Commit-ID: 7fc8442f2a8a77f40565b42c41e4f2d48b179a56 Gitweb: http://git.kernel.org/tip/7fc8442f2a8a77f40565b42c41e4f2d48b179a56 Author: Matt Fleming <[email protected]> AuthorDate: Mon, 25 Apr 2016 21:06:35 +0100 Committer: Ingo Molnar <[email protected]> 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 <[email protected]> Signed-off-by: Matt Fleming <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sai Praneeth Prakhya <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- 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.
