powerpc: Fix build by disabling attribute-alias warning for SYSCALL_DEFINEx

GCC 8.1 emits warnings such as the following. As arch/powerpc code is
built with -Werror, this breaks the build with GCC 8.1.

  In file included from arch/powerpc/kernel/pci_64.c:23:
  ./include/linux/syscalls.h:233:18: error: 'sys_pciconfig_iobase' alias
  between functions of incompatible types 'long int(long int, long
  unsigned int, long unsigned int)' and 'long int(long int, long int,
  long int)' [-Werror=attribute-alias]
    asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
                    ^~~
  ./include/linux/syscalls.h:222:2: note: in expansion of macro '__SYSCALL_DEFINEx'
    __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)

This patch inhibits those warnings.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Trim change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/pci_64.c

@@ -203,6 +203,9 @@ void pcibios_setup_phb_io_space(struct pci_controller *hose)
 #define IOBASE_ISA_IO		3
 #define IOBASE_ISA_MEM		4
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(pciconfig_iobase, long, which, unsigned long, in_bus,
 			  unsigned long, in_devfn)
 {
@@ -256,6 +259,7 @@ SYSCALL_DEFINE3(pciconfig_iobase, long, which, unsigned long, in_bus,
 
 	return -EOPNOTSUPP;
 }
+#pragma GCC diagnostic pop
 
 #ifdef CONFIG_NUMA
 int pcibus_to_node(struct pci_bus *bus)

arch/powerpc/kernel/rtas.c

@@ -1051,6 +1051,9 @@ struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
 }
 
 /* We assume to be passed big endian arguments */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 {
 	struct rtas_args args;
@@ -1137,6 +1140,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 
 	return 0;
 }
+#pragma GCC diagnostic pop
 
 /*
  * Call early during boot, before mem init, to retrieve the RTAS

arch/powerpc/kernel/signal_32.c

@@ -1037,6 +1037,9 @@ static int do_setcontext_tm(struct ucontext __user *ucp,
 }
 #endif
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 #ifdef CONFIG_PPC64
 COMPAT_SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
 		       struct ucontext __user *, new_ctx, int, ctx_size)
@@ -1132,6 +1135,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
 	set_thread_flag(TIF_RESTOREALL);
 	return 0;
 }
+#pragma GCC diagnostic pop
 
 #ifdef CONFIG_PPC64
 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
@@ -1228,6 +1232,9 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	return 0;
 }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 #ifdef CONFIG_PPC32
 SYSCALL_DEFINE3(debug_setcontext, struct ucontext __user *, ctx,
 			 int, ndbg, struct sig_dbg_op __user *, dbg)
@@ -1333,6 +1340,7 @@ SYSCALL_DEFINE3(debug_setcontext, struct ucontext __user *, ctx,
 	return 0;
 }
 #endif
+#pragma GCC diagnostic pop
 
 /*
  * OK, we're invoking a handler

arch/powerpc/kernel/signal_64.c

@@ -625,6 +625,9 @@ static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
 /*
  * Handle {get,set,swap}_context operations
  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
 		struct ucontext __user *, new_ctx, long, ctx_size)
 {
@@ -690,6 +693,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
 	set_thread_flag(TIF_RESTOREALL);
 	return 0;
 }
+#pragma GCC diagnostic pop
 
 
 /*

arch/powerpc/kernel/syscalls.c

@@ -62,6 +62,9 @@ static inline long do_mmap2(unsigned long addr, size_t len,
 	return ret;
 }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE6(mmap2, unsigned long, addr, size_t, len,
 		unsigned long, prot, unsigned long, flags,
 		unsigned long, fd, unsigned long, pgoff)
@@ -75,6 +78,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, size_t, len,
 {
 	return do_mmap2(addr, len, prot, flags, fd, offset, PAGE_SHIFT);
 }
+#pragma GCC diagnostic pop
 
 #ifdef CONFIG_PPC32
 /*

arch/powerpc/mm/subpage-prot.c

@@ -186,6 +186,9 @@ static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
  * in a 2-bit field won't allow writes to a page that is otherwise
  * write-protected.
  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wattribute-alias"
 SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
 		unsigned long, len, u32 __user *, map)
 {
@@ -269,3 +272,4 @@ SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
 	up_write(&mm->mmap_sem);
 	return err;
 }
+#pragma GCC diagnostic pop