[PATCH 3/6] LoongArch/kexec_file: Add initrd loading

[Youling Tang <youling.tang@linux.dev>]

From: Youling Tang <tangyouling@kylinos.cn>

Add inird loading support and pass it to the second kernel via the
cmdline 'initrd=start,size'.

Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
---
 arch/loongarch/kernel/machine_kexec_file.c | 71 ++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index bc91ae0afa4c..e1240644f529 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -34,13 +34,84 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
 	return kexec_image_post_load_cleanup_default(image);
 }
 
+/* Adds the "initrd=start,size" command line parameter to command line. */
+static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmplen,
+				char *modified_cmdline, unsigned long initrd)
+{
+	int initrd_strlen;
+
+	initrd_strlen = sprintf(modified_cmdline + (*cmdline_tmplen), "initrd=0x%lx,0x%lx ",
+		initrd, image->initrd_buf_len);
+	*cmdline_tmplen += initrd_strlen;
+}
+
+/*
+ * Tries to add the initrd to the image. If it is not possible to find
+ * valid locations, this function will undo changes to the image and return non
+ * zero.
+ */
 int load_other_segments(struct kimage *image,
 			unsigned long kernel_load_addr,
 			unsigned long kernel_size,
 			char *initrd, unsigned long initrd_len,
 			char *cmdline, unsigned long cmdline_len)
 {
+	struct kexec_buf kbuf;
+	unsigned long orig_segments = image->nr_segments;
+	char *modified_cmdline = NULL;
+	unsigned long cmdline_tmplen = 0;
+	unsigned long initrd_load_addr = 0;
+	int ret = 0;
+
+
+	kbuf.image = image;
+	/* not allocate anything below the kernel */
+	kbuf.buf_min = kernel_load_addr + kernel_size;
+
+	modified_cmdline = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
+	if (!modified_cmdline)
+		return -EINVAL;
+
+	/* Ensure it's nul terminated */
+	modified_cmdline[COMMAND_LINE_SIZE - 1] = '\0';
+
+	/* load initrd */
+	if (initrd) {
+		kbuf.buffer = initrd;
+		kbuf.bufsz = initrd_len;
+		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+		kbuf.memsz = initrd_len;
+		kbuf.buf_align = 0;
+		/* within 1GB-aligned window of up to 32GB in size */
+		kbuf.buf_max = round_down(kernel_load_addr, SZ_1G)
+						+ (unsigned long)SZ_1G * 32;
+		kbuf.top_down = false;
+
+		ret = kexec_add_buffer(&kbuf);
+		if (ret)
+			goto out_err;
+		initrd_load_addr = kbuf.mem;
+
+		kexec_dprintk("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+			      initrd_load_addr, kbuf.bufsz, kbuf.memsz);
+
+		/* Add the initrd=start,size parameter to the command line */
+		cmdline_add_initrd(image, &cmdline_tmplen, modified_cmdline, initrd_load_addr);
+	}
+
+	if (cmdline_len + cmdline_tmplen > COMMAND_LINE_SIZE) {
+		pr_err("Appending kdump cmdline exceeds cmdline size\n");
+		ret = -EINVAL;
+		goto out_err;
+	}
+	memcpy(modified_cmdline + cmdline_tmplen, cmdline, cmdline_len);
+	cmdline = modified_cmdline;
 	image->arch.cmdline_ptr = (unsigned long)cmdline;
 
 	return 0;
+
+out_err:
+	image->nr_segments = orig_segments;
+	kfree(modified_cmdline);
+	return ret;
 }
-- 
2.34.1