2018-03-27 03:23:30

by Philip Elcan

[permalink] [raw]
Subject: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

Several of the bits of the TLBI register operand are RES0 per the ARM
ARM, so TLBI operations should avoid writing non-zero values to these
bits.

This patch adds a macro __TLBI_VADDR(addr, asid) that creates the
operand register in the correct format and honors the RES0 bits.

Signed-off-by: Philip Elcan <[email protected]>
---
arch/arm64/include/asm/tlbflush.h | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index 9e82dd7..b1205e9 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -60,6 +60,15 @@
__tlbi(op, (arg) | USER_ASID_FLAG); \
} while (0)

+/* This macro creates a properly formatted VA operand for the TLBI */
+#define __TLBI_VADDR(addr, asid) \
+ ({ \
+ unsigned long __ta = (addr) >> 12; \
+ __ta &= GENMASK_ULL(43, 0); \
+ __ta |= (unsigned long)(asid) << 48; \
+ __ta; \
+ })
+
/*
* TLB Management
* ==============
@@ -117,7 +126,7 @@ static inline void flush_tlb_all(void)

static inline void flush_tlb_mm(struct mm_struct *mm)
{
- unsigned long asid = ASID(mm) << 48;
+ unsigned long asid = __TLBI_VADDR(0, ASID(mm));

dsb(ishst);
__tlbi(aside1is, asid);
@@ -128,7 +137,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
static inline void flush_tlb_page(struct vm_area_struct *vma,
unsigned long uaddr)
{
- unsigned long addr = uaddr >> 12 | (ASID(vma->vm_mm) << 48);
+ unsigned long addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));

dsb(ishst);
__tlbi(vale1is, addr);
@@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
return;
}

- start = asid | (start >> 12);
- end = asid | (end >> 12);
+ start = __TLBI_VADDR(start, asid);
+ end = __TLBI_VADDR(end, asid);

dsb(ishst);
for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12)) {
@@ -185,8 +194,8 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
return;
}

- start >>= 12;
- end >>= 12;
+ start = __TLBI_VADDR(start, 0);
+ end = __TLBI_VADDR(end, 0);

dsb(ishst);
for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12))
@@ -202,7 +211,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
static inline void __flush_tlb_pgtable(struct mm_struct *mm,
unsigned long uaddr)
{
- unsigned long addr = uaddr >> 12 | (ASID(mm) << 48);
+ unsigned long addr = __TLBI_VADDR(uaddr, ASID(mm));

__tlbi(vae1is, addr);
__tlbi_user(vae1is, addr);
--
Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.



2018-03-27 11:35:56

by Robin Murphy

[permalink] [raw]
Subject: Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

On 27/03/18 04:21, Philip Elcan wrote:
> Several of the bits of the TLBI register operand are RES0 per the ARM
> ARM, so TLBI operations should avoid writing non-zero values to these
> bits.
>
> This patch adds a macro __TLBI_VADDR(addr, asid) that creates the
> operand register in the correct format and honors the RES0 bits.
>
> Signed-off-by: Philip Elcan <[email protected]>
> ---
> arch/arm64/include/asm/tlbflush.h | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index 9e82dd7..b1205e9 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -60,6 +60,15 @@
> __tlbi(op, (arg) | USER_ASID_FLAG); \
> } while (0)
>
> +/* This macro creates a properly formatted VA operand for the TLBI */
> +#define __TLBI_VADDR(addr, asid) \
> + ({ \
> + unsigned long __ta = (addr) >> 12; \
> + __ta &= GENMASK_ULL(43, 0); \
> + __ta |= (unsigned long)(asid) << 48; \
> + __ta; \
> + })

I'd be inclined to make this a static inline function rather than a
macro, since it doesn't need to do any wacky type-dodging, but either
way the overall change now looks appropriate;

Acked-by: Robin Murphy <[email protected]>

Thanks,
Robin.

