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/* 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;
extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
/*
* Instead of the generic __SYSCALL_DEFINEx() definition, the x86 version takes
* struct pt_regs *regs as the only argument of the syscall stub(s) named as:
* __x64_sys_*() - 64-bit native syscall
* __ia32_sys_*() - 32-bit native syscall or common compat syscall
* __ia32_compat_sys_*() - 32-bit compat syscall
* __x32_compat_sys_*() - 64-bit X32 compat syscall
*
* The registers are decoded according to the ABI:
* 64-bit: RDI, RSI, RDX, R10, R8, R9
* 32-bit: EBX, ECX, EDX, ESI, EDI, EBP
*
* The stub then passes the decoded arguments to the __se_sys_*() wrapper to
* perform sign-extension (omitted for zero-argument syscalls). Finally the
* arguments are passed to the __do_sys_*() function which is the actual
* syscall. These wrappers are marked as inline so the compiler can optimize
* the functions where appropriate.
*
* Example assembly (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.
*/
/* 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)
#define __SYS_STUB0(abi, name) \
long __##abi##_##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \
long __##abi##_##name(const struct pt_regs *regs) \
__alias(__do_##name);
#define __SYS_STUBx(abi, name, ...) \
long __##abi##_##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \
long __##abi##_##name(const struct pt_regs *regs) \
{ \
return __se_##name(__VA_ARGS__); \
}
#define __COND_SYSCALL(abi, name) \
__weak long __##abi##_##name(const struct pt_regs *__unused) \
{ \
return sys_ni_syscall(); \
}
#define __SYS_NI(abi, name) \
SYSCALL_ALIAS(__##abi##_##name, sys_ni_posix_timers);
#ifdef CONFIG_X86_64
#define __X64_SYS_STUB0(name) \
__SYS_STUB0(x64, sys_##name)
#define __X64_SYS_STUBx(x, name, ...) \
__SYS_STUBx(x64, sys##name, \
SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
#define __X64_COND_SYSCALL(name) \
__COND_SYSCALL(x64, sys_##name)
#define __X64_SYS_NI(name) \
__SYS_NI(x64, sys_##name)
#else /* CONFIG_X86_64 */
#define __X64_SYS_STUB0(name)
#define __X64_SYS_STUBx(x, name, ...)
#define __X64_COND_SYSCALL(name)
#define __X64_SYS_NI(name)
#endif /* CONFIG_X86_64 */
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
#define __IA32_SYS_STUB0(name) \
__SYS_STUB0(ia32, sys_##name)
#define __IA32_SYS_STUBx(x, name, ...) \
__SYS_STUBx(ia32, sys##name, \
SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
#define __IA32_COND_SYSCALL(name) \
__COND_SYSCALL(ia32, sys_##name)
#define __IA32_SYS_NI(name) \
__SYS_NI(ia32, sys_##name)
#else /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
#define __IA32_SYS_STUB0(name)
#define __IA32_SYS_STUBx(x, name, ...)
#define __IA32_COND_SYSCALL(name)
#define __IA32_SYS_NI(name)
#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
#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(name) \
__SYS_STUB0(ia32, compat_sys_##name)
#define __IA32_COMPAT_SYS_STUBx(x, name, ...) \
__SYS_STUBx(ia32, compat_sys##name, \
SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
#define __IA32_COMPAT_COND_SYSCALL(name) \
__COND_SYSCALL(ia32, compat_sys_##name)
#define __IA32_COMPAT_SYS_NI(name) \
__SYS_NI(ia32, compat_sys_##name)
#else /* CONFIG_IA32_EMULATION */
#define __IA32_COMPAT_SYS_STUB0(name)
#define __IA32_COMPAT_SYS_STUBx(x, name, ...)
#define __IA32_COMPAT_COND_SYSCALL(name)
#define __IA32_COMPAT_SYS_NI(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(name) \
__SYS_STUB0(x32, compat_sys_##name)
#define __X32_COMPAT_SYS_STUBx(x, name, ...) \
__SYS_STUBx(x32, compat_sys##name, \
SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
#define __X32_COMPAT_COND_SYSCALL(name) \
__COND_SYSCALL(x32, compat_sys_##name)
#define __X32_COMPAT_SYS_NI(name) \
__SYS_NI(x32, compat_sys_##name)
#else /* CONFIG_X86_X32 */
#define __X32_COMPAT_SYS_STUB0(name)
#define __X32_COMPAT_SYS_STUBx(x, name, ...)
#define __X32_COMPAT_COND_SYSCALL(name)
#define __X32_COMPAT_SYS_NI(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 \
__do_compat_sys_##name(const struct pt_regs *__unused); \
__IA32_COMPAT_SYS_STUB0(name) \
__X32_COMPAT_SYS_STUB0(name) \
static long \
__do_compat_sys_##name(const struct pt_regs *__unused)
#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) \
__IA32_COMPAT_COND_SYSCALL(name) \
__X32_COMPAT_COND_SYSCALL(name)
#define COMPAT_SYS_NI(name) \
__IA32_COMPAT_SYS_NI(name) \
__X32_COMPAT_SYS_NI(name)
#endif /* CONFIG_COMPAT */
#define __SYSCALL_DEFINEx(x, name, ...) \
static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
__X64_SYS_STUBx(x, name, __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.
*/
#define SYSCALL_DEFINE0(sname) \
SYSCALL_METADATA(_##sname, 0); \
static long __do_sys_##sname(const struct pt_regs *__unused); \
__X64_SYS_STUB0(sname) \
__IA32_SYS_STUB0(sname) \
static long __do_sys_##sname(const struct pt_regs *__unused)
#define COND_SYSCALL(name) \
__X64_COND_SYSCALL(name) \
__IA32_COND_SYSCALL(name)
#define SYS_NI(name) \
__X64_SYS_NI(name) \
__IA32_SYS_NI(name)
/*
* For VSYSCALLS, we need to declare these three syscalls with the new
* pt_regs-based calling convention for in-kernel use.
*/
long __x64_sys_getcpu(const struct pt_regs *regs);
long __x64_sys_gettimeofday(const struct pt_regs *regs);
long __x64_sys_time(const struct pt_regs *regs);
#endif /* _ASM_X86_SYSCALL_WRAPPER_H */
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