[S390] Remove data execution protection
The noexec support on s390 does not rely on a bit in the page table
entry but utilizes the secondary space mode to distinguish between
memory accesses for instructions vs. data. The noexec code relies
on the assumption that the cpu will always use the secondary space
page table for data accesses while it is running in the secondary
space mode. Up to the z9-109 class machines this has been the case.
Unfortunately this is not true anymore with z10 and later machines.
The load-relative-long instructions lrl, lgrl and lgfrl access the
memory operand using the same addressing-space mode that has been
used to fetch the instruction.
This breaks the noexec mode for all user space binaries compiled
with march=z10 or later. The only option is to remove the current
noexec support.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 10c029c..64b61bf 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -196,18 +196,6 @@
} while (0)
#endif /* __s390x__ */
-/*
- * An executable for which elf_read_implies_exec() returns TRUE will
- * have the READ_IMPLIES_EXEC personality flag set automatically.
- */
-#define elf_read_implies_exec(ex, executable_stack) \
-({ \
- if (current->mm->context.noexec && \
- executable_stack != EXSTACK_DISABLE_X) \
- disable_noexec(current->mm, current); \
- current->mm->context.noexec == 0; \
-})
-
#define STACK_RND_MASK 0x7ffUL
#define ARCH_DLINFO \
diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index b56403c..799ed0f 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -111,21 +111,10 @@
{
pmd_t *pmdp = (pmd_t *) ptep;
- if (!MACHINE_HAS_IDTE) {
- __pmd_csp(pmdp);
- if (mm->context.noexec) {
- pmdp = get_shadow_table(pmdp);
- __pmd_csp(pmdp);
- }
- return;
- }
-
- __pmd_idte(address, pmdp);
- if (mm->context.noexec) {
- pmdp = get_shadow_table(pmdp);
+ if (MACHINE_HAS_IDTE)
__pmd_idte(address, pmdp);
- }
- return;
+ else
+ __pmd_csp(pmdp);
}
#define huge_ptep_set_access_flags(__vma, __addr, __ptep, __entry, __dirty) \
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index 65e172f..b8624d5 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -124,7 +124,7 @@
/* Address space pointer. */
__u32 kernel_asce; /* 0x02ac */
__u32 user_asce; /* 0x02b0 */
- __u32 user_exec_asce; /* 0x02b4 */
+ __u8 pad_0x02b4[0x02b8-0x02b4]; /* 0x02b4 */
/* SMP info area */
__u32 cpu_nr; /* 0x02b8 */
@@ -255,7 +255,7 @@
/* Address space pointer. */
__u64 kernel_asce; /* 0x0310 */
__u64 user_asce; /* 0x0318 */
- __u64 user_exec_asce; /* 0x0320 */
+ __u8 pad_0x0320[0x0328-0x0320]; /* 0x0320 */
/* SMP info area */
__u32 cpu_nr; /* 0x0328 */
diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
index 78522cde..818e829 100644
--- a/arch/s390/include/asm/mmu.h
+++ b/arch/s390/include/asm/mmu.h
@@ -5,19 +5,16 @@
atomic_t attach_count;
unsigned int flush_mm;
spinlock_t list_lock;
- struct list_head crst_list;
struct list_head pgtable_list;
unsigned long asce_bits;
unsigned long asce_limit;
unsigned long vdso_base;
- int noexec;
int has_pgste; /* The mmu context has extended page tables */
int alloc_pgste; /* cloned contexts will have extended page tables */
} mm_context_t;
#define INIT_MM_CONTEXT(name) \
.context.list_lock = __SPIN_LOCK_UNLOCKED(name.context.list_lock), \
- .context.crst_list = LIST_HEAD_INIT(name.context.crst_list), \
.context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list),
#endif
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index 8c277ca..5682f16 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -35,11 +35,9 @@
* and if has_pgste is set, it will create extended page
* tables.
