[PATCH v3 0/2] support gzipped kernels on arm

[PATCH v3 0/2] support gzipped kernels on arm

[Stefano Stabellini]

Hi all,

this patch series introduces support for gzipped kernels, such as the
standard Image.gz format used by Linux on arm64 by default, in Xen on
arm. Without it, Xen cannot load the default kernel shipped by distros,
such as CentOS 7.


Stefano Stabellini (2):
      xen: move perform_gunzip to common
      xen/arm: support gzip compressed kernels

 xen/arch/arm/kernel.c       |   66 +++++++++++++++++++++
 xen/arch/arm/setup.c        |    2 +-
 xen/arch/x86/bzimage.c      |  134 +-----------------------------------------
 xen/common/Makefile         |    1 +
 xen/common/gunzip.c         |  137 +++++++++++++++++++++++++++++++++++++++++++
 xen/include/asm-arm/setup.h |    2 +
 xen/include/xen/gunzip.h    |    7 +++
 7 files changed, 215 insertions(+), 134 deletions(-)
 create mode 100644 xen/common/gunzip.c
 create mode 100644 xen/include/xen/gunzip.h


Cheers,

Stefano

[PATCH v3 1/2] xen: move perform_gunzip to common

[Stefano Stabellini]

The current gunzip code to decompress the Dom0 kernel is implemented in
inflate.c which is included by bzimage.c.

I am looking to doing the same on ARM64 but there is quite a bit of
boilerplate definitions that I would need to import in order for
inflate.c to work correctly.

Instead of copying/pasting the code from x86/bzimage.c, move those
definitions to a new common file, gunzip.c. Export only perform_gunzip
and gzip_check. Leave output_length where it is.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: JBeulich@suse.com
CC: andrew.cooper3@citrix.com

---
Changes in v3:
- build gunzip.c as gunzip.init.o
- remove #include <xen/config.h>
- remove __init from declarations

Changes in v2:
- the patch has been reworked from scratch
---
 xen/arch/x86/bzimage.c   |  134 +--------------------------------------------
 xen/common/Makefile      |    1 +
 xen/common/gunzip.c      |  137 ++++++++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/gunzip.h |    7 +++
 4 files changed, 146 insertions(+), 133 deletions(-)
 create mode 100644 xen/common/gunzip.c
 create mode 100644 xen/include/xen/gunzip.h

diff --git a/xen/arch/x86/bzimage.c b/xen/arch/x86/bzimage.c
index c86c39e..50ebb84 100644
--- a/xen/arch/x86/bzimage.c
+++ b/xen/arch/x86/bzimage.c
@@ -4,148 +4,16 @@
 #include <xen/mm.h>
 #include <xen/string.h>
 #include <xen/types.h>
+#include <xen/gunzip.h>
 #include <xen/decompress.h>
 #include <xen/libelf.h>
 #include <asm/bzimage.h>
 
