Commit 7fc8442f authored Apr 25, 2016 by Matt Fleming Committed by Ingo Molnar Apr 28, 2016

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@amacapital.net>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-4-git-send-email-matt@codeblueprint.co.uk


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 14c43be6

arch/x86/mm/pageattr.c

+7 −1

Original line number	Original line	Diff line number	Diff line
	@@ -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,		static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
	int primary)		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);		return populate_pgd(cpa, vaddr);
			}

	/*		/*
	* Ignore all non primary paths.		* Ignore all non primary paths.