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From 13bb6d8dd9138927950a520a288401db82871dc9 Mon Sep 17 00:00:00 2001
From: Christian Marangi <ansuelsmth@gmail.com>
Date: Sun, 21 Jan 2024 23:36:57 +0100
Subject: [PATCH] ARM: decompressor: support for ATAGs rootblock parsing
The command-line arguments provided by the boot loader will be
appended to a new device tree property: bootloader-args.
If there is a property "append-rootblock" in DT under /chosen
and a root= option in bootloaders command line it will be parsed
and added to DT bootargs with the form: <append-rootblock>XX.
This is usefull in dual boot systems, to get the current root partition
without afecting the rest of the system.
Signed-off-by: Adrian Panella <ianchi74@outlook.com>
[ reworked to a cleaner patch ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
arch/arm/Kconfig | 10 +++
arch/arm/boot/compressed/atags_to_fdt.c | 102 ++++++++++++++++++++++--
init/main.c | 12 +++
3 files changed, 117 insertions(+), 7 deletions(-)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1578,6 +1578,16 @@ config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEN
The command-line arguments provided by the boot loader will be
appended to the the device tree bootargs property.
+config ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE
+ bool "Append rootblock parsing bootloader's kernel arguments"
+ help
+ The command-line arguments provided by the boot loader will be
+ appended to a new device tree property: bootloader-args.
+
+ If there is a property "append-rootblock" in DT under /chosen
+ and a root= option in bootloaders command line it will be parsed
+ and added to DT bootargs with the form: <append-rootblock>XX.
+
endchoice
config CMDLINE_OVERRIDE
--- a/arch/arm/boot/compressed/atags_to_fdt.c
+++ b/arch/arm/boot/compressed/atags_to_fdt.c
@@ -4,7 +4,8 @@
#include <libfdt.h>
#include "misc.h"
-#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND)
+#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND) || \
+ defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
#define do_extend_cmdline 1
#else
#define do_extend_cmdline 0
@@ -70,6 +71,83 @@ static uint32_t get_cell_size(const void
return cell_size;
}
+/**
+ * taken from arch/x86/boot/string.c
+ * local_strstr - Find the first substring in a %NUL terminated string
+ * @s1: The string to be searched
+ * @s2: The string to search for
+ */
+static char *local_strstr(const char *s1, const char *s2)
+{
+ size_t l1, l2;
+
+ l2 = strlen(s2);
+ if (!l2)
+ return (char *)s1;
+ l1 = strlen(s1);
+ while (l1 >= l2) {
+ l1--;
+ if (!memcmp(s1, s2, l2))
+ return (char *)s1;
+ s1++;
+ }
+ return NULL;
+}
+
+static char *append_rootblock(char *dest, const char *str, int len, void *fdt)
+{
+ char *ptr, *end, *tmp;
+ const char *root="root=";
+ const char *find_rootblock;
+ int i, l;
+ const char *rootblock;
+
+ find_rootblock = getprop(fdt, "/chosen", "find-rootblock", &l);
+ if (!find_rootblock)
+ find_rootblock = root;
+
+ /* ARM doesn't have __HAVE_ARCH_STRSTR, so it was copied from x86 */
+ ptr = local_strstr(str, find_rootblock);
+ if (!ptr)
+ return dest;
+
+ end = strchr(ptr, ' ');
+ end = end ? (end - 1) : (strchr(ptr, 0) - 1);
+
+ /* Some boards ubi.mtd=XX,ZZZZ, so let's check for '," too. */
+ tmp = strchr(ptr, ',');
+ if (tmp)
+ end = end < tmp ? end : tmp - 1;
+
+ /*
+ * find partition number
+ * (assumes format root=/dev/mtdXX | /dev/mtdblockXX | yy:XX | ubi.mtd=XX,ZZZZ )
+ */
+ for (i = 0; end >= ptr && *end >= '0' && *end <= '9'; end--, i++);
+
+ ptr = end + 1;
+
+ /* if append-rootblock property is set use it to append to command line */
+ rootblock = getprop(fdt, "/chosen", "append-rootblock", &l);
+ if (rootblock != NULL) {
+ if (*dest != ' ') {
+ *dest = ' ';
+ dest++;
+ len++;
+ }
+
+ if (len + l + i <= COMMAND_LINE_SIZE) {
+ memcpy(dest, rootblock, l);
+ dest += l - 1;
+
+ memcpy(dest, ptr, i);
+ dest += i;
+ }
+ }
+
+ return dest;
+}
+
static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
{
char cmdline[COMMAND_LINE_SIZE];
@@ -87,13 +165,23 @@ static void merge_fdt_bootargs(void *fdt
ptr += len - 1;
}
- /* and append the ATAG_CMDLINE */
if (fdt_cmdline) {
- len = strlen(fdt_cmdline);
- if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
- *ptr++ = ' ';
- memcpy(ptr, fdt_cmdline, len);
- ptr += len;
+ if (IS_ENABLED(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)) {
+ /*
+ * save original bootloader args
+ * and append ubi.mtd with root partition number
+ * to current cmdline
+ */
+ setprop_string(fdt, "/chosen", "bootloader-args", fdt_cmdline);
+ ptr = append_rootblock(ptr, fdt_cmdline, len, fdt);
+ } else {
+ /* and append the ATAG_CMDLINE */
+ len = strlen(fdt_cmdline);
+ if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
+ *ptr++ = ' ';
+ memcpy(ptr, fdt_cmdline, len);
+ ptr += len;
+ }
}
}
*ptr = '\0';
--- a/init/main.c
+++ b/init/main.c
@@ -28,6 +28,7 @@
#include <linux/initrd.h>
#include <linux/memblock.h>
#include <linux/acpi.h>
+#include <linux/of.h>
#include <linux/bootconfig.h>
#include <linux/console.h>
#include <linux/nmi.h>
@@ -932,6 +933,17 @@ void start_kernel(void)
pr_notice("Kernel command line: %s\n", saved_command_line);
/* parameters may set static keys */
jump_label_init();
+
+ /* Show bootloader's original command line for reference */
+ if (IS_ENABLED(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE) && of_chosen) {
+ const char *prop = of_get_property(of_chosen, "bootloader-args", NULL);
+
+ if(prop)
+ pr_notice("Bootloader command line (ignored): %s\n", prop);
+ else
+ pr_notice("Bootloader command line not present\n");
+ }
+
parse_early_param();
after_dashes = parse_args("Booting kernel",
static_command_line, __start___param,
|