-#define HEAPORDER 3
-
-static unsigned char *__initdata window;
-#define memptr long
-static memptr __initdata free_mem_ptr;
-static memptr __initdata free_mem_end_ptr;
-
-#define WSIZE           0x80000000
-
-static unsigned char *__initdata inbuf;
-static unsigned __initdata insize;
-
-/* Index of next byte to be processed in inbuf: */
-static unsigned __initdata inptr;
-
-/* Bytes in output buffer: */
-static unsigned __initdata outcnt;
-
-#define OF(args)        args
-#define STATIC          static
-
-#define memzero(s, n)   memset((s), 0, (n))
-
-typedef unsigned char   uch;
-typedef unsigned short  ush;
-typedef unsigned long   ulg;
-
-#define INIT            __init
-#define INITDATA        __initdata
-
-#define get_byte()      (inptr < insize ? inbuf[inptr++] : fill_inbuf())
-
-/* Diagnostic functions */
-#ifdef DEBUG
-#  define Assert(cond, msg) do { if (!(cond)) error(msg); } while (0)
-#  define Trace(x)      do { fprintf x; } while (0)
-#  define Tracev(x)     do { if (verbose) fprintf x ; } while (0)
-#  define Tracevv(x)    do { if (verbose > 1) fprintf x ; } while (0)
-#  define Tracec(c, x)  do { if (verbose && (c)) fprintf x ; } while (0)
-#  define Tracecv(c, x) do { if (verbose > 1 && (c)) fprintf x ; } while (0)
-#else
-#  define Assert(cond, msg)
-#  define Trace(x)
-#  define Tracev(x)
-#  define Tracevv(x)
-#  define Tracec(c, x)
-#  define Tracecv(c, x)
-#endif
-
-static long __initdata bytes_out;
-static void flush_window(void);
-
-static __init void error(char *x)
-{
-    panic("%s", x);
-}
-
-static __init int fill_inbuf(void)
-{
-        error("ran out of input data");
-        return 0;
-}
-
-
-#include "../../common/inflate.c"
-
-static __init void flush_window(void)
-{
-    /*
-     * The window is equal to the output buffer therefore only need to
-     * compute the crc.
-     */
-    unsigned long c = crc;
-    unsigned n;
-    unsigned char *in, ch;
-
-    in = window;
-    for ( n = 0; n < outcnt; n++ )
-    {
-        ch = *in++;
-        c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
-    }
-    crc = c;
-
-    bytes_out += (unsigned long)outcnt;
-    outcnt = 0;
-}
-
 static __init unsigned long output_length(char *image, unsigned long image_len)
 {
     return *(uint32_t *)&image[image_len - 4];
 }
 
-static __init int gzip_check(char *image, unsigned long image_len)
-{
-    unsigned char magic0, magic1;
-
-    if ( image_len < 2 )
-        return 0;
-
-    magic0 = (unsigned char)image[0];
-    magic1 = (unsigned char)image[1];
-
-    return (magic0 == 0x1f) && ((magic1 == 0x8b) || (magic1 == 0x9e));
-}
-
-static __init int perform_gunzip(char *output, char *image, unsigned long image_len)
-{
-    int rc;
-
-    if ( !gzip_check(image, image_len) )
-        return 1;
-
-    window = (unsigned char *)output;
-
-    free_mem_ptr = (unsigned long)alloc_xenheap_pages(HEAPORDER, 0);
-    free_mem_end_ptr = free_mem_ptr + (PAGE_SIZE << HEAPORDER);
-
-    inbuf = (unsigned char *)image;
-    insize = image_len;
-    inptr = 0;
-
-    makecrc();
-
-    if ( gunzip() < 0 )
-    {
-        rc = -EINVAL;
-    }
-    else
-    {
-        rc = 0;
-    }
-
-    free_xenheap_pages((void *)free_mem_ptr, HEAPORDER);
-
-    return rc;
-}
-
 struct __packed setup_header {
         uint8_t         _pad0[0x1f1];           /* skip uninteresting stuff */
         uint8_t         setup_sects;
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 3fdf931..e5713fa 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -55,6 +55,7 @@ obj-y += vmap.o
 obj-y += vsprintf.o
 obj-y += wait.o
 obj-y += xmalloc_tlsf.o
+obj-bin-y += gunzip.init.o
 
 obj-bin-$(CONFIG_X86) += $(foreach n,decompress bunzip2 unxz unlzma unlzo unlz4 earlycpio,$(n).init.o)
 
