powerepc/book3s64/hash: Align start/end address correctly with bolt mapping

This ensures we don't do a partial mapping of memory. With nvdimm, when
creating namespaces with size not aligned to 16MB, the kernel ends up partially
mapping the pages. This can result in kernel adding multiple hash page table
entries for the same range. A new namespace will result in
create_section_mapping() with start and end overlapping an already existing
bolted hash page table entry.

commit: 6acd7d5ef264 ("libnvdimm/namespace: Enforce memremap_compat_align()")
made sure that we always create namespaces aligned to 16MB. But we can do
better by avoiding mapping pages that are not aligned. This helps to catch
access to these partially mapped pages early.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200907072539.67310-1-aneesh.kumar@linux.ibm.com

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index c663e7ba801fce6969ea717958b7170c941935e8..7185bc43b24f9d607b35541f152e005d90d134c5 100644 (file)
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -260,8 +260,12 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
        DBG("htab_bolt_mapping(%lx..%lx -> %lx (%lx,%d,%d)\n",
            vstart, vend, pstart, prot, psize, ssize);
 
-       for (vaddr = vstart, paddr = pstart; vaddr < vend;
-            vaddr += step, paddr += step) {
+       /* Carefully map only the possible range */
+       vaddr = ALIGN(vstart, step);
+       paddr = ALIGN(pstart, step);
+       vend  = ALIGN_DOWN(vend, step);
+
+       for (; vaddr < vend; vaddr += step, paddr += step) {
                unsigned long hash, hpteg;
                unsigned long vsid = get_kernel_vsid(vaddr, ssize);
                unsigned long vpn  = hpt_vpn(vaddr, vsid, ssize);
@@ -343,7 +347,9 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
        if (!mmu_hash_ops.hpte_removebolted)
                return -ENODEV;
 
-       for (vaddr = vstart; vaddr < vend; vaddr += step) {
+       /* Unmap the full range specificied */
+       vaddr = ALIGN_DOWN(vstart, step);
+       for (;vaddr < vend; vaddr += step) {
                rc = mmu_hash_ops.hpte_removebolted(vaddr, psize, ssize);
                if (rc == -ENOENT) {
                        ret = -ENOENT;

diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index d5f0c10d752a37086146ab68c6ce6769d587ed81..5c8adeb8c95564455d2879ff49fbc9d3b9a42704 100644 (file)
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -276,6 +276,7 @@ static int __meminit create_physical_mapping(unsigned long start,
        int psize;
 
        start = ALIGN(start, PAGE_SIZE);
+       end   = ALIGN_DOWN(end, PAGE_SIZE);
        for (addr = start; addr < end; addr += mapping_size) {
                unsigned long gap, previous_size;
                int rc;