On Mon, Jun 15, 2020 at 11:10 AM Christoph Hellwig [off-list ref] wrote:

On Mon, Jun 15, 2020 at 04:46:15PM +0200, Arnd Bergmann wrote:

quoted

How about this one:

diff --git a/arch/x86/entry/syscall_x32.c b/arch/x86/entry/syscall_x32.c
index 3d8d70d3896c..0ce15807cf54 100644
--- a/arch/x86/entry/syscall_x32.c
+++ b/arch/x86/entry/syscall_x32.c

@@ -16,6 +16,9 @@
 #undef __SYSCALL_X32
 #undef __SYSCALL_COMMON

+#define __x32_sys_execve __x64_sys_execve
+#define __x32_sys_execveat __x64_sys_execveat
+

arch/x86/entry/syscall_x32.c:19:26: error: ‘__x64_sys_execve’ undeclared here (not in a function); did you mean ‘__x32_sys_execve’?
   19 | #define __x32_sys_execve __x64_sys_execve
      |                          ^~~~~~~~~~~~~~~~
arch/x86/entry/syscall_x32.c:22:39: note: in expansion of macro ‘__x32_sys_execve’
   22 | #define __SYSCALL_X32(nr, sym) [nr] = __x32_##sym,
      |                                       ^~~~~~
./arch/x86/include/generated/asm/syscalls_64.h:344:1: note: in expansion of macro ‘__SYSCALL_X32’
  344 | __SYSCALL_X32(520, sys_execve)
      | ^~~~~~~~~~~~~
arch/x86/entry/syscall_x32.c:20:28: error: ‘__x64_sys_execveat’ undeclared here (not in a function); did you mean ‘__x32_sys_execveat’?
   20 | #define __x32_sys_execveat __x64_sys_execveat
      |                            ^~~~~~~~~~~~~~~~~~
arch/x86/entry/syscall_x32.c:22:39: note: in expansion of macro ‘__x32_sys_execveat’
   22 | #define __SYSCALL_X32(nr, sym) [nr] = __x32_##sym,
      |                                       ^~~~~~
./arch/x86/include/generated/asm/syscalls_64.h:369:1: note: in expansion of macro ‘__SYSCALL_X32’
  369 | __SYSCALL_X32(545, sys_execveat)
      | ^~~~~~~~~~~~~
make[2]: *** [scripts/Makefile.build:281: arch/x86/entry/syscall_x32.o] Error 1
make[1]: *** [scripts/Makefile.build:497: arch/x86/entry] Error 2
make[1]: *** Waiting for unfinished jobs....
kernel/exit.o: warning: objtool: __x64_sys_exit_group()+0x14: unreachable instruction
make: *** [Makefile:1764: arch/x86] Error 2
make: *** Waiting for unfinished jobs....

If you move those aliases above all the __SYSCALL_* defines it will
work, since that will get the forward declaration too.  This would be
the simplest workaround.