[PATCH 4/4] kexec/arm64: Add support for handling zlib compressed (Image.gz) image

Bhupesh Sharma bhsharma at redhat.com
Wed Jul 10 12:54:29 PDT 2019


Currently the kexec_file_load() support for arm64 doesn't allow
handling zlib compressed (i.e. Image.gz) image.

Since most distributions use 'make zinstall' rule inside
'arch/arm64/boot/Makefile' to install the arm64
Image.gz compressed file inside the boot destination directory (for e.g.
/boot), currently we cannot use kexec_file_load() to load vmlinuz (or
Image.gz):

 # file /boot/vmlinuz
   /boot/vmlinuz: gzip compressed data, was "Image", <..snip..>, max
   compression, from Unix, original size 21945120

 Now, since via kexec_file_load() we pass the 'fd' of Image.gz
 (compressed file) via the following command line ...

 # kexec -s -l /boot/vmlinuz-`uname -r` --initrd=/boot/initramfs-`uname
   -r`.img --reuse-cmdline

... kernel returns -EINVAL error value, as it is not able to locate
the magic number =0x644d5241, which is expected in the 64-byte header
of the decompressed kernel image.

We can fix this in user-space kexec-tools, which handles an
'Image.gz' being passed via kexec_file_load(), using an approach
as follows:

a). Copy the contents of Image.gz to a temporary file.
b). Decompress (gunzip-decompress) the contents inside the
    temporary file.
c). Pass the 'fd' of the temporary file to the kernel space. So
    basically the kernel space still gets a decompressed kernel
    image to load via kexec-tools

I tested this patch for the following three use-cases:

1. Uncompressed Image file:
 #kexec -s -l Image --initrd=/boot/initramfs-`uname -r`.img --reuse-cmdline

2. Signed Image file:
 #kexec -s -l Image.signed --initrd=/boot/initramfs-`uname -r`.img --reuse-cmdline

3. zlib compressed Image.gz file:
 #kexec -s -l /boot/vmlinuz-`uname -r` --initrd=/boot/initramfs-`uname -r`.img --reuse-cmdline

Signed-off-by: Bhupesh Sharma <bhsharma at redhat.com>
---
 kexec/arch/arm64/Makefile             |   3 +-
 kexec/arch/arm64/kexec-arm64.c        |   1 +
 kexec/arch/arm64/kexec-arm64.h        |   7 ++
 kexec/arch/arm64/kexec-image-arm64.c  |   4 +-
 kexec/arch/arm64/kexec-zImage-arm64.c | 199 ++++++++++++++++++++++++++++++++++
 kexec/kexec.c                         |  12 ++
 6 files changed, 223 insertions(+), 3 deletions(-)
 create mode 100644 kexec/arch/arm64/kexec-zImage-arm64.c

diff --git a/kexec/arch/arm64/Makefile b/kexec/arch/arm64/Makefile
index 9d9111caa8ed..d27c8ee1b5e7 100644
--- a/kexec/arch/arm64/Makefile
+++ b/kexec/arch/arm64/Makefile
@@ -15,7 +15,8 @@ arm64_KEXEC_SRCS += \
 	kexec/arch/arm64/kexec-arm64.c \
 	kexec/arch/arm64/kexec-elf-arm64.c \
 	kexec/arch/arm64/kexec-uImage-arm64.c \
-	kexec/arch/arm64/kexec-image-arm64.c
+	kexec/arch/arm64/kexec-image-arm64.c \
+	kexec/arch/arm64/kexec-zImage-arm64.c
 
 arm64_UIMAGE = kexec/kexec-uImage.c
 
diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 2992bce8139f..eb3a3a37307c 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -71,6 +71,7 @@ struct file_type file_type[] = {
 	{"vmlinux", elf_arm64_probe, elf_arm64_load, elf_arm64_usage},
 	{"Image", image_arm64_probe, image_arm64_load, image_arm64_usage},
 	{"uImage", uImage_arm64_probe, uImage_arm64_load, uImage_arm64_usage},
+	{"zImage", zImage_arm64_probe, zImage_arm64_load, zImage_arm64_usage},
 };
 
 int file_types = sizeof(file_type) / sizeof(file_type[0]);
diff --git a/kexec/arch/arm64/kexec-arm64.h b/kexec/arch/arm64/kexec-arm64.h
index cc3419f4c10f..628de79b7f70 100644
--- a/kexec/arch/arm64/kexec-arm64.h
+++ b/kexec/arch/arm64/kexec-arm64.h
@@ -38,11 +38,18 @@ int image_arm64_probe(const char *kernel_buf, off_t kernel_size);
 int image_arm64_load(int argc, char **argv, const char *kernel_buf,
 	off_t kernel_size, struct kexec_info *info);
 void image_arm64_usage(void);
+
 int uImage_arm64_probe(const char *buf, off_t len);
 int uImage_arm64_load(int argc, char **argv, const char *buf, off_t len,
 		      struct kexec_info *info);
 void uImage_arm64_usage(void);
 
