Commit-ID: 7fc8442f2a8a77f40565b42c41e4f2d48b179a56
Gitweb: http://git.kernel.org/tip/7fc8442f2a8a77f40565b42c41e4f2d48b179a56
Author: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 25 Apr 2016 21:06:35 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 28 Apr 2016 11:33:48 +0200
x86/mm/pat: Document the (currently) EFI-only code path
It's not at all obvious that populate_pgd() and friends are only
executed when mapping EFI virtual memory regions or that no other
pageattr callers pass a ->pgd value.
Reported-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1461614832-17633-4-git-send-email-matt@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/mm/pageattr.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 01be9ec..a1f0e1d 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1125,8 +1125,14 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
int primary)
{
- if (cpa->pgd)
+ if (cpa->pgd) {
+ /*
+ * Right now, we only execute this code path when mapping
+ * the EFI virtual memory map regions, no other users
+ * provide a ->pgd value. This may change in the future.
+ */
return populate_pgd(cpa, vaddr);
+ }
/*
* Ignore all non primary paths.
--
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