CC linux-renesas-soc

On Tue, Oct 29, 2024 at 1:41 PM Geert Uytterhoeven [off-list ref] wrote:

On Wed, Oct 9, 2024 at 12:08 AM Oreoluwa Babatunde
[off-list ref] wrote:

quoted

Reserved memory regions defined in the devicetree can be broken up into
two groups:
i) Statically-placed reserved memory regions
i.e. regions defined with a static start address and size using the
     "reg" property.
ii) Dynamically-placed reserved memory regions.
i.e. regions defined by specifying an address range where they can be
     placed in memory using the "alloc_ranges" and "size" properties.

These regions are processed and set aside at boot time.
This is done in two stages as seen below:

Stage 1:
At this stage, fdt_scan_reserved_mem() scans through the child nodes of
the reserved_memory node using the flattened devicetree and does the
following:

1) If the node represents a statically-placed reserved memory region,
   i.e. if it is defined using the "reg" property:
   - Call memblock_reserve() or memblock_mark_nomap() as needed.
   - Add the information for that region into the reserved_mem array
     using fdt_reserved_mem_save_node().
     i.e. fdt_reserved_mem_save_node(node, name, base, size).

2) If the node represents a dynamically-placed reserved memory region,
   i.e. if it is defined using "alloc-ranges" and "size" properties:
   - Add the information for that region to the reserved_mem array with
     the starting address and size set to 0.
     i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
   Note: This region is saved to the array with a starting address of 0
   because a starting address is not yet allocated for it.

Stage 2:
After iterating through all the reserved memory nodes and storing their
relevant information in the reserved_mem array,fdt_init_reserved_mem() is
called and does the following:

1) For statically-placed reserved memory regions:
   - Call the region specific init function using
     __reserved_mem_init_node().
2) For dynamically-placed reserved memory regions:
   - Call __reserved_mem_alloc_size() which is used to allocate memory
     for each of these regions, and mark them as nomap if they have the
     nomap property specified in the DT.
   - Call the region specific init function.

The current size of the resvered_mem array is 64 as is defined by
MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
how many reserved memory regions can be specified on a system.
As systems continue to grow more and more complex, the number of
reserved memory regions needed are also growing and are starting to hit
this 64 count limit, hence the need to make the reserved_mem array
dynamically sized (i.e. dynamically allocating memory for the
reserved_mem array using membock_alloc_*).

On architectures such as arm64, memory allocated using memblock is
writable only after the page tables have been setup. This means that if
the reserved_mem array is going to be dynamically allocated, it needs to
happen after the page tables have been setup, not before.

Since the reserved memory regions are currently being processed and
added to the array before the page tables are setup, there is a need to
change the order in which some of the processing is done to allow for
the reserved_mem array to be dynamically sized.

It is possible to process the statically-placed reserved memory regions
without needing to store them in the reserved_mem array until after the
page tables have been setup because all the information stored in the
array is readily available in the devicetree and can be referenced at
any time.
Dynamically-placed reserved memory regions on the other hand get
assigned a start address only at runtime, and hence need a place to be
stored once they are allocated since there is no other referrence to the
start address for these regions.

Hence this patch changes the processing order of the reserved memory
regions in the following ways:

Step 1:
fdt_scan_reserved_mem() scans through the child nodes of
the reserved_memory node using the flattened devicetree and does the
following:

1) If the node represents a statically-placed reserved memory region,
   i.e. if 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. if it is defined using "alloc-ranges" and "size" properties:
   - Call __reserved_mem_alloc_size() which will:
     i) Allocate memory for the reserved region and call
     memblock_mark_nomap() as needed.
     ii) Call the region specific initialization function using
     fdt_init_reserved_mem_node().
     iii) Save the region information in the reserved_mem array using
     fdt_reserved_mem_save_node().

Step 2:
1) This stage of the reserved memory processing is now only used to add
   the statically-placed reserved memory regions into the reserved_mem
   array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
   region specific initialization functions.

2) This step has also been moved to be after the page tables are
   setup. Moving this will allow us to replace the reserved_mem
   array with a dynamically sized array before storing the rest of
   these regions.

Signed-off-by: Oreoluwa Babatunde <redacted>

Thanks for your patch, which is now commit 8a6e02d0c00e7b62
("of: reserved_mem: Restructure how the reserved memory regions
are processed") in dt-rh/for-next.

