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Diffstat (limited to 'arch/x86/include/asm/syscall_wrapper.h')
| -rw-r--r-- | arch/x86/include/asm/syscall_wrapper.h | 272 |
1 files changed, 272 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 000000000..a84333ade --- /dev/null +++ b/arch/x86/include/asm/syscall_wrapper.h @@ -0,0 +1,272 @@ +/* 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 + +struct pt_regs; + +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 + * __x32_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) \ + +/* 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) + +#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) \ + { \ + 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(x32, compat_sys_##name) + +#define __X32_COMPAT_SYS_STUBx(x, name, ...) \ + __SYS_STUBx(x32, compat_sys##name, \ + SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__)) + +#define __X32_COMPAT_COND_SYSCALL(name) \ + __COND_SYSCALL(x32, compat_sys_##name) + +#define __X32_COMPAT_SYS_NI(name) \ + __SYS_NI(x32, 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 */ |