| From 1900b7c08a5b74ec12729efacff06a1480943ebd Mon Sep 17 00:00:00 2001 |
| From: Christophe Leroy <christophe.leroy@c-s.fr> |
| Date: Mon, 19 Aug 2019 06:40:25 +0000 |
| Subject: [PATCH] powerpc/603: Fix handling of the DIRTY flag |
| |
| commit 415480dce2ef03bb8335deebd2f402f475443ce0 upstream. |
| |
| If a page is already mapped RW without the DIRTY flag, the DIRTY |
| flag is never set and a TLB store miss exception is taken forever. |
| |
| This is easily reproduced with the following app: |
| |
| void main(void) |
| { |
| volatile char *ptr = mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); |
| |
| *ptr = *ptr; |
| } |
| |
| When DIRTY flag is not set, bail out of TLB miss handler and take |
| a minor page fault which will set the DIRTY flag. |
| |
| Fixes: f8b58c64eaef ("powerpc/603: let's handle PAGE_DIRTY directly") |
| Cc: stable@vger.kernel.org # v5.1+ |
| Reported-by: Doug Crawford <doug.crawford@intelight-its.com> |
| Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> |
| Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
| Link: https://lore.kernel.org/r/80432f71194d7ee75b2f5043ecf1501cf1cca1f3.1566196646.git.christophe.leroy@c-s.fr |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S |
| index f255e22184b4..534dd2718795 100644 |
| --- a/arch/powerpc/kernel/head_32.S |
| +++ b/arch/powerpc/kernel/head_32.S |
| @@ -557,9 +557,9 @@ DataStoreTLBMiss: |
| cmplw 0,r1,r3 |
| mfspr r2, SPRN_SPRG_PGDIR |
| #ifdef CONFIG_SWAP |
| - li r1, _PAGE_RW | _PAGE_PRESENT | _PAGE_ACCESSED |
| + li r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT | _PAGE_ACCESSED |
| #else |
| - li r1, _PAGE_RW | _PAGE_PRESENT |
| + li r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT |
| #endif |
| bge- 112f |
| lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */ |
| -- |
| 2.7.4 |
| |
