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Groups > linux.kernel > #1707829 > unrolled thread
| Started by | Tycho Andersen <tycho@docker.com> |
|---|---|
| First post | 2017-08-09 22:10 +0200 |
| Last post | 2017-08-12 00:00 +0200 |
| Articles | 4 — 2 participants |
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[PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Tycho Andersen <tycho@docker.com> - 2017-08-09 22:10 +0200
Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Laura Abbott <labbott@redhat.com> - 2017-08-11 19:30 +0200
Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Tycho Andersen <tycho@docker.com> - 2017-08-11 23:20 +0200
Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled Tycho Andersen <tycho@docker.com> - 2017-08-12 00:00 +0200
| From | Tycho Andersen <tycho@docker.com> |
|---|---|
| Date | 2017-08-09 22:10 +0200 |
| Subject | [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled |
| Message-ID | <ucFsJ-3Hw-11@gated-at.bofh.it> |
From: Juerg Haefliger <juerg.haefliger@hpe.com>
XPFO (eXclusive Page Frame Ownership) doesn't support section mappings
yet, so disable it if XPFO is turned on.
Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Tested-by: Tycho Andersen <tycho@docker.com>
---
arch/arm64/mm/mmu.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index f1eb15e0e864..38026b3ccb46 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -176,6 +176,18 @@ static void alloc_init_cont_pte(pmd_t *pmd, unsigned long addr,
} while (addr = next, addr != end);
}
+static inline bool use_section_mapping(unsigned long addr, unsigned long next,
+ unsigned long phys)
+{
+ if (IS_ENABLED(CONFIG_XPFO))
+ return false;
+
+ if (((addr | next | phys) & ~SECTION_MASK) != 0)
+ return false;
+
+ return true;
+}
+
static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(void), int flags)
@@ -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);
--
2.11.0
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| From | Laura Abbott <labbott@redhat.com> |
|---|---|
| Date | 2017-08-11 19:30 +0200 |
| Subject | Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled |
| Message-ID | <udlUZ-6mk-19@gated-at.bofh.it> |
| In reply to | #1707829 |
On 08/09/2017 01:07 PM, Tycho Andersen wrote:
> From: Juerg Haefliger <juerg.haefliger@hpe.com>
>
> XPFO (eXclusive Page Frame Ownership) doesn't support section mappings
> yet, so disable it if XPFO is turned on.
>
> Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
> Tested-by: Tycho Andersen <tycho@docker.com>
> ---
> arch/arm64/mm/mmu.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index f1eb15e0e864..38026b3ccb46 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -176,6 +176,18 @@ static void alloc_init_cont_pte(pmd_t *pmd, unsigned long addr,
> } while (addr = next, addr != end);
> }
>
> +static inline bool use_section_mapping(unsigned long addr, unsigned long next,
> + unsigned long phys)
> +{
> + if (IS_ENABLED(CONFIG_XPFO))
> + return false;
> +
> + if (((addr | next | phys) & ~SECTION_MASK) != 0)
> + return false;
> +
> + return true;
> +}
> +
> static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
> phys_addr_t phys, pgprot_t prot,
> phys_addr_t (*pgtable_alloc)(void), int flags)
> @@ -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?
Thanks,
Laura
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| From | Tycho Andersen <tycho@docker.com> |
|---|---|
| Date | 2017-08-11 23:20 +0200 |
| Subject | Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled |
| Message-ID | <udpvA-6M-21@gated-at.bofh.it> |
| In reply to | #1709878 |
Hi Laura,
On Fri, Aug 11, 2017 at 10:25:14AM -0700, Laura Abbott wrote:
> On 08/09/2017 01:07 PM, Tycho Andersen wrote:
> > From: Juerg Haefliger <juerg.haefliger@hpe.com>
> >
> > XPFO (eXclusive Page Frame Ownership) doesn't support section mappings
> > yet, so disable it if XPFO is turned on.
> >
> > Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
> > Tested-by: Tycho Andersen <tycho@docker.com>
> > ---
> > arch/arm64/mm/mmu.c | 14 +++++++++++++-
> > 1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index f1eb15e0e864..38026b3ccb46 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -176,6 +176,18 @@ static void alloc_init_cont_pte(pmd_t *pmd, unsigned long addr,
> > } while (addr = next, addr != end);
> > }
> >
> > +static inline bool use_section_mapping(unsigned long addr, unsigned long next,
> > + unsigned long phys)
> > +{
> > + if (IS_ENABLED(CONFIG_XPFO))
> > + return false;
> > +
> > + if (((addr | next | phys) & ~SECTION_MASK) != 0)
> > + return false;
> > +
> > + return true;
> > +}
> > +
> > static void init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
> > phys_addr_t phys, pgprot_t prot,
> > phys_addr_t (*pgtable_alloc)(void), int flags)
> > @@ -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;
/*
* Take care not to create a writable alias for the
Cheers,
Tycho
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| From | Tycho Andersen <tycho@docker.com> |
|---|---|
| Date | 2017-08-12 00:00 +0200 |
| Subject | Re: [kernel-hardening] [PATCH v5 06/10] arm64/mm: Disable section mappings if XPFO is enabled |
| Message-ID | <udq8i-la-15@gated-at.bofh.it> |
| In reply to | #1709970 |
On Fri, Aug 11, 2017 at 03:13:02PM -0600, Tycho Andersen wrote: > You're suggesting something like this instead? Seems to work fine. And in fact, using this patch instead means that booting on 4k pages works too... I guess because NO_BLOCK_MAPPINGS is looked at in a few other places that matter too? Anyway, I'll use this patch instead, thanks for the suggestion! Tycho
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