diff --git a/xen/common/gunzip.c b/xen/common/gunzip.c
new file mode 100644
index 0000000..41d71ef
--- /dev/null
+++ b/xen/common/gunzip.c
@@ -0,0 +1,137 @@
+#include <xen/errno.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/mm.h>
+
+#define HEAPORDER 3
+
+static unsigned char *__initdata window;
+#define memptr long
+static memptr __initdata free_mem_ptr;
+static memptr __initdata free_mem_end_ptr;
+
+#define WSIZE           0x80000000
+
+static unsigned char *__initdata inbuf;
+static unsigned __initdata insize;
+
+/* Index of next byte to be processed in inbuf: */
+static unsigned __initdata inptr;
+
+/* Bytes in output buffer: */
+static unsigned __initdata outcnt;
+
+#define OF(args)        args
+#define STATIC          static
+
+#define memzero(s, n)   memset((s), 0, (n))
+
+typedef unsigned char   uch;
+typedef unsigned short  ush;
+typedef unsigned long   ulg;
+
+#define INIT            __init
+#define INITDATA        __initdata
+
+#define get_byte()      (inptr < insize ? inbuf[inptr++] : fill_inbuf())
+
+/* Diagnostic functions */
+#ifdef DEBUG
+#  define Assert(cond, msg) do { if (!(cond)) error(msg); } while (0)
+#  define Trace(x)      do { fprintf x; } while (0)
+#  define Tracev(x)     do { if (verbose) fprintf x ; } while (0)
+#  define Tracevv(x)    do { if (verbose > 1) fprintf x ; } while (0)
+#  define Tracec(c, x)  do { if (verbose && (c)) fprintf x ; } while (0)
+#  define Tracecv(c, x) do { if (verbose > 1 && (c)) fprintf x ; } while (0)
+#else
+#  define Assert(cond, msg)
+#  define Trace(x)
+#  define Tracev(x)
+#  define Tracevv(x)
+#  define Tracec(c, x)
+#  define Tracecv(c, x)
+#endif
+
+static long __initdata bytes_out;
+static void flush_window(void);
+
+static __init void error(char *x)
+{
+    panic("%s", x);
+}
+
+static __init int fill_inbuf(void)
+{
+        error("ran out of input data");
+        return 0;
+}
+
+
+#include "inflate.c"
+
+static __init void flush_window(void)
+{
+    /*
+     * The window is equal to the output buffer therefore only need to
+     * compute the crc.
+     */
+    unsigned long c = crc;
+    unsigned n;
+    unsigned char *in, ch;
+
+    in = window;
+    for ( n = 0; n < outcnt; n++ )
+    {
+        ch = *in++;
+        c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
+    }
+    crc = c;
+
+    bytes_out += (unsigned long)outcnt;
+    outcnt = 0;
+}
+
+__init int gzip_check(char *image, unsigned long image_len)
+{
+    unsigned char magic0, magic1;
+
+    if ( image_len < 2 )
+        return 0;
+
+    magic0 = (unsigned char)image[0];
+    magic1 = (unsigned char)image[1];
+
+    return (magic0 == 0x1f) && ((magic1 == 0x8b) || (magic1 == 0x9e));
+}
+
+__init int perform_gunzip(char *output, char *image, unsigned long image_len)
+{
+    int rc;
+
+    if ( !gzip_check(image, image_len) )
+        return 1;
+
+    window = (unsigned char *)output;
+
+    free_mem_ptr = (unsigned long)alloc_xenheap_pages(HEAPORDER, 0);
+    free_mem_end_ptr = free_mem_ptr + (PAGE_SIZE << HEAPORDER);
+
+    inbuf = (unsigned char *)image;
+    insize = image_len;
+    inptr = 0;
+
+    makecrc();
+
+    if ( gunzip() < 0 )
+    {
+        rc = -EINVAL;
+    }
+    else
+    {
+        rc = 0;
+    }
+
+    free_xenheap_pages((void *)free_mem_ptr, HEAPORDER);
+
+    return rc;
+}
diff --git a/xen/include/xen/gunzip.h b/xen/include/xen/gunzip.h
new file mode 100644
index 0000000..8058331
--- /dev/null
+++ b/xen/include/xen/gunzip.h
@@ -0,0 +1,7 @@
+#ifndef __XEN_GUNZIP_H
+#define __XEN_GUNZIP_H
+
+int gzip_check(char *image, unsigned long image_len);
+int perform_gunzip(char *output, char *image, unsigned long image_len);
+
+#endif
-- 
1.7.10.4

