android-mainline/ANDROID-Support-CONFIG_CMDLINE_EXTEND.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Carlos Llamas <cmllamas@google.com>
Date: Sun, 19 Sep 2021 01:30:28 +0000
Subject: ANDROID: Support CONFIG_CMDLINE_EXTEND

The old logic assumes CMDLINE_FROM_BOOTLOADER vs. CMDLINE_FORCE and
ignores CMDLINE_EXTEND.  Here's the old logic:

- CONFIG_CMDLINE_FORCE=true
    CONFIG_CMDLINE
- dt bootargs=non-empty:
    dt bootargs
- dt bootargs=empty, @data is non-empty string
    @data is left unchanged
- dt bootargs=empty, @data is empty string
    CONFIG_CMDLINE (or "" if that's not defined)

The new logic is now documented in of_fdt.h and is copied here for
reference:

- CONFIG_CMDLINE_FORCE=true
    CONFIG_CMDLINE
- CONFIG_CMDLINE_EXTEND=true, @data is non-empty string
    @data + dt bootargs (even if dt bootargs are empty)
- CONFIG_CMDLINE_EXTEND=true, @data is empty string
    CONFIG_CMDLINE + dt bootargs (even if dt bootargs are empty)
- CMDLINE_FROM_BOOTLOADER=true, dt bootargs=non-empty:
    dt bootargs
- CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is non-empty string
    @data is left unchanged
- CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is empty string
    CONFIG_CMDLINE (or "" if that's not defined)

[CPNOTE: 03/06/21] Lee: Pinged the bug and re-assigned Doug
[CPNOTE: 21/06/21] Lee: Will Deacon is continuing with this - bug now assigned to him
[CPNOTE: 05/08/21] Lee: There are competing replacements on the MLs - pinged Rob Herring for updates

Signed-off-by: Doug Anderson <dianders@chromium.org>
CC: devicetree-discuss@lists.ozlabs.org
CC: Grant Likely <grant.likely@secretlab.ca>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Rob Herring <rob.herring@calxeda.com>
Bug: 120440972
Change-Id: I40ace250847f813358125dfcaa8998fd32cf7ea3
Signed-off-by: Colin Cross <ccross@android.com>
[AmitP: Folded following android-4.9 commit changes into this patch
        e820270abb5d ("ANDROID: of: fix CONFIG_CMDLINE_EXTEND")
        9a4a74055444 ("ANDROID: of: Fix build warnings")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
---
 arch/arm64/Kconfig                 |  6 +++
 arch/arm64/kernel/idreg-override.c |  5 +-
 drivers/of/fdt.c                   | 74 ++++++++++++++++++++----------
 include/linux/of_fdt.h             | 21 +++++++++
 4 files changed, 80 insertions(+), 26 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1982,6 +1982,12 @@ config CMDLINE_FROM_BOOTLOADER
 	  the boot loader doesn't provide any, the default kernel command
 	  string provided in CMDLINE will be used.
 
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The command-line arguments provided by the boot loader will be
+	  appended to the default kernel command string.
+
 config CMDLINE_FORCE
 	bool "Always use the default kernel command string"
 	help
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -214,8 +214,11 @@ static __init void parse_cmdline(void)
 {
 	const u8 *prop = get_bootargs_cmdline();
 
-	if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !prop)
+	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
+	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
+	    !prop) {
 		__parse_cmdline(CONFIG_CMDLINE, true);
+	}
 
 	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop)
 		__parse_cmdline(prop, true);
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1124,16 +1124,40 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 	return 0;
 }
 
