Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 927 insertions, 0 deletions

diff --git a/scripts/dtc/flattree.c b/scripts/dtc/flattree.c
new file mode 100644
index 000000000..f3b698c17
--- /dev/null
+++ b/scripts/dtc/flattree.c
@@ -0,0 +1,927 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation.  2005.
+ */
+
+#include "dtc.h"
+#include "srcpos.h"
+
+#define FTF_FULLPATH	0x1
+#define FTF_VARALIGN	0x2
+#define FTF_NAMEPROPS	0x4
+#define FTF_BOOTCPUID	0x8
+#define FTF_STRTABSIZE	0x10
+#define FTF_STRUCTSIZE	0x20
+#define FTF_NOPS	0x40
+
+static struct version_info {
+	int version;
+	int last_comp_version;
+	int hdr_size;
+	int flags;
+} version_table[] = {
+	{1, 1, FDT_V1_SIZE,
+	 FTF_FULLPATH|FTF_VARALIGN|FTF_NAMEPROPS},
+	{2, 1, FDT_V2_SIZE,
+	 FTF_FULLPATH|FTF_VARALIGN|FTF_NAMEPROPS|FTF_BOOTCPUID},
+	{3, 1, FDT_V3_SIZE,
+	 FTF_FULLPATH|FTF_VARALIGN|FTF_NAMEPROPS|FTF_BOOTCPUID|FTF_STRTABSIZE},
+	{16, 16, FDT_V3_SIZE,
+	 FTF_BOOTCPUID|FTF_STRTABSIZE|FTF_NOPS},
+	{17, 16, FDT_V17_SIZE,
+	 FTF_BOOTCPUID|FTF_STRTABSIZE|FTF_STRUCTSIZE|FTF_NOPS},
+};
+
+struct emitter {
+	void (*cell)(void *, cell_t);
+	void (*string)(void *, const char *, int);
+	void (*align)(void *, int);
+	void (*data)(void *, struct data);
+	void (*beginnode)(void *, struct label *labels);
+	void (*endnode)(void *, struct label *labels);
+	void (*property)(void *, struct label *labels);
+};
+
+static void bin_emit_cell(void *e, cell_t val)
+{
+	struct data *dtbuf = e;
+
+	*dtbuf = data_append_cell(*dtbuf, val);
+}
+
+static void bin_emit_string(void *e, const char *str, int len)
+{
+	struct data *dtbuf = e;
+
+	if (len == 0)
+		len = strlen(str);
+
+	*dtbuf = data_append_data(*dtbuf, str, len);
+	*dtbuf = data_append_byte(*dtbuf, '\0');
+}
+
+static void bin_emit_align(void *e, int a)
+{
+	struct data *dtbuf = e;
+
+	*dtbuf = data_append_align(*dtbuf, a);
+}
+
+static void bin_emit_data(void *e, struct data d)
+{
+	struct data *dtbuf = e;
+
+	*dtbuf = data_append_data(*dtbuf, d.val, d.len);
+}
+
+static void bin_emit_beginnode(void *e, struct label *labels)
+{
+	bin_emit_cell(e, FDT_BEGIN_NODE);
+}
+
+static void bin_emit_endnode(void *e, struct label *labels)
+{
+	bin_emit_cell(e, FDT_END_NODE);
+}
+
+static void bin_emit_property(void *e, struct label *labels)
+{
+	bin_emit_cell(e, FDT_PROP);
+}
+
+static struct emitter bin_emitter = {
+	.cell = bin_emit_cell,
+	.string = bin_emit_string,
+	.align = bin_emit_align,
+	.data = bin_emit_data,
+	.beginnode = bin_emit_beginnode,
+	.endnode = bin_emit_endnode,
+	.property = bin_emit_property,
+};
+
+static void emit_label(FILE *f, const char *prefix, const char *label)
+{
+	fprintf(f, "\t.globl\t%s_%s\n", prefix, label);
+	fprintf(f, "%s_%s:\n", prefix, label);
