Commit aa0d6e70 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Martin Schwidefsky
Browse files

s390: autogenerate compat syscall wrappers 

Any system call that takes a pointer argument on s390 requires
a wrapper function to do a 31-to-64 zero-extension, these are
currently generated in arch/s390/kernel/compat_wrapper.c.

On arm64 and x86, we already generate similar wrappers for all
system calls in the place of their definition, just for a different
purpose (they load the arguments from pt_regs).

We can do the same thing here, by adding an asm/syscall_wrapper.h
file with a copy of all the relevant macros to override the generic
version. Besides the addition of the compat entry point, these also
rename the entry points with a __s390_ or __s390x_ prefix, similar
to what we do on arm64 and x86. This in turn requires renaming
a few things, and adding a proper ni_syscall() entry point.

In order to still compile system call definitions that pass an
loff_t argument, the __SC_COMPAT_CAST() macro checks for that
and forces an -ENOSYS error, which was the best I could come up
with. Those functions must obviously not get called from user
space, but instead require hand-written compat_sys_*() handlers,
which fortunately already exist.

Link: https://lore.kernel.org/lkml/20190116131527.2071570-5-arnd@arndb.de


Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
[heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT]
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent fef747ba

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ config S390 
	select ARCH_HAS_SET_MEMORY

	select ARCH_HAS_STRICT_KERNEL_RWX

	select ARCH_HAS_STRICT_MODULE_RWX

	select ARCH_HAS_SYSCALL_WRAPPER

	select ARCH_HAS_UBSAN_SANITIZE_ALL

	select ARCH_HAVE_NMI_SAFE_CMPXCHG

	select ARCH_INLINE_READ_LOCK

arch/s390/include/asm/syscall_wrapper.h

0 → 100644
+135 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * syscall_wrapper.h - s390 specific wrappers to syscall definitions

 *

 */



#ifndef _ASM_S390_SYSCALL_WRAPPER_H

#define _ASM_S390_SYSCALL_WRAPPER_H



#ifdef CONFIG_COMPAT

#define __SC_COMPAT_TYPE(t, a) \

	__typeof(__builtin_choose_expr(sizeof(t) > 4, 0L, (t)0)) a



#define __SC_COMPAT_CAST(t, a)						\

({									\

	long __ReS = a;							\

									\

	BUILD_BUG_ON((sizeof(t) > 4) && !__TYPE_IS_L(t) &&		\

		     !__TYPE_IS_UL(t) && !__TYPE_IS_PTR(t) &&		\

		     !__TYPE_IS_LL(t));					\

	if (__TYPE_IS_L(t))						\

		__ReS = (s32)a;						\

	if (__TYPE_IS_UL(t))						\

		__ReS = (u32)a;						\

	if (__TYPE_IS_PTR(t))						\

		__ReS = a & 0x7fffffff;					\

	if (__TYPE_IS_LL(t))						\

		return -ENOSYS;						\

	(t)__ReS;							\

})



#define __S390_SYS_STUBx(x, name, ...)					\

	asmlinkage long __s390_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))\

	ALLOW_ERROR_INJECTION(__s390_sys##name, ERRNO);			\

	asmlinkage long __s390_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))\

	{								\

		long ret = __s390x_sys##name(__MAP(x,__SC_COMPAT_CAST,__VA_ARGS__));\

		__MAP(x,__SC_TEST,__VA_ARGS__);				\

		return ret;						\

	}



/*

 * To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias

 * named __s390x_sys_*()

 */

#define COMPAT_SYSCALL_DEFINE0(sname)					\

	SYSCALL_METADATA(_##sname, 0);					\

	asmlinkage long __s390_compat_sys_##sname(void);		\

	ALLOW_ERROR_INJECTION(__s390_compat__sys_##sname, ERRNO);	\

	asmlinkage long __s390_compat_sys_##sname(void)



#define SYSCALL_DEFINE0(sname)						\

	SYSCALL_METADATA(_##sname, 0);					\

	asmlinkage long __s390x_sys_##sname(void);			\

	ALLOW_ERROR_INJECTION(__s390x_sys_##sname, ERRNO);		\

	asmlinkage long __s390_sys_##sname(void)			\

		__attribute__((alias(__stringify(__s390x_sys_##sname)))); \

	asmlinkage long __s390x_sys_##sname(void)



#define COND_SYSCALL(name)						\

	cond_syscall(__s390x_sys_##name);				\

	cond_syscall(__s390_sys_##name)



#define SYS_NI(name)							\

	SYSCALL_ALIAS(__s390x_sys_##name, sys_ni_posix_timers);		\

	SYSCALL_ALIAS(__s390_sys_##name, sys_ni_posix_timers)



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

	__diag_push();								\

	__diag_ignore(GCC, 8, "-Wattribute-alias",				\

		      "Type aliasing is used to sanitize syscall arguments");\

	asmlinkage long __s390_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));	\

	asmlinkage long __s390_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\

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

	ALLOW_ERROR_INJECTION(compat_sys##name, ERRNO);				\

	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\

	asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\

	asmlinkage long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))	\

	{									\

		long ret = __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\

		__MAP(x,__SC_TEST,__VA_ARGS__);					\

		return ret;							\

	}									\

	__diag_pop();								\

	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(__s390_compat_sys_##name)



#define COMPAT_SYS_NI(name)						\

	SYSCALL_ALIAS(__s390_compat_sys_##name, sys_ni_posix_timers)



#else /* CONFIG_COMPAT */



#define __S390_SYS_STUBx(x, fullname, name, ...)



