[PATCH v4 1/4] of: reserved_mem: Restruture how the reserved memory regions are processed
From: Oreoluwa Babatunde
Date: Fri Mar 08 2024 - 14:14:07 EST
The current implementation processes the reserved memory regions in two
stages which are done with two separate functions within the
early_init_fdt_scan_reserved_mem() function.
Within the two stages of processing, the reserved memory regions are
broken up into two groups which are processed differently:
i) Statically-placed reserved memory regions
i.e. regions defined with a static start address and size using the
"reg" property in the DT.
ii) Dynamically-placed reserved memory regions.
i.e. regions defined by specifying a range of addresses where they can
be placed in memory using the "alloc_ranges" and "size" properties
in the DT.
Stage 1: fdt_scan_reserved_mem()
This stage of the reserved memory processing is used to scan through the
reserved memory nodes defined in the devicetree and do the following on
each of the nodes:
1) If the node represents a statically-placed reserved memory region,
i.e. it is defined using the "reg" property:
- Call memblock_reserve() or memblock_mark_nomap() as needed.
- Add the information for the reserved region to the reserved_mem array.
eg: fdt_reserved_mem_save_node(node, name, base, size);
2) If the node represents a dynamically-placed reserved memory region,
i.e. it is defined using "alloc-ranges" and "size" properties:
- Add the information for the region to the reserved_mem array with
the starting address and size set to 0.
eg: fdt_reserved_mem_save_node(node, name, 0, 0);
Stage 2: fdt_init_reserved_mem()
This stage of the reserved memory processing is used to iterate through
the reserved_mem array which was populated in stage 1 and do the
following on each of the entries:
1) If the entry represents a statically-placed reserved memory region:
- Call the region specific init function.
2) If the entry represents a dynamically-placed reserved memory region:
- Call __reserved_mem_alloc_size() which is used to allocate memory
for the region using memblock_phys_alloc_range(), and call
memblock_mark_nomap() on the allocated region if the region is
specified as a no-map region.
- Call the region specific init function.
On architectures such as arm64, the dynamic allocation of the
reserved_mem array needs to be done after the page tables have been
setup because memblock allocated memory is not writable until then. This
means that the reserved_mem array will not be available to store any
reserved memory information until after the page tables have been setup.
It is possible to call memblock_reserve() and memblock_mark_nomap() on
the statically-placed reserved memory regions and not need to save them
to the reserved_mem array until later. This is because all the
information we need is present in the devicetree.
Dynamically-placed reserved memory regions on the other hand get assigned
a start address only at runtime, and since memblock_reserve() and
memblock_mark_nomap() need to be called before the memory mappings are
created, the allocation needs to happen before the page tables are setup.
To make it easier to handle dynamically-placed reserved memory regions
before the page tables are setup, this patch makes changes to the steps
above to process the reserved memory regions in the following ways:
Step 1: fdt_scan_reserved_mem()
This stage of the reserved memory processing is used to scan through the
reserved memory nodes defined in the devicetree and do the following on
each of the nodes:
1) If the node represents a statically-placed reserved memory region,
i.e. it is defined using the "reg" property:
- Call memblock_reserve() or memblock_mark_nomap() as needed.
2) If the node represents a dynamically-placed reserved memory region,
i.e. it is defined using "alloc-ranges" and "size" properties:
- Call __reserved_mem_alloc_size() which will:
i) Allocate memory for the reserved memory region.
ii) Call memblock_mark_nomap() as needed.
Note: There is no need to explicitly call memblock_reserve() here
because it is already called by memblock when the memory for the
region is being allocated.
iii) Save the information for the region in the reserved_mem array.
Step 2: fdt_init_reserved_mem()
This stage of the reserved memory processing is used to:
1) Add the information for the statically-placed reserved memory into
the reserved_mem array.
2) Iterate through all the entries in the array and call the region
specific init function for each of them.
