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

[Xiaoming Ni]

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