I have bisected a boot issue on RZ/Five to this commit.
With "earlycon keep_bootcon" (else there is no output):

    Oops - store (or AMO) access fault [#1]
    CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted
6.12.0-rc1-00015-g8a6e02d0c00e #201
    Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
    epc : __memset+0x60/0x100
     ra : __dma_alloc_from_coherent+0x150/0x17a
    epc : ffffffff8062d2bc ra : ffffffff80053a94 sp : ffffffc60000ba20
     gp : ffffffff812e9938 tp : ffffffd601920000 t0 : ffffffc6000d0000
     t1 : 0000000000000000 t2 : ffffffffe9600000 s0 : ffffffc60000baa0
     s1 : ffffffc6000d0000 a0 : ffffffc6000d0000 a1 : 0000000000000000
     a2 : 0000000000001000 a3 : ffffffc6000d1000 a4 : 0000000000000000
     a5 : 0000000000000000 a6 : ffffffd601adacc0 a7 : ffffffd601a841a8
     s2 : ffffffd6018573c0 s3 : 0000000000001000 s4 : ffffffd6019541e0
     s5 : 0000000200000022 s6 : ffffffd6018f8410 s7 : ffffffd6018573e8
     s8 : 0000000000000001 s9 : 0000000000000001 s10: 0000000000000010
     s11: 0000000000000000 t3 : 0000000000000000 t4 : ffffffffdefe62d1
     t5 : 000000001cd6a3a9 t6 : ffffffd601b2aad6
    status: 0000000200000120 badaddr: ffffffc6000d0000 cause: 0000000000000007
    [<ffffffff8062d2bc>] __memset+0x60/0x100
    [<ffffffff80053e1a>] dma_alloc_from_global_coherent+0x1c/0x28
    [<ffffffff80053056>] dma_direct_alloc+0x98/0x112
    [<ffffffff8005238c>] dma_alloc_attrs+0x78/0x86
    [<ffffffff8035fdb4>] rz_dmac_probe+0x3f6/0x50a
    [<ffffffff803a0694>] platform_probe+0x4c/0x8a
    [<ffffffff8039ea16>] really_probe+0xe4/0x1c8
    [<ffffffff8039ebc4>] __driver_probe_device+0xca/0xce
    [<ffffffff8039ec48>] driver_probe_device+0x34/0x92
    [<ffffffff8039ede8>] __driver_attach+0xb4/0xbe
    [<ffffffff8039ce58>] bus_for_each_dev+0x60/0xa0
    [<ffffffff8039e26a>] driver_attach+0x1a/0x22
    [<ffffffff8039dc20>] bus_add_driver+0xa4/0x184
    [<ffffffff8039f65c>] driver_register+0x8a/0xb4
    [<ffffffff803a051c>] __platform_driver_register+0x1c/0x24
    [<ffffffff808202f6>] rz_dmac_driver_init+0x1a/0x22
    [<ffffffff80800ef6>] do_one_initcall+0x64/0x134
    [<ffffffff8080122e>] kernel_init_freeable+0x200/0x202
    [<ffffffff80638126>] kernel_init+0x1e/0x10a
    [<ffffffff8063d58e>] ret_from_fork+0xe/0x18
    Code: 1007 82b3 40e2 0797 0000 8793 00e7 8305 97ba 8782 (b023) 00b2
    ---[ end trace 0000000000000000 ]---
    Kernel panic - not syncing: Fatal exception in interrupt
    ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---

Nothing really stands out in the kernel log, except for a delayed
initialization of the reserved mem nodes (they are the same
before/after):

 printk: debug: ignoring loglevel setting.
-OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
nomap non-reusable mmode_resv0@30000
-OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
nomap non-reusable mmode_resv1@40000
-OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
nomap non-reusable mmode_resv3@44000000
-OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
nomap non-reusable mmode_resv2@44040000
+earlycon: scif0 at MMIO 0x000000001004b800 (options '115200n8')
+printk: legacy bootconsole [scif0] enabled
+printk: debug: skip boot console de-registration.
 Reserved memory: created DMA memory pool at 0x0000000058000000, size 128 MiB
 OF: reserved mem: initialized node pma_resv0@58000000, compatible id
shared-dma-pool
 OF: reserved mem: 0x0000000058000000..0x000000005fffffff (131072 KiB)
nomap non-reusable pma_resv0@58000000
+OF: reserved mem: 0x0000000000030000..0x000000000003ffff (64 KiB)
nomap non-reusable mmode_resv0@30000
+OF: reserved mem: 0x0000000000040000..0x000000000004ffff (64 KiB)
nomap non-reusable mmode_resv1@40000
+OF: reserved mem: 0x0000000044040000..0x000000004405ffff (128 KiB)
nomap non-reusable mmode_resv2@44040000
+OF: reserved mem: 0x0000000044000000..0x000000004403ffff (256 KiB)
nomap non-reusable mmode_resv3@44000000
 Zone ranges:
   DMA32    [mem 0x0000000048000000-0x000000007fffffff]
   Normal   empty

Reverting commits 00c9a452a235c61f ("of: reserved_mem: Add code to
dynamically allocate reserved_mem array") and 8a6e02d0c00e7b62 fixes
the issue.

