Release 4.18 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 */
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Dominik Brodowski | 257 | 100.00% | 6 | 100.00% |
| Total | 257 | 100.00% | 6 | 100.00% |
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