Signed-off-by: Oreoluwa Babatunde <quic_obabatun@xxxxxxxxxxx>
---
drivers/of/fdt.c | 84 ++++++++++++++++++++++++++++++---
drivers/of/of_private.h | 2 +-
drivers/of/of_reserved_mem.c | 54 +++++++++------------
include/linux/of_fdt.h | 1 +
include/linux/of_reserved_mem.h | 9 ++++
5 files changed, 111 insertions(+), 39 deletions(-)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index bf502ba8da95..fe6c75c5a8c0 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -504,7 +504,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
phys_addr_t base, size;
int len;
const __be32 *prop;
- int first = 1;
bool nomap;
prop = of_get_flat_dt_prop(node, "reg", &len);
@@ -532,10 +531,6 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
uname, &base, (unsigned long)(size / SZ_1M));
len -= t_len;
- if (first) {
- fdt_reserved_mem_save_node(node, uname, base, size);
- first = 0;
- }
}
return 0;
}
@@ -563,12 +558,70 @@ static int __init __reserved_mem_check_root(unsigned long node)
return 0;
}
+/**
+ * fdt_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
+ * reserved memory regions.
+ *
+ * This function is used to scan through the DT and store the
+ * information for the reserved memory regions that are defined using
+ * the "reg" property. The region node number, name, base address, and
+ * size are all stored in the reserved_mem array by calling the
+ * fdt_reserved_mem_save_node() function.
+ */
+void __init fdt_scan_reserved_mem_reg_nodes(void)
+
+{
+ int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
+ const void *fdt = initial_boot_params;
+ phys_addr_t base, size;
+ const __be32 *prop;
+ int node, child;
+ int len;
+
+ node = fdt_path_offset(fdt, "/reserved-memory");
+ if (node < 0) {
+ pr_err("Reserved memory: Did not find reserved-memory node\n");
+ return;
+ }
+
+ if (__reserved_mem_check_root(node)) {
+ pr_err("Reserved memory: unsupported node format, ignoring\n");
+ return;
+ }
+
+ fdt_for_each_subnode(child, fdt, node) {
+ const char *uname;
+
+ prop = of_get_flat_dt_prop(child, "reg", &len);
+ if (!prop)
+ continue;
+
+ if (!of_fdt_device_is_available(fdt, child))
+ continue;
+
+ uname = fdt_get_name(fdt, child, NULL);
+ if (len && len % t_len != 0) {
+ pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
+ uname);
+ continue;
+ }
+
+ base = dt_mem_next_cell(dt_root_addr_cells, &prop);
+ size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+ if (size)
+ fdt_reserved_mem_save_node(child, uname, base, size);
+ }
+}
+
/*
* fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
*/
static int __init fdt_scan_reserved_mem(void)
{
int node, child;
+ int dynamic_nodes_cnt = 0;
+ int dynamic_nodes[MAX_RESERVED_REGIONS];
const void *fdt = initial_boot_params;
node = fdt_path_offset(fdt, "/reserved-memory");
@@ -590,8 +643,25 @@ static int __init fdt_scan_reserved_mem(void)
uname = fdt_get_name(fdt, child, NULL);
err = __reserved_mem_reserve_reg(child, uname);
- if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL))
- fdt_reserved_mem_save_node(child, uname, 0, 0);
+
+ /*
+ * Delay allocation of the dynamically-placed regions
+ * until after all other statically-placed regions have
+ * been reserved or marked as nomap
+ */
+ if (err == -ENOENT && of_get_flat_dt_prop(child, "size", NULL)) {
+ dynamic_nodes[dynamic_nodes_cnt] = child;
+ dynamic_nodes_cnt++;
+ }
+ }
+
+ for (int i = 0; i < dynamic_nodes_cnt; i++) {
+ const char *uname;
+
+ child = dynamic_nodes[i];
+ uname = fdt_get_name(fdt, child, NULL);
+
+ __reserved_mem_alloc_size(child, uname);
}
return 0;
}
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index f38397c7b582..542e37a37a24 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -36,6 +36,7 @@ struct alias_prop {
#endif
#define OF_ROOT_NODE_SIZE_CELLS_DEFAULT 1
+#define MAX_RESERVED_REGIONS 64
extern struct mutex of_mutex;
extern raw_spinlock_t devtree_lock;
@@ -175,7 +176,6 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
}
#endif
-void fdt_init_reserved_mem(void);
void fdt_reserved_mem_save_node(unsigned long node, const char *uname,
phys_addr_t base, phys_addr_t size);
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 7ec94cfcbddb..d62f1956024c 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -26,7 +26,6 @@
#include "of_private.h"
-#define MAX_RESERVED_REGIONS 64
static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
static int reserved_mem_count;
@@ -132,8 +131,7 @@ static int __init __reserved_mem_alloc_in_range(phys_addr_t size,
* __reserved_mem_alloc_size() - allocate reserved memory described by
* 'size', 'alignment' and 'alloc-ranges' properties.
