[PATCH 6.3 15/29] powerpc/mm: Convert to using lock_mm_and_find_vma()

Greg Kroah-Hartman
2023-06-29T18:46:26Z

From: Michael Ellerman <mpe@ellerman.id.au>

commit e6fe228c4ffafdfc970cf6d46883a1f481baf7ea upstream.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/mm/fault.c | 41 ++++-------------------------------------
2 files changed, 5 insertions(+), 37 deletions(-)

--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -263,6 +263,7 @@ config PPC
select IRQ_DOMAIN
select IRQ_FORCED_THREADING
select KASAN_VMALLOC if KASAN && MODULES
+ select LOCK_MM_AND_FIND_VMA
select MMU_GATHER_PAGE_SIZE
select MMU_GATHER_RCU_TABLE_FREE
select MMU_GATHER_MERGE_VMAS
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -84,11 +84,6 @@ static int __bad_area(struct pt_regs *re
return __bad_area_nosemaphore(regs, address, si_code);
}

-static noinline int bad_area(struct pt_regs *regs, unsigned long address)
-{
- return __bad_area(regs, address, SEGV_MAPERR);
-}
-
static noinline int bad_access_pkey(struct pt_regs *regs, unsigned long address,
struct vm_area_struct *vma)
{
@@ -481,40 +476,12 @@ static int ___do_page_fault(struct pt_re
* we will deadlock attempting to validate the fault against the
* address space. Luckily the kernel only validly references user
* space from well defined areas of code, which are listed in the
- * exceptions table.
- *
- * As the vast majority of faults will be valid we will only perform
- * the source reference check when there is a possibility of a deadlock.
- * Attempt to lock the address space, if we cannot we then validate the
- * source. If this is invalid we can skip the address space check,
- * thus avoiding the deadlock.
- */
- if (unlikely(!mmap_read_trylock(mm))) {
- if (!is_user && !search_exception_tables(regs->nip))
- return bad_area_nosemaphore(regs, address);
-
+ * exceptions table. lock_mm_and_find_vma() handles that logic.
+ */
retry:
- mmap_read_lock(mm);
- } else {
- /*
- * The above down_read_trylock() might have succeeded in
- * which case we'll have missed the might_sleep() from
- * down_read():
- */
- might_sleep();
- }
-
- vma = find_vma(mm, address);
+ vma = lock_mm_and_find_vma(mm, address, regs);
if (unlikely(!vma))
- return bad_area(regs, address);
-
- if (unlikely(vma->vm_start > address)) {
- if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
- return bad_area(regs, address);
-
- if (unlikely(expand_stack(vma, address)))
- return bad_area(regs, address);
- }
+ return bad_area_nosemaphore(regs, address);

if (unlikely(access_pkey_error(is_write, is_exec,
(error_code & DSISR_KEYFAULT), vma)))