Message-ID: <20240620001027.2326275-1-quic_obabatun@quicinc.com>
Date: Wed, 19 Jun 2024 17:10:27 -0700
From: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
To: <robh@...nel.org>
CC: <broonie@...nel.org>, <catalin.marinas@....com>, <conor@...nel.org>,
        <devicetree@...r.kernel.org>, <hch@....de>, <iommu@...ts.linux.dev>,
        <kernel@...cinc.com>, <linux-kernel@...r.kernel.org>,
        <m.szyprowski@...sung.com>, <nathan@...nel.org>,
        <oe-kbuild-all@...ts.linux.dev>, <quic_obabatun@...cinc.com>,
        <robin.murphy@....com>, <saravanak@...gle.com>, <will@...nel.org>
Subject: [PATCH v2] of: reserved_mem: Restructure code to call reserved mem init functions earlier

After all the reserved memory regions have been added to the
reserved_mem array, a region specific initialization function is called
on each of reserved memory regions in a loop to initialize them.

With recent changes made to allow the reserved_mem array be dynamically
allocated, the cma reserved memory regions are not initialized until
after the page tables are setup. This causes the warning seen in the
dump stack below:

	WARNING: CPU: 0 PID: 1 at mm/memory.c:2789 __apply_to_page_range+0x360/0x380
	CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.10.0-rc1-00007-ga46cccb0ee2d #1
	Hardware name: Generic DT based system
	Call trace:
	unwind_backtrace from show_stack+0x18/0x1c
	show_stack from dump_stack_lvl+0x54/0x68
	dump_stack_lvl from __warn+0x74/0x114
	__warn from warn_slowpath_fmt+0x13c/0x1c0
	warn_slowpath_fmt from __apply_to_page_range+0x360/0x380
	__apply_to_page_range from apply_to_page_range+0x24/0x2c
	apply_to_page_range from __alloc_from_contiguous+0xc4/0x158
	__alloc_from_contiguous from cma_allocator_alloc+0x3c/0x44
	cma_allocator_alloc from arch_dma_alloc+0x128/0x2b4
	arch_dma_alloc from dma_alloc_attrs+0x90/0x150
	dma_alloc_attrs from drm_gem_dma_create+0xa4/0x13c
	drm_gem_dma_create from drm_gem_dma_create_with_handle+0x24/0xac
	drm_gem_dma_create_with_handle from drm_gem_dma_dumb_create+0x44/0x50
	drm_gem_dma_dumb_create from drm_client_framebuffer_create+0x9c/0x164
	drm_client_framebuffer_create from drm_fbdev_dma_helper_fb_probe+0x84/0x23c
	drm_fbdev_dma_helper_fb_probe from __drm_fb_helper_initial_config_and_unlock+0x2e4/0x4f8
	__drm_fb_helper_initial_config_and_unlock from drm_fbdev_dma_client_hotplug+0x74/0xb8
	drm_fbdev_dma_client_hotplug from drm_client_register+0x5c/0x98
	drm_client_register from aspeed_gfx_probe+0x278/0x3c0
	aspeed_gfx_probe from platform_probe+0x60/0xb8
	platform_probe from really_probe+0xd4/0x3b4
	really_probe from __driver_probe_device+0x90/0x1dc
	__driver_probe_device from driver_probe_device+0x38/0xd0
	driver_probe_device from __driver_attach+0x118/0x1dc
	__driver_attach from bus_for_each_dev+0x84/0xd4
	bus_for_each_dev from bus_add_driver+0xec/0x1f0
	bus_add_driver from driver_register+0x84/0x11c
	driver_register from do_one_initcall+0x84/0x1c8
	do_one_initcall from kernel_init_freeable+0x1a4/0x230
	kernel_init_freeable from kernel_init+0x1c/0x138
	kernel_init from ret_from_fork+0x14/0x28
	Exception stack(0x9f015fb0 to 0x9f015ff8)
	5fa0:                                     00000000 00000000 00000000 00000000
	5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
	5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
	---[ end trace 0000000000000000 ]---
	aspeed_gfx 1e6e6000.display: [drm] fb0: aspeed-gfx-drmd frame buffer device

Hence, restructure the code to initialize the regions as soon as each
of them are added to the reserved_mem array.

Fixes: a46cccb0ee2d ("of: reserved_mem: Restruture how the reserved memory regions are processed")
Signed-off-by: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
---
v2:
- Fix kernel-doc for of_init_reserved_mem_node() in response to the
  below warning from v1:
  https://lore.kernel.org/all/202406181626.126X1Nbz-lkp@intel.com/

v1:
  https://lore.kernel.org/all/20240617193357.3929092-1-quic_obabatun@quicinc.com/

 drivers/of/fdt.c             |  2 +-
 drivers/of/of_private.h      |  2 +-
 drivers/of/of_reserved_mem.c | 83 +++++++++++++++++++++---------------
 3 files changed, 50 insertions(+), 37 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 9cde2abd2fc0..ea2dff0478c7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1239,7 +1239,7 @@ void __init unflatten_device_tree(void)
 	unittest_unflatten_overlay_base();
 
 	/* initialize the reserved memory regions */
-	of_init_reserved_mem();
+	of_scan_reserved_mem_reg_nodes();
 }
 
