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mm: simplify compat_sys_move_pages 

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.

Link: https://lkml.kernel.org/r/20210727144859.4150043-4-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Arnd Bergmann 2021-09-08 15:18:17 -07:00 committed by Linus Torvalds
parent 5d700a0fd7
commit 5b1b561ba7
1 changed files with 30 additions and 15 deletions
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45
mm/migrate.c
View File

@ -1900,6 +1900,23 @@ set_status:
mmap_read_unlock(mm);
}
static int get_compat_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;
for (i = 0; i < chunk_nr; i++) {
if (get_user(p, pages32 + i))
return -EFAULT;
chunk_pages[i] = compat_ptr(p);
}
return 0;
}
/*
* Determine the nodes of a user array of pages and store it in
* a user array of status.
@ -1919,8 +1936,15 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
chunk_nr = DO_PAGES_STAT_CHUNK_NR;
if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages)))
break;
if (in_compat_syscall()) {
if (get_compat_pages_array(chunk_pages, pages,
chunk_nr))
break;
} else {
if (copy_from_user(chunk_pages, pages,
chunk_nr * sizeof(*chunk_pages)))
break;
}
do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
@ -2025,23 +2049,14 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages,
compat_uptr_t __user *, pages32,
compat_uptr_t __user *, pages,
const int __user *, nodes,
int __user *, status,
int, flags)
{
const void __user * __user *pages;
int i;
pages = compat_alloc_user_space(nr_pages * sizeof(void *));
for (i = 0; i < nr_pages; i++) {
compat_uptr_t p;
if (get_user(p, pages32 + i) ||
put_user(compat_ptr(p), pages + i))
return -EFAULT;
}
return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);
return kernel_move_pages(pid, nr_pages,
(const void __user *__user *)pages,
nodes, status, flags);
}
#endif /* CONFIG_COMPAT */