diff options
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/syscall.h | 4 | ||||
| -rw-r--r-- | arch/x86/include/asm/syscall_wrapper.h | 70 | ||||
| -rw-r--r-- | arch/x86/include/asm/syscalls.h | 7 |
3 files changed, 81 insertions, 0 deletions
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h index 03eedc21246d..17c62373a6f9 100644 --- a/arch/x86/include/asm/syscall.h +++ b/arch/x86/include/asm/syscall.h @@ -20,9 +20,13 @@ #include <asm/thread_info.h> /* for TS_COMPAT */ #include <asm/unistd.h> +#ifdef CONFIG_SYSCALL_PTREGS +typedef asmlinkage long (*sys_call_ptr_t)(const struct pt_regs *); +#else typedef asmlinkage long (*sys_call_ptr_t)(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); +#endif /* CONFIG_SYSCALL_PTREGS */ extern const sys_call_ptr_t sys_call_table[]; #if defined(CONFIG_X86_32) diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h new file mode 100644 index 000000000000..702bdee377af --- /dev/null +++ b/arch/x86/include/asm/syscall_wrapper.h @@ -0,0 +1,70 @@ +/* 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 + +/* + * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes + * struct pt_regs *regs as the only argument of the syscall stub named + * sys_*(). It decodes just the registers it needs and passes them on to + * the SyS_*() wrapper and then to the SYSC_*() function doing the actual job. + * These wrappers and functions are inlined, meaning that the assembly looks + * as follows (slightly re-ordered): + * + * <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. + * + * 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, there is no need to override it. + */ +#define __SYSCALL_DEFINEx(x, name, ...) \ + asmlinkage long sys##name(const struct pt_regs *regs); \ + ALLOW_ERROR_INJECTION(sys##name, ERRNO); \ + static long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ + static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ + asmlinkage long sys##name(const struct pt_regs *regs) \ + { \ + return SyS##name(__MAP(x,__SC_ARGS \ + ,,regs->di,,regs->si,,regs->dx \ + ,,regs->r10,,regs->r8,,regs->r9)); \ + } \ + static long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ + { \ + long ret = SYSC##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 SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)) + +/* + * 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 sys_getcpu(const struct pt_regs *regs); /* di,si,dx */ +asmlinkage long sys_gettimeofday(const struct pt_regs *regs); /* di,si */ +asmlinkage long sys_time(const struct pt_regs *regs); /* di */ + +#endif /* _ASM_X86_SYSCALL_WRAPPER_H */ diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h index ae6e05fdc24b..e4ad93c05f02 100644 --- a/arch/x86/include/asm/syscalls.h +++ b/arch/x86/include/asm/syscalls.h @@ -18,6 +18,12 @@ /* Common in X86_32 and X86_64 */ /* kernel/ioport.c */ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on); + +#ifndef CONFIG_SYSCALL_PTREGS +/* + * If CONFIG_SYSCALL_PTREGS is enabled, a different syscall calling convention + * is used. Do not include these -- invalid -- prototypes then + */ asmlinkage long sys_ioperm(unsigned long, unsigned long, int); asmlinkage long sys_iopl(unsigned int); @@ -53,4 +59,5 @@ asmlinkage long sys_mmap(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); #endif /* CONFIG_X86_32 */ +#endif /* CONFIG_SYSCALL_PTREGS */ #endif /* _ASM_X86_SYSCALLS_H */ |