Merge patch series to add a "fallback" keyword to extlinux.conf parsing

This series from Martyn Welch <martyn.welch@collabora.com> adds the
ability to have a "fallback" option in extlinux.conf parsing, which can
be in turn used in A/B style update mechanisms.

Link: https://lore.kernel.org/u-boot/20241009131548.929439-1-martyn.welch@collabora.com/

boot/bootmeth-uclass.c

@@ -251,6 +251,31 @@ int bootmeth_set_order(const char *order_str)
 	return 0;
 }
 
+int bootmeth_set_property(const char *name, const char *property, const char *value)
+{
+	int ret;
+	int len;
+	struct udevice *dev;
+	const struct bootmeth_ops *ops;
+
+	len = strlen(name);
+
+	ret = uclass_find_device_by_namelen(UCLASS_BOOTMETH, name, len,
+					    &dev);
+	if (ret) {
+		printf("Unknown bootmeth '%s'\n", name);
+		return ret;
+	}
+
+	ops = bootmeth_get_ops(dev);
+	if (!ops->set_property) {
+		printf("set_property not found\n");
+		return -ENODEV;
+	}
+
+	return ops->set_property(dev, property, value);
+}
+
 int bootmeth_setup_fs(struct bootflow *bflow, struct blk_desc *desc)
 {
 	int ret;

boot/bootmeth_extlinux.c

@@ -21,6 +21,39 @@
 #include <mmc.h>
 #include <pxe_utils.h>
 
+struct extlinux_plat {
+	bool use_fallback;
+};
+
+enum extlinux_option_type {
+	EO_FALLBACK,
+	EO_INVALID
+};
+
+struct extlinux_option {
+	char *name;
+	enum extlinux_option_type option;
+};
+
+static const struct extlinux_option options[] = {
+	{"fallback", EO_FALLBACK},
+	{NULL, EO_INVALID}
+};
+
+static enum extlinux_option_type get_option(const char *option)
+{
+	int i = 0;
+
+	while (options[i].name) {
+		if (!strcmp(options[i].name, option))
+			return options[i].option;
+
+		i++;
+	}
+
+	return EO_INVALID;
+};
+
 static int extlinux_get_state_desc(struct udevice *dev, char *buf, int maxsize)
 {
 	if (IS_ENABLED(CONFIG_SANDBOX)) {
@@ -142,14 +175,18 @@ static int extlinux_boot(struct udevice *dev, struct bootflow *bflow)
 	struct cmd_tbl cmdtp = {};	/* dummy */
 	struct pxe_context ctx;
 	struct extlinux_info info;
+	struct extlinux_plat *plat;
 	ulong addr;
 	int ret;
 
 	addr = map_to_sysmem(bflow->buf);
 	info.dev = dev;
 	info.bflow = bflow;
+
+	plat = dev_get_plat(dev);
+
 	ret = pxe_setup_ctx(&ctx, &cmdtp, extlinux_getfile, &info, true,
-			    bflow->fname, false);
+			    bflow->fname, false, plat->use_fallback);
 	if (ret)
 		return log_msg_ret("ctx", -EINVAL);
 
@@ -160,6 +197,38 @@ static int extlinux_boot(struct udevice *dev, struct bootflow *bflow)
 	return 0;
 }
 
+static int extlinux_set_property(struct udevice *dev, const char *property, const char *value)
+{
+	struct extlinux_plat *plat;
+	static enum extlinux_option_type option;
+
+	plat = dev_get_plat(dev);
+
+	option = get_option(property);
+	if (option == EO_INVALID) {
+		printf("Invalid option\n");
+		return -EINVAL;
+	}
+
+	switch (option) {
+	case EO_FALLBACK:
+		if (!strcmp(value, "1")) {
+			plat->use_fallback = true;
+		} else if (!strcmp(value, "0")) {
+			plat->use_fallback = false;
+		} else {
+			printf("Unexpected value '%s'\n", value);
+			return -EINVAL;
+		}
+		break;
+	default:
+		printf("Unrecognised property '%s'\n", property);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int extlinux_bootmeth_bind(struct udevice *dev)
 {
 	struct bootmeth_uc_plat *plat = dev_get_uclass_plat(dev);
@@ -176,6 +245,7 @@ static struct bootmeth_ops extlinux_bootmeth_ops = {
 	.read_bootflow	= extlinux_read_bootflow,
 	.read_file	= bootmeth_common_read_file,
 	.boot		= extlinux_boot,
+	.set_property	= extlinux_set_property,
 };
 