> +
> /*
> * TLB Management
> * ==============
> @@ -117,7 +126,7 @@ static inline void flush_tlb_all(void)
>
> static inline void flush_tlb_mm(struct mm_struct *mm)
> {
> - unsigned long asid = ASID(mm) << 48;
> + unsigned long asid = __TLBI_VADDR(0, ASID(mm));
>
> dsb(ishst);
> __tlbi(aside1is, asid);
> @@ -128,7 +137,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
> static inline void flush_tlb_page(struct vm_area_struct *vma,
> unsigned long uaddr)
> {
> - unsigned long addr = uaddr >> 12 | (ASID(vma->vm_mm) << 48);
> + unsigned long addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
>
> dsb(ishst);
> __tlbi(vale1is, addr);
> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
> return;
> }
>
> - start = asid | (start >> 12);
> - end = asid | (end >> 12);
> + start = __TLBI_VADDR(start, asid);
> + end = __TLBI_VADDR(end, asid);
>
> dsb(ishst);
> for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12)) {
> @@ -185,8 +194,8 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
> return;
> }
>
> - start >>= 12;
> - end >>= 12;
> + start = __TLBI_VADDR(start, 0);
> + end = __TLBI_VADDR(end, 0);
>
> dsb(ishst);
> for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12))
> @@ -202,7 +211,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
> static inline void __flush_tlb_pgtable(struct mm_struct *mm,
> unsigned long uaddr)
> {
> - unsigned long addr = uaddr >> 12 | (ASID(mm) << 48);
> + unsigned long addr = __TLBI_VADDR(uaddr, ASID(mm));
>
> __tlbi(vae1is, addr);
> __tlbi_user(vae1is, addr);
>

2018-03-27 14:54:48

by Shanker Donthineni

[permalink] [raw]
Subject: Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits


On 03/27/2018 06:34 AM, Robin Murphy wrote:
> On 27/03/18 04:21, Philip Elcan wrote:
>> Several of the bits of the TLBI register operand are RES0 per the ARM
>> ARM, so TLBI operations should avoid writing non-zero values to these
>> bits.
>>
>> This patch adds a macro __TLBI_VADDR(addr, asid) that creates the
>> operand register in the correct format and honors the RES0 bits.
>>
>> Signed-off-by: Philip Elcan <[email protected]>
>> ---
>>   arch/arm64/include/asm/tlbflush.h | 23 ++++++++++++++++-------
>>   1 file changed, 16 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
>> index 9e82dd7..b1205e9 100644
>> --- a/arch/arm64/include/asm/tlbflush.h
>> +++ b/arch/arm64/include/asm/tlbflush.h
>> @@ -60,6 +60,15 @@
>>           __tlbi(op, (arg) | USER_ASID_FLAG);                \
>>   } while (0)
>>   +/* This macro creates a properly formatted VA operand for the TLBI */
>> +#define __TLBI_VADDR(addr, asid)                \
>> +    ({                            \
>> +        unsigned long __ta = (addr) >> 12;        \
>> +        __ta &= GENMASK_ULL(43, 0);            \
>> +        __ta |= (unsigned long)(asid) << 48;        \
>> +        __ta;                        \
>> +    })
>
> I'd be inclined to make this a static inline function rather than a macro, since it doesn't need to do any wacky type-dodging, but either way the overall change now looks appropriate;
>
> Acked-by: Robin Murphy <[email protected]>
>

