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From: Michael Ellerman <mpe@ellerman.id.au>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v6 16/22] powerpc/book3s64/kuap: Improve error reporting with KUAP
Date: Thu, 26 Nov 2020 20:29:16 +1100	[thread overview]
Message-ID: <87r1ogxy8j.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <87h7pctvdl.fsf@linux.ibm.com>

"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>
>> Le 25/11/2020 à 06:16, Aneesh Kumar K.V a écrit :
>>> With hash translation use DSISR_KEYFAULT to identify a wrong access.
>>> With Radix we look at the AMR value and type of fault.
>>> 
>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>> ---
>>>   arch/powerpc/include/asm/book3s/32/kup.h     |  4 +--
>>>   arch/powerpc/include/asm/book3s/64/kup.h     | 27 ++++++++++++++++----
>>>   arch/powerpc/include/asm/kup.h               |  4 +--
>>>   arch/powerpc/include/asm/nohash/32/kup-8xx.h |  4 +--
>>>   arch/powerpc/mm/fault.c                      |  2 +-
>>>   5 files changed, 29 insertions(+), 12 deletions(-)
>>> 
>>> diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
>>> index 32fd4452e960..b18cd931e325 100644
>>> --- a/arch/powerpc/include/asm/book3s/32/kup.h
>>> +++ b/arch/powerpc/include/asm/book3s/32/kup.h
>>> @@ -177,8 +177,8 @@ static inline void restore_user_access(unsigned long flags)
>>>   		allow_user_access(to, to, end - addr, KUAP_READ_WRITE);
>>>   }
>>>   
>>> -static inline bool
>>> -bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
>>> +static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
>>> +				  bool is_write, unsigned long error_code)
>>>   {
>>>   	unsigned long begin = regs->kuap & 0xf0000000;
>>>   	unsigned long end = regs->kuap << 28;
>>> diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
>>> index 4a3d0d601745..2922c442a218 100644
>>> --- a/arch/powerpc/include/asm/book3s/64/kup.h
>>> +++ b/arch/powerpc/include/asm/book3s/64/kup.h
>>> @@ -301,12 +301,29 @@ static inline void set_kuap(unsigned long value)
>>>   	isync();
>>>   }
>>>   
>>> -static inline bool
>>> -bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
>>> +#define RADIX_KUAP_BLOCK_READ	UL(0x4000000000000000)
>>> +#define RADIX_KUAP_BLOCK_WRITE	UL(0x8000000000000000)
>>> +
>>> +static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
>>> +				  bool is_write, unsigned long error_code)
>>>   {
>>> -	return WARN(mmu_has_feature(MMU_FTR_KUAP) &&
>>> -		    (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)),
>>> -		    "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
>>> +	if (!mmu_has_feature(MMU_FTR_KUAP))
>>> +		return false;
>>> +
>>> +	if (radix_enabled()) {
>>> +		/*
>>> +		 * Will be a storage protection fault.
>>> +		 * Only check the details of AMR[0]
>>> +		 */
>>> +		return WARN((regs->kuap & (is_write ? RADIX_KUAP_BLOCK_WRITE : RADIX_KUAP_BLOCK_READ)),
>>> +			    "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
>>
>> I think it is pointless to keep the WARN() here.
>>
>> I have a series aiming at removing them. See 
>> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/cc9129bdda1dbc2f0a09cf45fece7d0b0e690784.1605541983.git.christophe.leroy@csgroup.eu/
>
> Can we do this as a spearate patch as you posted above? We can drop the
> WARN in that while keeping the hash branch to look at DSISR value.

Yeah we can reconcile Christophe's series with yours later.

