On Fri, 21 Feb 2014 13:25:18 +0100, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:
> This patch adds support for static (defined by 'reg' property) reserved
> memory regions declared in device tree.
>
> Memory blocks can be reliably reserved only during early boot. This must
> happen before the whole memory management subsystem is initialized,
> because we need to ensure that the given contiguous blocks are not yet
> allocated by kernel. Also it must happen before kernel mappings for the
> whole low memory are created, to ensure that there will be no mappings
> (for reserved blocks). Typically, all this happens before device tree
> structures are unflattened, so we need to get reserved memory layout
> directly from fdt.
>
> Based on previous code provided by Josh Cartwright <joshc@xxxxxxxxxxxxxx>
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> drivers/of/fdt.c | 125 ++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/of_fdt.h | 3 ++
> 2 files changed, 128 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 758b4f8b30b7..12809e20ef71 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -440,6 +440,113 @@ struct boot_param_header *initial_boot_params;
> #ifdef CONFIG_OF_EARLY_FLATTREE
>
> /**
> + * res_mem_reserve_reg() - reserve all memory described in 'reg' property
> + */
> +static int __init __reserved_mem_reserve_reg(unsigned long node,
> + const char *uname)
> +{
> + int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> + phys_addr_t base, size;
> + unsigned long len;
> + __be32 *prop;
> + int nomap;
> +
> + prop = of_get_flat_dt_prop(node, "reg", &len);
> + if (!prop)
> + return -ENOENT;
> +
> + if (len && len % t_len != 0) {
> + pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
> + uname);
> + return -EINVAL;
> + }
> +
> + nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> +
> + while (len > 0) {
This is safer: while (len >= t_len) {
> + base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> + size = dt_mem_next_cell(dt_root_size_cells, &prop);
> +
> + if (base && size &&
> + early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
> + pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
> + uname, &base, (unsigned long)size / SZ_1M);
> + else
> + pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB\n",
> + uname, &base, (unsigned long)size / SZ_1M);
> +
> + len -= t_len;
> + }
> + return 0;
> +}
> +
> +static int __reserved_mem_check_root(unsigned long node)
Please document the purpose of this function. This function reflects a Linux
implementation limitation because it is easier than parsing a correctly
formed ranges property. Sometime in the future it may be fixed. It is
worth capturing all of that in a comment.
> +{
> + __be32 *prop;
> +
> + prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
> + if (prop && be32_to_cpup(prop) != dt_root_size_cells)
> + return -EINVAL;
> +
> + prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
> + if (prop && be32_to_cpup(prop) != dt_root_addr_cells)
> + return -EINVAL;
> +
> + prop = of_get_flat_dt_prop(node, "ranges", NULL);
> + if (!prop)
> + return -EINVAL;
> + return 0;
> +}
> +
> +/**
> + * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> + */
> +static int __init __fdt_scan_reserved_mem(unsigned long node, const char *uname,
> + int depth, void *data)
> +{
> + static int found;
> + const char *status;
> +
> + if (!found && depth == 1 && strcmp(uname, "reserved-memory") == 0) {
> + if (__reserved_mem_check_root(node) != 0) {
> + pr_err("Reserved memory: unsupported node format, ignoring\n");
> + /* break scan */
> + return 1;
> + }
> + found = 1;
> + /* scan next node */
> + return 0;
> + } else if (!found) {
> + /* scan next node */
> + return 0;
> + } else if (found && depth < 2) {
> + /* scanning of /reserved-memory has been finished */
> + return 1;
> + }
> +
> + status = of_get_flat_dt_prop(node, "status", NULL);
> + if (status && strcmp(status, "okay") != 0 && strcmp(status, "ok") != 0)
> + return 0;
> +
> + __reserved_mem_reserve_reg(node, uname);
> +
> + /* scan next node */
> + return 0;
> +}
> +
> +/**
> + * early_init_fdt_scan_reserved_mem() - create reserved memory regions
> + *
> + * This function grabs memory from early allocator for device exclusive use
> + * defined in device tree structures. It should be called by arch specific code
> + * once the early allocator (i.e. memblock) has been fully activated.
> + */
> +void __init early_init_fdt_scan_reserved_mem(void)
> +{
> + of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
> +}
Looks good.
> +
> +/**
> * of_scan_flat_dt - scan flattened tree blob and call callback on each.
> * @it: callback function
> * @data: context data pointer
> @@ -856,6 +963,16 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
> memblock_add(base, size);
> }
>
> +int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
> + phys_addr_t size, bool nomap)
> +{
> + if (memblock_is_region_reserved(base, size))
> + return -EBUSY;
> + if (nomap)
> + return memblock_remove(base, size);
> + return memblock_reserve(base, size);
> +}
> +
> /*
> * called from unflatten_device_tree() to bootstrap devicetree itself
> * Architectures can override this definition if memblock isn't used
> @@ -864,6 +981,14 @@ void * __init __weak early_init_dt_alloc_memory_arch(u64 size, u64 align)
> {
> return __va(memblock_alloc(size, align));
> }
> +#else
> +int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
> + phys_addr_t size, bool nomap)
> +{
> + pr_error("Reserved memory not supported, ignoring range 0x%llx - 0x%llx%s\n",
> + base, size, nomap ? " (nomap)" : "");
> + return -ENOSYS;
> +}
> #endif
>
> bool __init early_init_dt_scan(void *params)
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index 2b77058a7335..8610ad8d77d2 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -98,7 +98,10 @@ extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
> int depth, void *data);
> extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
> int depth, void *data);
> +extern void early_init_fdt_scan_reserved_mem(void);
> extern void early_init_dt_add_memory_arch(u64 base, u64 size);
> +extern int early_init_dt_reserve_memory_arch(phys_addr_t base, phys_addr_t size,
> + bool no_map);
> extern void * early_init_dt_alloc_memory_arch(u64 size, u64 align);
> extern u64 dt_mem_next_cell(int s, __be32 **cellp);
I think I'm happy with this one. Address my comments above and add my
Acked-by (so I remember I was okay with this one when you repost it) :-)
Acked-by: Grant Likely <grant.likely@xxxxxxxxxx>
>
> --
> 1.7.9.5
>
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