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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@c-s.fr>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>, npiggin@gmail.com,
        dja@axtens.net
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mm@kvack.org
Subject: Re: [PATCH v3 15/15] powerpc/32s: Activate CONFIG_VMAP_STACK
In-Reply-To: <a99bdfb64e287b16b8cd3f7ec1abfdfb50c7cc64.1568106758.git.christophe.leroy@c-s.fr>
References: <cover.1568106758.git.christophe.leroy@c-s.fr> <a99bdfb64e287b16b8cd3f7ec1abfdfb50c7cc64.1568106758.git.christophe.leroy@c-s.fr>
Date:   Tue, 19 Nov 2019 17:58:14 +1100
Message-ID: <875zjgcpyx.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
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Christophe Leroy <christophe.leroy@c-s.fr> writes:
> A few changes to retrieve DAR and DSISR from struct regs
> instead of retrieving them directly, as they may have
> changed due to a TLB miss.
>
> Also modifies hash_page() and friends to work with virtual
> data addresses instead of physical ones.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
>  arch/powerpc/kernel/entry_32.S         |  4 +++
>  arch/powerpc/kernel/head_32.S          | 19 +++++++++++---
>  arch/powerpc/kernel/head_32.h          |  4 ++-
>  arch/powerpc/mm/book3s32/hash_low.S    | 46 +++++++++++++++++++++-------------
>  arch/powerpc/mm/book3s32/mmu.c         |  9 +++++--
>  arch/powerpc/platforms/Kconfig.cputype |  2 ++
>  6 files changed, 61 insertions(+), 23 deletions(-)

This is faulting with qemu mac99 model:

  Key type id_resolver registered
  Key type id_legacy registered
  BUG: Unable to handle kernel data access on read at 0x2f0db684
  Faulting instruction address: 0x00004130
  Oops: Kernel access of bad area, sig: 11 [#1]
  BE PAGE_SIZE=4K MMU=Hash PowerMac
  Modules linked in:
  CPU: 0 PID: 65 Comm: modprobe Not tainted 5.4.0-rc2-gcc49+ #63
  NIP:  00004130 LR: 000008c8 CTR: b7eb86e0
  REGS: f106de80 TRAP: 0300   Not tainted  (5.4.0-rc2-gcc49+)
  MSR:  00003012 <FP,ME,DR,RI>  CR: 4106df38  XER: 20000000
  DAR: 2f0db684 DSISR: 40000000 
  GPR00: b7ec5d64 f106df38 00000000 bf988a70 00000000 2f0db540 b7ec3620 bf988d38 
  GPR08: 10000880 0000d032 72656773 f106df38 b7ed10ec 00000000 b7ed3d38 b7ee8900 
  GPR16: bf988d10 00000001 00000000 bf988d10 b7ec3620 bf988d50 b7ee76ec b7ee7320 
  GPR24: 10000878 00000000 b7ee8900 00000000 10029f00 10000879 b7ee7ff4 bf988d30 
  NIP [00004130] 0x4130
  LR [000008c8] 0x8c8
  Call Trace:
  [f106df38] [c0016224] ret_from_syscall+0x0/0x34 (unreliable)
  --- interrupt: c01 at 0xb7ed0f50
      LR = 0xb7ec5d64
  Instruction dump:
  db8300e0 XXXXXXXX XXXXXXXX XXXXXXXX fc00048e XXXXXXXX XXXXXXXX XXXXXXXX 
  60a52000 XXXXXXXX XXXXXXXX XXXXXXXX 80850144 XXXXXXXX XXXXXXXX XXXXXXXX 
  ---[ end trace 265da51c6d8b86c5 ]---


I think I'll have to drop this series for now.

cheers