[PATCH v2 07/14] 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 <redacted>
---
V1 -> V2: New patch.
---
 arch/powerpc/kernel/{systbl.S => systbl.c} | 27 ++++++++++----------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.c
similarity index 59%
rename from arch/powerpc/kernel/systbl.S
rename to arch/powerpc/kernel/systbl.c
index cb3358886203..99ffdfef6b9c 100644
--- a/arch/powerpc/kernel/systbl.S
+++ b/arch/powerpc/kernel/systbl.c

@@ -10,31 +10,32 @@
  * 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>
 
-.section .rodata,"a"
+#define __SYSCALL_WITH_COMPAT(nr, entry, compat) __SYSCALL(nr, entry)
 
-#ifdef CONFIG_PPC64
-	.p2align	3
-#define __SYSCALL(nr, entry)	.8byte entry
+#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+#define __SYSCALL(nr, entry) [nr] = __powerpc_##entry,
+#define __powerpc_sys_ni_syscall	sys_ni_syscall
 #else
-#define __SYSCALL(nr, entry)	.long entry
+#define __SYSCALL(nr, entry) [nr] = entry,
 #endif
 
-#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
-.globl sys_call_table
-sys_call_table:
+void *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
+void *compat_sys_call_table[] = {
 #include <asm/syscall_table_32.h>
-#endif
+};
+#endif /* CONFIG_COMPAT */

-- 
2.34.1

On Mon, 2022-07-25 at 16:28 +1000, Rohan McLure wrote:

Keep this until patch 10.

Otherwise looks alright to me.

 #else
-#define __SYSCALL(nr, entry)   .long entry
+#define __SYSCALL(nr, entry) [nr] = entry,
 #endif
 
-#define __SYSCALL_WITH_COMPAT(nr, native, compat)      __SYSCALL(nr,
native)
-.globl sys_call_table
-sys_call_table:
+void *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
+void *compat_sys_call_table[] = {
 #include <asm/syscall_table_32.h>
-#endif
+};
+#endif /* CONFIG_COMPAT */

-- 
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited