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s390: autogenerate compat syscall wrappers

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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: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
[heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Arnd Bergmann
2019-01-16 14:15:22 +01:00
committed by Martin Schwidefsky
parent fef747bab3
commit aa0d6e70d3
5 changed files with 147 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
arch/s390/kernel/compat_wrapper.c
View File

@@ -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);

4
arch/s390/kernel/entry.S
View File

@@ -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"

5
arch/s390/kernel/sys_s390.c
View File

@@ -95,3 +95,8 @@ SYSCALL_DEFINE1(s390_personality, unsigned int, personality)
return ret;
}
SYSCALL_DEFINE0(ni_syscall)
{
return -ENOSYS;
}