[PATCH V4] multiboot2: Implement quirk-modules-after-kernel

[Zide Chen]

In contrast to Mulitboot, in Mulitboot2, there is currently no way to
control where to load the modules to. This could be a problem, e.g., the
OS loaded by Multiboot2 needs to reserve low address for some particular
purposes and not for loading modules.

This patch implements the quirk quirk-modules-after-kernel to load modules
to address after the kernel for Multiboot2 by reusing the implementation
for Multiboot:

- remove "ifndef GRUB_USE_MULTIBOOT2" that is handling this quirk.
- define separate variables for both Multiboot and Multiboot2, e.g.,
  grub_multiboot_quirks, highest_load, etc.
- in grub_multiboot2_load(): calculate the highest load address of raw
  image and assign it to grub_multiboot2_highest_load.
- the existing code in multiboot_elfxx.c is able to calculate the
  highest_load for Mutiboot2 already.

Currently, lowest address for Multiboot2 modules allocation was 0x0.
With this patch, the lowest module load address is set to 1MB even if this
quirk is not enabled.

Tested on KBL NUC loading ACRN Hypervisor.

v3: update commit messages
v4: don't round up lowest_addr for Multiboot2

Signed-off-by: Zide Chen <address@hidden>
---
 grub-core/loader/i386/multiboot_mbi.c |  1 -
 grub-core/loader/multiboot.c          | 31 ++++++++++++++++++---------
 grub-core/loader/multiboot_elfxx.c    |  7 +++---
 grub-core/loader/multiboot_mbi2.c     |  2 ++
 include/grub/multiboot.h              |  1 +
 include/grub/multiboot2.h             |  8 +++++++
 6 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/grub-core/loader/i386/multiboot_mbi.c 
b/grub-core/loader/i386/multiboot_mbi.c
index ad3cc292fd18..18aaac847011 100644
--- a/grub-core/loader/i386/multiboot_mbi.c
+++ b/grub-core/loader/i386/multiboot_mbi.c
@@ -63,7 +63,6 @@ static int bootdev_set;
 static grub_size_t elf_sec_num, elf_sec_entsize;
 static unsigned elf_sec_shstrndx;
 static void *elf_sections;
-grub_multiboot_quirks_t grub_multiboot_quirks;
 
 static grub_err_t
 load_kernel (grub_file_t file, const char *filename,
diff --git a/grub-core/loader/multiboot.c b/grub-core/loader/multiboot.c
index 4a98d7082598..1227960f7bf3 100644
--- a/grub-core/loader/multiboot.c
+++ b/grub-core/loader/multiboot.c
@@ -32,6 +32,8 @@
 #include <grub/multiboot2.h>
 #define GRUB_MULTIBOOT_CONSOLE_FRAMEBUFFER GRUB_MULTIBOOT2_CONSOLE_FRAMEBUFFER
 #define GRUB_MULTIBOOT_CONSOLE_EGA_TEXT GRUB_MULTIBOOT2_CONSOLE_EGA_TEXT
+#define GRUB_MULTIBOOT_QUIRKS_NONE GRUB_MULTIBOOT2_QUIRKS_NONE
+#define GRUB_MULTIBOOT_QUIRK_MODULES_AFTER_KERNEL 
GRUB_MULTIBOOT2_QUIRK_MODULES_AFTER_KERNEL
 #define GRUB_MULTIBOOT(x) grub_multiboot2_ ## x
 #else
 #include <grub/multiboot.h>
@@ -210,7 +212,8 @@ grub_multiboot_unload (void)
   return GRUB_ERR_NONE;
 }
 
-static grub_uint64_t highest_load;
+GRUB_MULTIBOOT (quirks_t) GRUB_MULTIBOOT (quirks);
+grub_uint64_t GRUB_MULTIBOOT (highest_load);
 
 #define MULTIBOOT_LOAD_ELF64
 #include "multiboot_elfxx.c"
@@ -291,32 +294,32 @@ grub_cmd_multiboot (grub_command_t cmd __attribute__ 
((unused)),
 
   grub_loader_unset ();
 
-  highest_load = 0;
+  GRUB_MULTIBOOT (highest_load) = 0;
 
-#ifndef GRUB_USE_MULTIBOOT2
-  grub_multiboot_quirks = GRUB_MULTIBOOT_QUIRKS_NONE;
+  GRUB_MULTIBOOT (quirks) = GRUB_MULTIBOOT_QUIRKS_NONE;
   int option_found = 0;
 
   do
     {
       option_found = 0;
+#ifndef GRUB_USE_MULTIBOOT2
       if (argc != 0 && grub_strcmp (argv[0], "--quirk-bad-kludge") == 0)
        {
          argc--;
          argv++;
          option_found = 1;
-         grub_multiboot_quirks |= GRUB_MULTIBOOT_QUIRK_BAD_KLUDGE;
+         GRUB_MULTIBOOT (quirks) |= GRUB_MULTIBOOT_QUIRK_BAD_KLUDGE;
        }
+#endif
 
       if (argc != 0 && grub_strcmp (argv[0], "--quirk-modules-after-kernel") 
== 0)
        {
          argc--;
          argv++;
          option_found = 1;
-         grub_multiboot_quirks |= GRUB_MULTIBOOT_QUIRK_MODULES_AFTER_KERNEL;
+         GRUB_MULTIBOOT (quirks) |= GRUB_MULTIBOOT_QUIRK_MODULES_AFTER_KERNEL;
        }
     } while (option_found);
-#endif
 
   if (argc == 0)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
@@ -392,11 +395,19 @@ grub_cmd_module (grub_command_t cmd __attribute__ 
((unused)),
   if (! file)
     return grub_errno;
 
