[PATCH v2 3/5] ld: fix segfault on discarded input sections not fitting in memory regions

[Matthieu Longo]

In the case of non-contiguous memory regions, if an input section did not
fit in any of the designated memory regions, the linker marked it as
discarded, and warn_non_contiguous_discards() would only issue warning on
it, relying on later unresolved symbol errors to terminate the process
before a crash occur. This approach was insufficient, and crashes did occur
on AArch64.

This patch renames warn_non_contiguous_discards () to a name that does not
contain "discard" as it created some confusion with the /DISCARD/ output
section. It also promotes the warnings to errors, and ensures that the
link process terminates cleanly if any input section is not allocated to
an output section.
It also updates an AArch32 test expectations to match the corrected
behavior. Tests for the crash cases are added in a subsequent patch.
---
 ld/ldlang.c                                 | 30 ++++++++++++++-------
 ld/testsuite/ld-arm/non-contiguous-arm7.err |  9 +++----
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/ld/ldlang.c b/ld/ldlang.c
index bdda599a7a4..c7c4ba8a019 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -5576,7 +5576,7 @@ size_input_section
   lang_input_section_type *is = &((*this_ptr)->input_section);
   asection *i = is->section;
   asection *o = output_section_statement->bfd_section;
-  *removed = 0;
+  *removed = false;
 
   if (link_info.non_contiguous_regions)
     {
@@ -5587,7 +5587,7 @@ size_input_section
 	 have reinitialized its size.  */
       if (i->already_assigned && i->already_assigned != o)
 	{
-	  *removed = 1;
+	  *removed = true;
 	  return dot;
 	}
     }
@@ -5650,7 +5650,7 @@ size_input_section
 			     "would overflow `%pA' after it changed size).\n"),
 			   i, i->output_section);
 
-		  *removed = 1;
+		  *removed = true;
 		  dot = end;
 		  i->output_section = NULL;
 		  return dot;
@@ -8231,9 +8231,14 @@ lang_propagate_lma_regions (void)
     }
 }
 
+/* Checks whether any input section was not allocated to an output section.
+   If such a case is found, emits an error for the corresponding input section
+   and stops the link process.  */
+
 static void
-warn_non_contiguous_discards (void)
+error_non_contiguous_unallocated_sections (void)
 {
+  bool removed_section = false;
   LANG_FOR_EACH_INPUT_STATEMENT (file)
     {
       if ((file->the_bfd->flags & (BFD_LINKER_CREATED | DYNAMIC)) != 0
@@ -8242,10 +8247,16 @@ warn_non_contiguous_discards (void)
 
       for (asection *s = file->the_bfd->sections; s != NULL; s = s->next)
 	if (s->output_section == NULL && !s->veneer)
-	  einfo (_("%P: warning: --enable-non-contiguous-regions "
-		   "discards section `%pA' from `%pB'\n"),
-		 s, file->the_bfd);
+	  {
+	    einfo (_("%P: error: --enable-non-contiguous-regions was not able "
+		     "to allocate the input section `%pA' (%pB) to an output "
+		     "section\n"),
+		   s, file->the_bfd);
+	    removed_section = true;
+	  }
     }
+  if (removed_section)
+    fatal (_("%P: final link failed\n"));
 }
 
 static void
@@ -8663,9 +8674,8 @@ lang_process (void)
   if (command_line.check_section_addresses)
     lang_check_section_addresses ();
 
-  if (link_info.non_contiguous_regions
-      && link_info.non_contiguous_regions_warnings)
-    warn_non_contiguous_discards ();
+  if (link_info.non_contiguous_regions)
+    error_non_contiguous_unallocated_sections ();
 
   /* Check any required symbols are known.  */
   ldlang_check_require_defined_symbols ();
diff --git a/ld/testsuite/ld-arm/non-contiguous-arm7.err b/ld/testsuite/ld-arm/non-contiguous-arm7.err
index 7b3a3d8c3c9..21f71898eb1 100644
--- a/ld/testsuite/ld-arm/non-contiguous-arm7.err
+++ b/ld/testsuite/ld-arm/non-contiguous-arm7.err
@@ -1,5 +1,4 @@
-.* may change behaviour for section .?\.bss.? from .*
-.* may change behaviour for section .?\.bss\.MY_BUF.? from .*
-.* discards section .?\.bss\.MY_BUF.? from .*
-.* unresolvable R_ARM_ABS32 relocation against symbol .?MY_BUF.?
-.* final link failed
+.*: warning: --enable-non-contiguous-regions may change behaviour for section `\.bss' from `.*non-contiguous-arm7\.o' \(assigned to \.bss, but additional match: \.bss_ram2\)
+.*: warning: --enable-non-contiguous-regions may change behaviour for section `\.bss\.MY_BUF' from `.*non-contiguous-arm7\.o' \(assigned to \.bss, but additional match: \.bss_ram2\)
+.*: error: --enable-non-contiguous-regions was not able to allocate the input section `\.bss\.MY_BUF' \(.*non-contiguous-arm7\.o\) to an output section
+.*: final link failed
-- 
2.51.0