From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Mon, 8 Jul 2019 12:32:37 +0200

Subject: [PATCH] Handle multi-arch (64-on-32) boot in linuxefi loader.

Allow booting 64-bit kernels on 32-bit EFI on x86.

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

---

 grub-core/loader/efi/linux.c      |   9 +++-

 grub-core/loader/i386/efi/linux.c | 110 ++++++++++++++++++++++++++------------

 include/grub/i386/linux.h         |   7 ++-

 3 files changed, 89 insertions(+), 37 deletions(-)

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

index c8ecce6dfd..0622dfa48d 100644

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

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

@@ -69,12 +69,17 @@ grub_linuxefi_secure_validate (void *data, grub_uint32_t size)

 typedef void (*handover_func) (void *, grub_efi_system_table_t *, void *);

 grub_err_t

-grub_efi_linux_boot (void *kernel_addr, grub_off_t offset,

+grub_efi_linux_boot (void *kernel_addr, grub_off_t handover_offset,

 		     void *kernel_params)

 {

   handover_func hf;

+  int offset = 0;

-  hf = (handover_func)((char *)kernel_addr + offset);

+#ifdef __x86_64__

+  offset = 512;

+#endif

+

+  hf = (handover_func)((char *)kernel_addr + handover_offset + offset);

   hf (grub_efi_image_handle, grub_efi_system_table, kernel_params);

   return GRUB_ERR_BUG;

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

index 6b24cbb948..3017d0f3e5 100644

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

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

@@ -44,14 +44,10 @@ static char *linux_cmdline;

 static grub_err_t

 grub_linuxefi_boot (void)

 {

-  int offset = 0;

-

-#ifdef __x86_64__

-  offset = 512;

-#endif

   asm volatile ("cli");

-  return grub_efi_linux_boot ((char *)kernel_mem, handover_offset + offset,

+  return grub_efi_linux_boot ((char *)kernel_mem,

+			      handover_offset,

 			      params);

 }

@@ -153,14 +149,20 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),

   return grub_errno;

 }

+#define MIN(a, b) \

+  ({ typeof (a) _a = (a);  \

+     typeof (b) _b = (b); \

+     _a < _b ? _a : _b; })

+

 static grub_err_t

 grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

 		int argc, char *argv[])

 {

   grub_file_t file = 0;

-  struct linux_i386_kernel_header lh;

-  grub_ssize_t len, start, filelen;

+  struct linux_i386_kernel_header *lh = NULL;

+  grub_ssize_t start, filelen;

   void *kernel = NULL;

+  int setup_header_end_offset;

   int rc;

   grub_dl_ref (my_mod);

@@ -200,48 +202,79 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

       goto fail;

     }

-  params = grub_efi_allocate_pages_max (0x3fffffff, BYTES_TO_PAGES(16384));

-

+  params = grub_efi_allocate_pages_max (0x3fffffff,

+					BYTES_TO_PAGES(sizeof(*params)));

   if (! params)

     {

       grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot allocate kernel parameters");

       goto fail;

     }

-  grub_dprintf ("linux", "params = %lx\n", (unsigned long) params);

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

-  grub_memset (params, 0, 16384);

+  grub_memset (params, 0, sizeof(*params));

-  grub_memcpy (&lh, kernel, sizeof (lh));

-

-  if (lh.boot_flag != grub_cpu_to_le16 (0xaa55))

+  setup_header_end_offset = *((grub_uint8_t *)kernel + 0x201);

+  grub_dprintf ("linux", "copying %lu bytes from %p to %p\n",

+		MIN((grub_size_t)0x202+setup_header_end_offset,

+		    sizeof (*params)) - 0x1f1,

+		(grub_uint8_t *)kernel + 0x1f1,

+		(grub_uint8_t *)params + 0x1f1);

+  grub_memcpy ((grub_uint8_t *)params + 0x1f1,

+	       (grub_uint8_t *)kernel + 0x1f1,

+		MIN((grub_size_t)0x202+setup_header_end_offset,sizeof (*params)) - 0x1f1);

+  lh = (struct linux_i386_kernel_header *)params;

+  grub_dprintf ("linux", "lh is at %p\n", lh);

+  grub_dprintf ("linux", "checking lh->boot_flag\n");

+  if (lh->boot_flag != grub_cpu_to_le16 (0xaa55))

     {

       grub_error (GRUB_ERR_BAD_OS, N_("invalid magic number"));

       goto fail;

     }

-  if (lh.setup_sects > GRUB_LINUX_MAX_SETUP_SECTS)

+  grub_dprintf ("linux", "checking lh->setup_sects\n");

+  if (lh->setup_sects > GRUB_LINUX_MAX_SETUP_SECTS)

     {

       grub_error (GRUB_ERR_BAD_OS, N_("too many setup sectors"));

       goto fail;

     }

-  if (lh.version < grub_cpu_to_le16 (0x020b))

+  grub_dprintf ("linux", "checking lh->version\n");

+  if (lh->version < grub_cpu_to_le16 (0x020b))

     {

       grub_error (GRUB_ERR_BAD_OS, N_("kernel too old"));

       goto fail;

     }

-  if (!lh.handover_offset)

+  grub_dprintf ("linux", "checking lh->handover_offset\n");

+  if (!lh->handover_offset)

