[PATCH 5.9 227/252] xtensa: fix TLBTEMP area placement

Greg Kroah-Hartman
2020-11-23T13:06:33Z

From: Max Filippov <jcmvbkbc@gmail.com>

commit 481535c5b41d191b22775a6873de5ec0e1cdced1 upstream.

fast_second_level_miss handler for the TLBTEMP area has an assumption
that page table directory entry for the TLBTEMP address range is 0. For
it to be true the TLBTEMP area must be aligned to 4MB boundary and not
share its 4MB region with anything that may use a page table. This is
not true currently: TLBTEMP shares space with vmalloc space which
results in the following kinds of runtime errors when
fast_second_level_miss loads page table directory entry for the vmalloc
space instead of fixing up the TLBTEMP area:

Unable to handle kernel paging request at virtual address c7ff0e00
pc = d0009275, ra = 90009478
Oops: sig: 9 [#1] PREEMPT
CPU: 1 PID: 61 Comm: kworker/u9:2 Not tainted 5.10.0-rc3-next-20201110-00007-g1fe4962fa983-dirty #58
Workqueue: xprtiod xs_stream_data_receive_workfn
a00: 90009478 d11e1dc0 c7ff0e00 00000020 c7ff0000 00000001 7f8b8107 00000000
a08: 900c5992 d11e1d90 d0cc88b8 5506e97c 00000000 5506e97c d06c8074 d11e1d90
pc: d0009275, ps: 00060310, depc: 00000014, excvaddr: c7ff0e00
lbeg: d0009275, lend: d0009287 lcount: 00000003, sar: 00000010
Call Trace:
xs_stream_data_receive_workfn+0x43c/0x770
process_one_work+0x1a1/0x324
worker_thread+0x1cc/0x3c0
kthread+0x10d/0x124
ret_from_kernel_thread+0xc/0x18

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
Documentation/xtensa/mmu.rst | 9 ++++++---
arch/xtensa/include/asm/pgtable.h | 2 +-
2 files changed, 7 insertions(+), 4 deletions(-)

--- a/Documentation/xtensa/mmu.rst
+++ b/Documentation/xtensa/mmu.rst
@@ -82,7 +82,8 @@ Default MMUv2-compatible layout::
+------------------+
| VMALLOC area | VMALLOC_START 0xc0000000 128MB - 64KB
+------------------+ VMALLOC_END
- | Cache aliasing | TLBTEMP_BASE_1 0xc7ff0000 DCACHE_WAY_SIZE
+ +------------------+
+ | Cache aliasing | TLBTEMP_BASE_1 0xc8000000 DCACHE_WAY_SIZE
| remap area 1 |
+------------------+
| Cache aliasing | TLBTEMP_BASE_2 DCACHE_WAY_SIZE
@@ -124,7 +125,8 @@ Default MMUv2-compatible layout::
+------------------+
| VMALLOC area | VMALLOC_START 0xa0000000 128MB - 64KB
+------------------+ VMALLOC_END
- | Cache aliasing | TLBTEMP_BASE_1 0xa7ff0000 DCACHE_WAY_SIZE
+ +------------------+
+ | Cache aliasing | TLBTEMP_BASE_1 0xa8000000 DCACHE_WAY_SIZE
| remap area 1 |
+------------------+
| Cache aliasing | TLBTEMP_BASE_2 DCACHE_WAY_SIZE
@@ -167,7 +169,8 @@ Default MMUv2-compatible layout::
+------------------+
| VMALLOC area | VMALLOC_START 0x90000000 128MB - 64KB
+------------------+ VMALLOC_END
- | Cache aliasing | TLBTEMP_BASE_1 0x97ff0000 DCACHE_WAY_SIZE
+ +------------------+
+ | Cache aliasing | TLBTEMP_BASE_1 0x98000000 DCACHE_WAY_SIZE
| remap area 1 |
+------------------+
| Cache aliasing | TLBTEMP_BASE_2 DCACHE_WAY_SIZE
--- a/arch/xtensa/include/asm/pgtable.h
+++ b/arch/xtensa/include/asm/pgtable.h
@@ -69,7 +69,7 @@
*/
#define VMALLOC_START (XCHAL_KSEG_CACHED_VADDR - 0x10000000)
#define VMALLOC_END (VMALLOC_START + 0x07FEFFFF)
-#define TLBTEMP_BASE_1 (VMALLOC_END + 1)
+#define TLBTEMP_BASE_1 (VMALLOC_START + 0x08000000)
#define TLBTEMP_BASE_2 (TLBTEMP_BASE_1 + DCACHE_WAY_SIZE)
#if 2 * DCACHE_WAY_SIZE > ICACHE_WAY_SIZE
#define TLBTEMP_SIZE (2 * DCACHE_WAY_SIZE)