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 9struct pt_regs; 10 11extern long __x64_sys_ni_syscall(const struct pt_regs *regs); 12extern long __ia32_sys_ni_syscall(const struct pt_regs *regs); 13 14/* 15 * Instead of the generic __SYSCALL_DEFINEx() definition, the x86 version takes 16 * struct pt_regs *regs as the only argument of the syscall stub(s) named as: 17 * __x64_sys_*() - 64-bit native syscall 18 * __ia32_sys_*() - 32-bit native syscall or common compat syscall 19 * __ia32_compat_sys_*() - 32-bit compat syscall 20 * __x32_compat_sys_*() - 64-bit X32 compat syscall 21 * 22 * The registers are decoded according to the ABI: 23 * 64-bit: RDI, RSI, RDX, R10, R8, R9 24 * 32-bit: EBX, ECX, EDX, ESI, EDI, EBP 25 * 26 * The stub then passes the decoded arguments to the __se_sys_*() wrapper to 27 * perform sign-extension (omitted for zero-argument syscalls). Finally the 28 * arguments are passed to the __do_sys_*() function which is the actual 29 * syscall. These wrappers are marked as inline so the compiler can optimize 30 * the functions where appropriate. 31 * 32 * Example assembly (slightly re-ordered for better readability): 33 * 34 * <__x64_sys_recv>: <-- syscall with 4 parameters 35 * callq <__fentry__> 36 * 37 * mov 0x70(%rdi),%rdi <-- decode regs->di 38 * mov 0x68(%rdi),%rsi <-- decode regs->si 39 * mov 0x60(%rdi),%rdx <-- decode regs->dx 40 * mov 0x38(%rdi),%rcx <-- decode regs->r10 41 * 42 * xor %r9d,%r9d <-- clear %r9 43 * xor %r8d,%r8d <-- clear %r8 44 * 45 * callq __sys_recvfrom <-- do the actual work in __sys_recvfrom() 46 * which takes 6 arguments 47 * 48 * cltq <-- extend return value to 64-bit 49 * retq <-- return 50 * 51 * This approach avoids leaking random user-provided register content down 52 * the call chain. 53 */ 54 55/* Mapping of registers to parameters for syscalls on x86-64 and x32 */ 56#define SC_X86_64_REGS_TO_ARGS(x, ...) \ 57 __MAP(x,__SC_ARGS \ 58 ,,regs->di,,regs->si,,regs->dx \ 59 ,,regs->r10,,regs->r8,,regs->r9) \ 60 61 62/* SYSCALL_PT_ARGS is Adapted from s390x */ 63#define SYSCALL_PT_ARG6(m, t1, t2, t3, t4, t5, t6) \ 64 SYSCALL_PT_ARG5(m, t1, t2, t3, t4, t5), m(t6, (regs->bp)) 65#define SYSCALL_PT_ARG5(m, t1, t2, t3, t4, t5) \ 66 SYSCALL_PT_ARG4(m, t1, t2, t3, t4), m(t5, (regs->di)) 67#define SYSCALL_PT_ARG4(m, t1, t2, t3, t4) \ 68 SYSCALL_PT_ARG3(m, t1, t2, t3), m(t4, (regs->si)) 69#define SYSCALL_PT_ARG3(m, t1, t2, t3) \ 70 SYSCALL_PT_ARG2(m, t1, t2), m(t3, (regs->dx)) 71#define SYSCALL_PT_ARG2(m, t1, t2) \ 72 SYSCALL_PT_ARG1(m, t1), m(t2, (regs->cx)) 73#define SYSCALL_PT_ARG1(m, t1) m(t1, (regs->bx)) 74#define SYSCALL_PT_ARGS(x, ...) SYSCALL_PT_ARG##x(__VA_ARGS__) 75 76#define __SC_COMPAT_CAST(t, a) \ 77 (__typeof(__builtin_choose_expr(__TYPE_IS_L(t), 0, 0U))) \ 78 (unsigned int)a 79 80/* Mapping of registers to parameters for syscalls on i386 */ 81#define SC_IA32_REGS_TO_ARGS(x, ...) \ 82 SYSCALL_PT_ARGS(x, __SC_COMPAT_CAST, \ 83 __MAP(x, __SC_TYPE, __VA_ARGS__)) \ 84 85#define __SYS_STUB0(abi, name) \ 86 long __##abi##_##name(const struct pt_regs *regs); \ 87 ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \ 88 long __##abi##_##name(const struct pt_regs *regs) \ 89 __alias(__do_##name); 90 91#define __SYS_STUBx(abi, name, ...) \ 92 long __##abi##_##name(const struct pt_regs *regs); \ 93 ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \ 94 long __##abi##_##name(const struct pt_regs *regs) \ 95 { \ 96 return __se_##name(__VA_ARGS__); \ 97 } 98 99#define __COND_SYSCALL(abi, name) \ 100 __weak long __##abi##_##name(const struct pt_regs *__unused) \ 101 { \ 102 return sys_ni_syscall(); \ 103 } 104 105#define __SYS_NI(abi, name) \ 106 SYSCALL_ALIAS(__##abi##_##name, sys_ni_posix_timers); 107 108#ifdef CONFIG_X86_64 109#define __X64_SYS_STUB0(name) \ 110 __SYS_STUB0(x64, sys_##name) 111 112#define __X64_SYS_STUBx(x, name, ...) \ 113 __SYS_STUBx(x64, sys##name, \ 114 SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__)) 115 116#define __X64_COND_SYSCALL(name) \ 117 __COND_SYSCALL(x64, sys_##name) 118 119#define __X64_SYS_NI(name) \ 120 __SYS_NI(x64, sys_##name) 121#else /* CONFIG_X86_64 */ 122#define __X64_SYS_STUB0(name) 123#define __X64_SYS_STUBx(x, name, ...) 124#define __X64_COND_SYSCALL(name) 125#define __X64_SYS_NI(name) 126#endif /* CONFIG_X86_64 */ 127 128#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) 129#define __IA32_SYS_STUB0(name) \ 130 __SYS_STUB0(ia32, sys_##name) 131 132#define __IA32_SYS_STUBx(x, name, ...) \ 133 __SYS_STUBx(ia32, sys##name, \ 134 SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__)) 135 136#define __IA32_COND_SYSCALL(name) \ 137 __COND_SYSCALL(ia32, sys_##name) 138 139#define __IA32_SYS_NI(name) \ 140 __SYS_NI(ia32, sys_##name) 141#else /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */ 142#define __IA32_SYS_STUB0(name) 143#define __IA32_SYS_STUBx(x, name, ...) 144#define __IA32_COND_SYSCALL(name) 145#define __IA32_SYS_NI(name) 146#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */ 147 148#ifdef CONFIG_IA32_EMULATION 149/* 150 * For IA32 emulation, we need to handle "compat" syscalls *and* create 151 * additional wrappers (aptly named __ia32_sys_xyzzy) which decode the 152 * ia32 regs in the proper order for shared or "common" syscalls. As some 153 * syscalls may not be implemented, we need to expand COND_SYSCALL in 154 * kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this 155 * case as well. 156 */ 157#define __IA32_COMPAT_SYS_STUB0(name) \ 158 __SYS_STUB0(ia32, compat_sys_##name) 159 160#define __IA32_COMPAT_SYS_STUBx(x, name, ...) \ 161 __SYS_STUBx(ia32, compat_sys##name, \ 162 SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__)) 163 164#define __IA32_COMPAT_COND_SYSCALL(name) \ 165 __COND_SYSCALL(ia32, compat_sys_##name) 166 167#define __IA32_COMPAT_SYS_NI(name) \ 168 __SYS_NI(ia32, compat_sys_##name) 169 170#else /* CONFIG_IA32_EMULATION */ 171#define __IA32_COMPAT_SYS_STUB0(name) 172#define __IA32_COMPAT_SYS_STUBx(x, name, ...) 173#define __IA32_COMPAT_COND_SYSCALL(name) 174#define __IA32_COMPAT_SYS_NI(name) 175#endif /* CONFIG_IA32_EMULATION */ 176 177 178#ifdef CONFIG_X86_X32 179/* 180 * For the x32 ABI, we need to create a stub for compat_sys_*() which is aware 181 * of the x86-64-style parameter ordering of x32 syscalls. The syscalls common 182 * with x86_64 obviously do not need such care. 183 */ 184#define __X32_COMPAT_SYS_STUB0(name) \ 185 __SYS_STUB0(x32, compat_sys_##name) 186 187#define __X32_COMPAT_SYS_STUBx(x, name, ...) \ 188 __SYS_STUBx(x32, compat_sys##name, \ 189 SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__)) 190 191#define __X32_COMPAT_COND_SYSCALL(name) \ 192 __COND_SYSCALL(x32, compat_sys_##name) 193 194#define __X32_COMPAT_SYS_NI(name) \ 195 __SYS_NI(x32, compat_sys_##name) 196#else /* CONFIG_X86_X32 */ 197#define __X32_COMPAT_SYS_STUB0(name) 198#define __X32_COMPAT_SYS_STUBx(x, name, ...) 