soc: rockchip: add /proc/rk_zoneinfo/zoneinfo

The dump zone information using the following two commands:

1. cat /proc/rk_zoneinfo/zoneinfo
2. cat /proc/rk_zoneinfo/zoneinfo > /data/data/1.txt

NOTICE: dumping zone information should only be done during debugging.
The dump zone information holds the spinlock of the zone, which can
impact the performance of the memory subsystem.

==== ZONE & PAGE INFO (with page order) ====
Zone: DMA32
  managed_pages:  952984
  spanned_pages:  1048064
  present_pages:  978432

  Order: 0 | nr_free: 5
    Migrate type 0 => (empty)
    Migrate type 1 => page: fffffffe000a3940 | PFN: 00010469 | phys_addr: 0x00028e5000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 0
    Migrate type 1 => page: fffffffe0028d940 | PFN: 00041829 | phys_addr: 0x000a365000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 0
    Migrate type 2 => (empty)
    Migrate type 3 => page: fffffffe004085c0 | PFN: 00066071 | phys_addr: 0x0010217000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 0
    Migrate type 3 => page: fffffffe004089c0 | PFN: 00066087 | phys_addr: 0x0010227000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 0
    Migrate type 3 => page: fffffffe00408ac0 | PFN: 00066091 | phys_addr: 0x001022b000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 0
    Migrate type 4 => (empty)
    Migrate type 5 => (empty)

  Order: 1 | nr_free: 65
    Migrate type 0 => (empty)
    Migrate type 1 => page: fffffffe000a3980 | PFN: 00010470 | phys_addr: 0x00028e6000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 1
    Migrate type 1 => page: fffffffe0020d280 | PFN: 00033610 | phys_addr: 0x000834a000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 1
    Migrate type 1 => page: fffffffe0028d980 | PFN: 00041830 | phys_addr: 0x000a366000 | flags: 0x0 | compound: 0 | node: 0 | zone: DMA32 | buddy_order: 1
    Migrate type 2 => (empty)

Change-Id: If9227fefaa79d744ca6dde123bd50f033d30c39c
Signed-off-by: Simon Xue <xxm@rock-chips.com>

drivers/soc/rockchip/Kconfig

@@ -348,6 +348,12 @@ config RK_MEMBLOCK_PROCFS
 	  Extend memblock procfs to show size of each memblock, and shows the
 	  result of total size by KiB format.
 
+config RK_ZONEINFO_PROCFS
+	bool "Zoneinfo procfs support"
+	depends on PROC_FS
+	help
+	  Dump all zone information.
+
 source "drivers/soc/rockchip/minidump/Kconfig"
 
 endmenu

drivers/soc/rockchip/Makefile

@@ -34,4 +34,5 @@ obj-$(CONFIG_ROCKCHIP_NPOR_POWERGOOD) += rockchip_npor_powergood.o
 obj-$(CONFIG_RK_CMA_PROCFS) += rk_cma_procfs.o
 obj-$(CONFIG_RK_DMABUF_PROCFS) += rk_dmabuf_procfs.o
 obj-$(CONFIG_RK_MEMBLOCK_PROCFS) += rk_memblock_procfs.o
+obj-$(CONFIG_RK_ZONEINFO_PROCFS) += rk_zoneinfo_procfs.o
 obj-$(CONFIG_ROCKCHIP_MINIDUMP)	+= minidump/

drivers/soc/rockchip/rk_zoneinfo_procfs.c

@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Rockchip Electronics Co., Ltd.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/list.h>
+#include <linux/page-flags.h>
+#include <linux/pfn.h>
+#include <linux/proc_fs.h>
+
+/*
+ * This kernel module creates a procfs entry that prints
+ * detailed zone and page information, including the page's order if it
+ * is part of the buddy allocator (PageBuddy is set). It is updated for
+ * for_each_populated_zone(zone) iterates over all zones
+ * without referencing pgdat. For each zone and order, it shows:
+ *   - free_area info by migrate type
+ *   - each page in the free list, including:
+ *	   * page pointer
+ *	   * PFN (page frame number)
+ *	   * raw page flags
+ *	   * physical address
+ *	   * node ID
+ *	   * whether it's a compound page
+ *	   * the (buddy) order if PageBuddy is set
+ *
+ * Usage:
+ *   cat /proc/rk_zoneinfo/zoneinfo > /data/data/1.txt
+ */
+
+static int rk_zoneinfo_show(struct seq_file *m, void *v)
+{
+	struct zone *zone;
+	int order, type;
+	unsigned long flags;
+
+	seq_puts(m, "==== ZONE & PAGE INFO (with page order) ====\n");
+
+	for_each_populated_zone(zone) {
+		seq_printf(m, "Zone: %s\n", zone->name);
+		seq_printf(m, "  managed_pages:  %lu\n",
+			   atomic_long_read(&zone->managed_pages));
+		seq_printf(m, "  spanned_pages:  %lu\n", zone->spanned_pages);
+		seq_printf(m, "  present_pages:  %lu\n\n", zone->present_pages);
+
+		spin_lock_irqsave(&zone->lock, flags);
+
+		/* For each order in this zone, we examine the free lists */
+		for (order = 0; order < MAX_ORDER; order++) {
+			seq_printf(m, "\tOrder: %d | nr_free: %lu\n",
+				   order, zone->free_area[order].nr_free);
+
+			for (type = 0; type < MIGRATE_TYPES; type++) {
+				struct list_head *head =
+					&zone->free_area[order].free_list[type];
+				struct page *page;
+
+				if (list_empty(head)) {
+					seq_printf(m, "\t\tMigrate type %d => (empty)\n", type);
+					continue;
+				}
+
+				list_for_each_entry(page, head, lru) {
+					unsigned long pfn = page_to_pfn(page);
+					unsigned int buddy_order = 0;
+
+					if (PageBuddy(page))
+						buddy_order = page_private(page);
+
+					seq_printf(
+						m,
+						"\t\tMigrate type %d => page: %p | PFN: %08lu | phys_addr: 0x%010lx | flags: 0x%lx | compound: %d | node: %d | zone: %s | buddy_order: %u\n",
+						type,
+						page,
+						pfn,
+						(unsigned long)page_to_phys(page),
+						page->flags,
+						PageCompound(page),
+						page_to_nid(page),
+						zone->name,
+						buddy_order
+					);
+				}
+			}
+			seq_puts(m, "\n");
+		}
+		spin_unlock_irqrestore(&zone->lock, flags);
+		seq_puts(m, "----------------------------------------\n");
+	}
+
+	return 0;
+}
+
+static int rk_zoneinfo_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, rk_zoneinfo_show, NULL);
+}
+
+static const struct proc_ops rk_zoneinfo_proc_fops = {
+	.proc_open	= rk_zoneinfo_proc_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
+};
+
+static int __init rk_zoneinfo_procfs_init(void)
+{
+	struct proc_dir_entry *entry;
+
+	entry = proc_mkdir("rk_zoneinfo", NULL);
+	if (!entry)
+		return -ENOENT;
+
+	if (!proc_create("zoneinfo", 0444, entry, &rk_zoneinfo_proc_fops))
+		goto err;
+
+	pr_info("rk_zoneinfo_procfs module loaded.\n");
+
+	return 0;
+err:
+	remove_proc_subtree("rk_zoneinfo", NULL);
+
+	return -ENOENT;
+}
+
+module_init(rk_zoneinfo_procfs_init);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("xxm@rock-chips.com");
+MODULE_DESCRIPTION("iterating zones to show zone/page info and page order if buddy.");