x86_64: pmap: removed support code for mixed-size mappings.

Mixed-size mappings (e.g. composing a mapping from 4k and 2M pages) don't work
on x86 unless the physical and virtual addresses have matching alignments (a
2M mapping needs both a 2M aligned virtual and physical address).  Thus we
don't support this case in the default library OS.

The kernel doesn't care though and you can roll your own system where you
allocate physical memory that matches the alignment so that the first 2M
aligned virtual address lands on a 2M aligned physical address.

Signed-off-by: Simon Gerber <simon.gerber@hp.com>

diff --git a/lib/barrelfish/target/x86_64/pmap_target.c b/lib/barrelfish/target/x86_64/pmap_target.c
index f4bbbdd..e4e1f21 100644 (file)
--- a/lib/barrelfish/target/x86_64/pmap_target.c
+++ b/lib/barrelfish/target/x86_64/pmap_target.c
@@ -288,51 +288,24 @@ static errval_t do_map(struct pmap_x86 *pmap, genvaddr_t vaddr,
     size_t table_base = X86_64_PTABLE_BASE(vaddr);
     uint8_t map_bits  = X86_64_BASE_PAGE_BITS + X86_64_PTABLE_BITS;
     bool debug_out    = false;
-    vregion_flags_t mixed_mapping = 0;
-    if ((flags & VREGION_FLAGS_LARGE) &&
-        (vaddr & X86_64_LARGE_PAGE_MASK) == 0) {
-        // large page branch (2MB)
-        page_size  = X86_64_LARGE_PAGE_SIZE;
-        table_base = X86_64_PDIR_BASE(vaddr);
-        map_bits   = X86_64_LARGE_PAGE_BITS + X86_64_PTABLE_BITS;
-        if (flags & VREGION_FLAGS_HUGE) {
-            // take out huge flag from vregion flags and set mixed_mapping
-            // hint.
-            flags &= ~VREGION_FLAGS_HUGE;
-            mixed_mapping = VREGION_FLAGS_HUGE;
-        }
-        debug_out  = false;
-    } else if ((flags & VREGION_FLAGS_HUGE) &&
-               (vaddr & X86_64_HUGE_PAGE_MASK) == 0) {
-        // huge page branch (1GB); no mixed mappings for this configuration
+    if ((flags & VREGION_FLAGS_HUGE) &&
+        (vaddr & X86_64_HUGE_PAGE_MASK) == 0)
+    {
+        // huge page branch (1GB)
         page_size  = X86_64_HUGE_PAGE_SIZE;
         table_base = X86_64_PDPT_BASE(vaddr);
         map_bits   = X86_64_HUGE_PAGE_BITS + X86_64_PTABLE_BITS;
         debug_out  = false;
+        // remove large flag, if we're doing huge mapping
         flags     &= ~VREGION_FLAGS_LARGE;
-    } else if (flags & (VREGION_FLAGS_LARGE|VREGION_FLAGS_HUGE)) {
-        const char *flagstr = NULL;
-        switch (flags & (VREGION_FLAGS_LARGE|VREGION_FLAGS_HUGE)) {
-            case VREGION_FLAGS_LARGE:
-                flagstr = "VREGION_FLAGS_LARGE";
-                break;
-            case VREGION_FLAGS_HUGE:
-                flagstr = "VREGION_FLAGS_HUGE";
-                break;
-            case VREGION_FLAGS_HUGE|VREGION_FLAGS_LARGE:
-                flagstr = "VREGION_FLAGS_HUGE|VREGION_FLAGS_LARGE";
-                break;
-            default:
-                flagstr = "0";
-                break;
-        }
-        debug_printf("Treating '%s' as a hint for mixed-page-size mapping\n",
-                flagstr);
-        // take out actual large/huge flags for mixed mapping code
-        // and set mixed_mapping hint to set of large/huge flags that were
-        // present in original flags
-        mixed_mapping = flags & (VREGION_FLAGS_LARGE|VREGION_FLAGS_HUGE);
-        flags        &= ~(VREGION_FLAGS_LARGE|VREGION_FLAGS_HUGE);
+    } else if ((flags & VREGION_FLAGS_LARGE) &&
+               (vaddr & X86_64_LARGE_PAGE_MASK) == 0)
+    {
+        // large page branch (2MB)
+        page_size  = X86_64_LARGE_PAGE_SIZE;
+        table_base = X86_64_PDIR_BASE(vaddr);
+        map_bits   = X86_64_LARGE_PAGE_BITS + X86_64_PTABLE_BITS;
+        debug_out  = false;
     }
 
     // round to the next full page
@@ -362,7 +335,6 @@ static errval_t do_map(struct pmap_x86 *pmap, genvaddr_t vaddr,
 #endif
 
     // all mapping on one leaf table?
-    // TODO: needs some work for mixed-size mappings
     if (is_same_pdir(vaddr, vend) ||
         (flags & VREGION_FLAGS_LARGE && is_same_pdpt(vaddr, vend)) ||
         (flags & VREGION_FLAGS_HUGE && is_same_pml4(vaddr, vend))) {
@@ -599,7 +571,6 @@ static errval_t map(struct pmap *pmap, genvaddr_t vaddr, struct capref frame,
         max_slabs = max_slabs_for_mapping(size);
     }
 
-
     // Refill slab allocator if necessary
     size_t slabs_free = slab_freecount(&x86->slab);