x86/include/asm/syscall_wrapper.h

   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
   9 #include <asm/ptrace.h>
  10
  11 extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
  12 extern 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  * __x64_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         __weak long __##abi##_##name(const struct pt_regs *__unused)    \
 102         {                                                               \
 103                 return sys_ni_syscall();                                \
 104         }
 105
 106 #define __SYS_NI(abi, name)                                             \
 107         SYSCALL_ALIAS(__##abi##_##name, sys_ni_posix_timers);
 108
 109 #ifdef CONFIG_X86_64
 110 #define __X64_SYS_STUB0(name)                                           \
 111         __SYS_STUB0(x64, sys_##name)
 112
 113 #define __X64_SYS_STUBx(x, name, ...)                                   \
 114         __SYS_STUBx(x64, sys##name,                                     \
 115                     SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
 116
 117 #define __X64_COND_SYSCALL(name)                                        \
 118         __COND_SYSCALL(x64, sys_##name)
 119
 120 #define __X64_SYS_NI(name)                                              \
 121         __SYS_NI(x64, sys_##name)
 122 #else /* CONFIG_X86_64 */
 123 #define __X64_SYS_STUB0(name)
 124 #define __X64_SYS_STUBx(x, name, ...)
 125 #define __X64_COND_SYSCALL(name)
 126 #define __X64_SYS_NI(name)
 127 #endif /* CONFIG_X86_64 */
 128
 129 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 130 #define __IA32_SYS_STUB0(name)                                          \
 131         __SYS_STUB0(ia32, sys_##name)
 132
 133 #define __IA32_SYS_STUBx(x, name, ...)                                  \
 134         __SYS_STUBx(ia32, sys##name,                                    \
 135                     SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
 136
 137 #define __IA32_COND_SYSCALL(name)                                       \
 138         __COND_SYSCALL(ia32, sys_##name)
 139
 140 #define __IA32_SYS_NI(name)                                             \
 141         __SYS_NI(ia32, sys_##name)
 142 #else /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
 143 #define __IA32_SYS_STUB0(name)
 144 #define __IA32_SYS_STUBx(x, name, ...)
 145 #define __IA32_COND_SYSCALL(name)
 146 #define __IA32_SYS_NI(name)
 147 #endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
 148
 149 #ifdef CONFIG_IA32_EMULATION
 150 /*
 151  * For IA32 emulation, we need to handle "compat" syscalls *and* create
 152  * additional wrappers (aptly named __ia32_sys_xyzzy) which decode the
 153  * ia32 regs in the proper order for shared or "common" syscalls. As some
 154  * syscalls may not be implemented, we need to expand COND_SYSCALL in
 155  * kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this
 156  * case as well.
 157  */
 158 #define __IA32_COMPAT_SYS_STUB0(name)                                   \
 159         __SYS_STUB0(ia32, compat_sys_##name)
 160
 161 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)                           \
 162         __SYS_STUBx(ia32, compat_sys##name,                             \
 163                     SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
 164
 165 #define __IA32_COMPAT_COND_SYSCALL(name)                                \
 166         __COND_SYSCALL(ia32, compat_sys_##name)
 167
 168 #define __IA32_COMPAT_SYS_NI(name)                                      \
 169         __SYS_NI(ia32, compat_sys_##name)
 170
 171 #else /* CONFIG_IA32_EMULATION */
 172 #define __IA32_COMPAT_SYS_STUB0(name)
 173 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)
 174 #define __IA32_COMPAT_COND_SYSCALL(name)
 175 #define __IA32_COMPAT_SYS_NI(name)
 176 #endif /* CONFIG_IA32_EMULATION */
 177
 178
 179 #ifdef CONFIG_X86_X32_ABI
 180 /*
 181  * For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
 182  * of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
 183  * with x86_64 obviously do not need such care.
 184  */
 185 #define __X32_COMPAT_SYS_STUB0(name)                                    \
 186         __SYS_STUB0(x64, compat_sys_##name)
 187
 188 #define __X32_COMPAT_SYS_STUBx(x, name, ...)                            \
 189         __SYS_STUBx(x64, compat_sys##name,                              \
 190                     SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
 191
 192 #define __X32_COMPAT_COND_SYSCALL(name)                                 \
 193         __COND_SYSCALL(x64, compat_sys_##name)
 194
 195 #define __X32_COMPAT_SYS_NI(name)                                       \
 196         __SYS_NI(x64, compat_sys_##name)
 197 #else /* CONFIG_X86_X32_ABI */
 198 #define __X32_COMPAT_SYS_STUB0(name)
 199 #define __X32_COMPAT_SYS_STUBx(x, name, ...)
