From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Patrick Steinhardt <ps@pks.im>
Date: Thu, 21 Apr 2022 15:24:21 +1000
Subject: [PATCH] kern/efi/mm: Pass up errors from add_memory_regions()

The function add_memory_regions() is currently only called on system
initialization to allocate a fixed amount of pages. As such, it didn't
need to return any errors: in case it failed, we cannot proceed anyway.
This will change with the upcoming support for requesting more memory
from the firmware at runtime, where it doesn't make sense anymore to
fail hard.

Refactor the function to return an error to prepare for this. Note that
this does not change the behaviour when initializing the memory system
because grub_efi_mm_init() knows to call grub_fatal() in case
grub_efi_mm_add_regions() returns an error.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
(cherry picked from commit 15a015698921240adc1ac266a3b5bc5fcbd81521)
---
 grub-core/kern/efi/mm.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
index a1d3b51fe6..e0ebc65dba 100644
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -514,7 +514,7 @@ filter_memory_map (grub_efi_memory_descriptor_t *memory_map,
 }
 
 /* Add memory regions.  */
-static void
+static grub_err_t
 add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
 		    grub_efi_uintn_t desc_size,
 		    grub_efi_memory_descriptor_t *memory_map_end,
@@ -542,9 +542,9 @@ add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
 					   GRUB_EFI_ALLOCATE_ADDRESS,
 					   GRUB_EFI_LOADER_CODE);      
       if (! addr)
-	grub_fatal ("cannot allocate conventional memory %p with %u pages",
-		    (void *) ((grub_addr_t) start),
-		    (unsigned) pages);
+	return grub_error (GRUB_ERR_OUT_OF_MEMORY,
+			    "Memory starting at %p (%u pages) marked as free, but EFI would not allocate",
+			    (void *) ((grub_addr_t) start), (unsigned) pages);
 
       grub_mm_init_region (addr, PAGES_TO_BYTES (pages));
 
@@ -554,7 +554,11 @@ add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
     }
 
   if (required_pages > 0)
-    grub_fatal ("too little memory");
+    return grub_error (GRUB_ERR_OUT_OF_MEMORY,
+                       "could not allocate all requested memory: %" PRIuGRUB_UINT64_T " pages still required after iterating EFI memory map",
+                       required_pages);
+
+  return GRUB_ERR_NONE;
 }
 
 void
@@ -676,6 +680,7 @@ grub_efi_mm_add_regions (grub_size_t required_bytes)
   grub_efi_memory_descriptor_t *filtered_memory_map_end;
   grub_efi_uintn_t map_size;
   grub_efi_uintn_t desc_size;
+  grub_err_t err;
   int mm_status;
 
   grub_nx_init ();
@@ -722,8 +727,11 @@ grub_efi_mm_add_regions (grub_size_t required_bytes)
   sort_memory_map (filtered_memory_map, desc_size, filtered_memory_map_end);
 
   /* Allocate memory regions for GRUB's memory management.  */
-  add_memory_regions (filtered_memory_map, desc_size,
-		      filtered_memory_map_end, BYTES_TO_PAGES (required_bytes));
+  err = add_memory_regions (filtered_memory_map, desc_size,
+			    filtered_memory_map_end,
+			    BYTES_TO_PAGES (required_bytes));
+  if (err != GRUB_ERR_NONE)
+    return err;
 
 #if 0
   /* For debug.  */