[PATCH v3 2/2] xen/arm: support gzip compressed kernels

[Stefano Stabellini]

Free the memory used for the compressed kernel and update the relative
mod->start and mod->size parameters with the uncompressed ones.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: julien.grall@citrix.com
CC: ian.campbell@citrix.com

---

Changes in v3:
- better error checks in kernel_decompress
- free unneeded pages between output_size and kernel_order_out
- alloc pages from domheap

Changes in v2:
- use gzip_check
- avoid useless casts
- free original kernel image and update the mod with the new address and
size
- remove changes to common Makefile
- remove CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
---
 xen/arch/arm/kernel.c       |   66 +++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/setup.c        |    2 +-
 xen/include/asm-arm/setup.h |    2 ++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index f641b12..f6da7c1 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -13,6 +13,8 @@
 #include <asm/byteorder.h>
 #include <asm/setup.h>
 #include <xen/libfdt/libfdt.h>
+#include <xen/gunzip.h>
+#include <xen/vmap.h>
 
 #include "kernel.h"
 
@@ -257,6 +259,61 @@ static int kernel_uimage_probe(struct kernel_info *info,
     return 0;
 }
 
+static __init unsigned long output_length(char *image, unsigned long image_len)
+{
+    return *(uint32_t *)&image[image_len - 4];
+}
+
+static int kernel_decompress(struct kernel_info *info,
+                             paddr_t *addr, paddr_t *size)
+{
+    char *output, *input, *end;
+    char magic[2];
+    int rc;
+    unsigned kernel_order_out;
+    paddr_t output_size;
+    struct page_info *pages;
+    
+    if (*size < 2)
+        return -EINVAL;
+
+    copy_from_paddr(magic, *addr, sizeof(magic));
+
+    /* only gzip is supported */
+    if (!gzip_check(magic, *size))
+        return -EINVAL;
+
+    input = ioremap_cache(*addr, *size);
+    if (input == NULL)
+        return -EFAULT;
+
+    output_size = output_length(input, *size);
+    kernel_order_out = get_order_from_bytes(output_size);
+    pages = alloc_domheap_pages(NULL, kernel_order_out, 0);
+    if (pages == NULL)
+    {
+        iounmap(input);
+        return -ENOMEM;
+    }
+    output = page_to_virt(pages);
+
+
+    rc = perform_gunzip(output, input, *size);
+    clean_dcache_va_range(output, output_size);
+    iounmap(input);
+
+    *addr = virt_to_maddr(output);
+    *size = output_size;
+
+    end = output + (1 << (kernel_order_out + PAGE_SHIFT));
+    output += (output_size + PAGE_SIZE - 1) & PAGE_MASK;
+    for (; output < end; output += PAGE_SIZE)
+    {
+        free_domheap_page(virt_to_page(output));
+    }
+    return 0;
+}
+
 #ifdef CONFIG_ARM_64
 /*
  * Check if the image is a 64-bit Image.
@@ -463,6 +520,15 @@ int kernel_probe(struct kernel_info *info)
         printk("Loading ramdisk from boot module @ %"PRIpaddr"\n",
                info->initrd_bootmodule->start);
 
+    if (!kernel_decompress(info, &start, &size))
+    {
+        /* Free the original kernel, update the pointers to the
+         * decompressed kernel */
+        dt_unreserved_regions(mod->start, mod->start + mod->size,
+                init_domheap_pages, 0);
+        mod->start = start;
+        mod->size = size;
+    }
 #ifdef CONFIG_ARM_64
     rc = kernel_zimage64_probe(info, start, size);
     if (rc < 0)
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 6626eba..109c71c 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -165,7 +165,7 @@ static void __init processor_id(void)
     processor_setup();
 }
 