Tested-by: Shanker Donthineni <[email protected]>

> Thanks,
> Robin.
>
>> +
>>   /*
>>    *    TLB Management
>>    *    ==============
>> @@ -117,7 +126,7 @@ static inline void flush_tlb_all(void)
>>     static inline void flush_tlb_mm(struct mm_struct *mm)
>>   {
>> -    unsigned long asid = ASID(mm) << 48;
>> +    unsigned long asid = __TLBI_VADDR(0, ASID(mm));
>>         dsb(ishst);
>>       __tlbi(aside1is, asid);
>> @@ -128,7 +137,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
>>   static inline void flush_tlb_page(struct vm_area_struct *vma,
>>                     unsigned long uaddr)
>>   {
>> -    unsigned long addr = uaddr >> 12 | (ASID(vma->vm_mm) << 48);
>> +    unsigned long addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
>>         dsb(ishst);
>>       __tlbi(vale1is, addr);
>> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
>>           return;
>>       }
>>   -    start = asid | (start >> 12);
>> -    end = asid | (end >> 12);
>> +    start = __TLBI_VADDR(start, asid);
>> +    end = __TLBI_VADDR(end, asid);
>>         dsb(ishst);
>>       for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12)) {
>> @@ -185,8 +194,8 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
>>           return;
>>       }
>>   -    start >>= 12;
>> -    end >>= 12;
>> +    start = __TLBI_VADDR(start, 0);
>> +    end = __TLBI_VADDR(end, 0);
>>         dsb(ishst);
>>       for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12))
>> @@ -202,7 +211,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
>>   static inline void __flush_tlb_pgtable(struct mm_struct *mm,
>>                          unsigned long uaddr)
>>   {
>> -    unsigned long addr = uaddr >> 12 | (ASID(mm) << 48);
>> +    unsigned long addr = __TLBI_VADDR(uaddr, ASID(mm));
>>         __tlbi(vae1is, addr);
>>       __tlbi_user(vae1is, addr);
>>

--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

2018-03-27 17:38:45

by Will Deacon

[permalink] [raw]
Subject: Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

Hi Shanker,

On Tue, Mar 27, 2018 at 09:53:16AM -0500, Shanker Donthineni wrote:
> On 03/27/2018 06:34 AM, Robin Murphy wrote:
> > On 27/03/18 04:21, Philip Elcan wrote:
> >> Several of the bits of the TLBI register operand are RES0 per the ARM
> >> ARM, so TLBI operations should avoid writing non-zero values to these
> >> bits.
> >>
> >> This patch adds a macro __TLBI_VADDR(addr, asid) that creates the
> >> operand register in the correct format and honors the RES0 bits.
> >>
> >> Signed-off-by: Philip Elcan <[email protected]>
> >> ---
> >> ? arch/arm64/include/asm/tlbflush.h | 23 ++++++++++++++++-------
> >> ? 1 file changed, 16 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> >> index 9e82dd7..b1205e9 100644
> >> --- a/arch/arm64/include/asm/tlbflush.h
> >> +++ b/arch/arm64/include/asm/tlbflush.h
> >> @@ -60,6 +60,15 @@
> >> ????????? __tlbi(op, (arg) | USER_ASID_FLAG);??????????????? \
> >> ? } while (0)
> >> ? +/* This macro creates a properly formatted VA operand for the TLBI */
> >> +#define __TLBI_VADDR(addr, asid)??????????????? \
> >> +??? ({??????????????????????????? \
> >> +??????? unsigned long __ta = (addr) >> 12;??????? \
> >> +??????? __ta &= GENMASK_ULL(43, 0);??????????? \
> >> +??????? __ta |= (unsigned long)(asid) << 48;??????? \
> >> +??????? __ta;??????????????????????? \
> >> +??? })
> >
> > I'd be inclined to make this a static inline function rather than a
> > macro, since it doesn't need to do any wacky type-dodging, but either
> > way the overall change now looks appropriate;
> >
> > Acked-by: Robin Murphy <[email protected]>
> >
>
> Tested-by: Shanker Donthineni <[email protected]>

[...]

> >> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
> >> ????????? return;
> >> ????? }
> >> ? -??? start = asid | (start >> 12);
> >> -??? end = asid | (end >> 12);
> >> +??? start = __TLBI_VADDR(start, asid);
> >> +??? end = __TLBI_VADDR(end, asid);

Can you test this bit too, please? ;)