root@smarc-rzfive:/sys/firmware/devicetree/base/reserved-memory# ls -l
total 0
-r--r--r-- 1 root root  4 Oct 29 12:37 #address-cells
-r--r--r-- 1 root root  4 Oct 29 12:37 #size-cells
drwxr-xr-x 2 root root  0 Oct 29 12:37 mmode_resv0@30000
drwxr-xr-x 2 root root  0 Oct 29 12:37 mmode_resv1@40000
drwxr-xr-x 2 root root  0 Oct 29 12:37 mmode_resv2@44040000
drwxr-xr-x 2 root root  0 Oct 29 12:37 mmode_resv3@44000000
-r--r--r-- 1 root root 16 Oct 29 12:37 name
drwxr-xr-x 2 root root  0 Oct 29 12:37 pma_resv0@58000000
-r--r--r-- 1 root root  0 Oct 29 12:37 ranges

quoted

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 4d528c10df3a..d0dbc8183ac4 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c

@@ -511,8 +511,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
                        break;
                memblock_reserve(base, size);
        }
-
-       fdt_init_reserved_mem();
 }

 /**

@@ -1212,6 +1210,9 @@ void __init unflatten_device_tree(void)
 {
        void *fdt = initial_boot_params;

+       /* Save the statically-placed regions in the reserved_mem array */
+       fdt_scan_reserved_mem_reg_nodes();
+
        /* Don't use the bootloader provided DTB if ACPI is enabled */
        if (!acpi_disabled)
                fdt = NULL;

diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 04aa2a91f851..29525c0b9939 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h

@@ -9,6 +9,7 @@
  */

 #define FDT_ALIGN_SIZE 8
+#define MAX_RESERVED_REGIONS    64

 /**
  * struct alias_prop - Alias property in 'aliases' node

@@ -180,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
 #endif

 int fdt_scan_reserved_mem(void);
-void fdt_init_reserved_mem(void);
+void __init fdt_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 46e1c3fbc769..2011174211f9 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c

@@ -27,7 +27,6 @@

 #include "of_private.h"

-#define MAX_RESERVED_REGIONS   64
 static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
 static int reserved_mem_count;

@@ -56,6 +55,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
        return err;
 }

+static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem);
 /*
  * fdt_reserved_mem_save_node() - save fdt node for second pass initialization
  */

@@ -74,6 +74,9 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
        rmem->base = base;
        rmem->size = size;

+       /* Call the region specific initialization function */
+       fdt_init_reserved_mem_node(rmem);
+
        reserved_mem_count++;
        return;
 }

@@ -106,7 +109,6 @@ 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);

@@ -134,10 +136,6 @@ 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;
 }

@@ -165,12 +163,77 @@ static int __init __reserved_mem_check_root(unsigned long node)
        return 0;
 }

+static void __init __rmem_check_for_overlap(void);
+
+/**
+ * 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;
+
+       if (!fdt)
+               return;
+
+       node = fdt_path_offset(fdt, "/reserved-memory");
+       if (node < 0) {
+               pr_info("Reserved memory: No reserved-memory node in the DT\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);
+       }
+
+       /* check for overlapping reserved regions */
+       __rmem_check_for_overlap();
+}
+
+static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
+
 /*
  * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
  */
 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");

@@ -192,8 +255,24 @@ 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);
+               /*
+                * Save the nodes for the dynamically-placed regions
+                * into an array which will be used for allocation right
+                * after all the statically-placed regions are reserved
+                * or marked as no-map. This is done to avoid dynamically
+                * allocating from one of the statically-placed regions.
+                */
+               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;
 }

@@ -253,8 +332,7 @@ 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)
+static 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;

@@ -334,9 +412,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
                return -ENOMEM;
        }

-       *res_base = base;
-       *res_size = size;
-
+       /* Save region in the reserved_mem array */
+       fdt_reserved_mem_save_node(node, uname, base, size);
        return 0;
 }

@@ -425,48 +502,37 @@ static void __init __rmem_check_for_overlap(void)
 }

 /**
- * fdt_init_reserved_mem() - allocate and init all saved reserved memory regions
+ * fdt_init_reserved_mem_node() - Initialize a reserved memory region
+ * @rmem: reserved_mem struct of the memory region to be initialized.
+ *
+ * This function is used to call the region specific initialization
+ * function for a reserved memory region.
  */
-void __init fdt_init_reserved_mem(void)
+static void __init fdt_init_reserved_mem_node(struct reserved_mem *rmem)
 {
-       int i;
-
-       /* check for overlapping reserved regions */
-       __rmem_check_for_overlap();
-
-       for (i = 0; i < reserved_mem_count; i++) {
-               struct reserved_mem *rmem = &reserved_mem[i];
-               unsigned long node = rmem->fdt_node;
-               int err = 0;
-               bool nomap;
+       unsigned long node = rmem->fdt_node;
+       int err = 0;
+       bool nomap;

-               nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
+       nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;

-               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");
        }
 }

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds