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| Started by | Mark Rutland <mark.rutland@arm.com> |
|---|---|
| First post | 2017-08-12 13:20 +0200 |
| Last post | 2017-08-14 22:30 +0200 |
| Articles | 4 — 3 participants |
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Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Mark Rutland <mark.rutland@arm.com> - 2017-08-12 13:20 +0200
Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Tycho Andersen <tycho@docker.com> - 2017-08-14 18:30 +0200
Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Laura Abbott <labbott@redhat.com> - 2017-08-14 20:50 +0200
Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Tycho Andersen <tycho@docker.com> - 2017-08-14 22:30 +0200
| From | Mark Rutland <mark.rutland@arm.com> |
|---|---|
| Date | 2017-08-12 13:20 +0200 |
| Subject | Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled |
| Message-ID | <udCCu-8pQ-1@gated-at.bofh.it> |
Hi,
On Fri, Aug 11, 2017 at 03:13:02PM -0600, Tycho Andersen wrote:
> On Fri, Aug 11, 2017 at 10:25:14AM -0700, Laura Abbott wrote:
> > On 08/09/2017 01:07 PM, Tycho Andersen wrote:
> > > @@ -190,7 +202,7 @@ static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
> > > next = pmd_addr_end(addr, end);
> > >
> > > /* try section mapping first */
> > > - if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
> > > + if (use_section_mapping(addr, next, phys) &&
> > > (flags & NO_BLOCK_MAPPINGS) == 0) {
> > > pmd_set_huge(pmd, phys, prot);
> > >
> > >
> >
> > There is already similar logic to disable section mappings for
> > debug_pagealloc at the start of map_mem, can you take advantage
> > of that?
>
> You're suggesting something like this instead? Seems to work fine.
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 38026b3ccb46..3b2c17bbbf12 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -434,6 +434,8 @@ static void __init map_mem(pgd_t *pgd)
>
> if (debug_pagealloc_enabled())
> flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
> + if (IS_ENABLED(CONFIG_XPFO))
> + flags |= NO_BLOCK_MAPPINGS;
>
IIUC, XPFO carves out individual pages just like DEBUG_PAGEALLOC, so you'll
also need NO_CONT_MAPPINGS.
Thanks
Mark.
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| From | Tycho Andersen <tycho@docker.com> |
|---|---|
| Date | 2017-08-14 18:30 +0200 |
| Message-ID | <ueqpA-6qC-37@gated-at.bofh.it> |
| In reply to | #1710227 |
On Sat, Aug 12, 2017 at 12:17:34PM +0100, Mark Rutland wrote:
> Hi,
>
> On Fri, Aug 11, 2017 at 03:13:02PM -0600, Tycho Andersen wrote:
> > On Fri, Aug 11, 2017 at 10:25:14AM -0700, Laura Abbott wrote:
> > > On 08/09/2017 01:07 PM, Tycho Andersen wrote:
> > > > @@ -190,7 +202,7 @@ static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
> > > > next = pmd_addr_end(addr, end);
> > > >
> > > > /* try section mapping first */
> > > > - if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
> > > > + if (use_section_mapping(addr, next, phys) &&
> > > > (flags & NO_BLOCK_MAPPINGS) == 0) {
> > > > pmd_set_huge(pmd, phys, prot);
> > > >
> > > >
> > >
> > > There is already similar logic to disable section mappings for
> > > debug_pagealloc at the start of map_mem, can you take advantage
> > > of that?
> >
> > You're suggesting something like this instead? Seems to work fine.
> >
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index 38026b3ccb46..3b2c17bbbf12 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -434,6 +434,8 @@ static void __init map_mem(pgd_t *pgd)
> >
> > if (debug_pagealloc_enabled())
> > flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
> > + if (IS_ENABLED(CONFIG_XPFO))
> > + flags |= NO_BLOCK_MAPPINGS;
> >
>
> IIUC, XPFO carves out individual pages just like DEBUG_PAGEALLOC, so you'll
> also need NO_CONT_MAPPINGS.
Yes, thanks!
Tycho
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| From | Laura Abbott <labbott@redhat.com> |
|---|---|
| Date | 2017-08-14 20:50 +0200 |
| Message-ID | <uesB5-7Hs-31@gated-at.bofh.it> |
| In reply to | #1711160 |
On 08/14/2017 09:22 AM, Tycho Andersen wrote:
> On Sat, Aug 12, 2017 at 12:17:34PM +0100, Mark Rutland wrote:
>> Hi,
>>
>> On Fri, Aug 11, 2017 at 03:13:02PM -0600, Tycho Andersen wrote:
>>> On Fri, Aug 11, 2017 at 10:25:14AM -0700, Laura Abbott wrote:
>>>> On 08/09/2017 01:07 PM, Tycho Andersen wrote:
>>>>> @@ -190,7 +202,7 @@ static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
>>>>> next = pmd_addr_end(addr, end);
>>>>>
>>>>> /* try section mapping first */
>>>>> - if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
>>>>> + if (use_section_mapping(addr, next, phys) &&
>>>>> (flags & NO_BLOCK_MAPPINGS) == 0) {
>>>>> pmd_set_huge(pmd, phys, prot);
>>>>>
>>>>>
>>>>
>>>> There is already similar logic to disable section mappings for
>>>> debug_pagealloc at the start of map_mem, can you take advantage
>>>> of that?
>>>
>>> You're suggesting something like this instead? Seems to work fine.
>>>
>>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>>> index 38026b3ccb46..3b2c17bbbf12 100644
>>> --- a/arch/arm64/mm/mmu.c
>>> +++ b/arch/arm64/mm/mmu.c
>>> @@ -434,6 +434,8 @@ static void __init map_mem(pgd_t *pgd)
>>>
>>> if (debug_pagealloc_enabled())
>>> flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
>>> + if (IS_ENABLED(CONFIG_XPFO))
>>> + flags |= NO_BLOCK_MAPPINGS;
>>>
>>
>> IIUC, XPFO carves out individual pages just like DEBUG_PAGEALLOC, so you'll
>> also need NO_CONT_MAPPINGS.
>
> Yes, thanks!
>
> Tycho
>
Setting NO_CONT_MAPPINGS fixes the TLB conflict aborts I was seeing
on my machine.
Thanks,
Laura
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| From | Tycho Andersen <tycho@docker.com> |
|---|---|
| Date | 2017-08-14 22:30 +0200 |
| Message-ID | <ueu9Q-gF-27@gated-at.bofh.it> |
| In reply to | #1711347 |
On Mon, Aug 14, 2017 at 11:42:45AM -0700, Laura Abbott wrote:
> On 08/14/2017 09:22 AM, Tycho Andersen wrote:
> > On Sat, Aug 12, 2017 at 12:17:34PM +0100, Mark Rutland wrote:
> >> Hi,
> >>
> >> On Fri, Aug 11, 2017 at 03:13:02PM -0600, Tycho Andersen wrote:
> >>> On Fri, Aug 11, 2017 at 10:25:14AM -0700, Laura Abbott wrote:
> >>>> On 08/09/2017 01:07 PM, Tycho Andersen wrote:
> >>>>> @@ -190,7 +202,7 @@ static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
> >>>>> next = pmd_addr_end(addr, end);
> >>>>>
> >>>>> /* try section mapping first */
> >>>>> - if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
> >>>>> + if (use_section_mapping(addr, next, phys) &&
> >>>>> (flags & NO_BLOCK_MAPPINGS) == 0) {
> >>>>> pmd_set_huge(pmd, phys, prot);
> >>>>>
> >>>>>
> >>>>
> >>>> There is already similar logic to disable section mappings for
> >>>> debug_pagealloc at the start of map_mem, can you take advantage
> >>>> of that?
> >>>
> >>> You're suggesting something like this instead? Seems to work fine.
> >>>
> >>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> >>> index 38026b3ccb46..3b2c17bbbf12 100644
> >>> --- a/arch/arm64/mm/mmu.c
> >>> +++ b/arch/arm64/mm/mmu.c
> >>> @@ -434,6 +434,8 @@ static void __init map_mem(pgd_t *pgd)
> >>>
> >>> if (debug_pagealloc_enabled())
> >>> flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
> >>> + if (IS_ENABLED(CONFIG_XPFO))
> >>> + flags |= NO_BLOCK_MAPPINGS;
> >>>
> >>
> >> IIUC, XPFO carves out individual pages just like DEBUG_PAGEALLOC, so you'll
> >> also need NO_CONT_MAPPINGS.
> >
> > Yes, thanks!
> >
> > Tycho
> >
>
> Setting NO_CONT_MAPPINGS fixes the TLB conflict aborts I was seeing
> on my machine.
Great, thanks for testing! I've also fixed the lookup_page_ext bug you
noted in the other thread.
Tycho
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