#define SYSCALL_DEFINE0(sname)						\

	SYSCALL_METADATA(_##sname, 0);					\

	asmlinkage long __s390x_sys_##sname(void);			\

	ALLOW_ERROR_INJECTION(__s390x_sys_##sname, ERRNO);		\

	asmlinkage long __s390x_sys_##sname(void)



#define COND_SYSCALL(name)						\

	cond_syscall(__s390x_sys_##name)



#define SYS_NI(name)							\

	SYSCALL_ALIAS(__s390x_sys_##name, sys_ni_posix_timers);



#endif /* CONFIG_COMPAT */



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

	__diag_push();								\

	__diag_ignore(GCC, 8, "-Wattribute-alias",				\

		      "Type aliasing is used to sanitize syscall arguments");\

	asmlinkage long __s390x_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\

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

	ALLOW_ERROR_INJECTION(__s390x_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__));	\

	__S390_SYS_STUBx(x, name, __VA_ARGS__)					\

	asmlinkage 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__);					\

		return ret;							\

	}									\

	__diag_pop();								\

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



#endif /* _ASM_X86_SYSCALL_WRAPPER_H */

arch/s390/kernel/compat_wrapper.c

+4 −19
Original line number Diff line number Diff line
@@ -25,21 +25,6 @@ 
#define __SC_COMPAT_TYPE(t, a) \

	__typeof(__builtin_choose_expr(sizeof(t) > 4, 0L, (t)0)) a



#define __SC_COMPAT_CAST(t, a)						\

({									\

	long __ReS = a;							\

									\

	BUILD_BUG_ON((sizeof(t) > 4) && !__TYPE_IS_L(t) &&		\

		     !__TYPE_IS_UL(t) && !__TYPE_IS_PTR(t));		\

	if (__TYPE_IS_L(t))						\

		__ReS = (s32)a;						\

	if (__TYPE_IS_UL(t))						\

		__ReS = (u32)a;						\

	if (__TYPE_IS_PTR(t))						\

		__ReS = a & 0x7fffffff;					\

	(t)__ReS;							\

})



/*

 * The COMPAT_SYSCALL_WRAP macro generates system call wrappers to be used by

 * compat tasks. These wrappers will only be used for system calls where only
@@ -53,11 +38,11 @@ 
 * the regular system call wrappers.

 */

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

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

asmlinkage long notrace compat_sys##name(__MAP(x,__SC_COMPAT_TYPE,__VA_ARGS__));\

asmlinkage long notrace compat_sys##name(__MAP(x,__SC_COMPAT_TYPE,__VA_ARGS__))	\

asmlinkage long __s390_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));		\

asmlinkage long notrace __s390_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\

asmlinkage long notrace __s390_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\

{										\

	return sys##name(__MAP(x,__SC_COMPAT_CAST,__VA_ARGS__));		\

	return __s390_sys##name(__MAP(x,__SC_ARGS,__VA_ARGS__));		\

}



COMPAT_SYSCALL_WRAP2(creat, const char __user *, pathname, umode_t, mode);

arch/s390/kernel/entry.S

+2 −2
Original line number Diff line number Diff line
@@ -1512,7 +1512,7 @@ cleanup_critical: 
	.quad   .Lsie_skip - .Lsie_entry

#endif

	.section .rodata, "a"

#define SYSCALL(esame,emu)	.long esame

#define SYSCALL(esame,emu)	.long __s390x_ ## esame

	.globl	sys_call_table

sys_call_table:

#include "asm/syscall_table.h"
@@ -1520,7 +1520,7 @@ sys_call_table: 


#ifdef CONFIG_COMPAT



#define SYSCALL(esame,emu)	.long emu

#define SYSCALL(esame,emu)	.long __s390_ ## emu

	.globl	sys_call_table_emu

sys_call_table_emu:

#include "asm/syscall_table.h"

arch/s390/kernel/sys_s390.c

+5 −0
Original line number Diff line number Diff line
@@ -95,3 +95,8 @@ SYSCALL_DEFINE1(s390_personality, unsigned int, personality) 


	return ret;

}



SYSCALL_DEFINE0(ni_syscall)

{

	return -ENOSYS;

}

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