dts allows references both in integer context:
foo = <&bar>;
in which case it resolves to a phandle, but also in string/bytestring
context:
foo = &bar;
In which case it resolves to a path.
Runtime overlays, only support the former, but not the latter.
This patch implements resolving path references when applying overlays.
Signed-off-by: Ayush Singh <ayush@xxxxxxxxxxxxxxx>
---
fdtoverlay.c | 34 +++++++---
libfdt/fdt_overlay.c | 174 ++++++++++++++++++++++++++++++---------------------
libfdt/libfdt.h | 30 ++++++++-
libfdt/version.lds | 1 +
4 files changed, 160 insertions(+), 79 deletions(-)
diff --git a/fdtoverlay.c b/fdtoverlay.c
index ee1eb8f3ad28b14762aca9ab5c8a4e36aac967d8..3b6e666212f7c6742ab1e7897c5a0288ff4049ac 100644
--- a/fdtoverlay.c
+++ b/fdtoverlay.c
@@ -44,16 +44,36 @@ static void *apply_one(char *base, const char *overlay, size_t *buf_len,
const char *name)
{
char *tmp = NULL;
- char *tmpo;
+ char *tmpo = NULL;
int ret;
bool has_symbols;
+ size_t tmpo_len = fdt_totalsize(overlay);
- /*
- * We take copies first, because a failed apply can trash
- * both the base blob and the overlay
- */
- tmpo = xmalloc(fdt_totalsize(overlay));
+ /* Prepare DT overlay */
+ do {
+ tmpo = xrealloc(tmpo, tmpo_len);
+
+ ret = fdt_open_into(overlay, tmpo, tmpo_len);
+ if (ret) {
+ fprintf(stderr,
+ "\nFailed to make temporary copy of overlay: %s\n",
+ fdt_strerror(ret));
+ goto fail;
+ }
+
+ ret = fdt_overlay_prepare(base, tmpo);
+ if (ret == -FDT_ERR_NOSPACE) {
+ tmpo_len += BUF_INCREMENT;
+ }
+ } while (ret == -FDT_ERR_NOSPACE);
+
+ if (ret) {
+ fprintf(stderr, "\nFailed to prepare overlay '%s': %s\n", name,
+ fdt_strerror(ret));
+ goto fail;
+ }
+ /* Apply DT overlay to base tree */
do {
tmp = xrealloc(tmp, *buf_len);
ret = fdt_open_into(base, tmp, *buf_len);
@@ -66,8 +86,6 @@ static void *apply_one(char *base, const char *overlay, size_t *buf_len,
ret = fdt_path_offset(tmp, "/__symbols__");
has_symbols = ret >= 0;
- memcpy(tmpo, overlay, fdt_totalsize(overlay));
-
ret = fdt_overlay_apply(tmp, tmpo);
if (ret == -FDT_ERR_NOSPACE) {
*buf_len += BUF_INCREMENT;
diff --git a/libfdt/fdt_overlay.c b/libfdt/fdt_overlay.c
index 28b667ffc490e5a24a2b116714eb218d8d16a995..a912bfc580363b5a1376a2b89397db0e7e93a7df 100644
--- a/libfdt/fdt_overlay.c
+++ b/libfdt/fdt_overlay.c
@@ -10,6 +10,7 @@
#include <libfdt.h>
#include "libfdt_internal.h"
+#include "../util.h"
/**
* overlay_get_target_phandle - retrieves the target phandle of a fragment
@@ -306,7 +307,7 @@ static int overlay_update_local_references(void *fdto, uint32_t delta)
}
/**
- * overlay_fixup_one_phandle - Set an overlay phandle to the base one
+ * overlay_fixup_one_path_or_phandle - Set an overlay path/phandle to the base one
* @fdt: Base Device Tree blob
* @fdto: Device tree overlay blob
* @symbols_off: Node offset of the symbols node in the base device tree
@@ -315,27 +316,30 @@ static int overlay_update_local_references(void *fdto, uint32_t delta)
* @name: Name of the property holding the phandle reference in the overlay
* @name_len: number of name characters to consider
* @poffset: Offset within the overlay property where the phandle is stored
- * @phandle: Phandle referencing the node
+ * @symbol_path: path of the pointed node
*
- * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
- * a node in the base device tree.
+ * overlay_fixup_one_path_or_phandle() resolves an overlay path/phandle pointing
+ * to a node in the base device tree.
*
* This is part of the device tree overlay application process, when
- * you want all the phandles in the overlay to point to the actual
+ * you want all the paths/phandles in the overlay to point to the actual
* base dt nodes.
