On 02/24/2016 05:11 AM, Alexander Graf wrote:
The idea to generate our pages tables from an array of memory ranges
is very sound. However, instead of hard coding the code to create up
to 2 levels of 64k granule page tables, we really should just create
normal 4k page tables that allow us to set caching attributes on 2M
or 4k level later on.
So this patch moves the full_va mapping code to 4k page size and
makes it fully flexible to dynamically create as many levels as
necessary for a map (including dynamic 1G/2M pages). It also adds
support to dynamically split a large map into smaller ones when
some code wants to set dcache attributes.
With all this in place, there is very little reason to create your
own page tables in board specific files.
Signed-off-by: Alexander Graf <ag...@suse.de>
+/*
+ * This is a recursively called function to count the number of
+ * page tables we need to cover a particular PTE range. If you
+ * call this with level = -1 you basically get the full 48 bit
+ * coverage.
+ */
+static int count_required_pts(u64 addr, int level, u64 maxaddr)
I think this looks correct now. Nits below if a respin is needed for
other reasons.
+{
+ int levelshift = level2shift(level);
+ u64 levelsize = 1ULL << levelshift;
+ u64 levelmask = levelsize - 1;
+ u64 levelend = addr + levelsize;
+ int r = 0;
+ int i;
+ bool is_level = false;
I might suggest renaming that is_level_needed. It's not obvious to me
exactly what the name "is_level" is intended to represent; the name
seems to represent whether something (unspecified) is a level or not.
+
+ for (i = 0; i < ARRAY_SIZE(mem_map); i++) {
+ struct mm_region *map = &mem_map[i];
+ u64 start = map->base;
+ u64 end = start + map->size;
+
+ /* Check if the PTE would overlap with the map */
+ if (max(addr, start) <= min(levelend, end)) {
+ start = max(addr, start);
+ end = min(levelend, end);
+
+ /* We need a sub-pt for this level */
+ if ((start & levelmask) || (end & levelmask)) {
+ is_level = true;
+ break;
+ }
+
+ /* Lv0 can not do block PTEs, so do levels here too */
+ if (level <= 0) {
+ is_level = true;
+ break;
+ }
+ }
+ }
+
+ /*
+ * Block PTEs at this level are already covered by the parent page
+ * table, so we only need to count sub page tables.
+ */
+ if (is_level) {
+ int sublevel = level + 1;
+ u64 sublevelsize = 1ULL << level2shift(sublevel);
+
+ /* Account for the new sub page table ... */
+ r = 1;
"Account for the page table at /this/ level"? This may represent the
top-level (0/1) page table, not just sub page tables. The sub-level
accounting is via the recursive call to count_required_pts() I believe.
+
+ /* ... and for all child page tables that one might have */
+ for (i = 0; i < MAX_PTE_ENTRIES; i++) {
+ r += count_required_pts(addr, sublevel, maxaddr);
+ addr += sublevelsize;
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