-static void dt_unreserved_regions(paddr_t s, paddr_t e,
+void dt_unreserved_regions(paddr_t s, paddr_t e,
                                   void (*cb)(paddr_t, paddr_t), int first)
 {
     int i, nr = fdt_num_mem_rsv(device_tree_flattened);
diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h
index 81bb3da..30ac53b 100644
--- a/xen/include/asm-arm/setup.h
+++ b/xen/include/asm-arm/setup.h
@@ -54,6 +54,8 @@ void copy_from_paddr(void *dst, paddr_t paddr, unsigned long len);
 int construct_dom0(struct domain *d);
 
 void discard_initial_modules(void);
+void dt_unreserved_regions(paddr_t s, paddr_t e,
+                           void (*cb)(paddr_t, paddr_t), int first);
 
 size_t __init boot_fdt_info(const void *fdt, paddr_t paddr);
 const char __init *boot_fdt_cmdline(const void *fdt);
-- 
1.7.10.4

Re: [PATCH v3 1/2] xen: move perform_gunzip to common

[Jan Beulich]

>>> On 02.09.15 at 13:33, <stefano.stabellini@eu.citrix.com> wrote:
> The current gunzip code to decompress the Dom0 kernel is implemented in
> inflate.c which is included by bzimage.c.
> 
> I am looking to doing the same on ARM64 but there is quite a bit of
> boilerplate definitions that I would need to import in order for
> inflate.c to work correctly.
> 
> Instead of copying/pasting the code from x86/bzimage.c, move those
> definitions to a new common file, gunzip.c. Export only perform_gunzip
> and gzip_check. Leave output_length where it is.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
provided ...

> --- a/xen/common/Makefile
> +++ b/xen/common/Makefile
> @@ -55,6 +55,7 @@ obj-y += vmap.o
>  obj-y += vsprintf.o
>  obj-y += wait.o
>  obj-y += xmalloc_tlsf.o
> +obj-bin-y += gunzip.init.o

... this gets moved to its alphabetically correct place.

Jan

Re: [PATCH v3 2/2] xen/arm: support gzip compressed kernels

[Julien Grall]

Hi Stefano,

The code looks good to me. Only few coding style comment and request to
improve the comments.

On 02/09/15 12:33, Stefano Stabellini wrote:
> Free the memory used for the compressed kernel and update the relative
> mod->start and mod->size parameters with the uncompressed ones.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> CC: julien.grall@citrix.com
> CC: ian.campbell@citrix.com
> 
> ---
> 
> Changes in v3:
> - better error checks in kernel_decompress
> - free unneeded pages between output_size and kernel_order_out
> - alloc pages from domheap
> 
> Changes in v2:
> - use gzip_check
> - avoid useless casts
> - free original kernel image and update the mod with the new address and
> size
> - remove changes to common Makefile
> - remove CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> ---
>  xen/arch/arm/kernel.c       |   66 +++++++++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/setup.c        |    2 +-
>  xen/include/asm-arm/setup.h |    2 ++
>  3 files changed, 69 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
> index f641b12..f6da7c1 100644
> --- a/xen/arch/arm/kernel.c
> +++ b/xen/arch/arm/kernel.c
> @@ -13,6 +13,8 @@
>  #include <asm/byteorder.h>
>  #include <asm/setup.h>
>  #include <xen/libfdt/libfdt.h>
> +#include <xen/gunzip.h>
> +#include <xen/vmap.h>
>  
>  #include "kernel.h"
>  
> @@ -257,6 +259,61 @@ static int kernel_uimage_probe(struct kernel_info *info,
>      return 0;
>  }
>  
> +static __init unsigned long output_length(char *image, unsigned long image_len)
> +{

Should not you return a uint32_t rather than an unsigned long?

> +    return *(uint32_t *)&image[image_len - 4];
> +}
> +
> +static int kernel_decompress(struct kernel_info *info,
> +                             paddr_t *addr, paddr_t *size)

static __init as you call a function which live in init section (i.e
output_lenght)

> +{
> +    char *output, *input, *end;
> +    char magic[2];
> +    int rc;
> +    unsigned kernel_order_out;
> +    paddr_t output_size;
> +    struct page_info *pages;
> +    
> +    if (*size < 2)

if ( ... ) as for all the "if" and "for" within this function. AFAICT,
only kernel_probe is using the wrong coding style within this file.