 static const struct udevice_id extlinux_bootmeth_ids[] = {
@@ -190,4 +260,5 @@ U_BOOT_DRIVER(bootmeth_1extlinux) = {
 	.of_match	= extlinux_bootmeth_ids,
 	.ops		= &extlinux_bootmeth_ops,
 	.bind		= extlinux_bootmeth_bind,
+	.plat_auto	= sizeof(struct extlinux_plat)
 };

boot/bootmeth_pxe.c

@@ -150,7 +150,7 @@ static int extlinux_pxe_boot(struct udevice *dev, struct bootflow *bflow)
 	info.bflow = bflow;
 	info.cmdtp = &cmdtp;
 	ret = pxe_setup_ctx(ctx, &cmdtp, extlinux_pxe_getfile, &info, false,
-			    bflow->subdir, false);
+			    bflow->subdir, false, false);
 	if (ret)
 		return log_msg_ret("ctx", -EINVAL);
 

boot/pxe_utils.c

@@ -781,6 +781,7 @@ enum token_type {
 	T_IPAPPEND,
 	T_BACKGROUND,
 	T_KASLRSEED,
+	T_FALLBACK,
 	T_INVALID
 };
 
@@ -814,6 +815,7 @@ static const struct token keywords[] = {
 	{"ipappend", T_IPAPPEND,},
 	{"background", T_BACKGROUND,},
 	{"kaslrseed", T_KASLRSEED,},
+	{"fallback", T_FALLBACK,},
 	{NULL, T_INVALID}
 };
 
@@ -1356,6 +1358,18 @@ static int parse_pxefile_top(struct pxe_context *ctx, char *p, unsigned long bas
 
 			break;
 
+		case T_FALLBACK:
+			err = parse_sliteral(&p, &label_name);
+
+			if (label_name) {
+				if (cfg->fallback_label)
+					free(cfg->fallback_label);
+
+				cfg->fallback_label = label_name;
+			}
+
+			break;
+
 		case T_INCLUDE:
 			err = handle_include(ctx, &p,
 					     base + ALIGN(strlen(b), 4), cfg,
@@ -1395,6 +1409,7 @@ void destroy_pxe_menu(struct pxe_menu *cfg)
 
 	free(cfg->title);
 	free(cfg->default_label);
+	free(cfg->fallback_label);
 
 	list_for_each_safe(pos, n, &cfg->labels) {
 		label = list_entry(pos, struct pxe_label, list);
@@ -1421,6 +1436,16 @@ struct pxe_menu *parse_pxefile(struct pxe_context *ctx, unsigned long menucfg)
 
 	buf = map_sysmem(menucfg, 0);
 	r = parse_pxefile_top(ctx, buf, menucfg, cfg, 1);
+
+	if (ctx->use_fallback) {
+		if (cfg->fallback_label) {
+			printf("Setting use of fallback\n");
+			cfg->default_label = cfg->fallback_label;
+		} else {
+			printf("Selected fallback option, but not set\n");
+		}
+	}
+
 	unmap_sysmem(buf);
 	if (r < 0) {
 		destroy_pxe_menu(cfg);
@@ -1571,7 +1596,8 @@ void handle_pxe_menu(struct pxe_context *ctx, struct pxe_menu *cfg)
 
 int pxe_setup_ctx(struct pxe_context *ctx, struct cmd_tbl *cmdtp,
 		  pxe_getfile_func getfile, void *userdata,
-		  bool allow_abs_path, const char *bootfile, bool use_ipv6)
+		  bool allow_abs_path, const char *bootfile, bool use_ipv6,
+		  bool use_fallback)
 {
 	const char *last_slash;
 	size_t path_len = 0;
@@ -1582,6 +1608,7 @@ int pxe_setup_ctx(struct pxe_context *ctx, struct cmd_tbl *cmdtp,
 	ctx->userdata = userdata;
 	ctx->allow_abs_path = allow_abs_path;
 	ctx->use_ipv6 = use_ipv6;
+	ctx->use_fallback = use_fallback;
 
