[Xen-devel] [PATCH v5 2/2] xen/arm: support gzip compressed kernels

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
Reviewed-by: Julien Grall <julien.grall@xxxxxxxxxx>
CC: ian.campbell@xxxxxxxxxx

---

Changes in v5:
- code style

Changes in v4:
- return uint32_t from output_length
- __init kernel_decompress
- code style
- add comment
- if kernel_decompress fails with error, return

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       |   75 +++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/setup.c        |    2 +-
 xen/include/asm-arm/setup.h |    2 ++
 3 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index f641b12..baa5717 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 +259,63 @@ static int kernel_uimage_probe(struct kernel_info *info,
     return 0;
 }
 
+static __init uint32_t output_length(char *image, unsigned long image_len)
+{
+    return *(uint32_t *)&image[image_len - 4];
+}
+
+static __init 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));
+    /* 
+     * Need to free pages after output_size here because they won't be
+     * freed by discard_initial_modules
+     */
+    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 +522,22 @@ int kernel_probe(struct kernel_info *info)
         printk("Loading ramdisk from boot module @ %"PRIpaddr"\n",
                info->initrd_bootmodule->start);
 
+    /* if it is a gzip'ed image, 32bit or 64bit, uncompress it */
+    rc = kernel_decompress(info, &start, &size);
+    if (rc < 0 && rc != -EINVAL)
+        return rc;
+    else if (!rc)
+    {
+        /* 
+         * 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


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