From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Wed, 12 Sep 2018 16:12:27 -0400

Subject: [PATCH] x86-efi: Allow initrd+params+cmdline allocations above 4GB.

This enables everything except the kernel itself to be above 4GB.

Putting the kernel up there still doesn't work, because of the way

params->code32_start is used.

Signed-off-by: Peter Jones <pjones@redhat.com>

---

 grub-core/loader/i386/efi/linux.c | 67 +++++++++++++++++++++++++++++++++++----

 include/grub/i386/linux.h         |  6 +++-

 2 files changed, 65 insertions(+), 8 deletions(-)

diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c

index 3e4f7ef39f4..6bc18d5aef5 100644

--- a/grub-core/loader/i386/efi/linux.c

+++ b/grub-core/loader/i386/efi/linux.c

@@ -52,13 +52,22 @@ struct allocation_choice {

     grub_efi_allocate_type_t alloc_type;

 };

-static struct allocation_choice max_addresses[] =

+static struct allocation_choice max_addresses[4] =

   {

+    /* the kernel overrides this one with pref_address and

+     * GRUB_EFI_ALLOCATE_ADDRESS */

     { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },

+    /* this one is always below 4GB, which we still *prefer* even if the flag

+     * is set. */

     { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },

+    /* If the flag in params is set, this one gets changed to be above 4GB. */

     { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },

     { 0, 0 }

   };

+static struct allocation_choice saved_addresses[4];

+

+#define save_addresses() grub_memcpy(saved_addresses, max_addresses, sizeof(max_addresses))

+#define restore_addresses() grub_memcpy(max_addresses, saved_addresses, sizeof(max_addresses))

 static inline void

 kernel_free(void *addr, grub_efi_uintn_t size)

@@ -80,6 +89,11 @@ kernel_alloc(grub_efi_uintn_t size, const char * const errmsg)

       grub_uint64_t max = max_addresses[i].addr;

       grub_efi_uintn_t pages;

+      /*

+       * When we're *not* loading the kernel, or >4GB allocations aren't

+       * supported, these entries are basically all the same, so don't re-try

+       * the same parameters.

+       */

       if (max == prev_max)

 	continue;

@@ -168,6 +182,9 @@ read(grub_file_t file, grub_uint8_t *bufp, grub_size_t len)

   return bufpos;

 }

+#define LOW_U32(val) ((grub_uint32_t)(((grub_addr_t)(val)) & 0xffffffffull))

+#define HIGH_U32(val) ((grub_uint32_t)(((grub_addr_t)(val) >> 32) & 0xffffffffull))

+

 static grub_err_t

 grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),

                  int argc, char *argv[])

@@ -207,8 +224,12 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),

     goto fail;

   grub_dprintf ("linux", "initrd_mem = %p\n", initrd_mem);

-  params->ramdisk_size = size;

-  params->ramdisk_image = initrd_mem;

+  params->ramdisk_size = LOW_U32(size);

+  params->ramdisk_image = LOW_U32(initrd_mem);

+#if defined(__x86_64__)

+  params->ext_ramdisk_size = HIGH_U32(size);

+  params->ext_ramdisk_image = HIGH_U32(initrd_mem);

+#endif

   ptr = initrd_mem;

@@ -338,6 +359,18 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

     }

 #endif

+#if defined(__x86_64__)

+  if (lh->xloadflags & LINUX_XLF_CAN_BE_LOADED_ABOVE_4G)

+    {

+      grub_dprintf ("linux", "Loading kernel above 4GB is supported; enabling.\n");

+      max_addresses[2].addr = GRUB_EFI_MAX_USABLE_ADDRESS;

+    }

+  else

+    {

+      grub_dprintf ("linux", "Loading kernel above 4GB is not supported\n");

+    }

+#endif

+

   params = kernel_alloc (sizeof(*params), "cannot allocate kernel parameters");

   if (!params)

     goto fail;

@@ -372,21 +405,40 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

   grub_dprintf ("linux", "cmdline:%s\n", linux_cmdline);

   grub_dprintf ("linux", "setting lh->cmd_line_ptr to 0x%08x\n",

-		linux_cmdline);

-  lh->cmd_line_ptr = linux_cmdline;

+		LOW_U32(linux_cmdline));

+  lh->cmd_line_ptr = LOW_U32(linux_cmdline);

+#if defined(__x86_64__)

+  if ((grub_efi_uintn_t)linux_cmdline > 0xffffffffull)

+    {

+      grub_dprintf ("linux", "setting params->ext_cmd_line_ptr to 0x%08x\n",

+		    HIGH_U32(linux_cmdline));

+      params->ext_cmd_line_ptr = HIGH_U32(linux_cmdline);

+    }

+#endif

   handover_offset = lh->handover_offset;

   grub_dprintf("linux", "handover_offset: 0x%08x\n", handover_offset);

   start = (lh->setup_sects + 1) * 512;

+  /*

+   * AFAICS >4GB for kernel *cannot* work because of params->code32_start being

+   * 32-bit and getting called unconditionally in head_64.S from either entry

+   * point.

+   *

+   * so nerf that out here...

+   */

+  save_addresses();

   grub_dprintf ("linux", "lh->pref_address: %p\n", (void *)(grub_addr_t)lh->pref_address);

   if (lh->pref_address < (grub_uint64_t)GRUB_EFI_MAX_ALLOCATION_ADDRESS)

     {

       max_addresses[0].addr = lh->pref_address;

       max_addresses[0].alloc_type = GRUB_EFI_ALLOCATE_ADDRESS;

     }

+  max_addresses[1].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;

+  max_addresses[2].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;

   kernel_mem = kernel_alloc (lh->init_size, N_("can't allocate kernel"));

+  restore_addresses();

   if (!kernel_mem)

     goto fail;

   grub_dprintf("linux", "kernel_mem = %p\n", kernel_mem);

@@ -395,8 +447,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

   loaded = 1;

-  grub_dprintf ("linux", "setting lh->code32_start to %p\n", kernel_mem);

-  lh->code32_start = (grub_uint32_t)(grub_addr_t) kernel_mem;

+  grub_dprintf ("linux", "setting lh->code32_start to 0x%08x\n",

+		LOW_U32(kernel_mem));

+  lh->code32_start = LOW_U32(kernel_mem);

   grub_memcpy (kernel_mem, (char *)kernel + start, filelen - start);

diff --git a/include/grub/i386/linux.h b/include/grub/i386/linux.h

index 25ef52c04eb..fac22476cc5 100644

--- a/include/grub/i386/linux.h

+++ b/include/grub/i386/linux.h

@@ -236,7 +236,11 @@ struct linux_kernel_params

   grub_uint32_t ofw_cif_handler;	/* b8 */

   grub_uint32_t ofw_idt;		/* bc */

-  grub_uint8_t padding7[0x1b8 - 0xc0];

+  grub_uint32_t ext_ramdisk_image;	/* 0xc0 */

+  grub_uint32_t ext_ramdisk_size;	/* 0xc4 */

+  grub_uint32_t ext_cmd_line_ptr;	/* 0xc8 */

+

+  grub_uint8_t padding7[0x1b8 - 0xcc];

   union

     {