Will

2018-03-28 01:04:27

by Shanker Donthineni

[permalink] [raw]
Subject: Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

Hi Will,

On 03/27/2018 12:36 PM, Will Deacon wrote:
> Hi Shanker,
>
> On Tue, Mar 27, 2018 at 09:53:16AM -0500, Shanker Donthineni wrote:
>> On 03/27/2018 06:34 AM, Robin Murphy wrote:
>>> On 27/03/18 04:21, Philip Elcan wrote:
>>>> Several of the bits of the TLBI register operand are RES0 per the ARM
>>>> ARM, so TLBI operations should avoid writing non-zero values to these
>>>> bits.
>>>>
>>>> This patch adds a macro __TLBI_VADDR(addr, asid) that creates the
>>>> operand register in the correct format and honors the RES0 bits.
>>>>
>>>> Signed-off-by: Philip Elcan <[email protected]>
>>>> ---
>>>>   arch/arm64/include/asm/tlbflush.h | 23 ++++++++++++++++-------
>>>>   1 file changed, 16 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
>>>> index 9e82dd7..b1205e9 100644
>>>> --- a/arch/arm64/include/asm/tlbflush.h
>>>> +++ b/arch/arm64/include/asm/tlbflush.h
>>>> @@ -60,6 +60,15 @@
>>>>           __tlbi(op, (arg) | USER_ASID_FLAG);                \
>>>>   } while (0)
>>>>   +/* This macro creates a properly formatted VA operand for the TLBI */
>>>> +#define __TLBI_VADDR(addr, asid)                \
>>>> +    ({                            \
>>>> +        unsigned long __ta = (addr) >> 12;        \
>>>> +        __ta &= GENMASK_ULL(43, 0);            \
>>>> +        __ta |= (unsigned long)(asid) << 48;        \
>>>> +        __ta;                        \
>>>> +    })
>>>
>>> I'd be inclined to make this a static inline function rather than a
>>> macro, since it doesn't need to do any wacky type-dodging, but either
>>> way the overall change now looks appropriate;
>>>
>>> Acked-by: Robin Murphy <[email protected]>
>>>
>>
>> Tested-by: Shanker Donthineni <[email protected]>
>
> [...]
>
>>>> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
>>>>           return;
>>>>       }
>>>>   -    start = asid | (start >> 12);
>>>> -    end = asid | (end >> 12);
>>>> +    start = __TLBI_VADDR(start, asid);
>>>> +    end = __TLBI_VADDR(end, asid);
>
> Can you test this bit too, please? ;)
>

I've verified the basic boot functionality on QDF2400 platform. But I can see now
after your comments, it leads to TLB conflicts because of ASID is truncated to zero
due to two times 48bit shift.

Thanks for catching this one.

@@ -146,7 +155,7 @@ static inline void __flush_tlb_range(structvm_area_struct *
unsigned long start, unsigned long end,
bool last_level)
{
- unsigned long asid = ASID(vma->vm_mm) << 48;
+ unsigned long asid = ASID(vma->vm_mm);
unsigned long addr;

if ((end - start) > MAX_TLB_RANGE) {
@@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct
vm_area_struct *
return;
}

- start = asid | (start >> 12);
- end = asid | (end >> 12);
+ start = __TLBI_VADDR(start, asid);
+ end = __TLBI_VADDR(end, asid);


