1fa697140SDominik Brodowski /* SPDX-License-Identifier: GPL-2.0 */ 2fa697140SDominik Brodowski /* 3fa697140SDominik Brodowski * syscall_wrapper.h - x86 specific wrappers to syscall definitions 4fa697140SDominik Brodowski */ 5fa697140SDominik Brodowski 6fa697140SDominik Brodowski #ifndef _ASM_X86_SYSCALL_WRAPPER_H 7fa697140SDominik Brodowski #define _ASM_X86_SYSCALL_WRAPPER_H 8fa697140SDominik Brodowski 9ebeb8c82SDominik Brodowski /* Mapping of registers to parameters for syscalls on x86-64 and x32 */ 10ebeb8c82SDominik Brodowski #define SC_X86_64_REGS_TO_ARGS(x, ...) \ 11ebeb8c82SDominik Brodowski __MAP(x,__SC_ARGS \ 12ebeb8c82SDominik Brodowski ,,regs->di,,regs->si,,regs->dx \ 13ebeb8c82SDominik Brodowski ,,regs->r10,,regs->r8,,regs->r9) \ 14ebeb8c82SDominik Brodowski 15ebeb8c82SDominik Brodowski /* Mapping of registers to parameters for syscalls on i386 */ 16ebeb8c82SDominik Brodowski #define SC_IA32_REGS_TO_ARGS(x, ...) \ 17ebeb8c82SDominik Brodowski __MAP(x,__SC_ARGS \ 18ebeb8c82SDominik Brodowski ,,(unsigned int)regs->bx,,(unsigned int)regs->cx \ 19ebeb8c82SDominik Brodowski ,,(unsigned int)regs->dx,,(unsigned int)regs->si \ 20ebeb8c82SDominik Brodowski ,,(unsigned int)regs->di,,(unsigned int)regs->bp) 21ebeb8c82SDominik Brodowski 22ebeb8c82SDominik Brodowski #ifdef CONFIG_IA32_EMULATION 23ebeb8c82SDominik Brodowski /* 24ebeb8c82SDominik Brodowski * For IA32 emulation, we need to handle "compat" syscalls *and* create 25ebeb8c82SDominik Brodowski * additional wrappers (aptly named __sys_ia32_sys_xyzzy) which decode the 26ebeb8c82SDominik Brodowski * ia32 regs in the proper order for shared or "common" syscalls. As some 27ebeb8c82SDominik Brodowski * syscalls may not be implemented, we need to expand COND_SYSCALL in 28ebeb8c82SDominik Brodowski * kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this 29ebeb8c82SDominik Brodowski * case as well. 30ebeb8c82SDominik Brodowski */ 31ebeb8c82SDominik Brodowski #define COMPAT_SC_IA32_STUBx(x, name, ...) \ 32ebeb8c82SDominik Brodowski asmlinkage long __compat_sys_ia32##name(const struct pt_regs *regs);\ 33ebeb8c82SDominik Brodowski ALLOW_ERROR_INJECTION(__compat_sys_ia32##name, ERRNO); \ 34ebeb8c82SDominik Brodowski asmlinkage long __compat_sys_ia32##name(const struct pt_regs *regs)\ 35ebeb8c82SDominik Brodowski { \ 36ebeb8c82SDominik Brodowski return c_SyS##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\ 37ebeb8c82SDominik Brodowski } \ 38ebeb8c82SDominik Brodowski 39ebeb8c82SDominik Brodowski #define SC_IA32_WRAPPERx(x, name, ...) \ 40ebeb8c82SDominik Brodowski asmlinkage long __sys_ia32##name(const struct pt_regs *regs); \ 41ebeb8c82SDominik Brodowski ALLOW_ERROR_INJECTION(__sys_ia32##name, ERRNO); \ 42ebeb8c82SDominik Brodowski asmlinkage long __sys_ia32##name(const struct pt_regs *regs) \ 43ebeb8c82SDominik Brodowski { \ 44ebeb8c82SDominik Brodowski return SyS##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__)); \ 45ebeb8c82SDominik Brodowski } 46ebeb8c82SDominik Brodowski 47ebeb8c82SDominik Brodowski #define COND_SYSCALL(name) \ 48ebeb8c82SDominik Brodowski cond_syscall(sys_##name); \ 49ebeb8c82SDominik Brodowski cond_syscall(__sys_ia32_##name) 50ebeb8c82SDominik Brodowski 51ebeb8c82SDominik Brodowski #define SYS_NI(name) \ 52ebeb8c82SDominik Brodowski SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers); \ 53ebeb8c82SDominik Brodowski SYSCALL_ALIAS(__sys_ia32_##name, sys_ni_posix_timers) 54ebeb8c82SDominik Brodowski 55ebeb8c82SDominik Brodowski #else /* CONFIG_IA32_EMULATION */ 56ebeb8c82SDominik Brodowski #define COMPAT_SC_IA32_STUBx(x, name, ...) 57ebeb8c82SDominik Brodowski #define SC_IA32_WRAPPERx(x, fullname, name, ...) 