MSP430: Fix alignment of __*_array_start symbols in default linker script

__{preinit,init,fini}_array_start symbols must be word aligned in linker scripts. If the section preceding the __*_array_start symbol has an odd size, then a NULL byte will be present between the start symbol and the .*_array section itself, when the section gets automatically word-aligned. This results in a branch to an invalid address when the CRT startup code tries to run through the functions listed in the array sections. Some MSP430 linker scripts do not align the __*_array start symbols, so this added warning will catch that problem and help the user avoid the potential incorrect execution of the program. ld/ChangeLog: * emultempl/msp430.em (input_section_exists): New. (check_array_section_alignment): New. (gld${EMULATION_NAME}_finish): New. * scripttempl/elf32msp430.sc: Add ALIGN directives before the definition of __*_array_start symbols. * testsuite/ld-msp430-elf/finiarray-warn.ld: New test. * testsuite/ld-msp430-elf/finiarray-warn.r: New test. * testsuite/ld-msp430-elf/initarray-nowarn.ld: New test. * testsuite/ld-msp430-elf/initarray-warn.ld: New test. * testsuite/ld-msp430-elf/initarray-warn.r: New test. * testsuite/ld-msp430-elf/initarray.s: New test. * testsuite/ld-msp430-elf/msp430-elf.exp: Run new tests. * testsuite/ld-msp430-elf/preinitarray-warn.ld: New test. * testsuite/ld-msp430-elf/preinitarray-warn.r: New test.
6 years ago · 64b63c2993
13 changed files with 320 additions and 1 deletions
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@ -1,3 +1,20 @@
+2020-08-28  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
+
+	* emultempl/msp430.em (input_section_exists): New.
+	(check_array_section_alignment): New.
+	(gld${EMULATION_NAME}_finish): New.
+	* scripttempl/elf32msp430.sc: Add ALIGN directives before the
+	definition of __*_array_start symbols.
+	* testsuite/ld-msp430-elf/finiarray-warn.ld: New test.
+	* testsuite/ld-msp430-elf/finiarray-warn.r: New test.
+	* testsuite/ld-msp430-elf/initarray-nowarn.ld: New test.
+	* testsuite/ld-msp430-elf/initarray-warn.ld: New test.
+	* testsuite/ld-msp430-elf/initarray-warn.r: New test.
+	* testsuite/ld-msp430-elf/initarray.s: New test.
+	* testsuite/ld-msp430-elf/msp430-elf.exp: Run new tests.
+	* testsuite/ld-msp430-elf/preinitarray-warn.ld: New test.
+	* testsuite/ld-msp430-elf/preinitarray-warn.r: New test.
+
 2020-08-28  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

 	* ldmisc.c (vfinfo): Support new "%pU" format specifier.
--- a/ld/emultempl/msp430.em
+++ b/ld/emultempl/msp430.em
@ -826,6 +826,85 @@ msp430_elf_after_allocation (void)
  gld${EMULATION_NAME}_after_allocation ();
 }

+/* Return TRUE if a non-debug input section in L has positive size and matches
+   the given name.  */
+static int
+input_section_exists (lang_statement_union_type * l, const char * name)
+{
+  while (l != NULL)
+    {
+      switch (l->header.type)
+	{
+	case lang_input_section_enum:
+	  if ((l->input_section.section->flags & SEC_ALLOC)
+	      && l->input_section.section->size > 0
+	      && !strcmp (l->input_section.section->name, name))
+	    return TRUE;
+	  break;
+
+	case lang_wild_statement_enum:
+	  if (input_section_exists (l->wild_statement.children.head, name))
+	    return TRUE;
+	  break;
+
+	default:
+	  break;
+	}
+      l = l->header.next;
+    }
+  return FALSE;
+}
+
+/* Some MSP430 linker scripts do not include ALIGN directives to ensure
+   __preinit_array_start, __init_array_start or __fini_array_start are word
+   aligned.
+   If __*_array_start symbols are not word aligned, the code in crt0 to run
+   through the array and call the functions will crash.
+   To avoid warning unnecessarily when the .*_array sections are not being
+   used for running constructors/destructors, only emit the warning if
+   the associated section exists and has size.  */
+static void
+check_array_section_alignment (void)
+{
+  int i;
+  lang_output_section_statement_type * rodata_sec;
+  lang_output_section_statement_type * rodata2_sec;
+  const char * array_names[3][2] = { { ".init_array", "__init_array_start" },
+	{ ".preinit_array", "__preinit_array_start" },
+	{ ".fini_array", "__fini_array_start" } };
+
+  /* .{preinit,init,fini}_array could be in either .rodata or .rodata2.  */
+  rodata_sec = lang_output_section_find (".rodata");
+  rodata2_sec = lang_output_section_find (".rodata2");
+  if (rodata_sec == NULL && rodata2_sec == NULL)
+    return;
+
+  /* There are 3 .*_array sections which must be checked for alignment.  */
+  for (i = 0; i < 3; i++)
+    {
+      struct bfd_link_hash_entry * sym;
+      if (((rodata_sec && input_section_exists (rodata_sec->children.head,
+						array_names[i][0]))
+	   || (rodata2_sec && input_section_exists (rodata2_sec->children.head,
+						    array_names[i][0])))
+	  && (sym = bfd_link_hash_lookup (link_info.hash, array_names[i][1],
+					  FALSE, FALSE, TRUE))
+	  && sym->type == bfd_link_hash_defined
+	  && sym->u.def.value % 2)
+	{
+	  einfo ("%P: warning: \"%s\" symbol (%pU) is not word aligned\n",
+		 array_names[i][1], NULL);
+	}
+    }
+}
+
+static void
+gld${EMULATION_NAME}_finish (void)
+{
+  finish_default ();
+  check_array_section_alignment ();
+}
+
 struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
 {
  ${LDEMUL_BEFORE_PARSE-gld${EMULATION_NAME}_before_parse},
@ -842,7 +921,7 @@ struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
  ${LDEMUL_GET_SCRIPT-gld${EMULATION_NAME}_get_script},
  "${EMULATION_NAME}",
  "${OUTPUT_FORMAT}",
-  ${LDEMUL_FINISH-finish_default},
+  gld${EMULATION_NAME}_finish,
  ${LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS-NULL},
  ${LDEMUL_OPEN_DYNAMIC_ARCHIVE-NULL},
  ${LDEMUL_PLACE_ORPHAN-gld${EMULATION_NAME}_place_orphan},
--- a/ld/scripttempl/elf32msp430.sc
+++ b/ld/scripttempl/elf32msp430.sc
@ -208,15 +208,18 @@ SECTIONS