*
* returns:
* 0 on success
* Negative error code on failure
*/
-static int overlay_fixup_one_phandle(void *fdt, void *fdto,
- int symbols_off,
- const char *path, uint32_t path_len,
- const char *name, uint32_t name_len,
- int poffset, uint32_t phandle)
+static int overlay_fixup_one_path_or_phandle(const void *fdt, void *fdto,
+ int symbols_off, const char *path,
+ uint32_t path_len,
+ const char *name,
+ uint32_t name_len, int poffset,
+ const char *symbol_path)
{
+ const void *prop;
+ int fixup_off, prop_len, symbol_off;
+ uint32_t phandle;
fdt32_t phandle_prop;
- int fixup_off;
if (symbols_off < 0)
return symbols_off;
@@ -346,45 +350,60 @@ static int overlay_fixup_one_phandle(void *fdt, void *fdto,
if (fixup_off < 0)
return fixup_off;
- phandle_prop = cpu_to_fdt32(phandle);
- return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
- name, name_len, poffset,
- &phandle_prop,
- sizeof(phandle_prop));
+ prop = fdt_getprop_namelen(fdto, fixup_off, name, name_len, &prop_len);
+ if (!prop)
+ return -FDT_ERR_BADOVERLAY;
+
+ /* path references are empty dt properties in overlay */
+ if (prop_len == 0) {
+ return fdt_setprop_namelen_string(fdto, fixup_off, name,
+ name_len, symbol_path);
+ } else {
+ symbol_off = fdt_path_offset(fdt, symbol_path);
+ if (symbol_off < 0)
+ return symbol_off;
+
+ phandle = fdt_get_phandle(fdt, symbol_off);
+ if (!phandle)
+ return -FDT_ERR_NOTFOUND;
+ phandle_prop = cpu_to_fdt32(phandle);
+ return fdt_setprop_inplace_namelen_partial(
+ fdto, fixup_off, name, name_len, poffset, &phandle_prop,
+ sizeof(phandle_prop));
+ }
};
/**
- * overlay_fixup_phandle - Set an overlay phandle to the base one
+ * overlay_fixup_path_or_phandle - Set an overlay path/phandle to the base one
* @fdt: Base Device Tree blob
* @fdto: Device tree overlay blob
+ * @fixups: Device tree overlay ro copy
* @symbols_off: Node offset of the symbols node in the base device tree
* @property: Property offset in the overlay holding the list of fixups
*
- * overlay_fixup_phandle() resolves all the overlay phandles pointed
- * to in a __fixups__ property, and updates them to match the phandles
- * in use in the base device tree.
+ * overlay_fixup_path_or_phandle() resolves all the overlay paths/phandles
+ * pointed to in a __fixups__ property, and updates them to match the
+ * paths/phandles in use in the base device tree.
*
* This is part of the device tree overlay application process, when
- * you want all the phandles in the overlay to point to the actual
+ * you want all the paths/phandles in the overlay to point to the actual
* base dt nodes.
*
* returns:
* 0 on success
* Negative error code on failure
*/
-static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
- int property)
+static int overlay_fixup_path_or_phandle(const void *fdt, void *fdto,
+ const void *fixups, int symbols_off,
+ int property)
{
const char *value;
const char *label;
int len;
const char *symbol_path;
int prop_len;
- int symbol_off;
- uint32_t phandle;
- value = fdt_getprop_by_offset(fdto, property,
- &label, &len);
+ value = fdt_getprop_by_offset(fixups, property, &label, &len);
if (!value) {
if (len == -FDT_ERR_NOTFOUND)
return -FDT_ERR_INTERNAL;
@@ -395,14 +414,6 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
symbol_path = fdt_getprop(fdt, symbols_off, label, &prop_len);
if (!symbol_path)
return prop_len;
-
- symbol_off = fdt_path_offset(fdt, symbol_path);
- if (symbol_off < 0)
- return symbol_off;
-
- phandle = fdt_get_phandle(fdt, symbol_off);
- if (!phandle)
- return -FDT_ERR_NOTFOUND;
do {
const char *path, *name, *fixup_end;
@@ -415,6 +426,7 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
fixup_end = memchr(value, '\0', len);
if (!fixup_end)
return -FDT_ERR_BADOVERLAY;
+
fixup_len = fixup_end - fixup_str;
len -= fixup_len + 1;
@@ -443,9 +455,10 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
if ((*endptr != '\0') || (endptr <= (sep + 1)))
return -FDT_ERR_BADOVERLAY;
- ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
- path, path_len, name, name_len,
- poffset, phandle);
+ ret = overlay_fixup_one_path_or_phandle(fdt, fdto, symbols_off,
+ path, path_len, name,
+ name_len, poffset,
+ symbol_path);
if (ret)
return ret;
} while (len > 0);
@@ -454,26 +467,26 @@ static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
}
/**
- * overlay_fixup_phandles - Resolve the overlay phandles to the base
- * device tree
+ * overlay_fixup_paths_or_phandles - Resolve the overlay paths/phandles to the
+ * base device tree
* @fdt: Base Device Tree blob
* @fdto: Device tree overlay blob
*
- * overlay_fixup_phandles() resolves all the overlay phandles pointing
- * to nodes in the base device tree.
