Re: [PATCH] s390: fix build error for sys_call_table_emu

From: Xiaoming Ni
Date: Thu Jun 18 2020 - 09:49:40 EST


On 2020/6/18 19:27, Heiko Carstens wrote:
On Thu, Jun 18, 2020 at 07:03:20PM +0800, Xiaoming Ni wrote:
Build error on s390:
arch/s390/kernel/entry.o: in function `sys_call_table_emu':
>> (.rodata+0x1288): undefined reference to `__s390_'

In commit ("All arch: remove system call sys_sysctl")
148 common fdatasync sys_fdatasync sys_fdatasync
-149 common _sysctl sys_sysctl compat_sys_sysctl
+149 common _sysctl sys_ni_syscall
150 common mlock sys_mlock sys_mlock

After the patch is integrated, there is a format error in the generated
arch/s390/include/generated/asm/syscall_table.h:
SYSCALL(sys_fdatasync, sys_fdatasync)
SYSCALL(sys_ni_syscall,) /* cause build error */
SYSCALL(sys_mlock,sys_mlock)

There are holes in the system call number in
arch/s390/kernel/syscalls/syscall.tbl. When generating syscall_table.h,
these hole numbers will be automatically filled with "NI_SYSCALL".
Therefore, delete the number 149 to fix the current compilation failure.
Similarly, modify tools/perf/arch/s390/entry/syscalls/syscall.tbl.

Fixes: ("All arch: remove system call sys_sysctl")
Fixes: https://lore.kernel.org/linuxppc-dev/20200616030734.87257-1-nixiaoming@xxxxxxxxxx/
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
---
arch/s390/kernel/syscalls/syscall.tbl | 1 -
tools/perf/arch/s390/entry/syscalls/syscall.tbl | 1 -
2 files changed, 2 deletions(-)

diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index f17aaf6fe5de..bcaf93994e3c 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -138,7 +138,6 @@
146 common writev sys_writev compat_sys_writev
147 common getsid sys_getsid sys_getsid
148 common fdatasync sys_fdatasync sys_fdatasync
-149 common _sysctl sys_ni_syscall

This is not correct. It should be changed to:

149 common _sysctl - -

thanks for your guidance

Otherwise the generated __NR__sysctl define will be lost from
unistd.h, which should not happen. Looking at the link above it
_looks_ like a similar mistake was done for arm64.

Using holes will cause the definition of __NR__sysctl to be missing in include/asm/unistd_32.h and include/asm/unistd_64.h

For arm64, I observed that "sys_afs_syscall", "sys_get_kernel_syms" and other commented out syscalls have no corresponding definition _NR_XXX in unistd.h, is it not a problem on arm64?

/* 127 was sys_create_module */
__SYSCALL(127, sys_ni_syscall)

/* 130 was sys_get_kernel_syms */
__SYSCALL(130, sys_ni_syscall)

/* 137 was sys_afs_syscall */
__SYSCALL(137, sys_ni_syscall)


Thanks
Xiaoming Ni