+	fprintf(f, "_%s_%s:\n", prefix, label);
+}
+
+static void emit_offset_label(FILE *f, const char *label, int offset)
+{
+	fprintf(f, "\t.globl\t%s\n", label);
+	fprintf(f, "%s\t= . + %d\n", label, offset);
+}
+
+#define ASM_EMIT_BELONG(f, fmt, ...) \
+	{ \
+		fprintf((f), "\t.byte\t((" fmt ") >> 24) & 0xff\n", __VA_ARGS__); \
+		fprintf((f), "\t.byte\t((" fmt ") >> 16) & 0xff\n", __VA_ARGS__); \
+		fprintf((f), "\t.byte\t((" fmt ") >> 8) & 0xff\n", __VA_ARGS__); \
+		fprintf((f), "\t.byte\t(" fmt ") & 0xff\n", __VA_ARGS__); \
+	}
+
+static void asm_emit_cell(void *e, cell_t val)
+{
+	FILE *f = e;
+
+	fprintf(f, "\t.byte\t0x%02x\n" "\t.byte\t0x%02x\n"
+		"\t.byte\t0x%02x\n" "\t.byte\t0x%02x\n",
+		(val >> 24) & 0xff, (val >> 16) & 0xff,
+		(val >> 8) & 0xff, val & 0xff);
+}
+
+static void asm_emit_string(void *e, const char *str, int len)
+{
+	FILE *f = e;
+
+	if (len != 0)
+		fprintf(f, "\t.asciz\t\"%.*s\"\n", len, str);
+	else
+		fprintf(f, "\t.asciz\t\"%s\"\n", str);
+}
+
+static void asm_emit_align(void *e, int a)
+{
+	FILE *f = e;
+
+	fprintf(f, "\t.balign\t%d, 0\n", a);
+}
+
+static void asm_emit_data(void *e, struct data d)
+{
+	FILE *f = e;
+	unsigned int off = 0;
+	struct marker *m = d.markers;
+
+	for_each_marker_of_type(m, LABEL)
+		emit_offset_label(f, m->ref, m->offset);
+
+	while ((d.len - off) >= sizeof(uint32_t)) {
+		asm_emit_cell(e, dtb_ld32(d.val + off));
+		off += sizeof(uint32_t);
+	}
+
+	while ((d.len - off) >= 1) {
+		fprintf(f, "\t.byte\t0x%hhx\n", d.val[off]);
+		off += 1;
+	}
+
+	assert(off == d.len);
+}
+
+static void asm_emit_beginnode(void *e, struct label *labels)
+{
+	FILE *f = e;
+	struct label *l;
+
+	for_each_label(labels, l) {
+		fprintf(f, "\t.globl\t%s\n", l->label);
+		fprintf(f, "%s:\n", l->label);
+	}
+	fprintf(f, "\t/* FDT_BEGIN_NODE */\n");
+	asm_emit_cell(e, FDT_BEGIN_NODE);
+}
+
+static void asm_emit_endnode(void *e, struct label *labels)
+{
+	FILE *f = e;
+	struct label *l;
+
+	fprintf(f, "\t/* FDT_END_NODE */\n");
+	asm_emit_cell(e, FDT_END_NODE);
+	for_each_label(labels, l) {
+		fprintf(f, "\t.globl\t%s_end\n", l->label);
+		fprintf(f, "%s_end:\n", l->label);
+	}
+}
+
+static void asm_emit_property(void *e, struct label *labels)
+{
+	FILE *f = e;
+	struct label *l;
+
+	for_each_label(labels, l) {
+		fprintf(f, "\t.globl\t%s\n", l->label);
+		fprintf(f, "%s:\n", l->label);
+	}
+	fprintf(f, "\t/* FDT_PROP */\n");
+	asm_emit_cell(e, FDT_PROP);
+}
+
+static struct emitter asm_emitter = {
+	.cell = asm_emit_cell,
+	.string = asm_emit_string,
+	.align = asm_emit_align,
+	.data = asm_emit_data,
+	.beginnode = asm_emit_beginnode,
+	.endnode = asm_emit_endnode,
+	.property = asm_emit_property,
+};
+
+static int stringtable_insert(struct data *d, const char *str)
+{
+	unsigned int i;
