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: 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>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 41cafd2..b6e3d06 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -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

diff --git a/arch/s390/include/asm/syscall_wrapper.h b/arch/s390/include/asm/syscall_wrapper.h
new file mode 100644 (file)
index 0000000..5596c5c
--- /dev/null
+++ b/arch/s390/include/asm/syscall_wrapper.h
@@ -0,0 +1,135 @@
+/* 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 */

diff --git a/arch/s390/kernel/compat_wrapper.c b/arch/s390/kernel/compat_wrapper.c
index f54b7b7..9d07cd5 100644 (file)
--- a/arch/s390/kernel/compat_wrapper.c
+++ b/arch/s390/kernel/compat_wrapper.c
@@ -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);

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 39191a0..583d65e 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -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"

diff --git a/arch/s390/kernel/sys_s390.c b/arch/s390/kernel/sys_s390.c
index fd0cbbe..202fa73 100644 (file)
--- a/arch/s390/kernel/sys_s390.c
+++ b/arch/s390/kernel/sys_s390.c
@@ -95,3 +95,8 @@ SYSCALL_DEFINE1(s390_personality, unsigned int, personality)
 
        return ret;
 }
+
+SYSCALL_DEFINE0(ni_syscall)
+{
+       return -ENOSYS;
+}