[U-Boot] [PATCH v2 05/71] dm: Add a function to create a 'live' device tree
Simon Glass
sjg at chromium.org
Mon May 15 03:03:23 UTC 2017
Hi Lothar,
On 11 May 2017 at 08:59, Lothar Waßmann <LW at karo-electronics.de> wrote:
> Hi,
>
> On Wed, 10 May 2017 08:20:44 -0600 Simon Glass wrote:
>> This function converts the flat device tree into a hierarchical one with
>> C structures and pointers. This is easier to access.
>>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>> Changes in v2: None
>>
>> include/of_live.h | 24 ++++
>> lib/Makefile | 1 +
>> lib/of_live.c | 333 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 358 insertions(+)
>> create mode 100644 include/of_live.h
>> create mode 100644 lib/of_live.c
>>
>> diff --git a/include/of_live.h b/include/of_live.h
>> new file mode 100644
>> index 0000000000..f5303bb018
>> --- /dev/null
>> +++ b/include/of_live.h
>> @@ -0,0 +1,24 @@
>> +/*
>> + * Copyright (c) 2017 Google, Inc
>> + * Written by Simon Glass <sjg at chromium.org>
>> + *
>> + * SPDX-License-Identifier: GPL-2.0+
>> + *
>> + * Support for a 'live' (as opposed to flat) device tree
>> + */
>> +
>> +#ifndef _OF_LIVE_H
>> +#define _OF_LIVE_H
>> +
>> +struct device_node;
>> +
>> +/**
>> + * of_live_build() - build a live (hierarchical) tree from a flat DT
>> + *
>> + * @fdt_blob: Input tree to convert
>> + * @rootp: Returns live tree that was created
>> + * @return 0 if OK, -ve on error
>> + */
>> +int of_live_build(const void *fdt_blob, struct device_node **rootp);
>> +
>> +#endif
>> diff --git a/lib/Makefile b/lib/Makefile
>> index 23e9f1ef11..bc2fb0a361 100644
>> --- a/lib/Makefile
>> +++ b/lib/Makefile
>> @@ -15,6 +15,7 @@ obj-$(CONFIG_ZLIB) += zlib/
>> obj-$(CONFIG_BZIP2) += bzip2/
>> obj-$(CONFIG_TIZEN) += tizen/
>> obj-$(CONFIG_FIT) += libfdt/
>> +obj-$(CONFIG_OF_LIVE) += of_live.o
>> obj-$(CONFIG_CMD_DHRYSTONE) += dhry/
>>
>> obj-$(CONFIG_AES) += aes.o
>> diff --git a/lib/of_live.c b/lib/of_live.c
>> new file mode 100644
>> index 0000000000..51927f9e91
>> --- /dev/null
>> +++ b/lib/of_live.c
>> @@ -0,0 +1,333 @@
>> +/*
>> + * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
>> + * benh at kernel.crashing.org
>> + *
>> + * Based on parts of drivers/of/fdt.c from Linux v4.9
>> + * Modifications for U-Boot
>> + * Copyright (c) 2017 Google, Inc
>> + *
>> + * SPDX-License-Identifier: GPL-2.0+
>> + */
>> +
>> +#include <common.h>
>> +#include <libfdt.h>
>> +#include <of_live.h>
>> +#include <malloc.h>
>> +#include <dm/of_access.h>
>> +#include <linux/err.h>
>> +
>> +DECLARE_GLOBAL_DATA_PTR;
>> +
>> +static void *unflatten_dt_alloc(void **mem, unsigned long size,
>> + unsigned long align)
>> +{
>> + void *res;
>> +
>> + *mem = PTR_ALIGN(*mem, align);
>> + res = *mem;
>> + *mem += size;
>> +
>> + return res;
>> +}
>> +
>> +/**
>> + * unflatten_dt_node() - Alloc and populate a device_node from the flat tree
>> + * @blob: The parent device tree blob
>> + * @mem: Memory chunk to use for allocating device nodes and properties
>> + * @poffset: pointer to node in flat tree
>> + * @dad: Parent struct device_node
>> + * @nodepp: The device_node tree created by the call
>> + * @fpsize: Size of the node path up at t05he current depth.
>> + * @dryrun: If true, do not allocate device nodes but still calculate needed
>> + * memory size
>> + */
>> +static void *unflatten_dt_node(const void *blob, void *mem, int *poffset,
>> + struct device_node *dad,
>> + struct device_node **nodepp,
>> + unsigned long fpsize, bool dryrun)
>> +{
>> + const __be32 *p;
>> + struct device_node *np;
>> + struct property *pp, **prev_pp = NULL;
>> + const char *pathp;
>> + int l;
>> + unsigned int allocl;
>> + static int depth;
>> + int old_depth;
>> + int offset;
>> + int has_name = 0;
>> + int new_format = 0;
>> +
>> + pathp = fdt_get_name(blob, *poffset, &l);
>> + if (!pathp)
>> + return mem;
>> +
>> + allocl = ++l;
>> +
>> + /*
>> + * version 0x10 has a more compact unit name here instead of the full
>> + * path. we accumulate the full path size using "fpsize", we'll rebuild
>> + * it later. We detect this because the first character of the name is
>> + * not '/'.
>> + */
>> + if ((*pathp) != '/') {
>> + new_format = 1;
>> + if (fpsize == 0) {
>> + /*
>> + * root node: special case. fpsize accounts for path
>> + * plus terminating zero. root node only has '/', so
>> + * fpsize should be 2, but we want to avoid the first
>> + * level nodes to have two '/' so we use fpsize 1 here
>> + */
>> + fpsize = 1;
>> + allocl = 2;
>> + l = 1;
>> + pathp = "";
>> + } else {
>> + /*
>> + * account for '/' and path size minus terminal 0
>> + * already in 'l'
>> + */
>> + fpsize += l;
>> + allocl = fpsize;
>> + }
>> + }
>> +
>> + np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
>> + __alignof__(struct device_node));
>> + if (!dryrun) {
>> + char *fn;
>> +
>> + fn = (char *)np + sizeof(*np);
>> + np->full_name = fn;
>> + if (new_format) {
>> + /* rebuild full path for new format */
>> + if (dad && dad->parent) {
>> + strcpy(fn, dad->full_name);
>>
> strcpy() is EVIL! How do you ascertain, that the string
> at dad->full_name cannot overflow the buffer at fn?
The size has been calculated the code above. This is a two-pass
approach - one pass figures out the total size of the required buffer,
and the next pass actually copies in the data.
If the length were wrong that would indicate a bug in the code above.
See the part where it sets new_format to 1.
Regards,
Simon
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