+
+	/* FIXME: do this more efficiently? */
+
+	for (i = 0; i < d->len; i++) {
+		if (streq(str, d->val + i))
+			return i;
+	}
+
+	*d = data_append_data(*d, str, strlen(str)+1);
+	return i;
+}
+
+static void flatten_tree(struct node *tree, struct emitter *emit,
+			 void *etarget, struct data *strbuf,
+			 struct version_info *vi)
+{
+	struct property *prop;
+	struct node *child;
+	bool seen_name_prop = false;
+
+	if (tree->deleted)
+		return;
+
+	emit->beginnode(etarget, tree->labels);
+
+	if (vi->flags & FTF_FULLPATH)
+		emit->string(etarget, tree->fullpath, 0);
+	else
+		emit->string(etarget, tree->name, 0);
+
+	emit->align(etarget, sizeof(cell_t));
+
+	for_each_property(tree, prop) {
+		int nameoff;
+
+		if (streq(prop->name, "name"))
+			seen_name_prop = true;
+
+		nameoff = stringtable_insert(strbuf, prop->name);
+
+		emit->property(etarget, prop->labels);
+		emit->cell(etarget, prop->val.len);
+		emit->cell(etarget, nameoff);
+
+		if ((vi->flags & FTF_VARALIGN) && (prop->val.len >= 8))
+			emit->align(etarget, 8);
+
+		emit->data(etarget, prop->val);
+		emit->align(etarget, sizeof(cell_t));
+	}
+
+	if ((vi->flags & FTF_NAMEPROPS) && !seen_name_prop) {
+		emit->property(etarget, NULL);
+		emit->cell(etarget, tree->basenamelen+1);
+		emit->cell(etarget, stringtable_insert(strbuf, "name"));
+
+		if ((vi->flags & FTF_VARALIGN) && ((tree->basenamelen+1) >= 8))
+			emit->align(etarget, 8);
+
+		emit->string(etarget, tree->name, tree->basenamelen);
+		emit->align(etarget, sizeof(cell_t));
+	}
+
+	for_each_child(tree, child) {
+		flatten_tree(child, emit, etarget, strbuf, vi);
+	}
+
+	emit->endnode(etarget, tree->labels);
+}
+
+static struct data flatten_reserve_list(struct reserve_info *reservelist,
+				 struct version_info *vi)
+{
+	struct reserve_info *re;
+	struct data d = empty_data;
+	unsigned int j;
+
+	for (re = reservelist; re; re = re->next) {
+		d = data_append_re(d, re->address, re->size);
+	}
+	/*
+	 * Add additional reserved slots if the user asked for them.
+	 */
+	for (j = 0; j < reservenum; j++) {
+		d = data_append_re(d, 0, 0);
+	}
+
+	return d;
+}
+
+static void make_fdt_header(struct fdt_header *fdt,
+			    struct version_info *vi,
+			    int reservesize, int dtsize, int strsize,
+			    int boot_cpuid_phys)
+{
+	int reserve_off;
+
+	reservesize += sizeof(struct fdt_reserve_entry);
+
+	memset(fdt, 0xff, sizeof(*fdt));
+
+	fdt->magic = cpu_to_fdt32(FDT_MAGIC);
+	fdt->version = cpu_to_fdt32(vi->version);
+	fdt->last_comp_version = cpu_to_fdt32(vi->last_comp_version);
+
+	/* Reserve map should be doubleword aligned */
+	reserve_off = ALIGN(vi->hdr_size, 8);
+
+	fdt->off_mem_rsvmap = cpu_to_fdt32(reserve_off);
+	fdt->off_dt_struct = cpu_to_fdt32(reserve_off + reservesize);
