powerpc/mm: add exec protection on powerpc 603

The 603 doesn't have a HASH table, TLB misses are handled by
software. It is then possible to generate page fault when
_PAGE_EXEC is not set like in nohash/32.

There is one "reserved" PTE bit available, this patch uses
it for _PAGE_EXEC.

In order to support it, set_pte_filter() and
set_access_flags_filter() are made common, and the handling
is made dependent on MMU_FTR_HPTE_TABLE

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/book3s/32/hash.h b/arch/powerpc/include/asm/book3s/32/hash.h
index f2892c7ab73ecb8b5d65b0c9a8d18ddd9490b776..2a0a467d29855adc644dbbda59575489d123a957 100644 (file)
--- a/arch/powerpc/include/asm/book3s/32/hash.h
+++ b/arch/powerpc/include/asm/book3s/32/hash.h
@@ -26,6 +26,7 @@
 #define _PAGE_WRITETHRU        0x040   /* W: cache write-through */
 #define _PAGE_DIRTY    0x080   /* C: page changed */
 #define _PAGE_ACCESSED 0x100   /* R: page referenced */
+#define _PAGE_EXEC     0x200   /* software: exec allowed */
 #define _PAGE_RW       0x400   /* software: user write access allowed */
 #define _PAGE_SPECIAL  0x800   /* software: Special page */
 

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 727692fd6bca0a9f7a231918e17ef25b6699e561..49d76adb9bc58a3d931094b7a33450b9f2a8d48d 100644 (file)
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -10,9 +10,9 @@
 /* And here we include common definitions */
 
 #define _PAGE_KERNEL_RO                0
-#define _PAGE_KERNEL_ROX       0
+#define _PAGE_KERNEL_ROX       (_PAGE_EXEC)
 #define _PAGE_KERNEL_RW                (_PAGE_DIRTY | _PAGE_RW)
-#define _PAGE_KERNEL_RWX       (_PAGE_DIRTY | _PAGE_RW)
+#define _PAGE_KERNEL_RWX       (_PAGE_DIRTY | _PAGE_RW | _PAGE_EXEC)
 
 #define _PAGE_HPTEFLAGS _PAGE_HASHPTE
 
@@ -66,11 +66,11 @@ static inline bool pte_user(pte_t pte)
  */
 #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)
+#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)
+#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)
+#define PAGE_READONLY_X        __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 
 /* Permission masks used for kernel mappings */
 #define PAGE_KERNEL    __pgprot(_PAGE_BASE | _PAGE_KERNEL_RW)
@@ -318,7 +318,7 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
                                           int psize)
 {
        unsigned long set = pte_val(entry) &
-               (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW);
+               (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
 
        pte_update(ptep, 0, set);
 
@@ -371,7 +371,7 @@ 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_special(pte_t pte)       { return !!(pte_val(pte) & _PAGE_SPECIAL); }
 static inline int pte_none(pte_t pte)          { return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
-static inline bool pte_exec(pte_t pte)         { return true; }
+static inline bool pte_exec(pte_t pte)         { return pte_val(pte) & _PAGE_EXEC; }
 
 static inline int pte_present(pte_t pte)
 {
@@ -438,7 +438,7 @@ static inline pte_t pte_wrprotect(pte_t pte)
 
 static inline pte_t pte_exprotect(pte_t pte)
 {
-       return pte;
+       return __pte(pte_val(pte) & ~_PAGE_EXEC);
 }
 
 static inline pte_t pte_mkclean(pte_t pte)
@@ -453,7 +453,7 @@ static inline pte_t pte_mkold(pte_t pte)
 
 static inline pte_t pte_mkexec(pte_t pte)
 {
-       return pte;
+       return __pte(pte_val(pte) | _PAGE_EXEC);
 }
 
