multiboot: make GRUB_MULTIBOOT(make_mbi) return MBI's size

GRUB_MULTIBOOT(get_mbi_size) doesn't look like an accurate source of the final size, more like a minimal memory buffer size. Signed-off-by: Sergii Dmytruk <[email protected]>
TrenchBoot · Nov 22, 2023 · ba8dbc9 · ba8dbc9
1 parent ee8e036
commit ba8dbc9
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Showing 5 changed files with 12 additions and 6 deletions.
diff --git a/grub-core/loader/i386/multiboot_mbi.c b/grub-core/loader/i386/multiboot_mbi.c
@@ -450,7 +450,7 @@ retrieve_video_parameters (struct multiboot_info *mbi,
 }
 
 grub_err_t
-grub_multiboot_make_mbi (grub_uint32_t *target)
+grub_multiboot_make_mbi (grub_uint32_t *target, grub_uint32_t *size)
 {
   struct multiboot_info *mbi;
   struct multiboot_mod_list *modlist;
@@ -618,6 +618,8 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
     return err;
 #endif
 
+  *size = (char *) ptrorig - (char *) mbi;
+
   return GRUB_ERR_NONE;
 }
 

diff --git a/grub-core/loader/multiboot.c b/grub-core/loader/multiboot.c
@@ -202,6 +202,7 @@ static grub_err_t
 grub_multiboot_boot (void)
 {
   grub_err_t err;
+  grub_uint32_t mbi_size;
 
 #ifdef GRUB_USE_MULTIBOOT2
   struct grub_relocator32_state state = MULTIBOOT2_INITIAL_STATE;
@@ -210,7 +211,7 @@ grub_multiboot_boot (void)
 #endif
   state.MULTIBOOT_ENTRY_REGISTER = GRUB_MULTIBOOT (payload_eip);
 
-  err = GRUB_MULTIBOOT (make_mbi) (&state.MULTIBOOT_MBI_REGISTER);
+  err = GRUB_MULTIBOOT (make_mbi) (&state.MULTIBOOT_MBI_REGISTER, &mbi_size);
 
   if (err)
     return err;

diff --git a/grub-core/loader/multiboot_mbi2.c b/grub-core/loader/multiboot_mbi2.c
@@ -735,7 +735,7 @@ retrieve_video_parameters (grub_properly_aligned_t **ptrorig)
 }
 
 grub_err_t
-grub_multiboot2_make_mbi (grub_uint32_t *target)
+grub_multiboot2_make_mbi (grub_uint32_t *target, grub_uint32_t *size)
 {
   grub_properly_aligned_t *ptrorig;
   grub_properly_aligned_t *mbistart;
@@ -1041,7 +1041,9 @@ grub_multiboot2_make_mbi (grub_uint32_t *target)
       / sizeof (grub_properly_aligned_t);
   }
 
-  ((grub_uint32_t *) mbistart)[0] = (char *) ptrorig - (char *) mbistart;
+  *size = (char *) ptrorig - (char *) mbistart;
+
+  ((grub_uint32_t *) mbistart)[0] = *size;
   ((grub_uint32_t *) mbistart)[1] = 0;
 
   return GRUB_ERR_NONE;

diff --git a/include/grub/multiboot.h b/include/grub/multiboot.h
@@ -41,7 +41,7 @@ void grub_multiboot (int argc, char *argv[]);
 void grub_module (int argc, char *argv[]);
 
 void grub_multiboot_set_accepts_video (int val);
-grub_err_t grub_multiboot_make_mbi (grub_uint32_t *target);
+grub_err_t grub_multiboot_make_mbi (grub_uint32_t *target, grub_uint32_t *size);
 void grub_multiboot_free_mbi (void);
 grub_err_t grub_multiboot_init_mbi (int argc, char *argv[]);
 grub_err_t grub_multiboot_add_module (grub_addr_t start, grub_size_t size,

diff --git a/include/grub/multiboot2.h b/include/grub/multiboot2.h
@@ -33,7 +33,8 @@ void grub_multiboot2 (int argc, char *argv[]);
 void grub_module2 (int argc, char *argv[]);
 
 void grub_multiboot2_set_accepts_video (int val);
-grub_err_t grub_multiboot2_make_mbi (grub_uint32_t *target);
+grub_err_t grub_multiboot2_make_mbi (grub_uint32_t *target,
+                                     grub_uint32_t *size);
 void grub_multiboot2_free_mbi (void);
 grub_err_t grub_multiboot2_init_mbi (int argc, char *argv[]);
 grub_err_t grub_multiboot2_add_module (grub_addr_t start, grub_size_t size,