+	fdt->off_dt_strings = cpu_to_fdt32(reserve_off + reservesize
+					  + dtsize);
+	fdt->totalsize = cpu_to_fdt32(reserve_off + reservesize + dtsize + strsize);
+
+	if (vi->flags & FTF_BOOTCPUID)
+		fdt->boot_cpuid_phys = cpu_to_fdt32(boot_cpuid_phys);
+	if (vi->flags & FTF_STRTABSIZE)
+		fdt->size_dt_strings = cpu_to_fdt32(strsize);
+	if (vi->flags & FTF_STRUCTSIZE)
+		fdt->size_dt_struct = cpu_to_fdt32(dtsize);
+}
+
+void dt_to_blob(FILE *f, struct dt_info *dti, int version)
+{
+	struct version_info *vi = NULL;
+	unsigned int i;
+	struct data blob       = empty_data;
+	struct data reservebuf = empty_data;
+	struct data dtbuf      = empty_data;
+	struct data strbuf     = empty_data;
+	struct fdt_header fdt;
+	int padlen = 0;
+
+	for (i = 0; i < ARRAY_SIZE(version_table); i++) {
+		if (version_table[i].version == version)
+			vi = &version_table[i];
+	}
+	if (!vi)
+		die("Unknown device tree blob version %d\n", version);
+
+	flatten_tree(dti->dt, &bin_emitter, &dtbuf, &strbuf, vi);
+	bin_emit_cell(&dtbuf, FDT_END);
+
+	reservebuf = flatten_reserve_list(dti->reservelist, vi);
+
+	/* Make header */
+	make_fdt_header(&fdt, vi, reservebuf.len, dtbuf.len, strbuf.len,
+			dti->boot_cpuid_phys);
+
+	/*
+	 * If the user asked for more space than is used, adjust the totalsize.
+	 */
+	if (minsize > 0) {
+		padlen = minsize - fdt32_to_cpu(fdt.totalsize);
+		if (padlen < 0) {
+			padlen = 0;
+			if (quiet < 1)
+				fprintf(stderr,
+					"Warning: blob size %"PRIu32" >= minimum size %d\n",
+					fdt32_to_cpu(fdt.totalsize), minsize);
+		}
+	}
+
+	if (padsize > 0)
+		padlen = padsize;
+
+	if (alignsize > 0)
+		padlen = ALIGN(fdt32_to_cpu(fdt.totalsize) + padlen, alignsize)
+			- fdt32_to_cpu(fdt.totalsize);
+
+	if (padlen > 0) {
+		int tsize = fdt32_to_cpu(fdt.totalsize);
+		tsize += padlen;
+		fdt.totalsize = cpu_to_fdt32(tsize);
+	}
+
+	/*
+	 * Assemble the blob: start with the header, add with alignment
+	 * the reserve buffer, add the reserve map terminating zeroes,
+	 * the device tree itself, and finally the strings.
+	 */
+	blob = data_append_data(blob, &fdt, vi->hdr_size);
+	blob = data_append_align(blob, 8);
+	blob = data_merge(blob, reservebuf);
+	blob = data_append_zeroes(blob, sizeof(struct fdt_reserve_entry));
+	blob = data_merge(blob, dtbuf);
+	blob = data_merge(blob, strbuf);
+
+	/*
+	 * If the user asked for more space than is used, pad out the blob.
+	 */
+	if (padlen > 0)
+		blob = data_append_zeroes(blob, padlen);
+
+	if (fwrite(blob.val, blob.len, 1, f) != 1) {
+		if (ferror(f))
+			die("Error writing device tree blob: %s\n",
+			    strerror(errno));
+		else
+			die("Short write on device tree blob\n");
+	}
+
+	/*
+	 * data_merge() frees the right-hand element so only the blob
+	 * remains to be freed.