58ebeb8c82SDominik Brodowski #endif /* CONFIG_IA32_EMULATION */ 59ebeb8c82SDominik Brodowski 60ebeb8c82SDominik Brodowski 61ebeb8c82SDominik Brodowski #ifdef CONFIG_X86_X32 62ebeb8c82SDominik Brodowski /* 63ebeb8c82SDominik Brodowski * For the x32 ABI, we need to create a stub for compat_sys_*() which is aware 64ebeb8c82SDominik Brodowski * of the x86-64-style parameter ordering of x32 syscalls. The syscalls common 65ebeb8c82SDominik Brodowski * with x86_64 obviously do not need such care. 66ebeb8c82SDominik Brodowski */ 67ebeb8c82SDominik Brodowski #define COMPAT_SC_X32_STUBx(x, name, ...) \ 68ebeb8c82SDominik Brodowski asmlinkage long __compat_sys_x32##name(const struct pt_regs *regs);\ 69ebeb8c82SDominik Brodowski ALLOW_ERROR_INJECTION(__compat_sys_x32##name, ERRNO); \ 70ebeb8c82SDominik Brodowski asmlinkage long __compat_sys_x32##name(const struct pt_regs *regs)\ 71ebeb8c82SDominik Brodowski { \ 72ebeb8c82SDominik Brodowski return c_SyS##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\ 73ebeb8c82SDominik Brodowski } \ 74ebeb8c82SDominik Brodowski 75ebeb8c82SDominik Brodowski #else /* CONFIG_X86_X32 */ 76ebeb8c82SDominik Brodowski #define COMPAT_SC_X32_STUBx(x, name, ...) 77ebeb8c82SDominik Brodowski #endif /* CONFIG_X86_X32 */ 78ebeb8c82SDominik Brodowski 79ebeb8c82SDominik Brodowski 80ebeb8c82SDominik Brodowski #ifdef CONFIG_COMPAT 81ebeb8c82SDominik Brodowski /* 82ebeb8c82SDominik Brodowski * Compat means IA32_EMULATION and/or X86_X32. As they use a different 83ebeb8c82SDominik Brodowski * mapping of registers to parameters, we need to generate stubs for each 84ebeb8c82SDominik Brodowski * of them. There is no need to implement COMPAT_SYSCALL_DEFINE0, as it is 85ebeb8c82SDominik Brodowski * unused on x86. 86ebeb8c82SDominik Brodowski */ 87ebeb8c82SDominik Brodowski #define COMPAT_SYSCALL_DEFINEx(x, name, ...) \ 88ebeb8c82SDominik Brodowski static long c_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ 89ebeb8c82SDominik Brodowski static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ 90ebeb8c82SDominik Brodowski COMPAT_SC_IA32_STUBx(x, name, __VA_ARGS__) \ 91ebeb8c82SDominik Brodowski COMPAT_SC_X32_STUBx(x, name, __VA_ARGS__) \ 92ebeb8c82SDominik Brodowski static long c_SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ 93ebeb8c82SDominik Brodowski { \ 94ebeb8c82SDominik Brodowski return C_SYSC##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \ 95ebeb8c82SDominik Brodowski } \ 96ebeb8c82SDominik Brodowski static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) 97ebeb8c82SDominik Brodowski 98ebeb8c82SDominik Brodowski /* 99ebeb8c82SDominik Brodowski * As some compat syscalls may not be implemented, we need to expand 100ebeb8c82SDominik Brodowski * COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in 101ebeb8c82SDominik Brodowski * kernel/time/posix-stubs.c to cover this case as well. 102ebeb8c82SDominik Brodowski */ 103ebeb8c82SDominik Brodowski #define COND_SYSCALL_COMPAT(name) \ 104ebeb8c82SDominik Brodowski cond_syscall(__compat_sys_ia32_##name); \ 105ebeb8c82SDominik Brodowski cond_syscall(__compat_sys_x32_##name) 106ebeb8c82SDominik Brodowski 107ebeb8c82SDominik Brodowski #define COMPAT_SYS_NI(name) \ 108ebeb8c82SDominik Brodowski SYSCALL_ALIAS(__compat_sys_ia32_##name, sys_ni_posix_timers); \ 109ebeb8c82SDominik Brodowski SYSCALL_ALIAS(__compat_sys_x32_##name, sys_ni_posix_timers) 110ebeb8c82SDominik Brodowski 111ebeb8c82SDominik Brodowski #endif /* CONFIG_COMPAT */ 112ebeb8c82SDominik Brodowski 113ebeb8c82SDominik Brodowski 114fa697140SDominik Brodowski /* 115fa697140SDominik Brodowski * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes 116fa697140SDominik Brodowski * struct pt_regs *regs as the only argument of the syscall stub named 117fa697140SDominik Brodowski * sys_*(). It decodes just the registers it needs and passes them on to 118fa697140SDominik Brodowski * the SyS_*() wrapper and then to the SYSC_*() function doing the actual job. 119fa697140SDominik Brodowski * These wrappers and functions are inlined, meaning that the assembly looks 120fa697140SDominik Brodowski * as follows (slightly re-ordered): 121fa697140SDominik