I'm still not 100% convinced I want to drop that WARN.

cheers

  reply	other threads:[~2020-11-26  9:31 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-25  5:16 [PATCH v6 00/22] Kernel userspace access/execution prevention with hash translation Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 01/22] powerpc: Add new macro to handle NESTED_IFCLR Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 02/22] KVM: PPC: BOOK3S: PR: Ignore UAMOR SPR Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 03/22] powerpc/book3s64/kuap/kuep: Make KUAP and KUEP a subfeature of PPC_MEM_KEYS Aneesh Kumar K.V
2020-11-25 13:30   ` Christophe Leroy
2020-11-25 14:57     ` Aneesh Kumar K.V
2020-11-26  3:25   ` Michael Ellerman
2020-11-25  5:16 ` [PATCH v6 04/22] powerpc/book3s64/kuap/kuep: Move uamor setup to pkey init Aneesh Kumar K.V
2020-11-25 13:32   ` Christophe Leroy
2020-11-26  3:28   ` Michael Ellerman
2020-11-25  5:16 ` [PATCH v6 05/22] powerpc/book3s64/kuap: Move KUAP related function outside radix Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 06/22] powerpc/book3s64/kuep: Move KUEP " Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 07/22] powerpc/book3s64/kuap: Rename MMU_FTR_RADIX_KUAP to MMU_FTR_KUAP Aneesh Kumar K.V
2020-11-25 13:43   ` Christophe Leroy
2020-11-25 13:52     ` Aneesh Kumar K.V
2020-11-26  3:16   ` Michael Ellerman
2020-11-25  5:16 ` [PATCH v6 08/22] powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 09/22] powerpc/exec: Set thread.regs early during exec Aneesh Kumar K.V
2020-11-25 13:47   ` Christophe Leroy
2020-11-26  7:38     ` Aneesh Kumar K.V
2020-11-26  7:43       ` Christophe Leroy
2020-11-25  5:16 ` [PATCH v6 10/22] powerpc/book3s64/pkeys: Store/restore userspace AMR/IAMR correctly on entry and exit from kernel Aneesh Kumar K.V
2020-11-25 13:52   ` Christophe Leroy
2020-11-25 13:55     ` Aneesh Kumar K.V
2020-11-25 14:16       ` Christophe Leroy
2020-11-25  5:16 ` [PATCH v6 11/22] powerpc/book3s64/pkeys: Inherit correctly on fork Aneesh Kumar K.V
2020-11-25 13:54   ` Christophe Leroy
2020-11-25 13:56     ` Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 12/22] powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 13/22] powerpc/ptrace-view: Use pt_regs values instead of thread_struct based one Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 14/22] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 15/22] powerpc/book3s64/kuap: Restrict access to userspace based on userspace AMR Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 16/22] powerpc/book3s64/kuap: Improve error reporting with KUAP Aneesh Kumar K.V
2020-11-25 14:04   ` Christophe Leroy
2020-11-26  7:44     ` Aneesh Kumar K.V
2020-11-26  9:29       ` Michael Ellerman [this message]
2020-11-26 10:39         ` Christophe Leroy
2020-11-25  5:16 ` [PATCH v6 17/22] powerpc/book3s64/kuap: Use Key 3 to implement KUAP with hash translation Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 18/22] powerpc/book3s64/kuep: Use Key 3 to implement KUEP " Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 19/22] powerpc/book3s64/hash/kuap: Enable kuap on hash Aneesh Kumar K.V
2021-03-15 12:06   ` Christophe Leroy
2021-03-15 12:59     ` Aneesh Kumar K.V
2021-03-15 13:02       ` Christophe Leroy
2021-10-08  9:32   ` Christophe Leroy
2021-10-11  3:28     ` Michael Ellerman
2020-11-25  5:16 ` [PATCH v6 20/22] powerpc/book3s64/hash/kuep: Enable KUEP " Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 21/22] powerpc/book3s64/hash/kup: Don't hardcode kup key Aneesh Kumar K.V
2020-11-25  5:16 ` [PATCH v6 22/22] powerpc/book3s64/pkeys: Optimize FTR_KUAP and FTR_KUEP disabled case Aneesh Kumar K.V

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