bootmem: Clarify usage with bounce-buffer

Add bootmem_targets_usable_with_bounce() to handle
cases of payload loading via bounce-buffer.

Change-Id: I9ebbc621f8810c0317d7c97c6b4cdd41527ddcbb
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/26985
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 26 insertions, 3 deletions

diff --git a/src/include/bootmem.h b/src/include/bootmem.h
index 0a960c992a..28bc95bae8 100644
--- a/src/include/bootmem.h
+++ b/src/include/bootmem.h
@@ -97,6 +97,11 @@ bool bootmem_walk(range_action_t action, void *arg);
 /* Return 1 if region targets usable RAM, 0 otherwise. */
 int bootmem_region_targets_usable_ram(uint64_t start, uint64_t size);
 
+/* Return 1 if region targets usable RAM, and we allow memory ranges
+ * with type >BM_MEM_OS_CUTOFF to be overwritten at the time we jump
+ * to payload. 0 otherwise. */
+int bootmem_region_usable_with_bounce(uint64_t start, uint64_t size);
+
 /* Allocate a temporary buffer from the unused RAM areas. */
 void *bootmem_allocate_buffer(size_t size);
 
diff --git a/src/lib/bootmem.c b/src/lib/bootmem.c
index 90f4970d52..66d459207d 100644
--- a/src/lib/bootmem.c
+++ b/src/lib/bootmem.c
@@ -201,12 +201,12 @@ bool bootmem_walk(range_action_t action, void *arg)
 	return false;
 }
 
-int bootmem_region_targets_usable_ram(uint64_t start, uint64_t size)
+static int bootmem_region_targets_ram(uint64_t start, uint64_t end,
+				struct memranges *bm)
 {
 	const struct range_entry *r;
-	uint64_t end = start + size;
 
-	memranges_each_entry(r, &bootmem) {
+	memranges_each_entry(r, bm) {
 		/* All further bootmem entries are beyond this range. */
 		if (end <= range_entry_base(r))
 			break;
@@ -219,6 +219,24 @@ int bootmem_region_targets_usable_ram(uint64_t start, uint64_t size)
 	return 0;
 }
 
+/* Common testcase for loading any segments to bootmem.
+ * Returns 1 if the requested memory range is all tagged as type BM_MEM_RAM.
+ * Otherwise returns 0.
+ */
+int bootmem_region_targets_usable_ram(uint64_t start, uint64_t size)
+{
+	return bootmem_region_targets_ram(start, start + size, &bootmem);
+}
+
+/* Special testcase to use when loading payload segments when bounce-buffer is
+ * supported. Memory ranges tagged with >BM_MEM_OS_CUTOFF may be overwritten at
+ * the time we jump to payload.
+ */
+int bootmem_region_usable_with_bounce(uint64_t start, uint64_t size)
+{
+	return bootmem_region_targets_ram(start, start + size, &bootmem_os);
+}
+
 void *bootmem_allocate_buffer(size_t size)
 {
 	const struct range_entry *r;