+ * overlay_fixup_paths_or_phandles() resolves all the overlay paths/phandles
+ * pointing to nodes in the base device tree.
*
* This is one of the steps of the device tree overlay application
- * process, when you want all the phandles in the overlay to point to
+ * process, when you want all the paths/phandles in the overlay to point to
* the actual base dt nodes.
*
* returns:
* 0 on success
* Negative error code on failure
*/
-static int overlay_fixup_phandles(void *fdt, void *fdto)
+static int overlay_fixup_paths_or_phandles(const void *fdt, void *fdto)
{
- int fixups_off, symbols_off;
- int property;
+ void *tmp = NULL;
+ int fixups_off, symbols_off, property, depth = 0, ret;
/* We can have overlays without any fixups */
fixups_off = fdt_path_offset(fdto, "/__fixups__");
@@ -487,15 +500,30 @@ static int overlay_fixup_phandles(void *fdt, void *fdto)
if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
return symbols_off;
- fdt_for_each_property_offset(property, fdto, fixups_off) {
- int ret;
+ ret = fdt_next_node(fdto, fixups_off, &depth);
+ if (ret < 0)
+ return ret;
- ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
+ /* resolving path references will resize the overlay and make fixup references
+ * invalid. So use a ro copy for reading fixups.
+ */
+ tmp = xmalloc(fdt_totalsize(fdto));
+ memcpy(tmp, fdto, fdt_totalsize(fdto));
+
+ fdt_for_each_property_offset(property, tmp, fixups_off)
+ {
+ ret = overlay_fixup_path_or_phandle(fdt, fdto, tmp, symbols_off,
+ property);
if (ret)
- return ret;
+ goto cleanup;
}
- return 0;
+ ret = 0;
+
+cleanup:
+ free(tmp);
+
+ return ret;
}
/**
@@ -653,7 +681,7 @@ static int overlay_update_local_conflicting_references(void *fdto,
* 0 on success
* Negative error code on failure
*/
-static int overlay_prevent_phandle_overwrite_node(void *fdt, int fdtnode,
+static int overlay_prevent_phandle_overwrite_node(const void *fdt, int fdtnode,
void *fdto, int fdtonode)
{
uint32_t fdt_phandle, fdto_phandle;
@@ -712,7 +740,7 @@ static int overlay_prevent_phandle_overwrite_node(void *fdt, int fdtnode,
* 0 on success
* Negative error code on failure
*/
-static int overlay_prevent_phandle_overwrite(void *fdt, void *fdto)
+static int overlay_prevent_phandle_overwrite(const void *fdt, void *fdto)
{
int fragment;
@@ -766,8 +794,7 @@ static int overlay_prevent_phandle_overwrite(void *fdt, void *fdto)
* 0 on success
* Negative error code on failure
*/
-static int overlay_apply_node(void *fdt, int target,
- void *fdto, int node)
+static int overlay_apply_node(void *fdt, int target, const void *fdto, int node)
{
int property;
int subnode;
@@ -828,7 +855,7 @@ static int overlay_apply_node(void *fdt, int target,
* 0 on success
* Negative error code on failure
*/
-static int overlay_merge(void *fdt, void *fdto)
+static int overlay_merge(void *fdt, const void *fdto)
{
int fragment;
@@ -904,7 +931,7 @@ static int get_path_len(const void *fdt, int nodeoffset)
* 0 on success
* Negative error code on failure
*/
-static int overlay_symbol_update(void *fdt, void *fdto)
+static int overlay_symbol_update(void *fdt, const void *fdto)
{
int root_sym, ov_sym, prop, path_len, fragment, target;
int len, frag_name_len, ret, rel_path_len;
@@ -1039,7 +1066,7 @@ static int overlay_symbol_update(void *fdt, void *fdto)
return 0;
}
-int fdt_overlay_apply(void *fdt, void *fdto)
+int fdt_overlay_prepare(const void *fdt, void *fdto)
{
uint32_t delta;
int ret;
@@ -1061,8 +1088,8 @@ int fdt_overlay_apply(void *fdt, void *fdto)
if (ret)
goto err;
- /* Update fdto's phandles using symbols from fdt */
- ret = overlay_fixup_phandles(fdt, fdto);
+ /* Update fdto's paths and phandles using symbols from fdt */
+ ret = overlay_fixup_paths_or_phandles(fdt, fdto);
if (ret)
goto err;
@@ -1071,6 +1098,23 @@ int fdt_overlay_apply(void *fdt, void *fdto)
if (ret)
goto err;
+ return 0;
+err:
+ /*
+ * The overlay might have been damaged, erase its magic.
