On Thu, Jan 10, 2019 at 5:39 PM Will Deacon [off-list ref] wrote:

quoted

diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index 355fe2bc035b..19f3f58b6146 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h

@@ -823,6 +823,8 @@ __SYSCALL(__NR_rseq, sys_rseq)
 __SYSCALL(__NR_io_pgetevents, compat_sys_io_pgetevents)
 #define __NR_migrate_pages 400
 __SYSCALL(__NR_migrate_pages, sys_migrate_pages)
+#define __NR_kexec_file_load 401
+__SYSCALL(__NR_kexec_file_load, sys_kexec_file_load)

Hmm, I wonder if we need a compat wrapper for this, or are we assuming
that the early entry code has already zero-extended the long and pointer
arguments?

Yes, that is generally the assumption for compat syscalls.

s390 needs some extra magic to do a 31-to-64 extension on pointer
arguments, and I think sometimes we need a special wrapper to
do sign-extension of 32-bit arguments into 64-bit, but the arguments
here should not need that.

     Arnd