[PATCH 7/8] of: allow sending a NULL value to early_init_dt_scan_chosen

Daniel Walker
2021-04-16T04:09:51Z

It's possible that an architecture may want to populate
boot_command_line before calling the device tree code.
Currently, early_init_dt_scan_chosen won't accept a NULL
in the data parameter and it returns immediately if you
send one.

I changed early_init_dt_scan_nodes() to send a NULL into
early_init_dt_scan_chosen() , then I made
early_init_dt_scan_chosen() to do the initrd checking, and
the rng-seed checking and skip all the command line related
code.

Given lots of changes to the command line, I think it makes sense
to allow the initrd code and rng-seed code to be run without
forcing the command line handling. I'm also submitting changes
to arm64 which populate boot_command_line much early and this
device tree code overwrites boot_command_line in that case.

This code depends on all architecture to have a NULL
boot_command_line at boot up when this function runs, unless
it's already populated.

This code was boot tested on powerpc 32bit, x86, and arm64.

Cc: xe-linux-external@cisco.com
Signed-off-by: Daniel Walker <danielwa@cisco.com>
---
drivers/of/fdt.c | 44 +++++++++++++++++++++++++-------------------
1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index adb26aff481d..a1fda952ce60 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1052,36 +1052,38 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,

pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);

- if (depth != 1 || !data ||
- (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
+ if (depth != 1 || (strcmp(uname, "chosen") != 0
+ && strcmp(uname, "chosen@0") != 0))
return 0;

early_init_dt_check_for_initrd(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));
+ if (data) {
+ /* 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.
- */
+ /*
+ * 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);
+ 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);
+#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 */

- pr_debug("Command line is: %s\n", (char *)data);
+ pr_debug("Command line is: %s\n", (char *)data);
+ }

rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
if (rng_seed && l > 0) {
@@ -1202,7 +1204,11 @@ void __init early_init_dt_scan_nodes(void)
int rc = 0;

/* Retrieve various information from the /chosen node */
- rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+ if (boot_command_line[0])
+ rc = of_scan_flat_dt(early_init_dt_scan_chosen, NULL);
+ else
+ rc = of_scan_flat_dt(early_init_dt_scan_chosen,
+ boot_command_line);
if (!rc)
pr_warn("No chosen node found, continuing without\n");

--
2.25.1