 static inline pte_t pte_mkpte(pte_t pte)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 29f49a35d6eecee903ee04ccf3732fadc2971070..a0395ccbbe9e1e1e6b435851b07dbac18e938a7f 100644 (file)
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -296,7 +296,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTRS_PPC601        (CPU_FTR_COMMON | CPU_FTR_601 | \
        CPU_FTR_COHERENT_ICACHE | CPU_FTR_UNIFIED_ID_CACHE | CPU_FTR_USE_RTC)
 #define CPU_FTRS_603   (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | \
-           CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_PPC_LE)
+           CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_PPC_LE | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_604   (CPU_FTR_COMMON | CPU_FTR_PPC_LE)
 #define CPU_FTRS_740_NOTAU     (CPU_FTR_COMMON | \
            CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_L2CR | \
@@ -367,15 +367,15 @@ static inline void cpu_feature_keys_init(void) { }
            CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
            CPU_FTR_SPEC7450 | CPU_FTR_NAP_DISABLE_L2_PR | \
            CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
-#define CPU_FTRS_82XX  (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE)
+#define CPU_FTRS_82XX  (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_G2_LE (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | \
            CPU_FTR_MAYBE_CAN_NAP)
 #define CPU_FTRS_E300  (CPU_FTR_MAYBE_CAN_DOZE | \
            CPU_FTR_MAYBE_CAN_NAP | \
-           CPU_FTR_COMMON)
+           CPU_FTR_COMMON  | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_E300C2        (CPU_FTR_MAYBE_CAN_DOZE | \
            CPU_FTR_MAYBE_CAN_NAP | \
-           CPU_FTR_COMMON | CPU_FTR_FPU_UNAVAILABLE)
+           CPU_FTR_COMMON | CPU_FTR_FPU_UNAVAILABLE  | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_CLASSIC32     (CPU_FTR_COMMON)
 #define CPU_FTRS_8XX   (CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_40X   (CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 15108b8caf6e868d4e56b01c1c65b4d7e5104486..05b08db3901dc9cb58c55310a7dd6d230127f3cf 100644 (file)
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -503,7 +503,7 @@ InstructionTLBMiss:
        lis     r1,PAGE_OFFSET@h                /* check if kernel address */
        cmplw   0,r1,r3
        mfspr   r2,SPRN_SPRG_THREAD
-       li      r1,_PAGE_USER|_PAGE_PRESENT /* low addresses tested as user */
+       li      r1,_PAGE_USER|_PAGE_PRESENT|_PAGE_EXEC /* low addresses tested as user */
        lwz     r2,PGDIR(r2)
        bge-    112f
        mfspr   r2,SPRN_SRR1            /* and MSR_PR bit from SRR1 */

diff --git a/arch/powerpc/mm/dump_linuxpagetables-generic.c b/arch/powerpc/mm/dump_linuxpagetables-generic.c
index 1e3829ec13483403d08b447303f9ffe184e7ab73..3fe98a0974c62065720bc91de2adf57b2de0834c 100644 (file)
--- a/arch/powerpc/mm/dump_linuxpagetables-generic.c
+++ b/arch/powerpc/mm/dump_linuxpagetables-generic.c
@@ -21,13 +21,11 @@ static const struct flag_info flag_array[] = {
                .set    = "rw",
                .clear  = "r ",
        }, {
-#ifndef CONFIG_PPC_BOOK3S_32
                .mask   = _PAGE_EXEC,
                .val    = _PAGE_EXEC,
                .set    = " X ",
                .clear  = "   ",
        }, {
-#endif
                .mask   = _PAGE_PRESENT,
                .val    = _PAGE_PRESENT,
                .set    = "present",

diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 1e33dccbd176f5b6849d7cf7ac156beafd7e3ea3..d3d61d29b4f133a008bc1042748ccd3e4a60e62c 100644 (file)
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -74,7 +74,7 @@ static struct page *maybe_pte_to_page(pte_t pte)
  * support falls into the same category.
  */
 
-static pte_t set_pte_filter(pte_t pte)
+static pte_t set_pte_filter_hash(pte_t pte)
 {
        if (radix_enabled())
                return pte;
@@ -93,14 +93,12 @@ static pte_t set_pte_filter(pte_t pte)
        return pte;
 }
 
-static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
-                                    int dirty)
-{
-       return pte;
-}
-
 #else /* CONFIG_PPC_BOOK3S */
 
+static pte_t set_pte_filter_hash(pte_t pte) { return pte; }
+
+#endif /* CONFIG_PPC_BOOK3S */
+
 /* Embedded type MMU with HW exec support. This is a bit more complicated
  * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
  * instead we "filter out" the exec permission for non clean pages.
@@ -109,6 +107,9 @@ static pte_t set_pte_filter(pte_t pte)
 {
        struct page *pg;
 
+       if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
+               return set_pte_filter_hash(pte);
+
        /* No exec permission in the first place, move on */
        if (!pte_exec(pte) || !pte_looks_normal(pte))
                return pte;
@@ -138,6 +139,9 @@ static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
 {
        struct page *pg;
 
+       if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
+               return pte;
+
        /* So here, we only care about exec faults, as we use them
         * to recover lost _PAGE_EXEC and perform I$/D$ coherency
         * if necessary. Also if _PAGE_EXEC is already set, same deal,
@@ -172,8 +176,6 @@ static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
        return pte_mkexec(pte);
 }
 
-#endif /* CONFIG_PPC_BOOK3S */
-
 /*
  * set_pte stores a linux PTE into the linux page table.
  */