 	/* figure out the boot directory, if there is one */
 	if (bootfile && strlen(bootfile) >= MAX_TFTP_PATH_LEN)

cmd/bootmeth.c

@@ -103,10 +103,31 @@ static int do_bootmeth_order(struct cmd_tbl *cmdtp, int flag, int argc,
 	return 0;
 }
 
+static int do_bootmeth_set(struct cmd_tbl *cmdtp, int flag, int argc,
+			     char *const argv[])
+{
+	int ret;
+
+	if (argc < 4) {
+		printf("Required parameters not provided\n");
+		return CMD_RET_FAILURE;
+	}
+
+	ret = bootmeth_set_property(argv[1], argv[2], argv[3]);
+	if (ret) {
+		printf("Failed (err=%d)\n", ret);
+		return CMD_RET_FAILURE;
+	}
+
+	return 0;
+}
+
 U_BOOT_LONGHELP(bootmeth,
 	"list [-a]     - list available bootmeths (-a all)\n"
-	"bootmeth order [<bd> ...]  - select bootmeth order / subset to use");
+	"bootmeth order [<bd> ...]  - select bootmeth order / subset to use\n"
+	"bootmeth set <bootmeth> <property> <value> - set optional property");
 
 U_BOOT_CMD_WITH_SUBCMDS(bootmeth, "Boot methods", bootmeth_help_text,
 	U_BOOT_SUBCMD_MKENT(list, 2, 1, do_bootmeth_list),
-	U_BOOT_SUBCMD_MKENT(order, CONFIG_SYS_MAXARGS, 1, do_bootmeth_order));
+	U_BOOT_SUBCMD_MKENT(order, CONFIG_SYS_MAXARGS, 1, do_bootmeth_order),
+	U_BOOT_SUBCMD_MKENT(set, CONFIG_SYS_MAXARGS, 1, do_bootmeth_set));

cmd/pxe.c

@@ -138,7 +138,7 @@ int pxe_get(ulong pxefile_addr_r, char **bootdirp, ulong *sizep, bool use_ipv6)
 	int i;
 
 	if (pxe_setup_ctx(&ctx, cmdtp, do_get_tftp, NULL, false,
-			  env_get("bootfile"), use_ipv6))
+			  env_get("bootfile"), use_ipv6, false))
 		return -ENOMEM;
 
 	if (IS_ENABLED(CONFIG_BOOTP_PXE_DHCP_OPTION) &&
@@ -288,7 +288,7 @@ do_pxe_boot(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 	}
 
 	if (pxe_setup_ctx(&ctx, cmdtp, do_get_tftp, NULL, false,
-			  env_get("bootfile"), use_ipv6)) {
+			  env_get("bootfile"), use_ipv6, false)) {
 		printf("Out of memory\n");
 		return CMD_RET_FAILURE;
 	}

cmd/sysboot.c

@@ -105,7 +105,7 @@ static int do_sysboot(struct cmd_tbl *cmdtp, int flag, int argc,
 	}
 
 	if (pxe_setup_ctx(&ctx, cmdtp, sysboot_read_file, &info, true,
-			  filename, false)) {
+			  filename, false, false)) {
 		printf("Out of memory\n");
 		return CMD_RET_FAILURE;
 	}

doc/README.pxe

@@ -120,6 +120,11 @@ Unrecognized commands are ignored.
 default <label>	    - the label named here is treated as the default and is
 		      the first label 'pxe boot' attempts to boot.
 
+fallback <label>    - the label named here is treated as a fallback option that
+		      may be attempted should it be detected that booting of
+		      the default has failed to complete, for example via
+		      U-Boot's boot count limit functionality.
+
 menu title <string> - sets a title for the menu of labels being displayed.
 
 menu include <path> - use tftp to retrieve the pxe file at <path>, which

doc/develop/bootstd/overview.rst

@@ -103,6 +103,12 @@ provide a `read_bootflow()` method which checks whatever bootdevs it likes, then
 returns the bootflow, if found. Some of these bootmeths may be very slow, if
 they scan a lot of devices.
 