*/
-static int __init __reserved_mem_alloc_size(unsigned long node,
- const char *uname, phys_addr_t *res_base, phys_addr_t *res_size)
+int __init __reserved_mem_alloc_size(unsigned long node, const char *uname)
{
int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
phys_addr_t start = 0, end = 0;
@@ -212,10 +210,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
uname, (unsigned long)(size / SZ_1M));
return -ENOMEM;
}
-
- *res_base = base;
- *res_size = size;
-
+ fdt_reserved_mem_save_node(node, uname, base, size);
return 0;
}
@@ -310,6 +305,8 @@ void __init fdt_init_reserved_mem(void)
{
int i;
+ fdt_scan_reserved_mem_reg_nodes();
+
/* check for overlapping reserved regions */
__rmem_check_for_overlap();
@@ -328,30 +325,25 @@ void __init fdt_init_reserved_mem(void)
if (prop)
rmem->phandle = of_read_number(prop, len/4);
- if (rmem->size == 0)
- err = __reserved_mem_alloc_size(node, rmem->name,
- &rmem->base, &rmem->size);
- if (err == 0) {
- 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_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
-
- 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_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
+
+ 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");
}
}
}
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index d69ad5bb1eb1..7b2a5d93d719 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -73,6 +73,7 @@ extern int early_init_dt_scan_root(void);
extern bool early_init_dt_scan(void *params);
extern bool early_init_dt_verify(void *params);
extern void early_init_dt_scan_nodes(void);
+extern void fdt_scan_reserved_mem_reg_nodes(void);
extern const char *of_flat_dt_get_machine_name(void);
extern const void *of_flat_dt_match_machine(const void *default_match,
diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
index 4de2a24cadc9..2a3178920bae 100644
--- a/include/linux/of_reserved_mem.h
+++ b/include/linux/of_reserved_mem.h
@@ -32,12 +32,14 @@ typedef int (*reservedmem_of_init_fn)(struct reserved_mem *rmem);
#define RESERVEDMEM_OF_DECLARE(name, compat, init) \
_OF_DECLARE(reservedmem, name, compat, init, reservedmem_of_init_fn)
+void fdt_init_reserved_mem(void);
int of_reserved_mem_device_init_by_idx(struct device *dev,
struct device_node *np, int idx);
int of_reserved_mem_device_init_by_name(struct device *dev,
struct device_node *np,
const char *name);
void of_reserved_mem_device_release(struct device *dev);
+int __reserved_mem_alloc_size(unsigned long node, const char *uname);
struct reserved_mem *of_reserved_mem_lookup(struct device_node *np);
#else
@@ -45,6 +47,8 @@ struct reserved_mem *of_reserved_mem_lookup(struct device_node *np);
#define RESERVEDMEM_OF_DECLARE(name, compat, init) \
_OF_DECLARE_STUB(reservedmem, name, compat, init, reservedmem_of_init_fn)
+static inline void fdt_init_reserved_mem(void) { }
+
static inline int of_reserved_mem_device_init_by_idx(struct device *dev,
struct device_node *np, int idx)
{
@@ -60,6 +64,11 @@ static inline int of_reserved_mem_device_init_by_name(struct device *dev,
static inline void of_reserved_mem_device_release(struct device *pdev) { }
+static inline int __reserved_mem_alloc_size(unsigned long node, const char *uname)
+{
+ return -ENOSYS;
+}
+
static inline struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
{
return NULL;
--
2.34.1