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OpenCloudOS-Kernel/arch/arm64/include/asm/syscall_wrapper.h

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arm64: implement syscall wrappers To minimize the risk of userspace-controlled values being used under speculation, this patch adds pt_regs based syscall wrappers for arm64, which pass the minimum set of required userspace values to syscall implementations. For each syscall, a wrapper which takes a pt_regs argument is automatically generated, and this extracts the arguments before calling the "real" syscall implementation. Each syscall has three functions generated: * __do_<compat_>sys_<name> is the "real" syscall implementation, with the expected prototype. * __se_<compat_>sys_<name> is the sign-extension/narrowing wrapper, inherited from common code. This takes a series of long parameters, casting each to the requisite types required by the "real" syscall implementation in __do_<compat_>sys_<name>. This wrapper *may* not be necessary on arm64 given the AAPCS rules on unused register bits, but it seemed safer to keep the wrapper for now. * __arm64_<compat_>_sys_<name> takes a struct pt_regs pointer, and extracts *only* the relevant register values, passing these on to the __se_<compat_>sys_<name> wrapper. The syscall invocation code is updated to handle the calling convention required by __arm64_<compat_>_sys_<name>, and passes a single struct pt_regs pointer. The compiler can fold the syscall implementation and its wrappers, such that the overhead of this approach is minimized. Note that we play games with sys_ni_syscall(). It can't be defined with SYSCALL_DEFINE0() because we must avoid the possibility of error injection. Additionally, there are a couple of locations where we need to call it from C code, and we don't (currently) have a ksys_ni_syscall(). While it has no wrapper, passing in a redundant pt_regs pointer is benign per the AAPCS. When ARCH_HAS_SYSCALL_WRAPPER is selected, no prototype is defines for sys_ni_syscall(). Since we need to treat it differently for in-kernel calls and the syscall tables, the prototype is defined as-required. The wrappers are largely the same as their x86 counterparts, but simplified as we don't have a variety of compat calling conventions that require separate stubs. Unlike x86, we have some zero-argument compat syscalls, and must define COMPAT_SYSCALL_DEFINE0() to ensure that these are also given an __arm64_compat_sys_ prefix. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-07-11 21:56:56 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
/*
* syscall_wrapper.h - arm64 specific wrappers to syscall definitions
*
* Based on arch/x86/include/asm_syscall_wrapper.h
*/
#ifndef __ASM_SYSCALL_WRAPPER_H
#define __ASM_SYSCALL_WRAPPER_H
#define SC_ARM64_REGS_TO_ARGS(x, ...) \
__MAP(x,__SC_ARGS \
,,regs->regs[0],,regs->regs[1],,regs->regs[2] \
,,regs->regs[3],,regs->regs[4],,regs->regs[5])
#ifdef CONFIG_COMPAT
#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long __arm64_compat_sys##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__arm64_compat_sys##name, ERRNO); \
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__)); \
asmlinkage long __arm64_compat_sys##name(const struct pt_regs *regs) \
{ \
return __se_compat_sys##name(SC_ARM64_REGS_TO_ARGS(x,__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__))
#define COMPAT_SYSCALL_DEFINE0(sname) \
asmlinkage long __arm64_compat_sys_##sname(void); \
ALLOW_ERROR_INJECTION(__arm64_compat_sys_##sname, ERRNO); \
asmlinkage long __arm64_compat_sys_##sname(void)
#define COND_SYSCALL_COMPAT(name) \
cond_syscall(__arm64_compat_sys_##name);
#define COMPAT_SYS_NI(name) \
SYSCALL_ALIAS(__arm64_compat_sys_##name, sys_ni_posix_timers);
#endif /* CONFIG_COMPAT */
#define __SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long __arm64_sys##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__arm64_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 __arm64_sys##name(const struct pt_regs *regs) \
{ \
return __se_sys##name(SC_ARM64_REGS_TO_ARGS(x,__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__))
#ifndef SYSCALL_DEFINE0
#define SYSCALL_DEFINE0(sname) \
SYSCALL_METADATA(_##sname, 0); \
asmlinkage long __arm64_sys_##sname(void); \
ALLOW_ERROR_INJECTION(__arm64_sys_##sname, ERRNO); \
asmlinkage long __arm64_sys_##sname(void)
#endif
#ifndef COND_SYSCALL
#define COND_SYSCALL(name) cond_syscall(__arm64_sys_##name)
#endif
#ifndef SYS_NI
#define SYS_NI(name) SYSCALL_ALIAS(__arm64_sys_##name, sys_ni_posix_timers);
#endif
#endif /* __ASM_SYSCALL_WRAPPER_H */