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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH 1/2] xen/device-tree: add a helper to dump an FDT in DTS-like format
The device tree Xen builds for a dom0less domain is only ever consumed
by the guest, so a mistake in it surfaces as an obscure failure inside
the domain, far away from the code which produced the tree.
Add device_tree_dump(). The output follows dtc's format so that a dump
can be diffed against the source DTS or fed back to dtc; the value
formatting heuristics are ported from dtc's utilfdt_print_data() for
that reason. The walk itself goes through libfdt rather than decoding
the tag stream by hand as dtc's fdtdump does.
Dumping a whole tree is only useful while debugging and costs both code
size and a lot of console output, hence CONFIG_DEVICE_TREE_DEBUG. Mention
the dump in the help text of the option.
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
xen/Kconfig.debug | 3 +-
xen/common/device-tree/Makefile | 1 +
xen/common/device-tree/dom0less-build.c | 4 +
xen/common/device-tree/fdt-dump.c | 180 ++++++++++++++++++++++++
xen/include/xen/bootfdt.h | 13 ++
5 files changed, 200 insertions(+), 1 deletion(-)
create mode 100644 xen/common/device-tree/fdt-dump.c
diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index d900d926c555..664f50bf8a96 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -95,7 +95,8 @@ config DEVICE_TREE_DEBUG
depends on DEVICE_TREE_PARSE
help
Device tree parsing and DOM0 device tree building messages are
- logged in the Xen ring buffer.
+ logged in the Xen ring buffer. The device tree generated for each
+ dom0less domU is dumped there as well, in a DTS-like format.
If unsure, say N here.
config SCRUB_DEBUG
diff --git a/xen/common/device-tree/Makefile b/xen/common/device-tree/Makefile
index 9036e455d66a..959dd2a9fd30 100644
--- a/xen/common/device-tree/Makefile
+++ b/xen/common/device-tree/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_DOMAIN_BUILD_HELPERS) += domain-build.init.o
obj-$(filter $(CONFIG_DOM0LESS_BOOT),$(CONFIG_HAS_DEVICE_TREE_DISCOVERY)) +=
dom0less-build.init.o
obj-$(CONFIG_DOM0LESS_BOOT) += dom0less-bindings.init.o
obj-$(CONFIG_OVERLAY_DTB) += dt-overlay.o
+obj-$(CONFIG_DEVICE_TREE_DEBUG) += fdt-dump.init.o
obj-$(CONFIG_HAS_DEVICE_TREE_DISCOVERY) += intc.o
obj-$(CONFIG_DOMAIN_BUILD_HELPERS) += kernel.o
obj-$(CONFIG_STATIC_EVTCHN) += static-evtchn.init.o
diff --git a/xen/common/device-tree/dom0less-build.c
b/xen/common/device-tree/dom0less-build.c
index fcbeb8adbd73..182201384faf 100644
--- a/xen/common/device-tree/dom0less-build.c
+++ b/xen/common/device-tree/dom0less-build.c
@@ -1,5 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0-only */
+#include <xen/bootfdt.h>
#include <xen/bootinfo.h>
#include <xen/device_tree.h>
#include <xen/dom0less-build.h>
@@ -587,6 +588,9 @@ static int __init prepare_dtb_domU(struct domain *d, struct
kernel_info *kinfo)
if ( ret < 0 )
goto err;
+ dt_dprintk("Device tree for %pd:\n", d);
+ device_tree_dump(kinfo->fdt);
+
return 0;
err:
diff --git a/xen/common/device-tree/fdt-dump.c
b/xen/common/device-tree/fdt-dump.c
new file mode 100644
index 000000000000..fc3d9eca5891
--- /dev/null
+++ b/xen/common/device-tree/fdt-dump.c
@@ -0,0 +1,180 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Dump a flattened device tree blob in a DTS-like format.
+ *
+ * is_printable_string() and print_value() are derived from
+ * util_is_printable_string() and utilfdt_print_data() in the device tree
+ * compiler (dtc).
+ *
+ * Copyright 2011 The Chromium Authors, All Rights Reserved.
+ * Copyright 2008 Jon Loeliger, Freescale Semiconductor, Inc.
+ * util_is_printable_string contributed by
+ * Pantelis Antoniou <pantelis.antoniou AT gmail.com>
+ */
+
+#include <xen/bootfdt.h>
+#include <xen/ctype.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/libfdt/libfdt.h>
+#include <xen/types.h>
+
+/* Deeper nodes are still printed, but not indented any further. */
+#define DUMP_MAX_INDENT_DEPTH 32
+
+/* Indentation, in characters, of a node at depth @depth. */
+static int __init indent_of(int depth)
+{
+ return 2 * min(depth, DUMP_MAX_INDENT_DEPTH);
+}
+
+static bool __init is_printable_string(const void *data, unsigned int len)
+{
+ const char *s = data;
+ const char *se = s + len;
+
+ /* A zero length property, or one which isn't NUL terminated, isn't one. */
+ if ( (len == 0) || (s[len - 1] != '\0') )
+ return false;
+
+ while ( s < se )
+ {
+ const char *ss = s;
+
+ while ( (s < se) && *s && isprint(*s) )
+ s++;
+
+ /* Stopped on a non printable character, or the string is empty. */
+ if ( (*s != '\0') || (s == ss) )
+ return false;
+
+ s++;
+ }
+
+ return true;
+}
+
+/*
+ * Print the value of a property, using the same heuristics as dtc: a list of
+ * NUL terminated printable strings is printed as such, a value which is a
+ * multiple of 4 bytes as a list of cells, anything else as a byte string.
