[PATCH 06/11] of: reserved_mem: save /memreserve/ entries into reserved_mem array

[Chen Wandun]

Save /memreserve/ entries from the FDT header into the reserved_mem
array so they can be consumed as vmcore filtering metadata by kdump.

/memreserve/ regions hold firmware or bootloader state that is not
useful for kernel crash analysis, so saved /memreserve/ entries
default to no_dump=true and are tagged with name="memreserve" so
consumers can distinguish them from /reserved-memory/ child nodes.

Some DTBs declare the same or overlapping range in both
/memreserve/ and a /reserved-memory/ child. Commit b41328187629
("of: fdt: Scan /memreserve/ last") describes one such case on
Khadas Vim3 where the range is in /memreserve/ and also in a
/reserved-memory/ child carrying no-map. The /reserved-memory/
node's attributes (no-map, reusable, linux,no-dump) are the
explicit declaration and must win over the firmware default,
fdt_reserved_mem_save_memreserve() therefore inherits no_dump from
the overlapping /reserved-memory/ entry rather than silently
applying no_dump=true.

Signed-off-by: Chen Wandun <chenwandun at lixiang.com>
Tested-by: Zhao Meijing <zhaomeijing at lixiang.com>
---
 drivers/of/of_reserved_mem.c | 107 +++++++++++++++++++++++++++++------
 1 file changed, 91 insertions(+), 16 deletions(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index ac3d8b837d61..4b80420da2d2 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -252,6 +252,49 @@ static void __init __rmem_check_for_overlap(void)
 	}
 }
 
+/**
+ * fdt_reserved_mem_save_memreserve() - save a /memreserve/ entry
+ * @base: base address
+ * @size: size
+ *
+ * Save a /memreserve/ range into reserved_mem[] with no_dump=true
+ * as the firmware default. If the range overlaps a /reserved-memory/
+ * child already saved in this pass, inherit that entry's no_dump so
+ * node-level attributes (no-map, reusable, linux,no-dump) win over
+ * the firmware default.
+ */
+static void __init fdt_reserved_mem_save_memreserve(phys_addr_t base,
+						    phys_addr_t size)
+{
+	struct reserved_mem *rmem;
+	phys_addr_t end = base + size;
+	bool no_dump = true;
+	int i;
+
+	for (i = 0; i < reserved_mem_count; i++) {
+		phys_addr_t r_base = reserved_mem[i].base;
+		phys_addr_t r_end = r_base + reserved_mem[i].size;
+
+		if (base < r_end && end > r_base) {
+			no_dump = reserved_mem[i].no_dump;
+			break;
+		}
+	}
+
+	if (reserved_mem_count == total_reserved_mem_cnt) {
+		pr_err("not enough space for all defined regions.\n");
+		return;
+	}
+
+	rmem = &reserved_mem[reserved_mem_count];
+	rmem->name = "memreserve";
+	rmem->base = base;
+	rmem->size = size;
+	rmem->no_dump = no_dump;
+
+	reserved_mem_count++;
+}
+
 /**
  * fdt_scan_reserved_mem_late() - Scan FDT and initialize remaining reserved
  * memory regions.
@@ -260,6 +303,9 @@ static void __init __rmem_check_for_overlap(void)
  * "static" reserved memory regions, that are defined using the "reg"
  * property. Each such region is then initialized with its specific init
  * function and stored in the global reserved_mem array.
+ *
+ * In addition, /memreserve/ entries from the FDT header are saved into
+ * the reserved_mem array so they can be consumed as vmcore metadata.
  */
 void __init fdt_scan_reserved_mem_late(void)
 {
@@ -270,28 +316,32 @@ void __init fdt_scan_reserved_mem_late(void)
 	if (!fdt)
 		return;
 
+	/*
+	 * fdt_scan_reserved_mem() has set total_reserved_mem_cnt to the
+	 * total number of entries to be saved (reg-based + /memreserve/).
+	 * If it is zero there is nothing to allocate, save or check.
+	 */
+	if (!total_reserved_mem_cnt)
+		return;
+
+	/*
+	 * Allocate up front: /memreserve/ saves below may run on any
+	 * path and must write into a memblock-backed array, not the
+	 * __initdata reserved_mem_array which is freed at free_initmem().
+	 */
+	alloc_reserved_mem_array();
+
 	node = fdt_path_offset(fdt, "/reserved-memory");
 	if (node < 0) {
 		pr_info("Reserved memory: No reserved-memory node in the DT\n");
-		return;
+		goto memreserve;
 	}
 
 	if (__reserved_mem_check_root(node)) {
 		pr_err("Reserved memory: unsupported node format, ignoring\n");
-		return;
+		goto memreserve;
 	}
 
-	/*
-	 * fdt_scan_reserved_mem() sets total_reserved_mem_cnt to the
-	 * number of entries that need a slot in reserved_mem[]. If it is
-	 * zero there is nothing to allocate or save.
-	 */
-	if (!total_reserved_mem_cnt)
-		return;
-
-	/* Attempt dynamic allocation of a new reserved_mem array */
-	alloc_reserved_mem_array();
-
 	fdt_for_each_subnode(child, fdt, node) {
 		const char *uname;
 		int i, len;
@@ -342,6 +392,18 @@ void __init fdt_scan_reserved_mem_late(void)
 
 	/* check for overlapping reserved regions */
 	__rmem_check_for_overlap();
+
+memreserve:
+	/* Save /memreserve/ entries (independent of /reserved-memory) */
+	for (int i = 0; ; i++) {
+		u64 mbase, msize;
+
+		if (fdt_get_mem_rsv(fdt, i, &mbase, &msize))
+			break;
+		if (!msize)
+			break;
+		fdt_reserved_mem_save_memreserve(mbase, msize);
+	}
 }
 
 static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
@@ -365,11 +427,11 @@ int __init fdt_scan_reserved_mem(void)
 
 	node = fdt_path_offset(fdt, "/reserved-memory");
 	if (node < 0)
-		return -ENODEV;
+		goto memreserve;
 
 	if (__reserved_mem_check_root(node) != 0) {
 		pr_err("Reserved memory: unsupported node format, ignoring\n");
-		return -EINVAL;
+		goto memreserve;
 	}
 
 	fdt_for_each_subnode(child, fdt, node) {
@@ -406,8 +468,21 @@ int __init fdt_scan_reserved_mem(void)
 		if (!err)
 			count++;
 	}
+
+memreserve:
+	/* Count /memreserve/ entries (independent of /reserved-memory) */
+	for (int i = 0; ; i++) {
+		u64 base, size;
+
+		if (fdt_get_mem_rsv(fdt, i, &base, &size))
+			break;
+		if (!size)
+			break;
+		count++;
+	}
+
 	total_reserved_mem_cnt = count;
-	return 0;
+	return count ? 0 : -ENODEV;
 }
 
 /*
-- 
2.43.0