powerpc: Adopt SYSCALL_DEFINE for arch-specific syscall handlers

Arch-specific implementations of syscall handlers are currently used
over generic implementations for the following reasons:

1. Semantics unique to powerpc
2. Compatibility syscalls require 'argument padding' to comply with
   64-bit argument convention in ELF32 abi.
3. Parameter types or order is different in other architectures.

These syscall handlers have been defined prior to this patch series
without invoking the SYSCALL_DEFINE or COMPAT_SYSCALL_DEFINE macros with
custom input and output types. We remove every such direct definition in
favour of the aforementioned macros.

Also update syscalls.tbl in order to refer to the symbol names generated
by each of these macros. Since ppc64_personality can be called by both
64 bit and 32 bit binaries through compatibility, we must generate both
both compat_sys_ and sys_ symbols for this handler.

As an aside:
A number of architectures including arm and powerpc agree on an
alternative argument order and numbering for most of these arch-specific
handlers. A future patch series may allow for asm/unistd.h to signal
through its defines that a generic implementation of these syscall
handlers with the correct calling convention be emitted, through the
__ARCH_WANT_COMPAT_SYS_... convention.

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/20220921065605.1051927-16-rmclure@linux.ibm.com

1 files changed, 13 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
index 8d4b7f6d7cf3..68ebb23a5af4 100644
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -86,14 +86,23 @@ static long do_ppc64_personality(unsigned long personality)
 		ret = (ret & ~PER_MASK) | PER_LINUX;
 	return ret;
 }
-long ppc64_personality(unsigned long personality)
+
+SYSCALL_DEFINE1(ppc64_personality, unsigned long, personality)
 {
 	return do_ppc64_personality(personality);
 }
-#endif
 
-long ppc_fadvise64_64(int fd, int advice, u32 offset_high, u32 offset_low,
-		      u32 len_high, u32 len_low)
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE1(ppc64_personality, unsigned long, personality)
+{
+	return do_ppc64_personality(personality);
+}
+#endif /* CONFIG_COMPAT */
+#endif /* CONFIG_PPC64 */
+
+SYSCALL_DEFINE6(ppc_fadvise64_64,
+		int, fd, int, advice, u32, offset_high, u32, offset_low,
+		u32, len_high, u32, len_low)
 {
 	return ksys_fadvise64_64(fd, merge_64(offset_high, offset_low),
 				 merge_64(len_high, len_low), advice);