199#define __X32_COMPAT_COND_SYSCALL(name) 200#define __X32_COMPAT_SYS_NI(name) 201#endif /* CONFIG_X86_X32 */ 202 203 204#ifdef CONFIG_COMPAT 205/* 206 * Compat means IA32_EMULATION and/or X86_X32. As they use a different 207 * mapping of registers to parameters, we need to generate stubs for each 208 * of them. 209 */ 210#define COMPAT_SYSCALL_DEFINE0(name) \ 211 static long \ 212 __do_compat_sys_##name(const struct pt_regs *__unused); \ 213 __IA32_COMPAT_SYS_STUB0(name) \ 214 __X32_COMPAT_SYS_STUB0(name) \ 215 static long \ 216 __do_compat_sys_##name(const struct pt_regs *__unused) 217 218#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \ 219 static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ 220 static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ 221 __IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \ 222 __X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \ 223 static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ 224 { \ 225 return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\ 226 } \ 227 static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) 228 229/* 230 * As some compat syscalls may not be implemented, we need to expand 231 * COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in 232 * kernel/time/posix-stubs.c to cover this case as well. 233 */ 234#define COND_SYSCALL_COMPAT(name) \ 235 __IA32_COMPAT_COND_SYSCALL(name) \ 236 __X32_COMPAT_COND_SYSCALL(name) 237 238#define COMPAT_SYS_NI(name) \ 239 __IA32_COMPAT_SYS_NI(name) \ 240 __X32_COMPAT_SYS_NI(name) 241 242#endif /* CONFIG_COMPAT */ 243 244#define __SYSCALL_DEFINEx(x, name, ...) \ 245 static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ 246 static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ 247 __X64_SYS_STUBx(x, name, __VA_ARGS__) \ 248 __IA32_SYS_STUBx(x, name, __VA_ARGS__) \ 249 static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ 250 { \ 251 long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\ 252 __MAP(x,__SC_TEST,__VA_ARGS__); \ 253 __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ 254 return ret; \ 255 } \ 256 static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) 257 258/* 259 * As the generic SYSCALL_DEFINE0() macro does not decode any parameters for 260 * obvious reasons, and passing struct pt_regs *regs to it in %rdi does not 261 * hurt, we only need to re-define it here to keep the naming congruent to 262 * SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI() 263 * macros to work correctly. 264 */ 265#define SYSCALL_DEFINE0(sname) \ 266 SYSCALL_METADATA(_##sname, 0); \ 267 static long __do_sys_##sname(const struct pt_regs *__unused); \ 268 __X64_SYS_STUB0(sname) \ 269 __IA32_SYS_STUB0(sname) \ 270 static long __do_sys_##sname(const struct pt_regs *__unused) 271 272#define COND_SYSCALL(name) \ 273 __X64_COND_SYSCALL(name) \ 274 __IA32_COND_SYSCALL(name) 275 276#define SYS_NI(name) \ 277 __X64_SYS_NI(name) \ 278 __IA32_SYS_NI(name) 279 280 281/* 282 * For VSYSCALLS, we need to declare these three syscalls with the new 283 * pt_regs-based calling convention for in-kernel use. 284 */ 285long __x64_sys_getcpu(const struct pt_regs *regs); 286long __x64_sys_gettimeofday(const struct pt_regs *regs); 287long __x64_sys_time(const struct pt_regs *regs); 288 289#endif /* _ASM_X86_SYSCALL_WRAPPER_H */ 290