[PATCH v9 05/11] arm64: kexec_file: load initrd and device-tree

Hi Akashi,

On 18/05/18 08:42, AKASHI Takahiro wrote:

On Fri, May 18, 2018 at 04:11:35PM +0900, AKASHI Takahiro wrote:

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On Tue, May 15, 2018 at 05:20:00PM +0100, James Morse wrote:

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On 25/04/18 07:26, AKASHI Takahiro wrote:

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diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index f9ebf54ca247..b3b9b1725d8a 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c

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@@ -55,3 +74,144 @@ int arch_kexec_walk_mem(struct kexec_buf *kbuf,

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+	buf = vmalloc(buf_size);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto out_err;
+	}
+
+	ret = fdt_open_into(initial_boot_params, buf, buf_size);
+	if (ret)
+		goto out_err;
+
+	nodeoffset = fdt_path_offset(buf, "/chosen");
+	if (nodeoffset < 0)
+		goto out_err;
+
+	/* add bootargs */
+	if (cmdline) {
+		ret = fdt_setprop(buf, nodeoffset, "bootargs",
+						cmdline, cmdline_len + 1);

fdt_setprop_string()?

OK

cmdline_len is passed by system call, kexec_file_load(), and this means
that we can't believe that cmdline is always terminated with '\0'.

Yuck, we expect user-space to tell us how long the string is. It may be worth a
comment that it isn't necessarily null-terminated, as that is surprising!

(I assume the DT's property length is enough to make that safe for the new
kernel to read).

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+		/* within 1GB-aligned window of up to 32GB in size */
+		kbuf.buf_max = round_down(kern_seg->mem, 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;
+
+		pr_debug("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+				initrd_load_addr, initrd_len, initrd_len);
+	}
+
+	/* load dtb blob */
+	ret = setup_dtb(image, initrd_load_addr, initrd_len,
+				cmdline, cmdline_len, &dtb, &dtb_len);
+	if (ret) {
+		pr_err("Preparing for new dtb failed\n");
+		goto out_err;
+	}
+
+	kbuf.buffer = dtb;
+	kbuf.bufsz = dtb_len;
+	kbuf.memsz = dtb_len;
+	/* not across 2MB boundary */
+	kbuf.buf_align = SZ_2M;
+	kbuf.buf_max = ULONG_MAX;
+	kbuf.top_down = true;
+
+	ret = kexec_add_buffer(&kbuf);
+	if (ret)
+		goto out_err;
+	image->arch.dtb_mem = kbuf.mem;
+	image->arch.dtb_buf = dtb;
+
+	pr_debug("Loaded dtb at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+			kbuf.mem, dtb_len, dtb_len);
+
+	return 0;
+
+out_err:
+	vfree(dtb);
+	image->arch.dtb_buf = NULL;

Won't kimage_file_post_load_cleanup() always be called if we return an error
here? Why not leave the free()ing until then?

Right.
The reason why I left the code here was that we'd better locally clean up
all the stuff that were locally allocated if we trivially need to (and can)
do so.

As it's redundant, I will remove it.

will remove only "image->arch.dtb_buf = NULL."

Ah, because you haven't set the arch.dtb_buf pointer yet.

What about in patch 7 where you expect kimage_file_prepare_segments() to call
arch_kimage_file_post_load_cleanup() to free the arch.elf_headers? I'd expect
the free()ing to always happen in one place.


Thanks,

James