*/
- mm->context.noexec = 0;
mm->context.has_pgste = 1;
mm->context.alloc_pgste = 1;
} else {
- mm->context.noexec = (user_mode == SECONDARY_SPACE_MODE);
mm->context.has_pgste = 0;
mm->context.alloc_pgste = 0;
}
@@ -63,10 +61,8 @@
S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
if (user_mode != HOME_SPACE_MODE) {
/* Load primary space page table origin. */
- pgd = mm->context.noexec ? get_shadow_table(pgd) : pgd;
- S390_lowcore.user_exec_asce = mm->context.asce_bits | __pa(pgd);
asm volatile(LCTL_OPCODE" 1,1,%0\n"
- : : "m" (S390_lowcore.user_exec_asce) );
+ : : "m" (S390_lowcore.user_asce) );
} else
/* Load home space page table origin. */
asm volatile(LCTL_OPCODE" 13,13,%0"
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 082eb4e..739ff9e 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -19,14 +19,13 @@
#define check_pgt_cache() do {} while (0)
-unsigned long *crst_table_alloc(struct mm_struct *, int);
+unsigned long *crst_table_alloc(struct mm_struct *);
void crst_table_free(struct mm_struct *, unsigned long *);
void crst_table_free_rcu(struct mm_struct *, unsigned long *);
unsigned long *page_table_alloc(struct mm_struct *);
void page_table_free(struct mm_struct *, unsigned long *);
void page_table_free_rcu(struct mm_struct *, unsigned long *);
-void disable_noexec(struct mm_struct *, struct task_struct *);
static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
{
@@ -50,9 +49,6 @@
static inline void crst_table_init(unsigned long *crst, unsigned long entry)
{
clear_table(crst, entry, sizeof(unsigned long)*2048);
- crst = get_shadow_table(crst);
- if (crst)
- clear_table(crst, entry, sizeof(unsigned long)*2048);
}
#ifndef __s390x__
@@ -90,7 +86,7 @@
static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
{
- unsigned long *table = crst_table_alloc(mm, mm->context.noexec);
+ unsigned long *table = crst_table_alloc(mm);
if (table)
crst_table_init(table, _REGION3_ENTRY_EMPTY);
return (pud_t *) table;
@@ -99,7 +95,7 @@
static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long vmaddr)
{
- unsigned long *table = crst_table_alloc(mm, mm->context.noexec);
+ unsigned long *table = crst_table_alloc(mm);
if (table)
crst_table_init(table, _SEGMENT_ENTRY_EMPTY);
return (pmd_t *) table;
@@ -115,11 +111,6 @@
static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
{
pgd_populate_kernel(mm, pgd, pud);
- if (mm->context.noexec) {
- pgd = get_shadow_table(pgd);
- pud = get_shadow_table(pud);
- pgd_populate_kernel(mm, pgd, pud);
- }
}
static inline void pud_populate_kernel(struct mm_struct *mm,
@@ -131,11 +122,6 @@
static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
pud_populate_kernel(mm, pud, pmd);
- if (mm->context.noexec) {
- pud = get_shadow_table(pud);
- pmd = get_shadow_table(pmd);
- pud_populate_kernel(mm, pud, pmd);
- }
}
#endif /* __s390x__ */
@@ -143,10 +129,8 @@
static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
spin_lock_init(&mm->context.list_lock);
- INIT_LIST_HEAD(&mm->context.crst_list);
INIT_LIST_HEAD(&mm->context.pgtable_list);
- return (pgd_t *)
- crst_table_alloc(mm, user_mode == SECONDARY_SPACE_MODE);
+ return (pgd_t *) crst_table_alloc(mm);
}
#define pgd_free(mm, pgd) crst_table_free(mm, (unsigned long *) pgd)
@@ -160,10 +144,6 @@
pmd_t *pmd, pgtable_t pte)
{
pmd_populate_kernel(mm, pmd, pte);
- if (mm->context.noexec) {
- pmd = get_shadow_table(pmd);
- pmd_populate_kernel(mm, pmd, pte + PTRS_PER_PTE);
- }
}
#define pmd_pgtable(pmd) \
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 02ace34..763620e 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -256,8 +256,6 @@
#define _PAGE_TYPE_FILE 0x601 /* bit 0x002 is used for offset !! */
#define _PAGE_TYPE_RO 0x200
#define _PAGE_TYPE_RW 0x000
-#define _PAGE_TYPE_EX_RO 0x202
-#define _PAGE_TYPE_EX_RW 0x002
/*
* Only four types for huge pages, using the invalid bit and protection bit
@@ -287,8 +285,6 @@
* _PAGE_TYPE_FILE 11?1 -> 11?1
* _PAGE_TYPE_RO 0100 -> 1100
* _PAGE_TYPE_RW 0000 -> 1000
- * _PAGE_TYPE_EX_RO 0110 -> 1110
- * _PAGE_TYPE_EX_RW 0010 -> 1010
*
* pte_none is true for bits combinations 1000, 1010, 1100, 1110
* pte_present is true for bits combinations 0000, 0010, 0100, 0110, 1001
@@ -387,55 +383,33 @@
#define PAGE_NONE __pgprot(_PAGE_TYPE_NONE)
#define PAGE_RO __pgprot(_PAGE_TYPE_RO)
#define PAGE_RW __pgprot(_PAGE_TYPE_RW)
-#define PAGE_EX_RO __pgprot(_PAGE_TYPE_EX_RO)
-#define PAGE_EX_RW __pgprot(_PAGE_TYPE_EX_RW)
#define PAGE_KERNEL PAGE_RW
#define PAGE_COPY PAGE_RO
/*
- * Dependent on the EXEC_PROTECT option s390 can do execute protection.
