* which takes 6 arguments
	146	*
	147	* cltq <-- extend return value to 64-bit
	148	* retq <-- return
	149	*
	150	* This approach avoids leaking random user-provided register content down
	151	* the call chain.
	152	*
ebeb8c82	153	* If IA32_EMULATION is enabled, this macro generates an additional wrapper
e145242e	154	* named __ia32_sys_() which decodes the struct pt_regs regs according
ebeb8c82	155	* to the i386 calling convention (bx, cx, dx, si, di, bp).
fa697140 DB	156	*/
fa697140 DB	157	#define __SYSCALL_DEFINEx(x, name, ...) \
d5a00528 DB	158	asmlinkage long __x64_sys##name(const struct pt_regs *regs); \
d5a00528 DB	159	ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO); \
e145242e DB	160	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
e145242e DB	161	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
d5a00528	162	asmlinkage long __x64_sys##name(const struct pt_regs *regs) \
fa697140	163	{ \
e145242e	164	return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
fa697140	165	} \
c76fc982	166	__IA32_SYS_STUBx(x, name, __VA_ARGS__) \
e145242e	167	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
fa697140	168	{ \
e145242e	169	long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
fa697140 DB	170	__MAP(x,__SC_TEST,__VA_ARGS__); \
	171	__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
	172	return ret; \
	173	} \
e145242e	174	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
fa697140	175
d5a00528 DB	176	/*
	177	* As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
	178	* obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
	179	* hurt, we only need to re-define it here to keep the naming congruent to
	180	* SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI()
	181	* macros to work correctly.
	182	*/
	183	#ifndef SYSCALL_DEFINE0
	184	#define SYSCALL_DEFINE0(sname) \
	185	SYSCALL_METADATA(_##sname, 0); \
	186	asmlinkage long __x64_sys_##sname(void); \
	187	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \
	188	asmlinkage long __x64_sys_##sname(void)
	189	#endif
	190
	191	#ifndef COND_SYSCALL
	192	#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name)
	193	#endif
	194
	195	#ifndef SYS_NI
	196	#define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);
	197	#endif
	198
	199
fa697140 DB	200	/*
	201	* For VSYSCALLS, we need to declare these three syscalls with the new
	202	* pt_regs-based calling convention for in-kernel use.
	203	*/
	204	struct pt_regs;
d5a00528 DB	205	asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
	206	asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
	207	asmlinkage long __x64_sys_time(const struct pt_regs *regs);
fa697140 DB	208
fa697140 DB	209	#endif /* _ASM_X86_SYSCALL_WRAPPER_H */