> Will
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

2018-03-28 01:10:15

by Philip Elcan

[permalink] [raw]
Subject: Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

On 3/27/2018 9:03 PM, Shanker Donthineni wrote:
> Hi Will,
>
> On 03/27/2018 12:36 PM, Will Deacon wrote:
>> Hi Shanker,
>>
>> On Tue, Mar 27, 2018 at 09:53:16AM -0500, Shanker Donthineni wrote:
>>> On 03/27/2018 06:34 AM, Robin Murphy wrote:
>>>> On 27/03/18 04:21, Philip Elcan wrote:
>>>>> Several of the bits of the TLBI register operand are RES0 per the ARM
>>>>> ARM, so TLBI operations should avoid writing non-zero values to these
>>>>> bits.
>>>>>
>>>>> This patch adds a macro __TLBI_VADDR(addr, asid) that creates the
>>>>> operand register in the correct format and honors the RES0 bits.
>>>>>
>>>>> Signed-off-by: Philip Elcan <[email protected]>
>>>>> ---
>>>>>   arch/arm64/include/asm/tlbflush.h | 23 ++++++++++++++++-------
>>>>>   1 file changed, 16 insertions(+), 7 deletions(-)
>>>>>
>>>>> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
>>>>> index 9e82dd7..b1205e9 100644
>>>>> --- a/arch/arm64/include/asm/tlbflush.h
>>>>> +++ b/arch/arm64/include/asm/tlbflush.h
>>>>> @@ -60,6 +60,15 @@
>>>>>           __tlbi(op, (arg) | USER_ASID_FLAG);                \
>>>>>   } while (0)
>>>>>   +/* This macro creates a properly formatted VA operand for the TLBI */
>>>>> +#define __TLBI_VADDR(addr, asid)                \
>>>>> +    ({                            \
>>>>> +        unsigned long __ta = (addr) >> 12;        \
>>>>> +        __ta &= GENMASK_ULL(43, 0);            \
>>>>> +        __ta |= (unsigned long)(asid) << 48;        \
>>>>> +        __ta;                        \
>>>>> +    })
>>>>
>>>> I'd be inclined to make this a static inline function rather than a
>>>> macro, since it doesn't need to do any wacky type-dodging, but either
>>>> way the overall change now looks appropriate;
>>>>
>>>> Acked-by: Robin Murphy <[email protected]>
>>>>
>>>
>>> Tested-by: Shanker Donthineni <[email protected]>
>>
>> [...]
>>
>>>>> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
>>>>>           return;
>>>>>       }
>>>>>   -    start = asid | (start >> 12);
>>>>> -    end = asid | (end >> 12);
>>>>> +    start = __TLBI_VADDR(start, asid);
>>>>> +    end = __TLBI_VADDR(end, asid);
>>
>> Can you test this bit too, please? ;)
>>
>
> I've verified the basic boot functionality on QDF2400 platform. But I can see now
> after your comments, it leads to TLB conflicts because of ASID is truncated to zero
> due to two times 48bit shift.
>
> Thanks for catching this one.
>
> @@ -146,7 +155,7 @@ static inline void __flush_tlb_range(structvm_area_struct *
> unsigned long start, unsigned long end,
> bool last_level)
> {
> - unsigned long asid = ASID(vma->vm_mm) << 48;
> + unsigned long asid = ASID(vma->vm_mm);
> unsigned long addr;
>
> if ((end - start) > MAX_TLB_RANGE) {
> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct
> vm_area_struct *
> return;
> }
>
> - start = asid | (start >> 12);
> - end = asid | (end >> 12);
> + start = __TLBI_VADDR(start, asid);
> + end = __TLBI_VADDR(end, asid);
>
>
>> Will
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> [email protected]
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>

Thanks for catching that. I'll address with a v3 patch.

Philip

--
Qualcomm Datacenter Technologies as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

2018-03-28 12:00:13

by Will Deacon

[permalink] [raw]
Subject: Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

On Tue, Mar 27, 2018 at 08:03:07PM -0500, Shanker Donthineni wrote:
> On 03/27/2018 12:36 PM, Will Deacon wrote:
> > On Tue, Mar 27, 2018 at 09:53:16AM -0500, Shanker Donthineni wrote:
> >>>> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
> >>>> ????????? return;
> >>>> ????? }
> >>>> ? -??? start = asid | (start >> 12);
> >>>> -??? end = asid | (end >> 12);
> >>>> +??? start = __TLBI_VADDR(start, asid);
> >>>> +??? end = __TLBI_VADDR(end, asid);
> >
> > Can you test this bit too, please? ;)
> >
>
> I've verified the basic boot functionality on QDF2400 platform. But I can see now
> after your comments, it leads to TLB conflicts because of ASID is truncated to zero
> due to two times 48bit shift.
>
> Thanks for catching this one.

I just noticed it during review. In general, if you're making changes
relating to virtual memory stuff I'd *strongly* advise you to do more
than a basic boot test. It's amazing how much appears to run fine when
stuff like TLB invalidation is completely broken.

Anyway, thanks for turning around a new version so quickly.

Will