diff options
| author | David Hildenbrand <dahi@linux.vnet.ibm.com> | 2016-06-13 10:49:04 +0200 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2016-06-20 09:55:20 +0200 |
| commit | 01f719176f28016da1b588f6560a4eef18a98a93 (patch) | |
| tree | 1ce75d8a85c078e46bd23733cf7fc098dc21b8dd /arch/s390/mm | |
| parent | 5b6c963bcef5c3a857e3f8ba84aa9380069fc95f (diff) | |
s390/mm: don't fault everything in read-write in gmap_pte_op_fixup()
Let's not fault in everything in read-write but limit it to read-only
where possible.
When restricting access rights, we already have the required protection
level in our hands. When reading from guest 2 storage (gmap_read_table),
it is obviously PROT_READ. When shadowing a pte, the required protection
level is given via the guest 2 provided pte.
Based on an initial patch by Martin Schwidefsky.
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/mm')
| -rw-r--r-- | arch/s390/mm/gmap.c | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index d00e4abb559e..738d75495e56 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -811,19 +811,22 @@ static pte_t *gmap_pte_op_walk(struct gmap *gmap, unsigned long gaddr, * @gmap: pointer to guest mapping meta data structure * @gaddr: virtual address in the guest address space * @vmaddr: address in the host process address space + * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE * * Returns 0 if the caller can retry __gmap_translate (might fail again), * -ENOMEM if out of memory and -EFAULT if anything goes wrong while fixing * up or connecting the gmap page table. */ static int gmap_pte_op_fixup(struct gmap *gmap, unsigned long gaddr, - unsigned long vmaddr) + unsigned long vmaddr, int prot) { struct mm_struct *mm = gmap->mm; + unsigned int fault_flags; bool unlocked = false; BUG_ON(gmap_is_shadow(gmap)); - if (fixup_user_fault(current, mm, vmaddr, FAULT_FLAG_WRITE, &unlocked)) + fault_flags = (prot == PROT_WRITE) ? FAULT_FLAG_WRITE : 0; + if (fixup_user_fault(current, mm, vmaddr, fault_flags, &unlocked)) return -EFAULT; if (unlocked) /* lost mmap_sem, caller has to retry __gmap_translate */ @@ -875,7 +878,7 @@ static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr, vmaddr = __gmap_translate(gmap, gaddr); if (IS_ERR_VALUE(vmaddr)) return vmaddr; - rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr); + rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, prot); if (rc) return rc; continue; @@ -957,7 +960,7 @@ int gmap_read_table(struct gmap *gmap, unsigned long gaddr, unsigned long *val) rc = vmaddr; break; } - rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr); + rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, PROT_READ); if (rc) break; } @@ -1041,7 +1044,7 @@ static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr, radix_tree_preload_end(); if (rc) { kfree(rmap); - rc = gmap_pte_op_fixup(parent, paddr, vmaddr); + rc = gmap_pte_op_fixup(parent, paddr, vmaddr, prot); if (rc) return rc; continue; @@ -1910,10 +1913,12 @@ int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte) unsigned long vmaddr, paddr; spinlock_t *ptl; pte_t *sptep, *tptep; + int prot; int rc; BUG_ON(!gmap_is_shadow(sg)); parent = sg->parent; + prot = (pte_val(pte) & _PAGE_PROTECT) ? PROT_READ : PROT_WRITE; rmap = kzalloc(sizeof(*rmap), GFP_KERNEL); if (!rmap) @@ -1955,7 +1960,7 @@ int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte) radix_tree_preload_end(); if (!rc) break; - rc = gmap_pte_op_fixup(parent, paddr, vmaddr); + rc = gmap_pte_op_fixup(parent, paddr, vmaddr, prot); if (rc) break; } |