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authorChristophe Leroy <christophe.leroy@c-s.fr>2017-07-12 17:03:42 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2017-08-15 22:55:58 +1000
commitca8afd4046255ac046f8229d5159c6d213e37b22 (patch)
treed0a7b4617f6dc324d0c4ed42a2270a1995bdb2c8 /arch/powerpc/include/asm/book3s/64/pgtable.h
parent4cfac2f9c7f116af8516d0b3d0e7383189eca376 (diff)
powerpc/hugetlb: fix page rights verification in gup_hugepte()
gup_hugepte() checks if pages are present and readable, and when 'write' is set, also checks if the pages are writable. Initially this was done by checking if _PAGE_PRESENT and _PAGE_READ were set. In addition, _PAGE_WRITE was verified for write accesses. The problem is that we have to handle the three following cases: 1/ The target defines __PAGE_READ and __PAGE_WRITE 2/ The target defines __PAGE_RW 3/ The target defines __PAGE_RO In case 1/, this is obvious In case 2/, __PAGE_READ is defined as 0 and __PAGE_WRITE as __PAGE_RW so it works as well. But in case 3, __PAGE_RW is defined as 0, which means __PAGE_WRITE is 0 and then the test returns true (page writable) in all cases. A first correction was attempted in commit 6b8cb66a6a7cc ("powerpc: Fix usage of _PAGE_RO in hugepage"), but that fix is wrong: instead of checking that the page is writable when write is requested, it checks that the page is NOT writable when write is NOT requested. This patch adds a new pte_read() helper to check whether a page is readable or not. This avoids handling all possible cases in gup_hugepte(). Then gup_hugepte() is modified to use pte_present(), pte_read() and pte_write() instead of the raw flags. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/pgtable.h')
-rw-r--r--arch/powerpc/include/asm/book3s/64/pgtable.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 18a8580d3ddc..1071d52f382d 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -410,6 +410,11 @@ static inline int pte_write(pte_t pte)
return __pte_write(pte) || pte_savedwrite(pte);
}
+static inline int pte_read(pte_t pte)
+{
+ return !!(pte_raw(pte) & cpu_to_be64(_PAGE_READ));
+}
+
#define __HAVE_ARCH_PTEP_SET_WRPROTECT
static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)