kbuild: complain about missing system calls

Most system calls seems to get added to i386 first. This patch
automatically generates a warning for any new system call which is
implemented on i386 but not the architecture currently being compiled.
On PowerPC at the moment, for example, it results in these warnings:
init/missing_syscalls.h:935:3: warning: #warning syscall sync_file_range not implemented
init/missing_syscalls.h:947:3: warning: #warning syscall getcpu not implemented
init/missing_syscalls.h:950:3: warning: #warning syscall epoll_pwait not implemented

The file scripts/checksyscalls.sh list a number of legacy system calls
that are ignored because they only makes sense on i386 systems.

Other contributors to this patch are Russell King <rmk+lkml@arm.linux.org.uk>
and Stéphane Jourdois <kwisatz@rubis.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Kbuild

@@ -2,6 +2,7 @@
 # Kbuild for top-level directory of the kernel
 # This file takes care of the following:
 # 1) Generate asm-offsets.h
+# 2) Check for missing system calls
 
 #####
 # 1) Generate asm-offsets.h
@@ -46,3 +47,13 @@ $(obj)/$(offsets-file): arch/$(ARCH)/kernel/asm-offsets.s Kbuild
 	$(Q)mkdir -p $(dir $@)
 	$(call cmd,offsets)
 
+#####
+# 2) Check for missing system calls
+#
+
+quiet_cmd_syscalls = CALL    $<
+      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)
+
+PHONY += missing-syscalls
+missing-syscalls: scripts/checksyscalls.sh FORCE
+	$(call cmd,syscalls)

Makefile

@@ -856,6 +856,7 @@ archprepare: prepare1 scripts_basic
 
 prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
+	$(Q)$(MAKE) $(build)=. missing-syscalls
 
 # All the preparing..
 prepare: prepare0

scripts/checksyscalls.sh

+#!/bin/sh
+#
+# Check if current architecture are missing any function calls compared
+# to i386.
+# i386 define a number of legacy system calls that are i386 specific
+# and listed below so they are ignored.
+#
+# Usage:
+# syscallchk gcc gcc-options
+#
+
+ignore_list() {
+cat << EOF
+#include <asm/types.h>
+#include <asm/unistd.h>
+
+/* System calls for 32-bit kernels only */
+#if BITS_PER_LONG == 64
+#define __IGNORE_sendfile64
+#define __IGNORE_ftruncate64
+#define __IGNORE_truncate64
+#define __IGNORE_stat64
+#define __IGNORE_lstat64
+#define __IGNORE_fstat64
+#define __IGNORE_fcntl64
+#define __IGNORE_fadvise64_64
+#define __IGNORE_fstatat64
+#define __IGNORE_fstatfs64
+#define __IGNORE_statfs64
+#endif
+
+/* i386-specific or historical system calls */
+#define __IGNORE_break
+#define __IGNORE_stty
+#define __IGNORE_gtty
+#define __IGNORE_ftime
+#define __IGNORE_prof
+#define __IGNORE_lock
+#define __IGNORE_mpx
+#define __IGNORE_ulimit
+#define __IGNORE_profil
+#define __IGNORE_ioperm
+#define __IGNORE_iopl
+#define __IGNORE_idle
+#define __IGNORE_modify_ldt
+#define __IGNORE_ugetrlimit
+#define __IGNORE_mmap2
+#define __IGNORE_vm86
+#define __IGNORE_vm86old
+#define __IGNORE_set_thread_area
+#define __IGNORE_get_thread_area
+#define __IGNORE_madvise1
+#define __IGNORE_oldstat
+#define __IGNORE_oldfstat
+#define __IGNORE_oldlstat
+#define __IGNORE_oldolduname
+#define __IGNORE_olduname
+#define __IGNORE_umount2
+#define __IGNORE_umount
+#define __IGNORE_waitpid
+#define __IGNORE_stime
+#define __IGNORE_nice
+#define __IGNORE_signal
+#define __IGNORE_sigaction
+#define __IGNORE_sgetmask
+#define __IGNORE_sigsuspend
+#define __IGNORE_sigpending
+#define __IGNORE_ssetmask
+#define __IGNORE_readdir
+#define __IGNORE_socketcall
+#define __IGNORE_ipc
+#define __IGNORE_sigreturn
+#define __IGNORE_sigprocmask
+#define __IGNORE_bdflush
+#define __IGNORE__llseek
+#define __IGNORE__newselect
+#define __IGNORE_create_module
+#define __IGNORE_delete_module
+#define __IGNORE_query_module
+#define __IGNORE_get_kernel_syms
+/* ... including the "new" 32-bit uid syscalls */
+#define __IGNORE_lchown32
+#define __IGNORE_getuid32
+#define __IGNORE_getgid32
+#define __IGNORE_geteuid32
+#define __IGNORE_getegid32
+#define __IGNORE_setreuid32
+#define __IGNORE_setregid32
+#define __IGNORE_getgroups32
+#define __IGNORE_setgroups32
+#define __IGNORE_fchown32
+#define __IGNORE_setresuid32
+#define __IGNORE_getresuid32
+#define __IGNORE_setresgid32
+#define __IGNORE_getresgid32
+#define __IGNORE_chown32
+#define __IGNORE_setuid32
+#define __IGNORE_setgid32
+#define __IGNORE_setfsuid32
+#define __IGNORE_setfsgid32
+
+/* Unmerged syscalls for AFS, STREAMS, etc. */
+#define __IGNORE_afs_syscall
+#define __IGNORE_getpmsg
+#define __IGNORE_putpmsg
+#define __IGNORE_vserver
+EOF
+}
+
+syscall_list() {
+sed -n -e '/^\#define/ { s/[^_]*__NR_\([^[:space:]]*\).*/\
+\#if !defined \(__NR_\1\) \&\& !defined \(__IGNORE_\1\)\
+\#warning syscall \1 not implemented\
+\#endif/p }' $1
+}
+
+(ignore_list && syscall_list ${srctree}/include/asm-i386/unistd.h) | \
+$* -E -x c - > /dev/null