+int zImage_arm64_probe(const char *kernel_buf, off_t kernel_size);
+int zImage_arm64_load(int argc, char **argv, const char *kernel_buf,
+	off_t kernel_size, struct kexec_info *info);
+void zImage_arm64_usage(void);
+
+
 off_t initrd_base;
 off_t initrd_size;
 
diff --git a/kexec/arch/arm64/kexec-image-arm64.c b/kexec/arch/arm64/kexec-image-arm64.c
index 685a99352e39..aa8f2e22d72b 100644
--- a/kexec/arch/arm64/kexec-image-arm64.c
+++ b/kexec/arch/arm64/kexec-image-arm64.c
@@ -114,6 +114,6 @@ exit:
 void image_arm64_usage(void)
 {
 	printf(
-"     An ARM64 binary image, compressed or not, big or little endian.\n"
-"     Typically an Image, Image.gz or Image.lzma file.\n\n");
+"     An ARM64 binary image, uncompressed, big or little endian.\n"
+"     Typically an Image file.\n\n");
 }
diff --git a/kexec/arch/arm64/kexec-zImage-arm64.c b/kexec/arch/arm64/kexec-zImage-arm64.c
new file mode 100644
index 000000000000..2b83ef6bdffd
--- /dev/null
+++ b/kexec/arch/arm64/kexec-zImage-arm64.c
@@ -0,0 +1,199 @@
+/*
+ * ARM64 kexec zImage (Image.gz) support.
+ *
+ * Several distros use 'make zinstall' rule inside
+ * 'arch/arm64/boot/Makefile' to install the arm64
+ * Image.gz compressed file inside the boot destination
+ * directory (for e.g. /boot).
+ *
+ * Currently we cannot use kexec_file_load() to load vmlinuz
+ * (or Image.gz).
+ *
+ * To support Image.gz, we should:
+ * a). Copy the contents of Image.gz to a temporary file.
+ * b). Decompress (gunzip-decompress) the contents inside the
+ *     temporary file.
+ * c). Pass the 'fd' of the temporary file to the kernel space.
+ *
+ * So basically the kernel space still gets a decompressed
+ * kernel image to load via kexec-tools.
+ */
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include "crashdump-arm64.h"
+#include "image-header.h"
+#include "kexec.h"
+#include "kexec-arm64.h"
+#include "kexec-syscall.h"
+#include "kexec-zlib.h"
+#include "arch/options.h"
+
+#define FILENAME_IMAGE		"/tmp/ImageXXXXXX"
+
+/* Returns:
+ * -1 : in case of error/invalid format (not a valid Image.gz format.
+ *  fd: File descriptor of the temp file containing the decompressed
+ *      Image.
+ */
+int zImage_arm64_probe(const char *kernel_buf, off_t kernel_size)
+{
+	int kernel_fd = 0;
+	char *fname = NULL;
+	char *kernel_uncompressed_buf = NULL;
+	const struct arm64_image_header *h;
+
+	if (!is_zlib_file(kernel_buf, &kernel_size)) {
+		dbgprintf("%s: Not an zImage file (Image.gz).\n", __func__);
+		return -1;
+	}
+
+	if (!(fname = strdup(FILENAME_IMAGE))) {
+		dbgprintf("%s: Can't duplicate strings %s\n", __func__,
+				fname);
+		return -1;
+	}
+
+	if ((kernel_fd = mkstemp(fname)) < 0) {
+		dbgprintf("%s: Can't open file %s\n", __func__,
+				fname);
+		return -1;
+	}
+
+	kernel_uncompressed_buf =
+		(char *) calloc(kernel_size, sizeof(off_t));
+	if (!kernel_uncompressed_buf) {
+		dbgprintf("%s: Can't calloc %ld bytes\n",
+				__func__, kernel_size);
+		return -ENOMEM;
+	}
+
+	/* slurp in the input kernel */
+	dbgprintf("%s: ", __func__);
+	kernel_uncompressed_buf = slurp_decompress_file(kernel_buf,
+							&kernel_size);
+
+	/* check for correct header magic */
+	if (kernel_size < sizeof(struct arm64_image_header)) {
+		dbgprintf("%s: No arm64 image header.\n", __func__);
+		return -1;
+	}
+
+	h = (const struct arm64_image_header *)(kernel_uncompressed_buf);
+
+	if (!arm64_header_check_magic(h)) {
+		dbgprintf("%s: Bad arm64 image header.\n", __func__);
+		return -1;
+	}
+
+	if (write(kernel_fd, kernel_uncompressed_buf,
+				kernel_size) != kernel_size) {
