[PATCH 1/6] lmb: add LMB_FDT for fdt reserved regions

[rs at ti.com]

From: Randolph Sapp <rs at ti.com>

Add an LMB_FDT bit for fdt reserved regions, so we can reclaim them when
parsing a new device tree and properly warn people when a reservation
overlaps with an existing allocation.

If we don't at least warn the user of these reservation failures,
there's a chance that this region could be freed and reallocated for
something important later.

This useful warning mechanism was broken in:
5a6aa7d5913 ("boot: fdt: Handle already reserved memory in boot_fdt_reserve_region()")

Signed-off-by: Randolph Sapp <rs at ti.com>
---
 boot/image-fdt.c |  5 ++++-
 include/lmb.h    |  7 +++++++
 lib/lmb.c        | 23 +++++++++++++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/boot/image-fdt.c b/boot/image-fdt.c
index a3a4fb8b558..0f5857f24d2 100644
--- a/boot/image-fdt.c
+++ b/boot/image-fdt.c
@@ -73,6 +73,7 @@ static void boot_fdt_reserve_region(u64 addr, u64 size, u32 flags)
 {
 	long ret;
 	phys_addr_t rsv_addr;
+	flags |= LMB_FDT;
 
 	rsv_addr = (phys_addr_t)addr;
 	ret = lmb_alloc_mem(LMB_MEM_ALLOC_ADDR, 0, &rsv_addr, size, flags);
@@ -80,7 +81,7 @@ static void boot_fdt_reserve_region(u64 addr, u64 size, u32 flags)
 		debug("   reserving fdt memory region: addr=%llx size=%llx flags=%x\n",
 		      (unsigned long long)addr,
 		      (unsigned long long)size, flags);
-	} else if (ret != -EEXIST && ret != -EINVAL) {
+	} else if (ret != -EINVAL) {
 		puts("ERROR: reserving fdt memory region failed ");
 		printf("(addr=%llx size=%llx flags=%x)\n",
 		       (unsigned long long)addr,
@@ -108,6 +109,8 @@ void boot_fdt_add_mem_rsv_regions(void *fdt_blob)
 	if (fdt_check_header(fdt_blob) != 0)
 		return;
 
+	lmb_free_fdt_regions();
+
 	/* process memreserve sections */
 	total = fdt_num_mem_rsv(fdt_blob);
 	for (i = 0; i < total; i++) {
diff --git a/include/lmb.h b/include/lmb.h
index 5d5f037ccb9..1b59a63f61d 100644
--- a/include/lmb.h
+++ b/include/lmb.h
@@ -25,11 +25,13 @@
  * %LMB_NOMAP: Don't add to MMU configuration
  * %LMB_NOOVERWRITE: The memory region cannot be overwritten/re-reserved
  * %LMB_NONOTIFY: Do not notify other modules of changes to this memory region
+ * %LMB_FDT: A FDT reserved region that can be reclaimed if the FDT changes
  */
 #define LMB_NONE 0
 #define LMB_NOMAP BIT(1)
 #define LMB_NOOVERWRITE BIT(2)
 #define LMB_NONOTIFY BIT(3)
+#define LMB_FDT BIT(4)
 
 /**
  * enum lmb_mem_type - type of memory allocation request
@@ -215,6 +217,11 @@ phys_addr_t io_lmb_alloc(struct lmb *io_lmb, phys_size_t size, ulong align);
  */
 long io_lmb_free(struct lmb *io_lmb, phys_addr_t base, phys_size_t size);
 
+/**
+ * lmb_free_fdt_regions() - Reclaim all LMB_FDT tagged reserved regions
+ */
+void lmb_free_fdt_regions(void);
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_LMB_H */
diff --git a/lib/lmb.c b/lib/lmb.c
index e2d9fe86c14..542bb11dcf5 100644
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -669,6 +669,29 @@ long lmb_free(phys_addr_t base, phys_size_t size, u32 flags)
 	return lmb_map_update_notify(base, size, LMB_MAP_OP_FREE, flags);
 }
 
+void lmb_free_fdt_regions(void)
+{
+	struct alist *lmb_rgn_lst = &lmb.used_mem;
+	struct lmb_region *rgn = lmb_rgn_lst->data;
+	long ret;
+
+	for (int i = 0; i < lmb_rgn_lst->count; i++) {
+		phys_addr_t base = rgn[i].base;
+		phys_size_t size = rgn[i].size;
+		u32 flags = rgn[i].flags;
+
+		if (flags & LMB_FDT) {
+			ret = lmb_free(base, size, flags);
+			if (ret < 0) {
+				printf("Unable to free FDT memory at 0x%08lx",
+				       (ulong)base);
+				continue;
+			}
+			i--;
+		}
+	}
+}
+
 static int _lmb_alloc_base(phys_size_t size, ulong align,
 			   phys_addr_t *addr, u32 flags)
 {
-- 
2.53.0