[PATCH v4 1/2] powerpc32: adds handling of _PAGE_RO

From: Christophe Leroy
Date: Mon Jan 19 2015 - 11:04:45 EST

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Some powerpc like the 8xx don't have a RW bit in PTE bits but a RO (Read Only) bit.
This patch implements the handling of a _PAGE_RO flag to be used in place of _PAGE_RW

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>

---
v2 is a complete rework of v1
v3:
- cleared PTE can remain 0, no need of _PAGE_RO on PAGE_NONE
- fix __ptep_set_access_flags() to be independant of clear/set order in pte_update()
v4: no change

arch/powerpc/include/asm/pgtable-ppc32.h | 7 ++++---
arch/powerpc/include/asm/pgtable.h | 7 +++++--
arch/powerpc/include/asm/pte-common.h | 25 +++++++++++++++++--------
arch/powerpc/mm/gup.c | 2 ++
arch/powerpc/mm/pgtable_32.c | 2 +-
5 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h b/arch/powerpc/include/asm/pgtable-ppc32.h
index 543bb8e..caf094a 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -275,7 +275,7 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
- pte_update(ptep, (_PAGE_RW | _PAGE_HWWRITE), 0);
+ pte_update(ptep, (_PAGE_RW | _PAGE_HWWRITE), _PAGE_RO);
}
static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
@@ -286,9 +286,10 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,

static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
{
- unsigned long bits = pte_val(entry) &
+ unsigned long set = pte_val(entry) &
(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
- pte_update(ptep, 0, bits);
+ unsigned long clr = ~pte_val(entry) & _PAGE_RO;
+ pte_update(ptep, clr, set);
}

#define __HAVE_ARCH_PTE_SAME
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 316f9a5..0f713fa 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -30,7 +30,8 @@ struct mm_struct;
#include <asm/tlbflush.h>

/* Generic accessors to PTE bits */
-static inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_RW; }
+static inline int pte_write(pte_t pte)
+{ return (pte_val(pte) & (_PAGE_RW | _PAGE_RO)) != _PAGE_RO; }
static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; }
static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED; }
static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE; }
@@ -115,12 +116,14 @@ static inline unsigned long pte_pfn(pte_t pte) {

/* Generic modifiers for PTE bits */
static inline pte_t pte_wrprotect(pte_t pte) {
- pte_val(pte) &= ~(_PAGE_RW | _PAGE_HWWRITE); return pte; }
+ pte_val(pte) &= ~(_PAGE_RW | _PAGE_HWWRITE);
+ pte_val(pte) |= _PAGE_RO; return pte; }
static inline pte_t pte_mkclean(pte_t pte) {
pte_val(pte) &= ~(_PAGE_DIRTY | _PAGE_HWWRITE); return pte; }
static inline pte_t pte_mkold(pte_t pte) {
pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkwrite(pte_t pte) {
+ pte_val(pte) &= ~_PAGE_RO;
pte_val(pte) |= _PAGE_RW; return pte; }
static inline pte_t pte_mkdirty(pte_t pte) {
pte_val(pte) |= _PAGE_DIRTY; return pte; }
diff --git a/arch/powerpc/include/asm/pte-common.h b/arch/powerpc/include/asm/pte-common.h
index e040c35..2aef9b7 100644
--- a/arch/powerpc/include/asm/pte-common.h
+++ b/arch/powerpc/include/asm/pte-common.h
@@ -34,6 +34,12 @@
#ifndef _PAGE_PSIZE
#define _PAGE_PSIZE 0
#endif
+/* _PAGE_RO and _PAGE_RW shall not be defined at the same time */
+#ifndef _PAGE_RO
+#define _PAGE_RO 0
+#else
+#define _PAGE_RW 0
+#endif
#ifndef _PMD_PRESENT_MASK
#define _PMD_PRESENT_MASK _PMD_PRESENT
#endif
@@ -42,10 +48,10 @@
#define PMD_PAGE_SIZE(pmd) bad_call_to_PMD_PAGE_SIZE()
#endif
#ifndef _PAGE_KERNEL_RO
-#define _PAGE_KERNEL_RO 0
+#define _PAGE_KERNEL_RO (_PAGE_RO)
#endif
#ifndef _PAGE_KERNEL_ROX
-#define _PAGE_KERNEL_ROX (_PAGE_EXEC)
+#define _PAGE_KERNEL_ROX (_PAGE_EXEC | _PAGE_RO)
#endif
#ifndef _PAGE_KERNEL_RW
#define _PAGE_KERNEL_RW (_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE)
@@ -95,7 +101,7 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
/* Mask of bits returned by pte_pgprot() */
#define PAGE_PROT_BITS (_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
_PAGE_WRITETHRU | _PAGE_ENDIAN | _PAGE_4K_PFN | \
- _PAGE_USER | _PAGE_ACCESSED | \
+ _PAGE_USER | _PAGE_ACCESSED | _PAGE_RO | \
_PAGE_RW | _PAGE_HWWRITE | _PAGE_DIRTY | _PAGE_EXEC)

#ifdef CONFIG_NUMA_BALANCING
@@ -128,11 +134,14 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
*/
#define PAGE_NONE __pgprot(_PAGE_BASE)
#define PAGE_SHARED __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW)
-#define PAGE_SHARED_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | _PAGE_EXEC)
-#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER)
-#define PAGE_COPY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
-#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER)
-#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
+#define PAGE_SHARED_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | \
+ _PAGE_EXEC)
+#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RO)
+#define PAGE_COPY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RO | \
+ _PAGE_EXEC)
+#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RO)
+#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RO | \
+ _PAGE_EXEC)

#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
index d874668..fa287fc 100644
--- a/arch/powerpc/mm/gup.c
+++ b/arch/powerpc/mm/gup.c
@@ -30,6 +30,8 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
result = _PAGE_PRESENT|_PAGE_USER;
if (write)
result |= _PAGE_RW;
+ else
+ result |= _PAGE_RO;
mask = result | _PAGE_SPECIAL;

ptep = pte_offset_kernel(&pmd, addr);
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index a349089..5519168 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -148,7 +148,7 @@ void __iomem *
ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
{
/* writeable implies dirty for kernel addresses */
- if (flags & _PAGE_RW)
+ if ((flags & (_PAGE_RW | _PAGE_RO)) != _PAGE_RO)
flags |= _PAGE_DIRTY | _PAGE_HWWRITE;

/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
--
2.1.0

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Next message: Christophe Leroy: "[PATCH v4 2/2] powerpc/8xx: use _PAGE_RO instead of _PAGE_RW"
Previous message: Cyril Hrubis: "Re: [LTP] The Linux Test Project has been released for JANUARY 2015"
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