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authorDominik Brodowski <linux@dominikbrodowski.net>2018-04-05 11:53:03 +0200
committerIngo Molnar <mingo@kernel.org>2018-04-05 16:59:38 +0200
commit7303e30ec1d8fb5ca1f07c92d069241c32b2ee1b (patch)
tree9bf0343c73e0f5562bd8972c25bf8ffa280e8845 /include
parentfa697140f9a20119a9ec8fd7460cc4314fbdaff3 (diff)
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syscalls/core: Prepare CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y for compat syscalls
It may be useful for an architecture to override the definitions of the COMPAT_SYSCALL_DEFINE0() and __COMPAT_SYSCALL_DEFINEx() macros in <linux/compat.h>, in particular to use a different calling convention for syscalls. This patch provides a mechanism to do so, based on the previously introduced CONFIG_ARCH_HAS_SYSCALL_WRAPPER. If it is enabled, <asm/sycall_wrapper.h> is included in <linux/compat.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 compat syscall function prototypes in <linux/compat.h> are #ifndef'd out in that case. As some of the syscalls and/or compat syscalls may not be present, the COND_SYSCALL() and COND_SYSCALL_COMPAT() macros in kernel/sys_ni.c as well as the SYS_NI() and COMPAT_SYS_NI() macros in kernel/time/posix-stubs.c can be re-defined in <asm/syscall_wrapper.h> iff CONFIG_ARCH_HAS_SYSCALL_WRAPPER is enabled. Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> Acked-by: Linus 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/20180405095307.3730-5-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/compat.h22
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 9847c5a013c3..2d85ec5cfda2 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -24,6 +24,17 @@
#include <asm/siginfo.h>
#include <asm/signal.h>
+#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+/*
+ * It may be useful for an architecture to override the definitions of the
+ * COMPAT_SYSCALL_DEFINE0 and COMPAT_SYSCALL_DEFINEx() macros, in particular
+ * to use a different calling convention for syscalls. To allow for that,
+ + the prototypes for the compat_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 */
+
#ifndef COMPAT_USE_64BIT_TIME
#define COMPAT_USE_64BIT_TIME 0
#endif
@@ -32,10 +43,12 @@
#define __SC_DELOUSE(t,v) ((__force t)(unsigned long)(v))
#endif
+#ifndef COMPAT_SYSCALL_DEFINE0
#define COMPAT_SYSCALL_DEFINE0(name) \
asmlinkage long compat_sys_##name(void); \
ALLOW_ERROR_INJECTION(compat_sys_##name, ERRNO); \
asmlinkage long compat_sys_##name(void)
+#endif /* COMPAT_SYSCALL_DEFINE0 */
#define COMPAT_SYSCALL_DEFINE1(name, ...) \
COMPAT_SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
@@ -50,6 +63,7 @@
#define COMPAT_SYSCALL_DEFINE6(name, ...) \
COMPAT_SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)
+#ifndef COMPAT_SYSCALL_DEFINEx
#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))\
@@ -62,6 +76,7 @@
return C_SYSC##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \
} \
static inline long C_SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__))
+#endif /* COMPAT_SYSCALL_DEFINEx */
#ifndef compat_user_stack_pointer
#define compat_user_stack_pointer() current_user_stack_pointer()
@@ -517,7 +532,12 @@ int __compat_save_altstack(compat_stack_t __user *, unsigned long);
* Please note that these prototypes here are only provided for information
* purposes, for static analysis, and for linking from the syscall table.
* 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 compat_sys_io_setup(unsigned nr_reqs, u32 __user *ctx32p);
asmlinkage long compat_sys_io_submit(compat_aio_context_t ctx_id, int nr,
u32 __user *iocb);
@@ -955,6 +975,8 @@ asmlinkage long compat_sys_stime(compat_time_t __user *tptr);
/* obsolete: net/socket.c */
asmlinkage long compat_sys_socketcall(int call, u32 __user *args);
+#endif /* CONFIG_ARCH_HAS_SYSCALL_WRAPPER */
+
/*
* For most but not all architectures, "am I in a compat syscall?" and