> +        return -EINVAL;
> +
> +    copy_from_paddr(magic, *addr, sizeof(magic));
> +
> +    /* only gzip is supported */
> +    if (!gzip_check(magic, *size))
> +        return -EINVAL;
> +
> +    input = ioremap_cache(*addr, *size);
> +    if (input == NULL)
> +        return -EFAULT;
> +
> +    output_size = output_length(input, *size);
> +    kernel_order_out = get_order_from_bytes(output_size);
> +    pages = alloc_domheap_pages(NULL, kernel_order_out, 0);
> +    if (pages == NULL)
> +    {
> +        iounmap(input);
> +        return -ENOMEM;
> +    }
> +    output = page_to_virt(pages);
> +
> +

NIT: I think you can drop only line here.

> +    rc = perform_gunzip(output, input, *size);
> +    clean_dcache_va_range(output, output_size);
> +    iounmap(input);
> +
> +    *addr = virt_to_maddr(output);
> +    *size = output_size;
> +
> +    end = output + (1 << (kernel_order_out + PAGE_SHIFT));
> +    output += (output_size + PAGE_SIZE - 1) & PAGE_MASK;
> +    for (; output < end; output += PAGE_SIZE)

Can you add a comment to explain why you need to free pages that are unused?

> +    {
> +        free_domheap_page(virt_to_page(output));
> +    }

The brace are not necessary and it's missing a newline before the return.

> +    return 0;
> +}
> +
>  #ifdef CONFIG_ARM_64
>  /*
>   * Check if the image is a 64-bit Image.
> @@ -463,6 +520,15 @@ int kernel_probe(struct kernel_info *info)
>          printk("Loading ramdisk from boot module @ %"PRIpaddr"\n",
>                 info->initrd_bootmodule->start);
>  
> +    if (!kernel_decompress(info, &start, &size))

NIT: Maybe a comment to explain that we need to do it for everyone?

> +    {
> +        /* Free the original kernel, update the pointers to the
> +         * decompressed kernel */
> +        dt_unreserved_regions(mod->start, mod->start + mod->size,
> +                init_domheap_pages, 0);

The indentation looks wrong here. I think it should be

dt_unreserved_regions(....
                      init_domheap_pages, 0);

> +        mod->start = start;
> +        mod->size = size;
> +    }

NIT: I would add a newline here to make clear.

>  #ifdef CONFIG_ARM_64
>      rc = kernel_zimage64_probe(info, start, size);
>      if (rc < 0)

Regards,

-- 
Julien Grall

Re: [PATCH v3 2/2] xen/arm: support gzip compressed kernels

[Julien Grall]

On 02/09/15 12:33, Stefano Stabellini wrote:
> @@ -463,6 +520,15 @@ int kernel_probe(struct kernel_info *info)
>          printk("Loading ramdisk from boot module @ %"PRIpaddr"\n",
>                 info->initrd_bootmodule->start);
>  
> +    if (!kernel_decompress(info, &start, &size))

Thinking a bit more about this check. It can fail either because the
kernel is uncompressed or because we fail to decompress/allocate memory.

I think we shouldn't continue if we are in the a latter. I know that we
are continuing all the others caller but this is wrong and make the user
confuse because it will see a message "Loading ELF image into guest" ...

Doing the checking will also make obvious that we support uncompress
kernel when reading the code. It's not straigh-forward while reading the
patch.

> +    {
> +        /* Free the original kernel, update the pointers to the
> +         * decompressed kernel */
> +        dt_unreserved_regions(mod->start, mod->start + mod->size,
> +                init_domheap_pages, 0);
> +        mod->start = start;
> +        mod->size = size;
> +    }
>  #ifdef CONFIG_ARM_64
>      rc = kernel_zimage64_probe(info, start, size);
>      if (rc < 0)

Regards,

-- 
Julien Grall