+The extlinux bootmeth also allows for bootmeth specific configuration to be
+set. A bootmeth that wishes to support this provides the `set_property()`
+method. This allows string properties and values to be passed to the bootmeth.
+It is up to the bootmeth to determine what action to take when this method is
+called.
+
 
 Boot process
 ------------
@@ -459,8 +465,8 @@ Three commands are available:
     See :doc:`/usage/cmd/bootflow`
 
 `bootmeth`
-    Allow listing of available bootmethds and setting the order in which they
-    are tried. See :doc:`/usage/cmd/bootmeth`
+    Allow listing of available bootmethds, setting the order in which they are
+    tried and bootmeth specific configuration. See :doc:`/usage/cmd/bootmeth`
 
 .. _BootflowStates:
 

doc/usage/cmd/bootmeth.rst

@@ -12,7 +12,8 @@ Synopsis
 ::
 
     bootmeth list [-a]          - list selected bootmeths (-a for all)
-    bootmeth order "[<bm> ...]" - select the order of bootmeths\n"
+    bootmeth order "[<bm> ...]" - select the order of bootmeths
+    bootmeth set <bootmeth> <property> <value> - set optional property
 
 
 Description
@@ -112,3 +113,38 @@ which are not::
         -    4  efi_mgr             EFI bootmgr flow
     -----  ---  ------------------  ------------------
     (5 bootmeths)
+
+
+bootmeth set
+~~~~~~~~~~~~
+
+Allows setting of bootmeth specific configuration. This allows finer grain
+control over the boot process in specific instances.
+
+
+Supported Configuration Options
+-------------------------------
+
+The following configuration options are currently supported:
+
+========  ===================  ======  ===============================
+Property  Supported Bootmeths  Values  Description
+========  ===================  ======  ===============================
+fallback  extlinux             0 | 1     Enable or disable fallback path
+========  ===================  ======  ===============================
+
+
+Bootmeth set Example
+--------------------
+
+With the bootcount functionality enabled, when the bootlimit is reached, the
+`altbootcmd` environment variable lists the command used for booting rather
+than `bootcmd`. We can set the fallback configuration to cause the fallback
+boot option to be preferred, to revert to a previous known working boot option
+after a failed update for example. So if `bootcmd` is set to::
+
+    bootflow scan -lb
+
+We would set "altbootcmd" to::
+
+    bootmeth set extlinux fallback 1; bootflow scan -lb

include/bootmeth.h

@@ -146,6 +146,22 @@ struct bootmeth_ops {
 	 *	something changes, other -ve on other error
 	 */
 	int (*boot)(struct udevice *dev, struct bootflow *bflow);
+
+	/**
+	 * set_property() - set the bootmeth property
+	 *
+	 * This allows the setting of boot method specific properties to enable
+	 * automated finer grain control of the boot process
+	 *
+	 * @name: String containing the name of the relevant boot method
+	 * @property: String containing the name of the property to set
+	 * @value: String containing the value to be set for the specified
+	 *         property
+	 * Return: 0 if OK, -ENODEV if an unknown bootmeth or property is
+	 *      provided, -ENOENT if there are no bootmeth devices
+	 */
+	int (*set_property)(struct udevice *dev, const char *property,
+			    const char *value);
 };
 
 #define bootmeth_get_ops(dev)  ((struct bootmeth_ops *)(dev)->driver->ops)
@@ -290,6 +306,21 @@ int bootmeth_setup_iter_order(struct bootflow_iter *iter, bool include_global);
  */
 int bootmeth_set_order(const char *order_str);
 
+/**
+ * bootmeth_set_property() - Set the bootmeth property
+ *
+ * This allows the setting of boot method specific properties to enable
+ * automated finer grain control of the boot process
+ *
+ * @name: String containing the name of the relevant boot method
+ * @property: String containing the name of the property to set
+ * @value: String containing the value to be set for the specified property
+ * Return: 0 if OK, -ENODEV if an unknown bootmeth or property is provided,
+ * -ENOENT if there are no bootmeth devices
+ */
+int bootmeth_set_property(const char *name, const char *property,
+			  const char *value);
+
 /**
  * bootmeth_setup_fs() - Set up read to read a file
  *

