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Edit File: 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 #include <asm/ptrace.h> 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 * __x64_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) \ /* SYSCALL_PT_ARGS is Adapted from s390x */ #define SYSCALL_PT_ARG6(m, t1, t2, t3, t4, t5, t6) \ SYSCALL_PT_ARG5(m, t1, t2, t3, t4, t5), m(t6, (regs->bp)) #define SYSCALL_PT_ARG5(m, t1, t2, t3, t4, t5) \ SYSCALL_PT_ARG4(m, t1, t2, t3, t4), m(t5, (regs->di)) #define SYSCALL_PT_ARG4(m, t1, t2, t3, t4) \ SYSCALL_PT_ARG3(m, t1, t2, t3), m(t4, (regs->si)) #define SYSCALL_PT_ARG3(m, t1, t2, t3) \ SYSCALL_PT_ARG2(m, t1, t2), m(t3, (regs->dx)) #define SYSCALL_PT_ARG2(m, t1, t2) \ SYSCALL_PT_ARG1(m, t1), m(t2, (regs->cx)) #define SYSCALL_PT_ARG1(m, t1) m(t1, (regs->bx)) #define SYSCALL_PT_ARGS(x, ...) SYSCALL_PT_ARG##x(__VA_ARGS__) #define __SC_COMPAT_CAST(t, a) \ (__typeof(__builtin_choose_expr(__TYPE_IS_L(t), 0, 0U))) \ (unsigned int)a /* Mapping of registers to parameters for syscalls on i386 */ #define SC_IA32_REGS_TO_ARGS(x, ...) \ SYSCALL_PT_ARGS(x, __SC_COMPAT_CAST, \ __MAP(x, __SC_TYPE, __VA_ARGS__)) \ #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); \ __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(x64, compat_sys_##name) #define __X32_COMPAT_SYS_STUBx(x, name, ...) \ __SYS_STUBx(x64, compat_sys##name, \ SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__)) #define __X32_COMPAT_COND_SYSCALL(name) \ __COND_SYSCALL(x64, compat_sys_##name) #define __X32_COMPAT_SYS_NI(name) \ __SYS_NI(x64, 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 */