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Commit 1bd21c6c authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Ingo Molnar
Browse files

syscalls/core: Introduce CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y 



It may be useful for an architecture to override the definitions of the
SYSCALL_DEFINE0() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>,
in particular to use a different calling convention for syscalls.

This patch provides a mechanism to do so: It introduces
CONFIG_ARCH_HAS_SYSCALL_WRAPPER. If it is enabled, <asm/sycall_wrapper.h>
is included in <linux/syscalls.h> and may be used to define the macros
mentioned above. Moreover, as the syscall calling convention may be
different if CONFIG_ARCH_HAS_SYSCALL_WRAPPER is set, the syscall function
prototypes in <linux/syscalls.h> are #ifndef'd out in that case.

Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180405095307.3730-3-linux@dominikbrodowski.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent dfe64506

include/linux/syscalls.h

+23 −0
Original line number Original line Diff line number Diff line
@@ -81,6 +81,17 @@ union bpf_attr; 
#include <linux/key.h>

#include <linux/key.h>

#include <trace/syscall.h>

#include <trace/syscall.h>





#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER

/*

 * It may be useful for an architecture to override the definitions of the

 * SYSCALL_DEFINE0() and __SYSCALL_DEFINEx() macros, in particular to use a

 * different calling convention for syscalls. To allow for that, the prototypes

 * for the sys_*() functions below will *not* be included if

 * CONFIG_ARCH_HAS_SYSCALL_WRAPPER is enabled.

 */

#include <asm/syscall_wrapper.h>

#endif /* CONFIG_ARCH_HAS_SYSCALL_WRAPPER */



/*

/*

 * __MAP - apply a macro to syscall arguments

 * __MAP - apply a macro to syscall arguments

 * __MAP(n, m, t1, a1, t2, a2, ..., tn, an) will expand to

 * __MAP(n, m, t1, a1, t2, a2, ..., tn, an) will expand to
@@ -189,11 +200,13 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) 
}

}

#endif

#endif





#ifndef SYSCALL_DEFINE0

#define SYSCALL_DEFINE0(sname)					\

#define SYSCALL_DEFINE0(sname)					\

	SYSCALL_METADATA(_##sname, 0);				\

	SYSCALL_METADATA(_##sname, 0);				\

	asmlinkage long sys_##sname(void);			\

	asmlinkage long sys_##sname(void);			\

	ALLOW_ERROR_INJECTION(sys_##sname, ERRNO);		\

	ALLOW_ERROR_INJECTION(sys_##sname, ERRNO);		\

	asmlinkage long sys_##sname(void)

	asmlinkage long sys_##sname(void)

#endif /* SYSCALL_DEFINE0 */





#define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)

#define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)

#define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)

#define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
@@ -209,6 +222,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) 
	__SYSCALL_DEFINEx(x, sname, __VA_ARGS__)

	__SYSCALL_DEFINEx(x, sname, __VA_ARGS__)





#define __PROTECT(...) asmlinkage_protect(__VA_ARGS__)

#define __PROTECT(...) asmlinkage_protect(__VA_ARGS__)



#ifndef __SYSCALL_DEFINEx

#define __SYSCALL_DEFINEx(x, name, ...)					\

#define __SYSCALL_DEFINEx(x, name, ...)					\

	asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\

	asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\

		__attribute__((alias(__stringify(SyS##name))));		\

		__attribute__((alias(__stringify(SyS##name))));		\
@@ -223,6 +238,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) 
		return ret;						\

		return ret;						\

	}								\

	}								\

	static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__))

	static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__))

#endif /* __SYSCALL_DEFINEx */





/*

/*

 * Called before coming back to user-mode. Returning to user-mode with an

 * Called before coming back to user-mode. Returning to user-mode with an
@@ -252,7 +268,12 @@ static inline void addr_limit_user_check(void) 
 * Please note that these prototypes here are only provided for information

 * Please note that these prototypes here are only provided for information

 * purposes, for static analysis, and for linking from the syscall table.

 * purposes, for static analysis, and for linking from the syscall table.

 * These functions should not be called elsewhere from kernel code.

 * These functions should not be called elsewhere from kernel code.

 *

 * As the syscall calling convention may be different from the default

 * for architectures overriding the syscall calling convention, do not

 * include the prototypes if CONFIG_ARCH_HAS_SYSCALL_WRAPPER is enabled.

 */

 */

#ifndef CONFIG_ARCH_HAS_SYSCALL_WRAPPER

asmlinkage long sys_io_setup(unsigned nr_reqs, aio_context_t __user *ctx);

asmlinkage long sys_io_setup(unsigned nr_reqs, aio_context_t __user *ctx);

asmlinkage long sys_io_destroy(aio_context_t ctx);

asmlinkage long sys_io_destroy(aio_context_t ctx);

asmlinkage long sys_io_submit(aio_context_t, long,

asmlinkage long sys_io_submit(aio_context_t, long,
@@ -1076,6 +1097,8 @@ asmlinkage long sys_old_mmap(struct mmap_arg_struct __user *arg); 
 */

 */

asmlinkage long sys_ni_syscall(void);

asmlinkage long sys_ni_syscall(void);





#endif /* CONFIG_ARCH_HAS_SYSCALL_WRAPPER */







/*

/*

 * Kernel code should not call syscalls (i.e., sys_xyzyyz()) directly.

 * Kernel code should not call syscalls (i.e., sys_xyzyyz()) directly.

init/Kconfig

+7 −0
Original line number Original line Diff line number Diff line
@@ -1923,3 +1923,10 @@ source "kernel/Kconfig.locks" 




config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE

config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE

	bool

	bool



# It may be useful for an architecture to override the definitions of the

# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>,

# in particular to use a different calling convention for syscalls.

config ARCH_HAS_SYSCALL_WRAPPER

	def_bool n

	depends on !COMPAT