bzimage: Limit the maximum allocation address
There are restrictions on the addresses that we pass as arguments to
the kernel, mainly due to the way that the early page tables work. If
we allocate addresses above the first 1GB of memory the kernel will
fail to run. Cap key data structures at 0x3fffffff so that the kernel
can access them with its early page tables.
These limitations were discovered when running efilinux under Qemu
with multiple gigabytes of RAM.
Reported-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
diff --git a/loaders/bzimage/bzimage.c b/loaders/bzimage/bzimage.c
index 7f0c631..8789876 100644
--- a/loaders/bzimage/bzimage.c
+++ b/loaders/bzimage/bzimage.c
@@ -167,7 +167,7 @@
* load_kernel - Load a kernel image into memory from the boot device
*/
EFI_STATUS
-load_kernel(EFI_HANDLE image, CHAR16 *name, char *cmdline)
+load_kernel(EFI_HANDLE image, CHAR16 *name, char *_cmdline)
{
UINTN map_size, _map_size, map_key;
EFI_PHYSICAL_ADDRESS kernel_start, addr;
@@ -183,6 +183,7 @@
struct file *file;
UINTN desc_size;
EFI_STATUS err;
+ char *cmdline;
UINT64 size;
int i, j = 0;
@@ -262,6 +263,22 @@
/* Don't need an allocated ID, we're a prototype */
buf->hdr.loader_id = 0x1;
+ /*
+ * The kernel expects cmdline to be allocated pretty low,
+ * Documentation/x86/boot.txt says,
+ *
+ * "The kernel command line can be located anywhere
+ * between the end of the setup heap and 0xA0000"
+ */
+ addr = 0xA0000;
+ err = allocate_pages(AllocateMaxAddress, EfiLoaderData,
+ EFI_SIZE_TO_PAGES(strlen(_cmdline) + 1),
+ &addr);
+ if (err != EFI_SUCCESS)
+ goto out;
+ cmdline = (char *)(UINTN)addr;
+ memcpy(cmdline, _cmdline, strlen(_cmdline) + 1);
+
parse_initrd(buf, cmdline);
buf->hdr.cmd_line_ptr = (UINT32)(UINTN)cmdline;
@@ -290,7 +307,9 @@
if (err != EFI_SUCCESS)
goto out;
- err = emalloc(16384, 1, &addr);
+ addr = 0x3fffffff;
+ err = allocate_pages(AllocateMaxAddress, EfiLoaderData,
+ EFI_SIZE_TO_PAGES(16384), &addr);
if (err != EFI_SUCCESS)
goto out;