+		dbgprintf("%s: Can't write the uncompressed file %s\n",
+				__func__, fname);
+		return -1;
+	}
+
+	close(kernel_fd);
+
+	/* Open the tmp file again, this time in O_RDONLY mode, as
+	 * opening the file in O_RDWR and calling kexec_file_load()
+	 * causes the kernel to return -ETXTBSY
+	 */
+	kernel_fd = open(fname, O_RDONLY);
+	if (kernel_fd == -1) {
+		dbgprintf("%s: Failed to open file %s\n",
+				__func__, fname);
+		return -1;
+	}
+
+	return kernel_fd;
+}
+
+int zImage_arm64_load(int argc, char **argv, const char *kernel_buf,
+	off_t kernel_size, struct kexec_info *info)
+{
+	const struct arm64_image_header *header;
+	unsigned long kernel_segment;
+	int result;
+
+	if (info->file_mode) {
+		if (arm64_opts.initrd) {
+			info->initrd_fd = open(arm64_opts.initrd, O_RDONLY);
+			if (info->initrd_fd == -1) {
+				fprintf(stderr,
+					"Could not open initrd file %s:%s\n",
+					arm64_opts.initrd, strerror(errno));
+				result = EFAILED;
+				goto exit;
+			}
+		}
+
+		if (arm64_opts.command_line) {
+			info->command_line = (char *)arm64_opts.command_line;
+			info->command_line_len =
+					strlen(arm64_opts.command_line) + 1;
+		}
+
+		return 0;
+	}
+
+	header = (const struct arm64_image_header *)(kernel_buf);
+
+	if (arm64_process_image_header(header))
+		return EFAILED;
+
+	kernel_segment = arm64_locate_kernel_segment(info);
+
+	if (kernel_segment == ULONG_MAX) {
+		dbgprintf("%s: Kernel segment is not allocated\n", __func__);
+		result = EFAILED;
+		goto exit;
+	}
+
+	dbgprintf("%s: kernel_segment: %016lx\n", __func__, kernel_segment);
+	dbgprintf("%s: text_offset:    %016lx\n", __func__,
+		arm64_mem.text_offset);
+	dbgprintf("%s: image_size:     %016lx\n", __func__,
+		arm64_mem.image_size);
+	dbgprintf("%s: phys_offset:    %016lx\n", __func__,
+		arm64_mem.phys_offset);
+	dbgprintf("%s: vp_offset:      %016lx\n", __func__,
+		arm64_mem.vp_offset);
+	dbgprintf("%s: PE format:      %s\n", __func__,
+		(arm64_header_check_pe_sig(header) ? "yes" : "no"));
+
+	/* create and initialize elf core header segment */
+	if (info->kexec_flags & KEXEC_ON_CRASH) {
+		result = load_crashdump_segments(info);
+		if (result) {
+			dbgprintf("%s: Creating eflcorehdr failed.\n",
+								__func__);
+			goto exit;
+		}
+	}
+
+	/* load the kernel */
+	add_segment_phys_virt(info, kernel_buf, kernel_size,
+			kernel_segment + arm64_mem.text_offset,
+			arm64_mem.image_size, 0);
+
+	/* load additional data */
+	result = arm64_load_other_segments(info, kernel_segment
+		+ arm64_mem.text_offset);
+
+exit:
+	if (result)
+		fprintf(stderr, "kexec: load failed.\n");
+	return result;
+}
+
+void zImage_arm64_usage(void)
+{
+	printf(
+"     An ARM64 zImage, compressed, big or little endian.\n"
+"     Typically an Image.gz or Image.lzma file.\n\n");
+}
diff --git a/kexec/kexec.c b/kexec/kexec.c
index 8ca3b457cac8..bc6ab3dbd10b 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -1206,8 +1206,20 @@ static int do_kexec_file_load(int fileind, int argc, char **argv,
 	kernel_buf = slurp_decompress_file(kernel, &kernel_size);
 
 	for (i = 0; i < file_types; i++) {
+#ifdef __aarch64__
+		/* handle Image.gz like cases */
+		if (is_zlib_file(kernel, &kernel_size)) {
+			if ((ret = file_type[i].probe(kernel, kernel_size)) >= 0) {
+				kernel_fd = ret;
+				break;
+			}
+		} else
+			if (file_type[i].probe(kernel_buf, kernel_size) >= 0)
+				break;
+#else
 		if (file_type[i].probe(kernel_buf, kernel_size) >= 0)
 			break;
+#endif
 	}
 
 	if (i == file_types) {
-- 
2.7.4




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