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 --- Documentation/xtensa/mmu.rst | 9 ++++++--- arch/xtensa/include/asm/pgtable.h | 2 +- 2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/Documentation/xtensa/mmu.rst b/Documentation/xtensa/mmu.rst index e52a12960fdc..450573afa31a 100644 --- 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 diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm/pgtable.h index fa054a1772e1..4dc04e6c01d7 100644 --- 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)