Re: [PATCH 3/4] mm: remove compat_sys_move_pages
From: Christoph Hellwig
Date: Sat Sep 19 2020 - 01:38:14 EST
On Fri, Sep 18, 2020 at 03:24:38PM +0200, Arnd Bergmann wrote:
> The compat move_pages() implementation uses compat_alloc_user_space()
> for converting the pointer array. Moving the compat handling into
> the function itself is a bit simpler and lets us avoid the
> compat_alloc_user_space() call.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> arch/arm64/include/asm/unistd32.h | 2 +-
> arch/mips/kernel/syscalls/syscall_n32.tbl | 2 +-
> arch/mips/kernel/syscalls/syscall_o32.tbl | 2 +-
> arch/parisc/kernel/syscalls/syscall.tbl | 2 +-
> arch/powerpc/kernel/syscalls/syscall.tbl | 2 +-
> arch/s390/kernel/syscalls/syscall.tbl | 2 +-
> arch/sparc/kernel/syscalls/syscall.tbl | 2 +-
> arch/x86/entry/syscalls/syscall_32.tbl | 2 +-
> arch/x86/entry/syscalls/syscall_64.tbl | 2 +-
> include/linux/compat.h | 5 ---
> include/uapi/asm-generic/unistd.h | 2 +-
> kernel/sys_ni.c | 1 -
> mm/migrate.c | 45 +++++++++++------------
> 13 files changed, 32 insertions(+), 39 deletions(-)
>
> diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
> index b6517df74037..af793775ba98 100644
> --- a/arch/arm64/include/asm/unistd32.h
> +++ b/arch/arm64/include/asm/unistd32.h
> @@ -699,7 +699,7 @@ __SYSCALL(__NR_tee, sys_tee)
> #define __NR_vmsplice 343
> __SYSCALL(__NR_vmsplice, compat_sys_vmsplice)
> #define __NR_move_pages 344
> -__SYSCALL(__NR_move_pages, compat_sys_move_pages)
> +__SYSCALL(__NR_move_pages, sys_move_pages)
> #define __NR_getcpu 345
> __SYSCALL(__NR_getcpu, sys_getcpu)
> #define __NR_epoll_pwait 346
> diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
> index ad157aab4c09..7fa1ca45e44c 100644
> --- a/arch/mips/kernel/syscalls/syscall_n32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
> @@ -279,7 +279,7 @@
> 268 n32 sync_file_range sys_sync_file_range
> 269 n32 tee sys_tee
> 270 n32 vmsplice compat_sys_vmsplice
> -271 n32 move_pages compat_sys_move_pages
> +271 n32 move_pages sys_move_pages
> 272 n32 set_robust_list compat_sys_set_robust_list
> 273 n32 get_robust_list compat_sys_get_robust_list
> 274 n32 kexec_load sys_kexec_load
> diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
> index 57baf6c8008f..194c7fbeedf7 100644
> --- a/arch/mips/kernel/syscalls/syscall_o32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
> @@ -319,7 +319,7 @@
> 305 o32 sync_file_range sys_sync_file_range sys32_sync_file_range
> 306 o32 tee sys_tee
> 307 o32 vmsplice sys_vmsplice compat_sys_vmsplice
> -308 o32 move_pages sys_move_pages compat_sys_move_pages
> +308 o32 move_pages sys_move_pages
> 309 o32 set_robust_list sys_set_robust_list compat_sys_set_robust_list
> 310 o32 get_robust_list sys_get_robust_list compat_sys_get_robust_list
> 311 o32 kexec_load sys_kexec_load
> diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
> index 778bf166d7bd..5c17edaffe70 100644
> --- a/arch/parisc/kernel/syscalls/syscall.tbl
> +++ b/arch/parisc/kernel/syscalls/syscall.tbl
> @@ -331,7 +331,7 @@
> 292 64 sync_file_range sys_sync_file_range
> 293 common tee sys_tee
> 294 common vmsplice sys_vmsplice compat_sys_vmsplice
> -295 common move_pages sys_move_pages compat_sys_move_pages
> +295 common move_pages sys_move_pages
> 296 common getcpu sys_getcpu
> 297 common epoll_pwait sys_epoll_pwait compat_sys_epoll_pwait
> 298 common statfs64 sys_statfs64 compat_sys_statfs64
> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> index f128ba8b9a71..04fb42d7b377 100644
> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> @@ -389,7 +389,7 @@
> 298 common faccessat sys_faccessat
> 299 common get_robust_list sys_get_robust_list compat_sys_get_robust_list
> 300 common set_robust_list sys_set_robust_list compat_sys_set_robust_list
> -301 common move_pages sys_move_pages compat_sys_move_pages
> +301 common move_pages sys_move_pages
> 302 common getcpu sys_getcpu
> 303 nospu epoll_pwait sys_epoll_pwait compat_sys_epoll_pwait
> 304 32 utimensat sys_utimensat_time32
> diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
> index d45952058be2..3197965d45e9 100644
> --- a/arch/s390/kernel/syscalls/syscall.tbl
> +++ b/arch/s390/kernel/syscalls/syscall.tbl
> @@ -317,7 +317,7 @@
> 307 common sync_file_range sys_sync_file_range compat_sys_s390_sync_file_range
> 308 common tee sys_tee sys_tee
> 309 common vmsplice sys_vmsplice compat_sys_vmsplice
