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| Started by | Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> |
|---|---|
| First post | 2015-10-17 01:30 +0200 |
| Last post | 2015-10-17 20:30 +0200 |
| Articles | 3 — 3 participants |
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[PATCH V2] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> - 2015-10-17 01:30 +0200
Re: [PATCH V2] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled Borislav Petkov <bp@alien8.de> - 2015-10-17 11:50 +0200
Re: [PATCH V2] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-17 20:30 +0200
| From | Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> |
|---|---|
| Date | 2015-10-17 01:30 +0200 |
| Subject | [PATCH V2] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled |
| Message-ID | <qkmBI-4t3-3@gated-at.bofh.it> |
From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are
monitored to see whether address falls in direct mapping or kernel text
mapping (see Documentation/x86/x86_64/mm.txt for details), if it does
not kernel panics. During 1:1 mapping of EFI runtime services we access
virtual addresses which are == physical addresses, thus the 1:1 mapping
and these addresses donot fall in either of the above two regions and
hence when passed as arguments to __pa() kernel panics as reported by
Dave Hansen here https://lkml.kernel.org/r/5462999A.7090706@intel.com.
So, before calling __pa() virtual addresses should be validated which
results in skipping call to split_page_count() and that should be fine
because it is used to keep track of everything *but* 1:1 mappings.
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Reported-by: Dave Hansen <dave.hansen@intel.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Glenn P Williamson <glenn.p.williamson@intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Changes since v1:
Made commit message more clear by adding reference to
Documentation/x86/x86_64/mm.txt, instead of addresses "below 4G"
changed it to "virtual addresses == physical addresses" quoted
mail with k.org redirector and changed last line "to keep track of
evrything *but* 1:1 mappings." Also made code more readable by adding a
variable.
---
arch/x86/mm/pageattr.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 727158cb3b3c..9abe0c9b1098 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -648,9 +648,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot)));
- if (pfn_range_is_mapped(PFN_DOWN(__pa(address)),
- PFN_DOWN(__pa(address)) + 1))
- split_page_count(level);
+ if (virt_addr_valid(address)) {
+ unsigned long pfn = PFN_DOWN(__pa(address));
+
+ if (pfn_range_is_mapped(pfn, pfn + 1))
+ split_page_count(level);
+ }
/*
* Install the new, split up pagetable.
--
2.1.4
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| From | Borislav Petkov <bp@alien8.de> |
|---|---|
| Date | 2015-10-17 11:50 +0200 |
| Subject | Re: [PATCH V2] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled |
| Message-ID | <qkwhI-1Ly-17@gated-at.bofh.it> |
| In reply to | #1249217 |
On Fri, Oct 16, 2015 at 04:20:27PM -0700, Sai Praneeth Prakhya wrote:
> From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
>
> When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are
> monitored to see whether address falls in direct mapping or kernel text
> mapping (see Documentation/x86/x86_64/mm.txt for details), if it does
> not kernel panics.
At least a comma and a "the" here:
"..., if it does not, the kernel panics."
> During 1:1 mapping of EFI runtime services we access
> virtual addresses which are == physical addresses, thus the 1:1 mapping
> and these addresses donot fall in either of the above two regions and
do not
> hence when passed as arguments to __pa() kernel panics as reported by
> Dave Hansen here https://lkml.kernel.org/r/5462999A.7090706@intel.com.
> So, before calling __pa() virtual addresses should be validated which
> results in skipping call to split_page_count() and that should be fine
> because it is used to keep track of everything *but* 1:1 mappings.
>
> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
> Reported-by: Dave Hansen <dave.hansen@intel.com>
> Cc: Matt Fleming <matt.fleming@intel.com>
> Cc: Ricardo Neri <ricardo.neri@intel.com>
> Cc: Glenn P Williamson <glenn.p.williamson@intel.com>
> Cc: Ravi Shankar <ravi.v.shankar@intel.com>
>
> Changes since v1:
> Made commit message more clear by adding reference to
> Documentation/x86/x86_64/mm.txt, instead of addresses "below 4G"
> changed it to "virtual addresses == physical addresses" quoted
> mail with k.org redirector and changed last line "to keep track of
> evrything *but* 1:1 mappings." Also made code more readable by adding a
> variable.
> ---
> arch/x86/mm/pageattr.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 727158cb3b3c..9abe0c9b1098 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -648,9 +648,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
> for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
> set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot)));
>
> - if (pfn_range_is_mapped(PFN_DOWN(__pa(address)),
> - PFN_DOWN(__pa(address)) + 1))
> - split_page_count(level);
> + if (virt_addr_valid(address)) {
> + unsigned long pfn = PFN_DOWN(__pa(address));
> +
> + if (pfn_range_is_mapped(pfn, pfn + 1))
> + split_page_count(level);
> + }
>
> /*
> * Install the new, split up pagetable.
> --
Looks ok to me, these minor nitpicks can be adjusted when applying, no
need to send another version.
Which brings me to the next question: Matt, are you picking this up or
should I?
If you, then
Reviewed-by: Borislav Petkov <bp@suse.de>
Thanks!
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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| From | Matt Fleming <matt@codeblueprint.co.uk> |
|---|---|
| Date | 2015-10-17 20:30 +0200 |
| Subject | Re: [PATCH V2] x86/efi: Fix kernel panic when CONFIG_DEBUG_VIRTUAL is enabled |
| Message-ID | <qkEoW-5xv-5@gated-at.bofh.it> |
| In reply to | #1249292 |
On Sat, 17 Oct, at 11:47:38AM, Borislav Petkov wrote: > > Looks ok to me, these minor nitpicks can be adjusted when applying, no > need to send another version. > > Which brings me to the next question: Matt, are you picking this up or > should I? I'll pick it up and make your suggested changes. > If you, then > > Reviewed-by: Borislav Petkov <bp@suse.de> Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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