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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. The goal of thie hack is to to add support for Linksys MX4300, a dual firmware AP. This device's default kernel command lines aren't compatiailbe with OpenWrt's UBI, so we leverage find and replace to dynamically patch the cmd from u-boot. Signed-off-by: Qiyuan Zhang <[email protected]>
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Qiyuan Zhang
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Aug 4, 2024
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target/linux/qualcommax/patches-6.6/0911-arm64-cmdline-replacement.patch
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| --- a/drivers/of/fdt.c | ||
| +++ b/drivers/of/fdt.c | ||
| @@ -1157,6 +1157,14 @@ 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"); | ||
| @@ -1185,6 +1193,69 @@ 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)); |