Brodowski * 122fa697140SDominik Brodowski * <sys_recv>: <-- syscall with 4 parameters 123fa697140SDominik Brodowski * callq <__fentry__> 124fa697140SDominik Brodowski * 125fa697140SDominik Brodowski * mov 0x70(%rdi),%rdi <-- decode regs->di 126fa697140SDominik Brodowski * mov 0x68(%rdi),%rsi <-- decode regs->si 127fa697140SDominik Brodowski * mov 0x60(%rdi),%rdx <-- decode regs->dx 128fa697140SDominik Brodowski * mov 0x38(%rdi),%rcx <-- decode regs->r10 129fa697140SDominik Brodowski * 130fa697140SDominik Brodowski * xor %r9d,%r9d <-- clear %r9 131fa697140SDominik Brodowski * xor %r8d,%r8d <-- clear %r8 132fa697140SDominik Brodowski * 133fa697140SDominik Brodowski * callq __sys_recvfrom <-- do the actual work in __sys_recvfrom() 134fa697140SDominik Brodowski * which takes 6 arguments 135fa697140SDominik Brodowski * 136fa697140SDominik Brodowski * cltq <-- extend return value to 64-bit 137fa697140SDominik Brodowski * retq <-- return 138fa697140SDominik Brodowski * 139fa697140SDominik Brodowski * This approach avoids leaking random user-provided register content down 140fa697140SDominik Brodowski * the call chain. 141fa697140SDominik Brodowski * 142ebeb8c82SDominik Brodowski * If IA32_EMULATION is enabled, this macro generates an additional wrapper 143ebeb8c82SDominik Brodowski * named __sys_ia32_*() which decodes the struct pt_regs *regs according 144ebeb8c82SDominik Brodowski * to the i386 calling convention (bx, cx, dx, si, di, bp). 145ebeb8c82SDominik Brodowski * 146fa697140SDominik Brodowski * As the generic SYSCALL_DEFINE0() macro does not decode any parameters for 147fa697140SDominik Brodowski * obvious reasons, and passing struct pt_regs *regs to it in %rdi does not 148ebeb8c82SDominik Brodowski * hurt, there is no need to override it, or to define it differently for 149ebeb8c82SDominik Brodowski * IA32_EMULATION. 150fa697140SDominik Brodowski */ 151fa697140SDominik Brodowski #define __SYSCALL_DEFINEx(x, name, ...) \ 152fa697140SDominik Brodowski asmlinkage long sys##name(const struct pt_regs *regs); \ 153fa697140SDominik Brodowski ALLOW_ERROR_INJECTION(sys##name, ERRNO); \ 154fa697140SDominik Brodowski static long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ 155fa697140SDominik Brodowski static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ 156fa697140SDominik Brodowski asmlinkage long sys##name(const struct pt_regs *regs) \ 157fa697140SDominik Brodowski { \ 158ebeb8c82SDominik Brodowski return SyS##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\ 159fa697140SDominik Brodowski } \ 160ebeb8c82SDominik Brodowski SC_IA32_WRAPPERx(x, name, __VA_ARGS__) \ 161fa697140SDominik Brodowski static long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ 162fa697140SDominik Brodowski { \ 163fa697140SDominik Brodowski long ret = SYSC##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \ 164fa697140SDominik Brodowski __MAP(x,__SC_TEST,__VA_ARGS__); \ 165fa697140SDominik Brodowski __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ 166fa697140SDominik Brodowski return ret; \ 167fa697140SDominik Brodowski } \ 168fa697140SDominik Brodowski static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) 169fa697140SDominik Brodowski 170fa697140SDominik Brodowski /* 171fa697140SDominik Brodowski * For VSYSCALLS, we need to declare these three syscalls with the new 172fa697140SDominik Brodowski * pt_regs-based calling convention for in-kernel use. 173fa697140SDominik Brodowski */ 174fa697140SDominik Brodowski struct pt_regs; 175fa697140SDominik Brodowski asmlinkage long sys_getcpu(const struct pt_regs *regs); /* di,si,dx */ 176fa697140SDominik Brodowski asmlinkage long sys_gettimeofday(const struct pt_regs *regs); /* di,si */ 177fa697140SDominik Brodowski asmlinkage long sys_time(const struct pt_regs *regs); /* di */ 178fa697140SDominik Brodowski 179fa697140SDominik Brodowski #endif /* _ASM_X86_SYSCALL_WRAPPER_H */ 180