diff options
Diffstat (limited to 'arch/x86/include/asm/syscall_wrapper.h')
| -rw-r--r-- | arch/x86/include/asm/syscall_wrapper.h | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h new file mode 100644 index 000000000000..e046a405743d --- /dev/null +++ b/arch/x86/include/asm/syscall_wrapper.h @@ -0,0 +1,209 @@ +/* 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 + +/* 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) + +#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_STUBx(x, name, ...) \ + asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\ + ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO); \ + asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\ + { \ + return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\ + } \ + +#define __IA32_SYS_STUBx(x, name, ...) \ + asmlinkage long __ia32_sys##name(const struct pt_regs *regs); \ + ALLOW_ERROR_INJECTION(__ia32_sys##name, ERRNO); \ + asmlinkage long __ia32_sys##name(const struct pt_regs *regs) \ + { \ + return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\ + } + +/* + * To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias + * named __ia32_sys_*() + */ +#define SYSCALL_DEFINE0(sname) \ + SYSCALL_METADATA(_##sname, 0); \ + asmlinkage long __x64_sys_##sname(void); \ + ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \ + SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname); \ + asmlinkage long __x64_sys_##sname(void) + +#define COND_SYSCALL(name) \ + cond_syscall(__x64_sys_##name); \ + cond_syscall(__ia32_sys_##name) + +#define SYS_NI(name) \ + SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers); \ + SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers) + +#else /* CONFIG_IA32_EMULATION */ +#define __IA32_COMPAT_SYS_STUBx(x, name, ...) +#define __IA32_SYS_STUBx(x, fullname, 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_STUBx(x, name, ...) \ + asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\ + ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO); \ + asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\ + { \ + return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\ + } \ + +#else /* CONFIG_X86_X32 */ +#define __X32_COMPAT_SYS_STUBx(x, 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_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) \ + cond_syscall(__ia32_compat_sys_##name); \ + cond_syscall(__x32_compat_sys_##name) + +#define COMPAT_SYS_NI(name) \ + SYSCALL_ALIAS(__ia32_compat_sys_##name, sys_ni_posix_timers); \ + SYSCALL_ALIAS(__x32_compat_sys_##name, sys_ni_posix_timers) + +#endif /* CONFIG_COMPAT */ + + +/* + * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes + * struct pt_regs *regs as the only argument of the syscall stub named + * __x64_sys_*(). It decodes just the registers it needs and passes them on to + * the __se_sys_*() wrapper performing sign extension and then to the + * __do_sys_*() function doing the actual job. These wrappers and functions + * are inlined (at least in very most cases), meaning that the assembly looks + * as follows (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. + * + * If IA32_EMULATION is enabled, this macro generates an additional wrapper + * named __ia32_sys_*() which decodes the struct pt_regs *regs according + * to the i386 calling convention (bx, cx, dx, si, di, bp). + */ +#define __SYSCALL_DEFINEx(x, name, ...) \ + asmlinkage long __x64_sys##name(const struct pt_regs *regs); \ + ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO); \ + static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ + static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ + asmlinkage long __x64_sys##name(const struct pt_regs *regs) \ + { \ + return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__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. + */ +#ifndef SYSCALL_DEFINE0 +#define SYSCALL_DEFINE0(sname) \ + SYSCALL_METADATA(_##sname, 0); \ + asmlinkage long __x64_sys_##sname(void); \ + ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO); \ + asmlinkage long __x64_sys_##sname(void) +#endif + +#ifndef COND_SYSCALL +#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name) +#endif + +#ifndef SYS_NI +#define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers); +#endif + + +/* + * For VSYSCALLS, we need to declare these three syscalls with the new + * pt_regs-based calling convention for in-kernel use. + */ +struct pt_regs; +asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs); +asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs); +asmlinkage long __x64_sys_time(const struct pt_regs *regs); + +#endif /* _ASM_X86_SYSCALL_WRAPPER_H */ |