of: fdt: Honor CONFIG_CMDLINE* even without /chosen node, take 2

I do not read a strict requirement on /chosen node in either ePAPR or in
Documentation/devicetree. Help text for CONFIG_CMDLINE and
CONFIG_CMDLINE_EXTEND doesn't make their behavior explicitly dependent on
the presence of /chosen or the presense of /chosen/bootargs.

However the early check for /chosen and bailing out in
early_init_dt_scan_chosen() skips CONFIG_CMDLINE handling which is not
really related to /chosen node or the particular method of passing cmdline
from bootloader.

This leads to counterintuitive combinations (assuming
CONFIG_CMDLINE_EXTEND=y):

a) bootargs="foo", CONFIG_CMDLINE="bar" => cmdline=="foo bar"
b) /chosen missing, CONFIG_CMDLINE="bar" => cmdline==""
c) bootargs="", CONFIG_CMDLINE="bar" => cmdline==" bar"

Rework early_init_dt_scan_chosen() so that the cmdline config options are
always handled.

[commit msg written by Alexander Sverdlin]

Cc: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Tested-by: Geoff Levand <geoff@infradead.org>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20230103-dt-cmdline-fix-v1-2-7038e88b18b6@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 4f88e8bbdd279529d96099bd6d0a682dfb253507..f08b25195ae79d2b51468dd89d6d3e3c20b93f2d 100644 (file)
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1163,18 +1163,32 @@ int __init early_init_dt_scan_chosen(char *cmdline)
        if (node < 0)
                node = fdt_path_offset(fdt, "/chosen@0");
        if (node < 0)
-               return -ENOENT;
+               /* Handle the cmdline config options even if no /chosen node */
+               goto handle_cmdline;
 
        chosen_node_offset = node;
 
        early_init_dt_check_for_initrd(node);
        early_init_dt_check_for_elfcorehdr(node);
 
+       rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
+       if (rng_seed && l > 0) {
+               add_bootloader_randomness(rng_seed, l);
+
+               /* try to clear seed so it won't be found. */
+               fdt_nop_property(initial_boot_params, node, "rng-seed");
+
+               /* update CRC check value */
+               of_fdt_crc32 = crc32_be(~0, initial_boot_params,
+                               fdt_totalsize(initial_boot_params));
+       }
+
        /* Retrieve command line */
        p = of_get_flat_dt_prop(node, "bootargs", &l);
        if (p != NULL && l > 0)
                strscpy(cmdline, p, min(l, COMMAND_LINE_SIZE));
 
+handle_cmdline:
        /*
         * CONFIG_CMDLINE is meant to be a default in case nothing else
         * managed to set the command line, unless CONFIG_CMDLINE_FORCE
@@ -1195,18 +1209,6 @@ int __init early_init_dt_scan_chosen(char *cmdline)
 
        pr_debug("Command line is: %s\n", (char *)cmdline);
 
-       rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
-       if (rng_seed && l > 0) {
-               add_bootloader_randomness(rng_seed, l);
-
-               /* try to clear seed so it won't be found. */
-               fdt_nop_property(initial_boot_params, node, "rng-seed");
-
-               /* update CRC check value */
-               of_fdt_crc32 = crc32_be(~0, initial_boot_params,
-                               fdt_totalsize(initial_boot_params));
-       }
-
        return 0;
 }