+ */
+ fdt_set_magic(fdto, ~0);
+
+ return ret;
+}
+
+int fdt_overlay_apply(void *fdt, const void *fdto)
+{
+ int ret = 0;
+
+ FDT_RO_PROBE(fdt);
+ FDT_RO_PROBE(fdto);
+
ret = overlay_merge(fdt, fdto);
if (ret)
goto err;
@@ -1079,19 +1123,9 @@ int fdt_overlay_apply(void *fdt, void *fdto)
if (ret)
goto err;
- /*
- * The overlay has been damaged, erase its magic.
- */
- fdt_set_magic(fdto, ~0);
-
return 0;
err:
- /*
- * The overlay might have been damaged, erase its magic.
- */
- fdt_set_magic(fdto, ~0);
-
/*
* The base device tree might have been damaged, erase its
* magic.
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index 999b3800dff5c001b9c1babf370d45024c81a9aa..c14b778108427d0d578b86bc79f18dc88be05524 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -2215,6 +2215,34 @@ int fdt_add_subnode(void *fdt, int parentoffset, const char *name);
*/
int fdt_del_node(void *fdt, int nodeoffset);
+/**
+ * fdt_overlay_prepare - Prepares DT overlay for merging with base DT
+ * @fdt: const pointer to the base device tree blob
+ * @fdto: pointer to the device tree overlay blob
+ *
+ * fdt_overlay_prepare() will take care of any resizing/prepartion of the
+ * given device tree overlay.
+ *
+ * returns:
+ * 0, on success
+ * -FDT_ERR_NOSPACE, there's not enough space in the device tree overlay
+ * -FDT_ERR_NOTFOUND, the overlay points to some nonexistent nodes or
+ * properties in the base DT
+ * -FDT_ERR_BADPHANDLE,
+ * -FDT_ERR_BADOVERLAY,
+ * -FDT_ERR_NOPHANDLES,
+ * -FDT_ERR_INTERNAL,
+ * -FDT_ERR_BADLAYOUT,
+ * -FDT_ERR_BADMAGIC,
+ * -FDT_ERR_BADOFFSET,
+ * -FDT_ERR_BADPATH,
+ * -FDT_ERR_BADVERSION,
+ * -FDT_ERR_BADSTRUCTURE,
+ * -FDT_ERR_BADSTATE,
+ * -FDT_ERR_TRUNCATED, standard meanings
+ */
+int fdt_overlay_prepare(const void *fdt, void *fdto);
+
/**
* fdt_overlay_apply - Applies a DT overlay on a base DT
* @fdt: pointer to the base device tree blob
@@ -2244,7 +2272,7 @@ int fdt_del_node(void *fdt, int nodeoffset);
* -FDT_ERR_BADSTATE,
* -FDT_ERR_TRUNCATED, standard meanings
*/
-int fdt_overlay_apply(void *fdt, void *fdto);
+int fdt_overlay_apply(void *fdt, const void *fdto);
/**
* fdt_overlay_target_offset - retrieves the offset of a fragment's target
diff --git a/libfdt/version.lds b/libfdt/version.lds
index 989cd89f1051ce59255a3b3e60493be4e5e985cc..88ef44bb19ec69aabac61a1254264966e0a9d668 100644
--- a/libfdt/version.lds
+++ b/libfdt/version.lds
@@ -66,6 +66,7 @@ LIBFDT_1.2 {
fdt_stringlist_search;
fdt_stringlist_get;
fdt_resize;
+ fdt_overlay_prepare;
fdt_overlay_apply;
fdt_get_string;
fdt_find_max_phandle;
--
2.47.0