+/*
+ * Convert configs to something easy to use in C code
+ */
+#if defined(CONFIG_CMDLINE_FORCE)
+static const int overwrite_incoming_cmdline = 1;
+static const int read_dt_cmdline;
+static const int concat_cmdline;
+#elif defined(CONFIG_CMDLINE_EXTEND)
+static const int overwrite_incoming_cmdline;
+static const int read_dt_cmdline = 1;
+static const int concat_cmdline = 1;
+#else /* CMDLINE_FROM_BOOTLOADER */
+static const int overwrite_incoming_cmdline;
+static const int read_dt_cmdline = 1;
+static const int concat_cmdline;
+#endif
+
+#ifdef CONFIG_CMDLINE
+static const char *config_cmdline = CONFIG_CMDLINE;
+#else
+static const char *config_cmdline = "";
+#endif
+
 int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 				     int depth, void *data)
 {
-	int l;
-	const char *p;
+	int l = 0;
+	const char *p = NULL;
 	const void *rng_seed;
+	char *cmdline = data;
 
 	pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
 
-	if (depth != 1 || !data ||
+	if (depth != 1 || !cmdline ||
 	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
 		return 0;
 
@@ -1141,28 +1165,28 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 	early_init_dt_check_for_elfcorehdr(node);
 	early_init_dt_check_for_usable_mem_range(node);
 
-	/* Retrieve command line */
-	p = of_get_flat_dt_prop(node, "bootargs", &l);
-	if (p != NULL && l > 0)
-		strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
-
-	/*
-	 * CONFIG_CMDLINE is meant to be a default in case nothing else
-	 * managed to set the command line, unless CONFIG_CMDLINE_FORCE
-	 * is set in which case we override whatever was found earlier.
-	 */
-#ifdef CONFIG_CMDLINE
-#if defined(CONFIG_CMDLINE_EXTEND)
-	strlcat(data, " ", COMMAND_LINE_SIZE);
-	strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
-#elif defined(CONFIG_CMDLINE_FORCE)
-	strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
-#else
-	/* No arguments from boot loader, use kernel's  cmdl*/
-	if (!((char *)data)[0])
-		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
-#endif
-#endif /* CONFIG_CMDLINE */
+	/* Put CONFIG_CMDLINE in if forced or if data had nothing in it to start */
+	if (overwrite_incoming_cmdline || !cmdline[0])
+		strlcpy(cmdline, config_cmdline, COMMAND_LINE_SIZE);
+
+	/* Retrieve command line unless forcing */
+	if (read_dt_cmdline)
+		p = of_get_flat_dt_prop(node, "bootargs", &l);
+
+	if (p != NULL && l > 0) {
+		if (concat_cmdline) {
+			int cmdline_len;
+			int copy_len;
+			strlcat(cmdline, " ", COMMAND_LINE_SIZE);
+			cmdline_len = strlen(cmdline);
+			copy_len = COMMAND_LINE_SIZE - cmdline_len - 1;
+			copy_len = min((int)l, copy_len);
+			strncpy(cmdline + cmdline_len, p, copy_len);
+			cmdline[cmdline_len + copy_len] = '\0';
+		} else {
+			strlcpy(cmdline, p, min(l, COMMAND_LINE_SIZE));
+		}
+	}
 
 	pr_debug("Command line is: %s\n", (char *)data);
 
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -58,6 +58,27 @@ extern int of_flat_dt_is_compatible(unsigned long node, const char *name);
 extern unsigned long of_get_flat_dt_root(void);
 extern uint32_t of_get_flat_dt_phandle(unsigned long node);
 
+/*
+ * early_init_dt_scan_chosen - scan the device tree for ramdisk and bootargs
+ *
+ * The boot arguments will be placed into the memory pointed to by @data.
+ * That memory should be COMMAND_LINE_SIZE big and initialized to be a valid
+ * (possibly empty) string.  Logic for what will be in @data after this
+ * function finishes:
+ *
+ * - CONFIG_CMDLINE_FORCE=true
+ *     CONFIG_CMDLINE
+ * - CONFIG_CMDLINE_EXTEND=true, @data is non-empty string
+ *     @data + dt bootargs (even if dt bootargs are empty)
+ * - CONFIG_CMDLINE_EXTEND=true, @data is empty string
+ *     CONFIG_CMDLINE + dt bootargs (even if dt bootargs are empty)
+ * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=non-empty:
+ *     dt bootargs
+ * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is non-empty string
+ *     @data is left unchanged
+ * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is empty string
+ *     CONFIG_CMDLINE (or "" if that's not defined)
+ */
 extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
 				     int depth, void *data);
 extern int early_init_dt_scan_memory(unsigned long node, const char *uname,