+	 */
+	data_free(blob);
+}
+
+static void dump_stringtable_asm(FILE *f, struct data strbuf)
+{
+	const char *p;
+	int len;
+
+	p = strbuf.val;
+
+	while (p < (strbuf.val + strbuf.len)) {
+		len = strlen(p);
+		fprintf(f, "\t.asciz \"%s\"\n", p);
+		p += len+1;
+	}
+}
+
+void dt_to_asm(FILE *f, struct dt_info *dti, int version)
+{
+	struct version_info *vi = NULL;
+	unsigned int i;
+	struct data strbuf = empty_data;
+	struct reserve_info *re;
+	const char *symprefix = "dt";
+
+	for (i = 0; i < ARRAY_SIZE(version_table); i++) {
+		if (version_table[i].version == version)
+			vi = &version_table[i];
+	}
+	if (!vi)
+		die("Unknown device tree blob version %d\n", version);
+
+	fprintf(f, "/* autogenerated by dtc, do not edit */\n\n");
+
+	emit_label(f, symprefix, "blob_start");
+	emit_label(f, symprefix, "header");
+	fprintf(f, "\t/* magic */\n");
+	asm_emit_cell(f, FDT_MAGIC);
+	fprintf(f, "\t/* totalsize */\n");
+	ASM_EMIT_BELONG(f, "_%s_blob_abs_end - _%s_blob_start",
+			symprefix, symprefix);
+	fprintf(f, "\t/* off_dt_struct */\n");
+	ASM_EMIT_BELONG(f, "_%s_struct_start - _%s_blob_start",
+		symprefix, symprefix);
+	fprintf(f, "\t/* off_dt_strings */\n");
+	ASM_EMIT_BELONG(f, "_%s_strings_start - _%s_blob_start",
+		symprefix, symprefix);
+	fprintf(f, "\t/* off_mem_rsvmap */\n");
+	ASM_EMIT_BELONG(f, "_%s_reserve_map - _%s_blob_start",
+		symprefix, symprefix);
+	fprintf(f, "\t/* version */\n");
+	asm_emit_cell(f, vi->version);
+	fprintf(f, "\t/* last_comp_version */\n");
+	asm_emit_cell(f, vi->last_comp_version);
+
+	if (vi->flags & FTF_BOOTCPUID) {
+		fprintf(f, "\t/* boot_cpuid_phys */\n");
+		asm_emit_cell(f, dti->boot_cpuid_phys);
+	}
+
+	if (vi->flags & FTF_STRTABSIZE) {
+		fprintf(f, "\t/* size_dt_strings */\n");
+		ASM_EMIT_BELONG(f, "_%s_strings_end - _%s_strings_start",
+				symprefix, symprefix);
+	}
+
+	if (vi->flags & FTF_STRUCTSIZE) {
+		fprintf(f, "\t/* size_dt_struct */\n");
+		ASM_EMIT_BELONG(f, "_%s_struct_end - _%s_struct_start",
+			symprefix, symprefix);
+	}
+
+	/*
+	 * Reserve map entries.
+	 * Align the reserve map to a doubleword boundary.
+	 * Each entry is an (address, size) pair of u64 values.
+	 * Always supply a zero-sized termination entry.
+	 */
+	asm_emit_align(f, 8);
+	emit_label(f, symprefix, "reserve_map");
+
+	fprintf(f, "/* Memory reserve map from source file */\n");
+
+	/*
+	 * Use .long on high and low halves of u64s to avoid .quad
+	 * as it appears .quad isn't available in some assemblers.
+	 */
+	for (re = dti->reservelist; re; re = re->next) {
+		struct label *l;
+
+		for_each_label(re->labels, l) {
+			fprintf(f, "\t.globl\t%s\n", l->label);
+			fprintf(f, "%s:\n", l->label);
+		}
+		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->address >> 32));
+		ASM_EMIT_BELONG(f, "0x%08x",
+				(unsigned int)(re->address & 0xffffffff));
+		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->size >> 32));
+		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->size & 0xffffffff));
+	}
+	for (i = 0; i < reservenum; i++) {
+		fprintf(f, "\t.long\t0, 0\n\t.long\t0, 0\n");
+	}
+
+	fprintf(f, "\t.long\t0, 0\n\t.long\t0, 0\n");
+
+	emit_label(f, symprefix, "struct_start");
+	flatten_tree(dti->dt, &asm_emitter, f, &strbuf, vi);
+
+	fprintf(f, "\t/* FDT_END */\n");
+	asm_emit_cell(f, FDT_END);
+	emit_label(f, symprefix, "struct_end");
+
+	emit_label(f, symprefix, "strings_start");
+	dump_stringtable_asm(f, strbuf);
+	emit_label(f, symprefix, "strings_end");
+
+	emit_label(f, symprefix, "blob_end");
+
+	/*
+	 * If the user asked for more space than is used, pad it out.