include/pxe_utils.h

@@ -62,6 +62,7 @@ struct pxe_label {
  *
  * title - the name of the menu as given by a 'menu title' line.
  * default_label - the name of the default label, if any.
+ * fallback_label - the name of the fallback label, if any.
  * bmp - the bmp file name which is displayed in background
  * timeout - time in tenths of a second to wait for a user key-press before
  *           booting the default label.
@@ -73,6 +74,7 @@ struct pxe_label {
 struct pxe_menu {
 	char *title;
 	char *default_label;
+	char *fallback_label;
 	char *bmp;
 	int timeout;
 	int prompt;
@@ -94,6 +96,8 @@ typedef int (*pxe_getfile_func)(struct pxe_context *ctx, const char *file_path,
  *	allocated
  * @pxe_file_size: Size of the PXE file
  * @use_ipv6: TRUE : use IPv6 addressing, FALSE : use IPv4 addressing
+ * @use_fallback: TRUE : use "fallback" option as default, FALSE : use
+ *	"default" option as default
  */
 struct pxe_context {
 	struct cmd_tbl *cmdtp;
@@ -114,6 +118,7 @@ struct pxe_context {
 	char *bootdir;
 	ulong pxe_file_size;
 	bool use_ipv6;
+	bool use_fallback;
 };
 
 /**
@@ -213,12 +218,17 @@ int format_mac_pxe(char *outbuf, size_t outbuf_len);
  *	none
  * @use_ipv6: TRUE : use IPv6 addressing
  *            FALSE : use IPv4 addressing
+ * @use_fallback: TRUE : Use "fallback" option instead of "default" should no
+ *                       other choice be selected
+ *                FALSE : Use "default" option should no other choice be
+ *                        selected
  * Return: 0 if OK, -ENOMEM if out of memory, -E2BIG if bootfile is larger than
  *	MAX_TFTP_PATH_LEN bytes
  */
 int pxe_setup_ctx(struct pxe_context *ctx, struct cmd_tbl *cmdtp,
 		  pxe_getfile_func getfile, void *userdata,
-		  bool allow_abs_path, const char *bootfile, bool use_ipv6);
+		  bool allow_abs_path, const char *bootfile, bool use_ipv6,
+		  bool use_fallback);
 
 /**
  * pxe_destroy_ctx() - Destroy a PXE context

test/boot/bootmeth.c

@@ -127,6 +127,53 @@ static int bootmeth_cmd_order_glob(struct unit_test_state *uts)
 }
 BOOTSTD_TEST(bootmeth_cmd_order_glob, UTF_DM | UTF_SCAN_FDT | UTF_CONSOLE);
 
+/* Check 'bootmeth set' command */
+static int bootmeth_cmd_set(struct unit_test_state *uts)
+{
+	/* Check we can enable extlinux fallback */
+	console_record_reset_enable();
+	ut_assertok(run_command("bootmeth set extlinux fallback 1", 0));
+	ut_assert_console_end();
+
+	/* Check we can disable extlinux fallback */
+	console_record_reset_enable();
+	ut_assertok(run_command("bootmeth set extlinux fallback 0", 0));
+	ut_assert_console_end();
+
+	/* Check extlinux fallback unexpected value */
+	console_record_reset_enable();
+	ut_asserteq(1, run_command("bootmeth set extlinux fallback fred", 0));
+	ut_assert_nextline("Unexpected value 'fred'");
+	ut_assert_nextline("Failed (err=-22)");
+	ut_assert_console_end();
+
+	/* Check that we need to provide right number of parameters */
+	ut_asserteq(1, run_command("bootmeth set extlinux fallback", 0));
+	ut_assert_nextline("Required parameters not provided");
+	ut_assert_console_end();
+
+	/* Check that we need to provide a valid bootmethod */
+	ut_asserteq(1, run_command("bootmeth set fred fallback 0", 0));
+	ut_assert_nextline("Unknown bootmeth 'fred'");
+	ut_assert_nextline("Failed (err=-19)");
+	ut_assert_console_end();
+
+	/* Check that we need to provide a valid property */
+	ut_asserteq(1, run_command("bootmeth set extlinux fred 0", 0));
+	ut_assert_nextline("Invalid option");
+	ut_assert_nextline("Failed (err=-22)");
+	ut_assert_console_end();
+
+	/* Check that we need to provide a bootmeth that supports properties */
+	ut_asserteq(1, run_command("bootmeth set efi fallback 0", 0));
+	ut_assert_nextline("set_property not found");
+	ut_assert_nextline("Failed (err=-19)");
+	ut_assert_console_end();
+
+	return 0;
+}
+BOOTSTD_TEST(bootmeth_cmd_set, UTF_DM | UTF_SCAN_FDT);
+
 /* Check 'bootmeths' env var */
 static int bootmeth_env(struct unit_test_state *uts)
 {