qualcommax: add kernel cmdline replacement hack

Add kernel command line replacement hack to qualcommax. Now we can
find and replace arguments in the kernel command line by setting
bootargs-find-1, bootargs-replace-1, bootargs-exact-match-1
and bootargs-find-2, bootargs-replace-2, bootargs-exact-match-2
under the chosen node in the device tree.

This hack replaces the first occurence of bootargs-find-X with
bootargs-replace-X. When bootargs-exact-match-X is set to "y",
then the replacement happens only if the kernel command line is
identical to bootargs-find-X.

Signed-off-by: Qiyuan Zhang <zhang.github@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/16070
Signed-off-by: Robert Marko <robimarko@gmail.com>

diff --git a/target/linux/qualcommax/patches-6.6/0911-arm64-cmdline-replacement.patch b/target/linux/qualcommax/patches-6.6/0911-arm64-cmdline-replacement.patch
new file mode 100644 (file)
index 0000000..afc71bf
--- /dev/null
+++ b/target/linux/qualcommax/patches-6.6/0911-arm64-cmdline-replacement.patch
@@ -0,0 +1,105 @@
+Subject: qualcommax: add kernel cmdline replacement hack 
+
+Add kernel command line replacement hack to qualcommax. Now we can
+find and replace arguments in the kernel command line by setting
+bootargs-find-1, bootargs-replace-1, bootargs-exact-match-1
+and bootargs-find-2, bootargs-replace-2, bootargs-exact-match-2
+under the chosen node in the device tree.
+
+This hack replaces the first occurence of bootargs-find-X with
+bootargs-replace-X. If bootargs-exact-match-X is set to "y",
+then the replacement happens only if the kernel command line is
+identical to bootargs-find-X.
+
+Signed-off-by: Qiyuan Zhang <zhang.github@outlook.com>
+---
+ drivers/of/fdt.c |   71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 71 insertions(+)
+
+--- a/drivers/of/fdt.c
++++ b/drivers/of/fdt.c
+@@ -1158,6 +1158,14 @@ int __init early_init_dt_scan_chosen(cha
+       const void *rng_seed;
+       const void *fdt = initial_boot_params;
+ 
++      int i, cmd_len, f_len, r_len, offset, step;
++      char *s_ptr, *l_end, *r_end, *cur_ptr, *end_ptr;
++      const char *exact_match;
++      const int bootargs_replace_num = 2;
++      const char *bootargs_replace_props[2][3] =
++              { {"bootargs-find-1", "bootargs-replace-1", "bootargs-exact-match-1"},
++              {"bootargs-find-2", "bootargs-replace-2", "bootargs-exact-match-2"} };
++
+       node = fdt_path_offset(fdt, "/chosen");
+       if (node < 0)
+               node = fdt_path_offset(fdt, "/chosen@0");
+@@ -1186,6 +1194,69 @@ int __init early_init_dt_scan_chosen(cha
+       p = of_get_flat_dt_prop(node, "bootargs", &l);
+       if (p != NULL && l > 0)
+               strscpy(cmdline, p, min(l, COMMAND_LINE_SIZE));
++
++      for(i = 0; i < bootargs_replace_num; i++) {
++              p = of_get_flat_dt_prop(node, bootargs_replace_props[i][0], &f_len);
++
++              if (p == NULL || f_len == 0 )
++                      continue;
++
++              exact_match = of_get_flat_dt_prop(node, bootargs_replace_props[i][2], &l);
++
++              if (exact_match != NULL && l > 0 && exact_match[0] == 'y') {
++                      if(strncmp(cmdline, p, r_len) == 0)
++                              s_ptr = cmdline;
++                      else
++                              s_ptr = NULL;
++              } else {
++                      s_ptr = strstr(cmdline, p);
++              }
++
++              if(!s_ptr)
++                      continue;
++
++              p = of_get_flat_dt_prop(node, bootargs_replace_props[i][1], &r_len);
++
++              if (p == NULL || r_len == 0)
++                      continue;
++
++              pr_info("Input kernel commad line: %s\n", cmdline);
++
++              cmd_len = strlen(cmdline);
++
++              if (cmd_len - f_len + r_len < COMMAND_LINE_SIZE) {
++
++                      pr_info("Replace kernel command line with %s\n", bootargs_replace_props[i][1]);
++
++                      offset = r_len - f_len;
++
++                      if (offset != 0) {
++                              l_end = s_ptr + f_len - 1;
++                              r_end = cmdline + cmd_len;
++
++                              if (offset > 0) {
++                                      step = -1;
++                                      cur_ptr = r_end;
++                                      end_ptr = l_end + step;
++                              } else {
++                                      step = 1;
++                                      cur_ptr = l_end;
++                                      end_ptr = r_end + step;
++                              }
++
++                              for (; cur_ptr != end_ptr; cur_ptr += step)
++                                      *(cur_ptr + offset) = *cur_ptr;
++                      }
++
++                      strncpy(s_ptr, p, r_len - 1);
++
++                      pr_info("Kernel command line after replacement: %s\n", cmdline);
++              } else {
++                      pr_err("Replace kernel command line with %s failed\n", bootargs_replace_props[i][1]);
++              }
++
++      }
++
+       p = of_get_flat_dt_prop(node, "bootargs-append", &l);
+       if (p != NULL && l > 0)
+               strlcat(cmdline, p, min_t(int, strlen(cmdline) + (int)l, COMMAND_LINE_SIZE));