+	 */
+	if (minsize > 0) {
+		fprintf(f, "\t.space\t%d - (_%s_blob_end - _%s_blob_start), 0\n",
+			minsize, symprefix, symprefix);
+	}
+	if (padsize > 0) {
+		fprintf(f, "\t.space\t%d, 0\n", padsize);
+	}
+	if (alignsize > 0)
+		asm_emit_align(f, alignsize);
+	emit_label(f, symprefix, "blob_abs_end");
+
+	data_free(strbuf);
+}
+
+struct inbuf {
+	char *base, *limit, *ptr;
+};
+
+static void inbuf_init(struct inbuf *inb, void *base, void *limit)
+{
+	inb->base = base;
+	inb->limit = limit;
+	inb->ptr = inb->base;
+}
+
+static void flat_read_chunk(struct inbuf *inb, void *p, int len)
+{
+	if ((inb->ptr + len) > inb->limit)
+		die("Premature end of data parsing flat device tree\n");
+
+	memcpy(p, inb->ptr, len);
+
+	inb->ptr += len;
+}
+
+static uint32_t flat_read_word(struct inbuf *inb)
+{
+	fdt32_t val;
+
+	assert(((inb->ptr - inb->base) % sizeof(val)) == 0);
+
+	flat_read_chunk(inb, &val, sizeof(val));
+
+	return fdt32_to_cpu(val);
+}
+
+static void flat_realign(struct inbuf *inb, int align)
+{
+	int off = inb->ptr - inb->base;
+
+	inb->ptr = inb->base + ALIGN(off, align);
+	if (inb->ptr > inb->limit)
+		die("Premature end of data parsing flat device tree\n");
+}
+
+static const char *flat_read_string(struct inbuf *inb)
+{
+	int len = 0;
+	const char *p = inb->ptr;
+	const char *str;
+
+	do {
+		if (p >= inb->limit)
+			die("Premature end of data parsing flat device tree\n");
+		len++;
+	} while ((*p++) != '\0');
+
+	str = inb->ptr;
+
+	inb->ptr += len;
+
+	flat_realign(inb, sizeof(uint32_t));
+
+	return str;
+}
+
+static struct data flat_read_data(struct inbuf *inb, int len)
+{
+	struct data d = empty_data;
+
+	if (len == 0)
+		return empty_data;
+
+	d = data_grow_for(d, len);
+	d.len = len;
+
+	flat_read_chunk(inb, d.val, len);
+
+	flat_realign(inb, sizeof(uint32_t));
+
+	return d;
+}
+
+static char *flat_read_stringtable(struct inbuf *inb, int offset)
+{
+	const char *p;
+
+	p = inb->base + offset;
+	while (1) {
+		if (p >= inb->limit || p < inb->base)
+			die("String offset %d overruns string table\n",
+			    offset);
+
+		if (*p == '\0')
+			break;
+
+		p++;
+	}
+
+	return xstrdup(inb->base + offset);
+}
+
+static struct property *flat_read_property(struct inbuf *dtbuf,
+					   struct inbuf *strbuf, int flags)
+{
+	uint32_t proplen, stroff;
+	char *name;
+	struct data val;
+
+	proplen = flat_read_word(dtbuf);
+	stroff = flat_read_word(dtbuf);
+
+	name = flat_read_stringtable(strbuf, stroff);
+
+	if ((flags & FTF_VARALIGN) && (proplen >= 8))
+		flat_realign(dtbuf, 8);
+
+	val = flat_read_data(dtbuf, proplen);
+
+	return build_property(name, val, NULL);
+}
+
+
+static struct reserve_info *flat_read_mem_reserve(struct inbuf *inb)
+{
+	struct reserve_info *reservelist = NULL;
+	struct reserve_info *new;
+	struct fdt_reserve_entry re;
+
+	/*
+	 * Each entry is a pair of u64 (addr, size) values for 4 cell_t's.