-#ifndef GRUB_USE_MULTIBOOT2
   lowest_addr = 0x100000;
-  if (grub_multiboot_quirks & GRUB_MULTIBOOT_QUIRK_MODULES_AFTER_KERNEL)
-    lowest_addr = ALIGN_UP (highest_load + 1048576, 4096);
+  if (GRUB_MULTIBOOT (quirks) & GRUB_MULTIBOOT_QUIRK_MODULES_AFTER_KERNEL) {
+#ifdef GRUB_USE_MULTIBOOT2
+    lowest_addr = GRUB_MULTIBOOT (highest_load);
+#else
+    /*
+     * Either Multiboot or Multiboot2, supposedly there is no requirement for 
this
+     * address round up. But not sure if there was any historical reason why it
+     * was here.
+     */
+    lowest_addr = ALIGN_UP (GRUB_MULTIBOOT (highest_load) + 1048576, 4096);
 #endif
+  }
 
   size = grub_file_size (file);
   if (size)
diff --git a/grub-core/loader/multiboot_elfxx.c 
b/grub-core/loader/multiboot_elfxx.c
index 70cd1db513e6..8adce7b3489b 100644
--- a/grub-core/loader/multiboot_elfxx.c
+++ b/grub-core/loader/multiboot_elfxx.c
@@ -89,17 +89,18 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld)
     if (phdr(i)->p_type == PT_LOAD)
       {
        mld->link_base_addr = grub_min (mld->link_base_addr, phdr(i)->p_paddr);
-       highest_load = grub_max (highest_load, phdr(i)->p_paddr + 
phdr(i)->p_memsz);
+       GRUB_MULTIBOOT (highest_load) = grub_max (GRUB_MULTIBOOT (highest_load),
+                       phdr(i)->p_paddr + phdr(i)->p_memsz);
       }
 
 #ifdef MULTIBOOT_LOAD_ELF64
-  if (highest_load >= 0x100000000)
+  if (GRUB_MULTIBOOT(highest_load) >= 0x100000000)
     return grub_error (GRUB_ERR_BAD_OS, "segment crosses 4 GiB border");
 #endif
 
   if (mld->relocatable)
     {
-      load_size = highest_load - mld->link_base_addr;
+      load_size = GRUB_MULTIBOOT(highest_load) - mld->link_base_addr;
 
       grub_dprintf ("multiboot_loader", "align=0x%lx, preference=0x%x, "
                    "load_size=0x%x, avoid_efi_boot_services=%d\n",
diff --git a/grub-core/loader/multiboot_mbi2.c 
b/grub-core/loader/multiboot_mbi2.c
index 18e766c7b31c..3883732df531 100644
--- a/grub-core/loader/multiboot_mbi2.c
+++ b/grub-core/loader/multiboot_mbi2.c
@@ -315,8 +315,10 @@ grub_multiboot2_load (grub_file_t file, const char 
*filename)
          grub_free (mld.buffer);
          return err;
        }
+
       mld.link_base_addr = load_addr;
       mld.load_base_addr = get_physical_target_address (ch);
+      grub_multiboot2_highest_load = mld.load_base_addr + code_size;
       source = get_virtual_current_address (ch);
 
       grub_dprintf ("multiboot_loader", "link_base_addr=0x%x, 
load_base_addr=0x%x, "
diff --git a/include/grub/multiboot.h b/include/grub/multiboot.h
index bd0a9873e6c1..3d7c5ad29318 100644
--- a/include/grub/multiboot.h
+++ b/include/grub/multiboot.h
@@ -107,6 +107,7 @@ grub_multiboot_load_elf (mbi_load_data_t *mld);
 extern grub_size_t grub_multiboot_pure_size;
 extern grub_size_t grub_multiboot_alloc_mbi;
 extern grub_uint32_t grub_multiboot_payload_eip;
+extern grub_uint64_t grub_multiboot_highest_load;
 
 
 #endif /* ! GRUB_MULTIBOOT_HEADER */
diff --git a/include/grub/multiboot2.h b/include/grub/multiboot2.h
index 502d34ef1804..fa74508afcda 100644
--- a/include/grub/multiboot2.h
+++ b/include/grub/multiboot2.h
@@ -27,6 +27,13 @@
 #include <grub/types.h>
 #include <grub/err.h>
 
+typedef enum
+  {
+    GRUB_MULTIBOOT2_QUIRKS_NONE = 0,
+    GRUB_MULTIBOOT2_QUIRK_MODULES_AFTER_KERNEL = 1
+  } grub_multiboot2_quirks_t;
+extern grub_multiboot2_quirks_t grub_multiboot2_quirks;
+
 extern struct grub_relocator *grub_multiboot2_relocator;
 
 void grub_multiboot2 (int argc, char *argv[]);
@@ -99,6 +106,7 @@ grub_multiboot2_load_elf (mbi_load_data_t *mld);
 extern grub_size_t grub_multiboot2_pure_size;
 extern grub_size_t grub_multiboot2_alloc_mbi;
 extern grub_uint32_t grub_multiboot2_payload_eip;
+extern grub_uint64_t grub_multiboot2_highest_load;
 
 
 #endif /* ! GRUB_MULTIBOOT_HEADER */
-- 
2.17.1