[igt-dev] [PATCH i-g-t 2/3] tools/aubdump: Add bitmap to track gtt pages that have been mapped

[Jordan Justen]

This will allow us to map ranges as they are used, but prevents
remapping already mapped regions.

By mapping ranges as they are used, we can support pinned pages
without having to map all pages of the first 32-bits.

v2:
 * Make bitmap manipulation functions independent from 4k page size.
   Maybe will be usable also for 1GB pages with PPGTT.

Cc: Scott D Phillips <scott.d.phillips at intel.com>
Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
---
 tools/aubdump.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 95 insertions(+), 1 deletion(-)

diff --git a/tools/aubdump.c b/tools/aubdump.c
index bf4be82d..dc5db9dc 100644
--- a/tools/aubdump.c
+++ b/tools/aubdump.c
@@ -383,7 +383,7 @@ register_write_out(uint32_t addr, uint32_t value)
 }
 
 static void
-gen8_map_ggtt_range(uint64_t start, uint64_t end)
+gen8_emit_ggtt_pte_for_range(uint64_t start, uint64_t end)
 {
 	uint64_t entry_addr;
 	uint64_t page_num;
@@ -410,6 +410,100 @@ gen8_map_ggtt_range(uint64_t start, uint64_t end)
 	} while (entry_addr < end);
 }
 
+/**
+ * Sets bits `start` through `end` - 1 in the bitmap array.
+ */
+static void
+set_bitmap_range(uint32_t *bitmap, uint32_t start, uint32_t end)
+{
+	uint32_t pos = start;
+	while (pos < end) {
+		const uint32_t bit = 1 << (pos & 0x1f);
+		if (bit == 1 && (end - pos) > 32) {
+			bitmap[pos >> 5] = 0xffffffff;
+			pos += 32;
+		} else {
+			bitmap[pos >> 5] |= bit;
+			pos++;
+		}
+	}
+}
+
+/**
+ * Finds the next `set` (or clear) bit in the bitmap array.
+ *
+ * The search starts at `*start` and only checks until `end` - 1.
+ *
+ * If found, returns true, and the found bit index in `*start`.
+ */
+static bool
+find_bitmap_bit(uint32_t *bitmap, bool set, uint32_t *start, uint32_t end)
+{
+	uint32_t pos = *start;
+	const uint32_t neg_dw = set ? 0 : -1;
+	while (pos < end) {
+		const uint32_t dw = bitmap[pos >> 5];
+		const uint32_t bit = 1 << (pos & 0x1f);
+		if (!!(dw & bit) == set) {
+			*start = pos;
+			return true;
+		} else if (bit == 1 && dw == neg_dw)
+			pos += 32;
+		else
+			pos++;
+	}
+	return false;
+}
+
+/**
+ * Finds a range of clear bits within the bitmap array.
+ *
+ * The search starts at `*start` and only checks until `*end` - 1.
+ *
+ * If found, returns true, and `*start` and `*end` are set for the
+ * range of clear bits.
+ */
+static bool
+find_bitmap_clear_bit_range(uint32_t *bitmap, uint32_t *start, uint32_t *end)
+{
+	if (find_bitmap_bit(bitmap, false, start, *end)) {
+		uint32_t found_end = *start;
+		if (find_bitmap_bit(bitmap, true, &found_end, *end))
+			*end = found_end;
+		return true;
+	}
+	return false;
+}
+
+static void
+gen8_map_ggtt_range(uint64_t start, uint64_t end)
+{
+	uint32_t pos1, pos2, end_pos;
+	static uint32_t *bitmap = NULL;
+	if (bitmap == NULL) {
+		/* 4GiB (32-bits) of 4KiB pages (12-bits) in dwords (5-bits) */
+		bitmap = calloc(1 << (32 - 12 - 5), sizeof(*bitmap));
+		if (bitmap == NULL)
+			return;
+	}
+
+	pos1 = start >> 12;
+	end_pos = (end + 4096 - 1) >> 12;
+	while (pos1 < end_pos) {
+		pos2 = end_pos;
+		if (!find_bitmap_clear_bit_range(bitmap, &pos1, &pos2))
+			break;
+
+		if (verbose)
+			printf("MAPPING 0x%08lx-0x%08lx\n",
+			       (uint64_t)pos1 << 12, (uint64_t)pos2 << 12);
+		gen8_emit_ggtt_pte_for_range((uint64_t)pos1 << 12,
+		                             (uint64_t)pos2 << 12);
+		set_bitmap_range(bitmap, (uint64_t)pos1, (uint64_t)pos2);
+		pos1 = pos2;
+	}
+}
+
 static void
 gen10_write_header(void)
 {
-- 
2.16.1