Le 24/09/2021 à 08:39, Liu Shixin a écrit :
On platform PPC_FSL_BOOK3E, all lowmem is managed by tlbcam. That means
we didn't really map the kfence pool with page granularity. Therefore,
if KFENCE is enabled, the system will hit the following panic:
Could you please explain a bit more what the problem is ?
KFENCE has been implemented with the same logic as DEBUG_PAGEALLOC.
DEBUG_PAGEALLOC is enabled on FSL_BOOK3E.
In MMU_setup(), __map_without_ltlbs is set to 1 when KFENCE is enabled.
__map_without_ltlbs should disable the use of tlbcam.
So what's wrong really ?
Does DEBUG_PAGEALLOC work on FSL_BOOK3E ?
Thanks
Christophe
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc01de598
Oops: Kernel access of bad area, sig: 11 [#1]
BE PAGE_SIZE=4K SMP NR_CPUS=4 MPC8544 DS
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc3+ #298
NIP: c01de598 LR: c08ae9c4 CTR: 00000000
REGS: c0b4bea0 TRAP: 0300 Not tainted (5.12.0-rc3+)
MSR: 00021000 <CE,ME> CR: 24000228 XER: 20000000
DEAR: 00000000 ESR: 00000000
GPR00: c08ae9c4 c0b4bf60 c0ad64e0 ef720000 00021000 00000000 00000000
00000200
GPR08: c0ad5000 00000000 00000000 00000004 00000000 008fbb30 00000000
00000000
GPR16: 00000000 00000000 00000000 00000000 c0000000 00000000 00000000
00000000
GPR24: c08ca004 c08ca004 c0b6a0e0 c0b60000 c0b58f00 c0850000 c08ca000
ef720000
NIP [c01de598] kfence_protect+0x44/0x6c
LR [c08ae9c4] kfence_init+0xfc/0x2a4
Call Trace:
[c0b4bf60] [efffe160] 0xefffe160 (unreliable)
[c0b4bf70] [c08ae9c4] kfence_init+0xfc/0x2a4
[c0b4bfb0] [c0894d3c] start_kernel+0x3bc/0x574
[c0b4bff0] [c0000470] set_ivor+0x14c/0x188
Instruction dump:
7c0802a6 8109d594 546a653a 90010014 54630026 39200000 7d48502e 2c0a0000
41820010 554a0026 5469b53a 7d295214 <81490000> 38831000 554a003c 91490000
random: get_random_bytes called from print_oops_end_marker+0x40/0x78 with
crng_init=0
---[ end trace 0000000000000000 ]---
Signed-off-by: Liu Shixin <liushix...@huawei.com>
---
arch/powerpc/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d46db0bfb998..cffd57bcb5e4 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,7 +185,7 @@ config PPC
select HAVE_ARCH_KASAN if PPC32 && PPC_PAGE_SHIFT <= 14
select HAVE_ARCH_KASAN_VMALLOC if PPC32 && PPC_PAGE_SHIFT <= 14
select HAVE_ARCH_KGDB
- select HAVE_ARCH_KFENCE if PPC32
+ select HAVE_ARCH_KFENCE if PPC32 && !PPC_FSL_BOOK3E
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_NVRAM_OPS