     {

       grub_error (GRUB_ERR_BAD_OS, N_("kernel doesn't support EFI handover"));

       goto fail;

     }

+#if defined(__x86_64__) || defined(__aarch64__)

+  grub_dprintf ("linux", "checking lh->xloadflags\n");

+  if (!(lh->xloadflags & LINUX_XLF_KERNEL_64))

+    {

+      grub_error (GRUB_ERR_BAD_OS, N_("kernel doesn't support 64-bit CPUs"));

+      goto fail;

+    }

+#endif

+

+#if defined(__i386__)

+  if ((lh->xloadflags & LINUX_XLF_KERNEL_64) &&

+      !(lh->xloadflags & LINUX_XLF_EFI_HANDOVER_32))

+    {

+      grub_error (GRUB_ERR_BAD_OS,

+		  N_("kernel doesn't support 32-bit handover"));

+      goto fail;

+    }

+#endif

+

   grub_dprintf ("linux", "setting up cmdline\n");

   linux_cmdline = grub_efi_allocate_pages_max(0x3fffffff,

-					 BYTES_TO_PAGES(lh.cmdline_size + 1));

-

+					 BYTES_TO_PAGES(lh->cmdline_size + 1));

   if (!linux_cmdline)

     {

       grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("can't allocate cmdline"));

@@ -254,22 +287,24 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

   grub_memcpy (linux_cmdline, LINUX_IMAGE, sizeof (LINUX_IMAGE));

   grub_create_loader_cmdline (argc, argv,

                               linux_cmdline + sizeof (LINUX_IMAGE) - 1,

-			      lh.cmdline_size - (sizeof (LINUX_IMAGE) - 1),

+			      lh->cmdline_size - (sizeof (LINUX_IMAGE) - 1),

 			      GRUB_VERIFY_KERNEL_CMDLINE);

-  lh.cmd_line_ptr = (grub_uint32_t)(grub_addr_t)linux_cmdline;

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

+  grub_dprintf ("linux", "setting lh->cmd_line_ptr\n");

+  lh->cmd_line_ptr = (grub_uint32_t)(grub_addr_t)linux_cmdline;

-  handover_offset = lh.handover_offset;

+  grub_dprintf ("linux", "computing handover offset\n");

+  handover_offset = lh->handover_offset;

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

-  len = grub_file_size(file) - start;

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

-  kernel_mem = grub_efi_allocate_pages_max(lh.pref_address,

-					   BYTES_TO_PAGES(lh.init_size));

+  kernel_mem = grub_efi_allocate_pages_max(lh->pref_address,

+					   BYTES_TO_PAGES(lh->init_size));

   if (!kernel_mem)

     kernel_mem = grub_efi_allocate_pages_max(0x3fffffff,

-					     BYTES_TO_PAGES(lh.init_size));

+					     BYTES_TO_PAGES(lh->init_size));

   if (!kernel_mem)

     {

@@ -277,14 +312,21 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

       goto fail;

     }

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

+  grub_dprintf ("linux", "kernel_mem = %lx\n", (unsigned long) kernel_mem);

+

   grub_loader_set (grub_linuxefi_boot, grub_linuxefi_unload, 0);

   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;

-  lh.code32_start = (grub_uint32_t)(grub_uint64_t) kernel_mem;

-  grub_memcpy (params, &lh, 2 * 512);

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

-  params->type_of_loader = 0x21;

+  grub_dprintf ("linux", "setting lh->type_of_loader\n");

+  lh->type_of_loader = 0x6;

+

+  grub_dprintf ("linux", "setting lh->ext_loader_{type,ver}\n");

+  params->ext_loader_type = 0;

+  params->ext_loader_ver = 2;

   grub_dprintf("linux", "kernel_mem: %p handover_offset: %08x\n",

 	       kernel_mem, handover_offset);

@@ -301,10 +343,10 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),

       loaded = 0;

     }

-  if (linux_cmdline && !loaded)

+  if (linux_cmdline && lh && !loaded)

     grub_efi_free_pages ((grub_efi_physical_address_t)(grub_addr_t)

 			 linux_cmdline,

-			 BYTES_TO_PAGES(lh.cmdline_size + 1));

+			 BYTES_TO_PAGES(lh->cmdline_size + 1));

   if (kernel_mem && !loaded)

     grub_efi_free_pages ((grub_efi_physical_address_t)(grub_addr_t)kernel_mem,

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

index eddf9251d9..25ef52c04e 100644

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

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

@@ -138,7 +138,12 @@ struct linux_i386_kernel_header

   grub_uint32_t kernel_alignment;

   grub_uint8_t relocatable;

   grub_uint8_t min_alignment;

-  grub_uint8_t pad[2];

+#define LINUX_XLF_KERNEL_64                   (1<<0)

+#define LINUX_XLF_CAN_BE_LOADED_ABOVE_4G      (1<<1)

+#define LINUX_XLF_EFI_HANDOVER_32             (1<<2)

+#define LINUX_XLF_EFI_HANDOVER_64             (1<<3)

+#define LINUX_XLF_EFI_KEXEC                   (1<<4)

+  grub_uint16_t xloadflags;

   grub_uint32_t cmdline_size;

   grub_uint32_t hardware_subarch;

   grub_uint64_t hardware_subarch_data;