+	 * List terminates at an entry with size equal to zero.
+	 *
+	 * First pass, count entries.
+	 */
+	while (1) {
+		uint64_t address, size;
+
+		flat_read_chunk(inb, &re, sizeof(re));
+		address  = fdt64_to_cpu(re.address);
+		size = fdt64_to_cpu(re.size);
+		if (size == 0)
+			break;
+
+		new = build_reserve_entry(address, size);
+		reservelist = add_reserve_entry(reservelist, new);
+	}
+
+	return reservelist;
+}
+
+
+static const char *nodename_from_path(const char *ppath, const char *cpath)
+{
+	int plen;
+
+	plen = strlen(ppath);
+
+	if (!strstarts(cpath, ppath))
+		die("Path \"%s\" is not valid as a child of \"%s\"\n",
+		    cpath, ppath);
+
+	/* root node is a special case */
+	if (!streq(ppath, "/"))
+		plen++;
+
+	return cpath + plen;
+}
+
+static struct node *unflatten_tree(struct inbuf *dtbuf,
+				   struct inbuf *strbuf,
+				   const char *parent_flatname, int flags)
+{
+	struct node *node;
+	const char *flatname;
+	uint32_t val;
+
+	node = build_node(NULL, NULL, NULL);
+
+	flatname = flat_read_string(dtbuf);
+
+	if (flags & FTF_FULLPATH)
+		node->name = xstrdup(nodename_from_path(parent_flatname,
+							flatname));
+	else
+		node->name = xstrdup(flatname);
+
+	do {
+		struct property *prop;
+		struct node *child;
+
+		val = flat_read_word(dtbuf);
+		switch (val) {
+		case FDT_PROP:
+			if (node->children)
+				fprintf(stderr, "Warning: Flat tree input has "
+					"subnodes preceding a property.\n");
+			prop = flat_read_property(dtbuf, strbuf, flags);
+			add_property(node, prop);
+			break;
+
+		case FDT_BEGIN_NODE:
+			child = unflatten_tree(dtbuf,strbuf, flatname, flags);
+			add_child(node, child);
+			break;
+
+		case FDT_END_NODE:
+			break;
+
+		case FDT_END:
+			die("Premature FDT_END in device tree blob\n");
+			break;
+
+		case FDT_NOP:
+			if (!(flags & FTF_NOPS))
+				fprintf(stderr, "Warning: NOP tag found in flat tree"
+					" version <16\n");
+
+			/* Ignore */
+			break;
+
+		default:
+			die("Invalid opcode word %08x in device tree blob\n",
+			    val);
+		}
+	} while (val != FDT_END_NODE);
+
+	return node;
+}
+
+
+struct dt_info *dt_from_blob(const char *fname)
+{
+	FILE *f;
+	fdt32_t magic_buf, totalsize_buf;
+	uint32_t magic, totalsize, version, size_dt, boot_cpuid_phys;
+	uint32_t off_dt, off_str, off_mem_rsvmap;
+	int rc;
+	char *blob;
+	struct fdt_header *fdt;
+	char *p;
+	struct inbuf dtbuf, strbuf;
+	struct inbuf memresvbuf;
+	int sizeleft;
+	struct reserve_info *reservelist;
+	struct node *tree;
+	uint32_t val;
+	int flags = 0;
+	unsigned int dtsflags = DTSF_V1;
+
+	f = srcfile_relative_open(fname, NULL);
+
+	rc = fread(&magic_buf, sizeof(magic_buf), 1, f);
+	if (ferror(f))
+		die("Error reading DT blob magic number: %s\n",
+		    strerror(errno));
+	if (rc < 1) {
+		if (feof(f))
+			die("EOF reading DT blob magic number\n");
+		else
+			die("Mysterious short read reading magic number\n");
+	}
+