> -310 common move_pages sys_move_pages compat_sys_move_pages
> +310 common move_pages sys_move_pages
> 311 common getcpu sys_getcpu sys_getcpu
> 312 common epoll_pwait sys_epoll_pwait compat_sys_epoll_pwait
> 313 common utimes sys_utimes sys_utimes_time32
> diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
> index a46edcdd950d..e36ac364e61a 100644
> --- a/arch/sparc/kernel/syscalls/syscall.tbl
> +++ b/arch/sparc/kernel/syscalls/syscall.tbl
> @@ -370,7 +370,7 @@
> 304 common get_mempolicy sys_get_mempolicy compat_sys_get_mempolicy
> 305 common set_mempolicy sys_set_mempolicy compat_sys_set_mempolicy
> 306 common kexec_load sys_kexec_load sys_kexec_load
> -307 common move_pages sys_move_pages compat_sys_move_pages
> +307 common move_pages sys_move_pages
> 308 common getcpu sys_getcpu
> 309 common epoll_pwait sys_epoll_pwait compat_sys_epoll_pwait
> 310 32 utimensat sys_utimensat_time32
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index 7e4140b78aad..b3263b8b2eae 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -328,7 +328,7 @@
> 314 i386 sync_file_range sys_ia32_sync_file_range
> 315 i386 tee sys_tee
> 316 i386 vmsplice sys_vmsplice compat_sys_vmsplice
> -317 i386 move_pages sys_move_pages compat_sys_move_pages
> +317 i386 move_pages sys_move_pages
> 318 i386 getcpu sys_getcpu
> 319 i386 epoll_pwait sys_epoll_pwait
> 320 i386 utimensat sys_utimensat_time32
> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
> index 9986f5f08278..4a997a0cbf47 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -389,7 +389,7 @@
> 530 x32 set_robust_list compat_sys_set_robust_list
> 531 x32 get_robust_list compat_sys_get_robust_list
> 532 x32 vmsplice compat_sys_vmsplice
> -533 x32 move_pages compat_sys_move_pages
> +533 x32 move_pages sys_move_pages
> 534 x32 preadv compat_sys_preadv64
> 535 x32 pwritev compat_sys_pwritev64
> 536 x32 rt_tgsigqueueinfo compat_sys_rt_tgsigqueueinfo
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index a7a5a0ff59ef..db1d7ac2c9e0 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -763,11 +763,6 @@ asmlinkage long compat_sys_set_mempolicy(int mode, compat_ulong_t __user *nmask,
> asmlinkage long compat_sys_migrate_pages(compat_pid_t pid,
> compat_ulong_t maxnode, const compat_ulong_t __user *old_nodes,
> const compat_ulong_t __user *new_nodes);
> -asmlinkage long compat_sys_move_pages(pid_t pid, compat_ulong_t nr_pages,
> - __u32 __user *pages,
> - const int __user *nodes,
> - int __user *status,
> - int flags);
>
> asmlinkage long compat_sys_rt_tgsigqueueinfo(compat_pid_t tgid,
> compat_pid_t pid, int sig,
> diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> index 83f1fc7fd3d7..4da51702fb21 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -681,7 +681,7 @@ __SC_COMP(__NR_set_mempolicy, sys_set_mempolicy, compat_sys_set_mempolicy)
> #define __NR_migrate_pages 238
> __SC_COMP(__NR_migrate_pages, sys_migrate_pages, compat_sys_migrate_pages)
> #define __NR_move_pages 239
> -__SC_COMP(__NR_move_pages, sys_move_pages, compat_sys_move_pages)
> +__SYSCALL(__NR_move_pages, sys_move_pages)
> #endif
>
> #define __NR_rt_tgsigqueueinfo 240
> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> index c925d1e1777e..783a24ceee88 100644
> --- a/kernel/sys_ni.c
> +++ b/kernel/sys_ni.c
> @@ -290,7 +290,6 @@ COND_SYSCALL_COMPAT(set_mempolicy);
> COND_SYSCALL(migrate_pages);
> COND_SYSCALL_COMPAT(migrate_pages);
> COND_SYSCALL(move_pages);
> -COND_SYSCALL_COMPAT(move_pages);
>
> COND_SYSCALL(perf_event_open);
> COND_SYSCALL(accept4);
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 34a842a8eb6a..e9dfbde5f12c 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1835,6 +1835,27 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
> mmap_read_unlock(mm);
> }
>
> +static int put_pages_array(const void __user *chunk_pages[],
> + const void __user * __user *pages,
> + unsigned long chunk_nr)
> +{
> + compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages;
> + compat_uptr_t p;
> + int i;
> +
> + if (!in_compat_syscall())
> + return copy_from_user(chunk_pages, pages,
> + chunk_nr * sizeof(*chunk_pages));
> +
> + for (i = 0; i < chunk_nr; i++) {
> + if (get_user(p, pages32 + i))
> + return -EFAULT;
> + chunk_pages[i] = compat_ptr(p);
> + }
> +
> + return 0;
I'd just keep the native version inline and have the compat one in
a helper, but that is just a minor detail.