 /**
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 01b33c4b1e9f..7412aed903df 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -181,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
 #endif
 
 int fdt_scan_reserved_mem(void);
-void of_init_reserved_mem(void);
+void of_scan_reserved_mem_reg_nodes(void);
 
 bool of_fdt_device_is_available(const void *blob, unsigned long node);
 
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index eb54490a0a11..b31001728866 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -97,6 +97,8 @@ static void __init alloc_reserved_mem_array(void)
 	reserved_mem = new_array;
 }
 
+static void __init of_init_reserved_mem_node(struct reserved_mem *rmem);
+
 /*
  * of_reserved_mem_save_node() - save fdt node for second pass initialization
  */
@@ -115,6 +117,12 @@ static void __init of_reserved_mem_save_node(struct device_node *node, const cha
 	rmem->base = base;
 	rmem->size = size;
 
+	/*
+	 * Run the region specific initialization function for the rmem
+	 * node.
+	 */
+	of_init_reserved_mem_node(rmem);
+
 	reserved_mem_count++;
 	return;
 }
@@ -201,6 +209,8 @@ static int __init __fdt_reserved_mem_check_root(unsigned long node)
 	return 0;
 }
 
+static void __init __rmem_check_for_overlap(void);
+
 /**
  * of_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
  * reserved memory regions.
@@ -211,7 +221,7 @@ static int __init __fdt_reserved_mem_check_root(unsigned long node)
  * size are all stored in the reserved_mem array by calling the
  * of_reserved_mem_save_node() function.
  */
-static void __init of_scan_reserved_mem_reg_nodes(void)
+void __init of_scan_reserved_mem_reg_nodes(void)
 {
 	struct device_node *node, *child;
 	phys_addr_t base, size;
@@ -222,6 +232,13 @@ static void __init of_scan_reserved_mem_reg_nodes(void)
 		return;
 	}
 
+	/*
+	 * Before moving forward, allocate the exact size needed for the
+	 * reserved_mem array and copy all previously saved contents
+	 * into the new array if successful.
+	 */
+	alloc_reserved_mem_array();
+
 	for_each_child_of_node(node, child) {
 		int ret = 0;
 		const char *uname;
@@ -246,6 +263,8 @@ static void __init of_scan_reserved_mem_reg_nodes(void)
 		if (size)
 			of_reserved_mem_save_node(child, uname, base, size);
 	}
+	/* check for overlapping reserved regions */
+	__rmem_check_for_overlap();
 }
 
 static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
@@ -526,44 +545,38 @@ static void __init __rmem_check_for_overlap(void)
 }
 
 /**
- * of_init_reserved_mem() - allocate and init all saved reserved memory regions
+ * of_init_reserved_mem_node() - Initialize a saved reserved memory region.
+ * @rmem: reserved_mem object of the memory region to be initialized.
+ *
+ * This function is used to call the region specific initialization
+ * function on the rmem object passed as an argument. The rmem object
+ * will contain the base address, size, node name, and device_node of
+ * the reserved memory region to be initialized.
  */
-void __init of_init_reserved_mem(void)
+static void __init of_init_reserved_mem_node(struct reserved_mem *rmem)
 {
-	int i;
-
-	alloc_reserved_mem_array();
-
-	of_scan_reserved_mem_reg_nodes();
+	int err;
+	bool nomap;
+	struct device_node *node = rmem->dev_node;
 
-	/* check for overlapping reserved regions */
-	__rmem_check_for_overlap();
+	nomap = of_property_present(node, "no-map");
 
-	for (i = 0; i < reserved_mem_count; i++) {
-		struct reserved_mem *rmem = &reserved_mem[i];
-		struct device_node *node = rmem->dev_node;
-		int err = 0;
-		bool nomap;
-
-		nomap = of_property_present(node, "no-map");
-
-		err = __reserved_mem_init_node(rmem);
-		if (err != 0 && err != -ENOENT) {
-			pr_info("node %s compatible matching fail\n", rmem->name);
-			if (nomap)
-				memblock_clear_nomap(rmem->base, rmem->size);
-			else
-				memblock_phys_free(rmem->base, rmem->size);
-		} else {
-			phys_addr_t end = rmem->base + rmem->size - 1;
-			bool reusable = of_property_present(node, "reusable");
-
-			pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
-				&rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
-				nomap ? "nomap" : "map",
-				reusable ? "reusable" : "non-reusable",
-				rmem->name ? rmem->name : "unknown");
-		}
+	err = __reserved_mem_init_node(rmem);
+	if (err != 0 && err != -ENOENT) {
+		pr_info("node %s compatible matching fail\n", rmem->name);
+		if (nomap)
+			memblock_clear_nomap(rmem->base, rmem->size);
+		else
+			memblock_phys_free(rmem->base, rmem->size);
+	} else {
+		phys_addr_t end = rmem->base + rmem->size - 1;
+		bool reusable = of_property_present(node, "reusable");
+
+		pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
+			&rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
+			nomap ? "nomap" : "map",
+			reusable ? "reusable" : "non-reusable",
+			rmem->name ? rmem->name : "unknown");
 	}
 }
 
-- 
2.34.1

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