[PATCH 17/23] powerpc: Enable compile-time check for syscall handlers

[Rohan McLure]

The table of syscall handlers and registered compatibility syscall
handlers has in past been produced using assembly, with function
references resolved at link time. This moves link-time errors to
compile-time, by rewriting systbl.S in C, and including the
linux/syscalls.h, linux/compat.h and asm/syscalls.h headers for
prototypes.

Reported-by: Arnd Bergmann <arnd at arndb.de>
Signed-off-by: Rohan McLure <rmclure at linux.ibm.com>
Reported-by: Nicholas Piggin <npiggin at gmail.com>
---
V1 -> V2: New patch.
V4 -> V5: For this patch only, represent handler function pointers as
unsigned long. Remove reference to syscall wrappers. Use asm/syscalls.h
which implies asm/syscall.h
---
 arch/powerpc/kernel/{systbl.S => systbl.c} | 28 ++++++++------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.c
similarity index 61%
rename from arch/powerpc/kernel/systbl.S
rename to arch/powerpc/kernel/systbl.c
index 6c1db3b6de2d..ce52bd2ec292 100644
--- a/arch/powerpc/kernel/systbl.S
+++ b/arch/powerpc/kernel/systbl.c
@@ -10,32 +10,26 @@
  * PPC64 updates by Dave Engebretsen (engebret at us.ibm.com) 
  */
 
-#include <asm/ppc_asm.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <asm/unistd.h>
+#include <asm/syscalls.h>
 
-.section .rodata,"a"
+#define __SYSCALL_WITH_COMPAT(nr, entry, compat) __SYSCALL(nr, entry)
+#define __SYSCALL(nr, entry) [nr] = (unsigned long) &entry,
 
-#ifdef CONFIG_PPC64
-	.p2align	3
-#define __SYSCALL(nr, entry)	.8byte entry
-#else
-	.p2align	2
-#define __SYSCALL(nr, entry)	.long entry
-#endif
-
-#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
-.globl sys_call_table
-sys_call_table:
+const unsigned long sys_call_table[] = {
 #ifdef CONFIG_PPC64
 #include <asm/syscall_table_64.h>
 #else
 #include <asm/syscall_table_32.h>
 #endif
+};
 
 #ifdef CONFIG_COMPAT
 #undef __SYSCALL_WITH_COMPAT
 #define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)
-.globl compat_sys_call_table
-compat_sys_call_table:
-#define compat_sys_sigsuspend	sys_sigsuspend
+const unsigned long compat_sys_call_table[] = {
 #include <asm/syscall_table_32.h>
-#endif
+};
+#endif /* CONFIG_COMPAT */
-- 
2.34.1