+ *
+ * The caller has already started the line (and with it selected the log
+ * level), so no XENLOG_* prefix may be used here.
+ */
+static void __init print_value(const void *data, unsigned int len)
+{
+ unsigned int i;
+
+ /* Empty property, nothing to print. */
+ if ( len == 0 )
+ return;
+
+ if ( is_printable_string(data, len) )
+ {
+ const char *s = data;
+ const char *end = data + len;
+
+ printk(" = ");
+ while ( s < end )
+ {
+ printk("\"%s\"", s);
+ s += strlen(s) + 1;
+ if ( s < end )
+ printk(", ");
+ }
+ }
+ else if ( IS_ALIGNED(len, sizeof(fdt32_t)) )
+ {
+ const fdt32_t *cell = data;
+
+ printk(" = <");
+ for ( i = 0; i < len / sizeof(*cell); i++ )
+ printk("%s0x%08x", i ? " " : "", fdt32_ld(&cell[i]));
+ printk(">");
+ }
+ else
+ {
+ const uint8_t *byte = data;
+
+ printk(" = [");
+ for ( i = 0; i < len; i++ )
+ printk("%s%02x", i ? " " : "", byte[i]);
+ printk("]");
+ }
+}
+
+static void __init print_properties(const void *fdt, int node, int indent)
+{
+ int prop;
+
+ fdt_for_each_property_offset ( prop, fdt, node )
+ {
+ const char *name;
+ const void *data;
+ int len;
+
+ data = fdt_getprop_by_offset(fdt, prop, &name, &len);
+ if ( !data )
+ {
+ printk(XENLOG_DEBUG "%*scouldn't read property at offset %d: %s\n",
+ indent, "", prop, fdt_strerror(len));
+ return;
+ }
+
+ printk(XENLOG_DEBUG "%*s%s", indent, "", name);
+ print_value(data, len);
+ printk(";\n");
+ }
+
+ if ( (prop < 0) && (prop != -FDT_ERR_NOTFOUND) )
+ printk(XENLOG_DEBUG "%*scouldn't walk the properties: %s\n",
+ indent, "", fdt_strerror(prop));
+}
+
+void __init device_tree_dump(const void *fdt)
+{
+ int node, depth = 0;
+ /* Depth up to which nodes are open and still have to be closed. */
+ int open_depth = 0;
+
+ printk(XENLOG_DEBUG "/dts-v1/;\n");
+
+ /*
+ * fdt_next_node() signals the end of the subtree it was started on by
+ * making the depth negative, and only returns an error when the blob
+ * itself is malformed.
+ */
+ for ( node = 0; (node >= 0) && (depth >= 0);
+ node = fdt_next_node(fdt, node, &depth) )
+ {
+ const char *name = fdt_get_name(fdt, node, NULL);
+
+ /* Close the nodes which aren't a parent of the current one. */
+ while ( open_depth > depth )
+ printk(XENLOG_DEBUG "%*s};\n", indent_of(--open_depth), "");
+
+ printk(XENLOG_DEBUG "%*s%s {\n", indent_of(depth), "",
+ (depth == 0) ? "/" : (name ?: "<unknown>"));
+ print_properties(fdt, node, indent_of(depth) + 2);
+
+ open_depth = depth + 1;
+ }
+
+ while ( open_depth > 0 )
+ printk(XENLOG_DEBUG "%*s};\n", indent_of(--open_depth), "");
+
+ if ( node < 0 )
+ printk(XENLOG_DEBUG "The device tree dump is incomplete: %s\n",
+ fdt_strerror(node));
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/xen/bootfdt.h b/xen/include/xen/bootfdt.h
index 0e82ccea2f84..08983375209b 100644
--- a/xen/include/xen/bootfdt.h
+++ b/xen/include/xen/bootfdt.h
@@ -99,6 +99,19 @@ int device_tree_for_each_node(const void *fdt, int node,
device_tree_node_func func,
void *data);
+/*
+ * device_tree_dump - print a device tree blob in a DTS-like format
+ * @fdt: flat device tree.
+ *
+ * The tree is printed at debug log level and is only meant to be used for
+ * debugging, so it is a no-op unless CONFIG_DEVICE_TREE_DEBUG is enabled.
+ */
+#ifdef CONFIG_DEVICE_TREE_DEBUG
+void device_tree_dump(const void *fdt);
+#else
+static inline void device_tree_dump(const void *fdt) {}
+#endif
+
typedef enum {
BOOTMOD_XEN,
BOOTMOD_FDT,
--
2.55.0
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