lkml.org 
[lkml]   [2021]   [Sep]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH] powerpc: don't select KFENCE on platform PPC_FSL_BOOK3E
From
Date
On 2021/9/24 14:41, Christophe Leroy wrote:
>
>
> 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
hi Christophe,

In the last e-mail I have said that DEBUG_PAGEALLOC works well on FSL_BOOK3E, that is wrong.
Actually, I add some printed information and find DEBUG_PAGEALLOC Skip all pages.
So neither DEBUG_PAGEALLOC nor kfence is really working.

diff --git a/mm/memory.c b/mm/memory.c
index 25fc46e87214..37fb1b14bc3f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2564,8 +2564,10 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
}
do {
next = pmd_addr_end(addr, end);
- if (pmd_none(*pmd) && !create)
+ if (pmd_none(*pmd) && !create) {
+ pr_info("---------pmd_none----------\n");
continue;
+ }
if (WARN_ON_ONCE(pmd_leaf(*pmd)))
return -EINVAL;
if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
>
>>
>> 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 <liushixin2@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
>>
> .
>

\
 
 \ /
  Last update: 2021-09-28 05:08    [W:0.179 / U:0.364 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site