powerpc: Enable compile-time check for syscall handlers

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@arndb.de>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-18-rmclure@linux.ibm.com

diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.c
similarity index 57%
rename from arch/powerpc/kernel/systbl.S
rename to arch/powerpc/kernel/systbl.c
index 280d6b6..ce52bd2 100644 (file)
--- a/arch/powerpc/kernel/systbl.S
+++ b/arch/powerpc/kernel/systbl.c
@@ -10,36 +10,26 @@
  * PPC64 updates by Dave Engebretsen (engebret@us.ibm.com) 
  */
 
-#include <asm/ppc_asm.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <asm/unistd.h>
+#include <asm/syscalls.h>
 
-#ifdef CONFIG_RELOCATABLE
-.section .data.rel.ro,"aw"
-#else
-.section .rodata,"a"
-#endif
+#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 */