- * Write permission always implies read permission. In theory with a
- * primary/secondary page table execute only can be implemented but
- * it would cost an additional bit in the pte to distinguish all the
- * different pte types. To avoid that execute permission currently
- * implies read permission as well.
+ * On s390 the page table entry has an invalid bit and a read-only bit.
+ * Read permission implies execute permission and write permission
+ * implies read permission.
*/
/*xwr*/
#define __P000 PAGE_NONE
#define __P001 PAGE_RO
#define __P010 PAGE_RO
#define __P011 PAGE_RO
-#define __P100 PAGE_EX_RO
-#define __P101 PAGE_EX_RO
-#define __P110 PAGE_EX_RO
-#define __P111 PAGE_EX_RO
+#define __P100 PAGE_RO
+#define __P101 PAGE_RO
+#define __P110 PAGE_RO
+#define __P111 PAGE_RO
#define __S000 PAGE_NONE
#define __S001 PAGE_RO
#define __S010 PAGE_RW
#define __S011 PAGE_RW
-#define __S100 PAGE_EX_RO
-#define __S101 PAGE_EX_RO
-#define __S110 PAGE_EX_RW
-#define __S111 PAGE_EX_RW
-
-#ifndef __s390x__
-# define PxD_SHADOW_SHIFT 1
-#else /* __s390x__ */
-# define PxD_SHADOW_SHIFT 2
-#endif /* __s390x__ */
-
-static inline void *get_shadow_table(void *table)
-{
- unsigned long addr, offset;
- struct page *page;
-
- addr = (unsigned long) table;
- offset = addr & ((PAGE_SIZE << PxD_SHADOW_SHIFT) - 1);
- page = virt_to_page((void *)(addr ^ offset));
- return (void *)(addr_t)(page->index ? (page->index | offset) : 0UL);
-}
+#define __S100 PAGE_RO
+#define __S101 PAGE_RO
+#define __S110 PAGE_RW
+#define __S111 PAGE_RW
/*
* Certain architectures need to do special things when PTEs
@@ -446,14 +420,6 @@
pte_t *ptep, pte_t entry)
{
*ptep = entry;
- if (mm->context.noexec) {
- if (!(pte_val(entry) & _PAGE_INVALID) &&
- (pte_val(entry) & _PAGE_SWX))
- pte_val(entry) |= _PAGE_RO;
- else
- pte_val(entry) = _PAGE_TYPE_EMPTY;
- ptep[PTRS_PER_PTE] = entry;
- }
}
/*
@@ -662,11 +628,7 @@
static inline void pgd_clear(pgd_t * pgd)
{
- pgd_t *shadow = get_shadow_table(pgd);
-
pgd_clear_kernel(pgd);
- if (shadow)
- pgd_clear_kernel(shadow);
}
static inline void pud_clear_kernel(pud_t *pud)
@@ -677,13 +639,8 @@
static inline void pud_clear(pud_t *pud)
{
- pud_t *shadow = get_shadow_table(pud);
-
pud_clear_kernel(pud);
- if (shadow)
- pud_clear_kernel(shadow);
}
-
#endif /* __s390x__ */
static inline void pmd_clear_kernel(pmd_t * pmdp)
@@ -693,18 +650,12 @@
static inline void pmd_clear(pmd_t *pmd)
{
- pmd_t *shadow = get_shadow_table(pmd);
-
pmd_clear_kernel(pmd);
- if (shadow)
- pmd_clear_kernel(shadow);
}
static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
- if (mm->context.noexec)
- pte_val(ptep[PTRS_PER_PTE]) = _PAGE_TYPE_EMPTY;
}
/*
@@ -903,10 +854,6 @@
}
__ptep_ipte(address, ptep);
pte_val(*ptep) = _PAGE_TYPE_EMPTY;
- if (mm->context.noexec) {
- __ptep_ipte(address, ptep + PTRS_PER_PTE);
- pte_val(*(ptep + PTRS_PER_PTE)) = _PAGE_TYPE_EMPTY;
- }
}
/*
diff --git a/arch/s390/include/asm/tlbflush.h b/arch/s390/include/asm/tlbflush.h
index 29d5d6d..4fdcefc 100644
--- a/arch/s390/include/asm/tlbflush.h
+++ b/arch/s390/include/asm/tlbflush.h
@@ -80,16 +80,11 @@
* on all cpus instead of doing a local flush if the mm
* only ran on the local cpu.
*/
- if (MACHINE_HAS_IDTE) {
- if (mm->context.noexec)
- __tlb_flush_idte((unsigned long)
- get_shadow_table(mm->pgd) |
- mm->context.asce_bits);
+ if (MACHINE_HAS_IDTE)
__tlb_flush_idte((unsigned long) mm->pgd |
mm->context.asce_bits);
- return;
- }
- __tlb_flush_full(mm);
+ else
+ __tlb_flush_full(mm);
}
static inline void __tlb_flush_mm_cond(struct mm_struct * mm)