 200 #define __X32_COMPAT_COND_SYSCALL(name)
 201 #define __X32_COMPAT_SYS_NI(name)
 202 #endif /* CONFIG_X86_X32_ABI */
 203
 204
 205 #ifdef CONFIG_COMPAT
 206 /*
 207  * Compat means IA32_EMULATION and/or X86_X32. As they use a different
 208  * mapping of registers to parameters, we need to generate stubs for each
 209  * of them.
 210  */
 211 #define COMPAT_SYSCALL_DEFINE0(name)                                    \
 212         static long                                                     \
 213         __do_compat_sys_##name(const struct pt_regs *__unused);         \
 214         __IA32_COMPAT_SYS_STUB0(name)                                   \
 215         __X32_COMPAT_SYS_STUB0(name)                                    \
 216         static long                                                     \
 217         __do_compat_sys_##name(const struct pt_regs *__unused)
 218
 219 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)                                    \
 220         static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));      \
 221         static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
 222         __IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__)                           \
 223         __X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__)                            \
 224         static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))       \
 225         {                                                                       \
 226                 return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
 227         }                                                                       \
 228         static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 229
 230 /*
 231  * As some compat syscalls may not be implemented, we need to expand
 232  * COND_SYSCALL_COMPAT in kernel/sys_ni.c and COMPAT_SYS_NI in
 233  * kernel/time/posix-stubs.c to cover this case as well.
 234  */
 235 #define COND_SYSCALL_COMPAT(name)                                       \
 236         __IA32_COMPAT_COND_SYSCALL(name)                                \
 237         __X32_COMPAT_COND_SYSCALL(name)
 238
 239 #define COMPAT_SYS_NI(name)                                             \
 240         __IA32_COMPAT_SYS_NI(name)                                      \
 241         __X32_COMPAT_SYS_NI(name)
 242
 243 #endif /* CONFIG_COMPAT */
 244
 245 #define __SYSCALL_DEFINEx(x, name, ...)                                 \
 246         static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));     \
 247         static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
 248         __X64_SYS_STUBx(x, name, __VA_ARGS__)                           \
 249         __IA32_SYS_STUBx(x, name, __VA_ARGS__)                          \
 250         static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))      \
 251         {                                                               \
 252                 long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
 253                 __MAP(x,__SC_TEST,__VA_ARGS__);                         \
 254                 __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__));       \
 255                 return ret;                                             \
 256         }                                                               \
 257         static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 258
 259 /*
 260  * As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
 261  * obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
 262  * hurt, we only need to re-define it here to keep the naming congruent to
 263  * SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI()
 264  * macros to work correctly.
 265  */
 266 #define SYSCALL_DEFINE0(sname)                                          \
 267         SYSCALL_METADATA(_##sname, 0);                                  \
 268         static long __do_sys_##sname(const struct pt_regs *__unused);   \
 269         __X64_SYS_STUB0(sname)                                          \
 270         __IA32_SYS_STUB0(sname)                                         \
 271         static long __do_sys_##sname(const struct pt_regs *__unused)
 272
 273 #define COND_SYSCALL(name)                                              \
 274         __X64_COND_SYSCALL(name)                                        \
 275         __IA32_COND_SYSCALL(name)
 276
 277 #define SYS_NI(name)                                                    \
 278         __X64_SYS_NI(name)                                              \
 279         __IA32_SYS_NI(name)
 280
 281
 282 /*
 283  * For VSYSCALLS, we need to declare these three syscalls with the new
 284  * pt_regs-based calling convention for in-kernel use.
 285  */
 286 long __x64_sys_getcpu(const struct pt_regs *regs);
 287 long __x64_sys_gettimeofday(const struct pt_regs *regs);
 288 long __x64_sys_time(const struct pt_regs *regs);
 289
 290 #endif /* _ASM_X86_SYSCALL_WRAPPER_H */