linux-kernel - [tip:x86/asm] x86/mm: Honour passed pgprot in track_pfn_insert() and track_pfn

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Date:	Tue, 9 Feb 2016 08:09:54 -0800
From:	tip-bot for Matthew Wilcox <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	keescook@...omium.org, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, mingo@...nel.org,
	luto@...capital.net, peterz@...radead.org, willy@...ux.intel.com,
	luto@...nel.org, torvalds@...ux-foundation.org, hpa@...or.com,
	akpm@...ux-foundation.org
Subject: [tip:x86/asm] x86/mm: Honour passed pgprot in track_pfn_insert()
  and track_pfn_remap()

Commit-ID:  dd7b6847670a84b7bb7c38f8e69b2f12059bca66
Gitweb:     http://git.kernel.org/tip/dd7b6847670a84b7bb7c38f8e69b2f12059bca66
Author:     Matthew Wilcox <willy@...ux.intel.com>
AuthorDate: Mon, 25 Jan 2016 12:25:15 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 9 Feb 2016 15:25:36 +0100

x86/mm: Honour passed pgprot in track_pfn_insert() and track_pfn_remap()

track_pfn_insert() overwrites the pgprot that is passed in with a value
based on the VMA's page_prot.  This is a problem for people trying to
do clever things with the new vm_insert_pfn_prot() as it will simply
overwrite the passed protection flags.  If we use the current value of
the pgprot as the base, then it will behave as people are expecting.

Also fix track_pfn_remap() in the same way.

Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>
Acked-by: Andy Lutomirski <luto@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/1453742717-10326-2-git-send-email-matthew.r.wilcox@intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/pat.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index f4ae536..04e2e71 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -943,7 +943,7 @@ int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 			return -EINVAL;
 	}
 
-	*prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
+	*prot = __pgprot((pgprot_val(*prot) & (~_PAGE_CACHE_MASK)) |
 			 cachemode2protval(pcm));
 
 	return 0;
@@ -959,7 +959,7 @@ int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
 
 	/* Set prot based on lookup */
 	pcm = lookup_memtype(pfn_t_to_phys(pfn));
-	*prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
+	*prot = __pgprot((pgprot_val(*prot) & (~_PAGE_CACHE_MASK)) |
 			 cachemode2protval(pcm));
 
 	return 0;