+	magic = fdt32_to_cpu(magic_buf);
+	if (magic != FDT_MAGIC)
+		die("Blob has incorrect magic number\n");
+
+	rc = fread(&totalsize_buf, sizeof(totalsize_buf), 1, f);
+	if (ferror(f))
+		die("Error reading DT blob size: %s\n", strerror(errno));
+	if (rc < 1) {
+		if (feof(f))
+			die("EOF reading DT blob size\n");
+		else
+			die("Mysterious short read reading blob size\n");
+	}
+
+	totalsize = fdt32_to_cpu(totalsize_buf);
+	if (totalsize < FDT_V1_SIZE)
+		die("DT blob size (%d) is too small\n", totalsize);
+
+	blob = xmalloc(totalsize);
+
+	fdt = (struct fdt_header *)blob;
+	fdt->magic = cpu_to_fdt32(magic);
+	fdt->totalsize = cpu_to_fdt32(totalsize);
+
+	sizeleft = totalsize - sizeof(magic) - sizeof(totalsize);
+	p = blob + sizeof(magic)  + sizeof(totalsize);
+
+	while (sizeleft) {
+		if (feof(f))
+			die("EOF before reading %d bytes of DT blob\n",
+			    totalsize);
+
+		rc = fread(p, 1, sizeleft, f);
+		if (ferror(f))
+			die("Error reading DT blob: %s\n",
+			    strerror(errno));
+
+		sizeleft -= rc;
+		p += rc;
+	}
+
+	off_dt = fdt32_to_cpu(fdt->off_dt_struct);
+	off_str = fdt32_to_cpu(fdt->off_dt_strings);
+	off_mem_rsvmap = fdt32_to_cpu(fdt->off_mem_rsvmap);
+	version = fdt32_to_cpu(fdt->version);
+	boot_cpuid_phys = fdt32_to_cpu(fdt->boot_cpuid_phys);
+
+	if (off_mem_rsvmap >= totalsize)
+		die("Mem Reserve structure offset exceeds total size\n");
+
+	if (off_dt >= totalsize)
+		die("DT structure offset exceeds total size\n");
+
+	if (off_str > totalsize)
+		die("String table offset exceeds total size\n");
+
+	if (version >= 3) {
+		uint32_t size_str = fdt32_to_cpu(fdt->size_dt_strings);
+		if ((off_str+size_str < off_str) || (off_str+size_str > totalsize))
+			die("String table extends past total size\n");
+		inbuf_init(&strbuf, blob + off_str, blob + off_str + size_str);
+	} else {
+		inbuf_init(&strbuf, blob + off_str, blob + totalsize);
+	}
+
+	if (version >= 17) {
+		size_dt = fdt32_to_cpu(fdt->size_dt_struct);
+		if ((off_dt+size_dt < off_dt) || (off_dt+size_dt > totalsize))
+			die("Structure block extends past total size\n");
+	}
+
+	if (version < 16) {
+		flags |= FTF_FULLPATH | FTF_NAMEPROPS | FTF_VARALIGN;
+	} else {
+		flags |= FTF_NOPS;
+	}
+
+	inbuf_init(&memresvbuf,
+		   blob + off_mem_rsvmap, blob + totalsize);
+	inbuf_init(&dtbuf, blob + off_dt, blob + totalsize);
+
+	reservelist = flat_read_mem_reserve(&memresvbuf);
+
+	val = flat_read_word(&dtbuf);
+
+	if (val != FDT_BEGIN_NODE)
+		die("Device tree blob doesn't begin with FDT_BEGIN_NODE (begins with 0x%08x)\n", val);
+
+	tree = unflatten_tree(&dtbuf, &strbuf, "", flags);
+
+	val = flat_read_word(&dtbuf);
+	if (val != FDT_END)
+		die("Device tree blob doesn't end with FDT_END\n");
+
+	free(blob);
+
+	fclose(f);
+
+	if (get_subnode(tree, "__fixups__") || get_subnode(tree, "__local_fixups__"))
+		dtsflags |= DTSF_PLUGIN;
+
+	return build_dt_info(dtsflags, reservelist, tree, boot_cpuid_phys);
+}