    KEEP (*(.gcc_except_table)) *(.gcc_except_table.*)

+    . = ALIGN(2);
    PROVIDE (__preinit_array_start = .);
    KEEP (*(.preinit_array))
    PROVIDE (__preinit_array_end = .);

+    . = ALIGN(2);
    PROVIDE (__init_array_start = .);
    KEEP (*(SORT(.init_array.*)))
    KEEP (*(.init_array))
    PROVIDE (__init_array_end = .);

+    . = ALIGN(2);
    PROVIDE (__fini_array_start = .);
    KEEP (*(.fini_array))
    KEEP (*(SORT(.fini_array.*)))
--- a/ld/testsuite/ld-msp430-elf/finiarray-warn.ld
+++ b/ld/testsuite/ld-msp430-elf/finiarray-warn.ld
@ -0,0 +1,46 @@
+/* Script for ld testsuite */
+OUTPUT_ARCH(msp430)
+ENTRY(_start)
+
+SECTIONS
+{
+  .text :
+  {
+    PROVIDE (_start = .);
+    . = ALIGN(2);
+    *(.text .stub .text.* .gnu.linkonce.t.* .text:*)
+  }
+
+  .rodata :
+  {
+    *(.rodata.* .rodata)
+    . = ALIGN(2);
+    PROVIDE (__preinit_array_start = .);
+    KEEP (*(SORT(.preinit_array.*)))
+    KEEP (*(.preinit_array))
+    PROVIDE (__preinit_array_end = .);
+    . = ALIGN(2);
+    PROVIDE (__init_array_start = .);
+    KEEP (*(SORT(.init_array.*)))
+    KEEP (*(.init_array))
+    PROVIDE (__init_array_end = .);
+    . = ALIGN(2);
+    . += 1;
+    PROVIDE (__fini_array_start = .);
+    KEEP (*(SORT(.fini_array.*)))
+    KEEP (*(.fini_array))
+    PROVIDE (__fini_array_end = .);
+  }
+
+  .data :
+  {
+    . = ALIGN(2);
+    *(.data.* .data)
+  }
+
+  .bss :
+  {
+    . = ALIGN(2);
+    *(.bss.* .bss)
+  }
+}
--- a/ld/testsuite/ld-msp430-elf/finiarray-warn.r
+++ b/ld/testsuite/ld-msp430-elf/finiarray-warn.r
@ -0,0 +1 @@
+.*warning: "__fini_array_start" symbol \(finiarray-warn.ld\) is not word aligned
--- a/ld/testsuite/ld-msp430-elf/initarray-nowarn.ld
+++ b/ld/testsuite/ld-msp430-elf/initarray-nowarn.ld
@ -0,0 +1,45 @@
+/* Script for ld testsuite */
+OUTPUT_ARCH(msp430)
+ENTRY(_start)
+
+SECTIONS
+{
+  .text :
+  {
+    PROVIDE (_start = .);
+    . = ALIGN(2);
+    *(.text .stub .text.* .gnu.linkonce.t.* .text:*)
+  }
+
+  .rodata :
+  {
+    *(.rodata.* .rodata)
+    . = ALIGN(2);
+    PROVIDE (__preinit_array_start = .);
+    KEEP (*(SORT(.preinit_array.*)))
+    KEEP (*(.preinit_array))
+    PROVIDE (__preinit_array_end = .);
+    . = ALIGN(2);
+    PROVIDE (__init_array_start = .);
+    KEEP (*(SORT(.init_array.*)))
+    KEEP (*(.init_array))
+    PROVIDE (__init_array_end = .);
+    . = ALIGN(2);
+    PROVIDE (__fini_array_start = .);
+    KEEP (*(SORT(.fini_array.*)))
+    KEEP (*(.fini_array))
+    PROVIDE (__fini_array_end = .);
+  }
+
+  .data :
+  {
+    . = ALIGN(2);
+    *(.data.* .data)
+  }
+
+  .bss :
+  {
+    . = ALIGN(2);
+    *(.bss.* .bss)
+  }
+}
--- a/ld/testsuite/ld-msp430-elf/initarray-nowarn.r
+++ b/ld/testsuite/ld-msp430-elf/initarray-nowarn.r
--- a/ld/testsuite/ld-msp430-elf/initarray-warn.ld
+++ b/ld/testsuite/ld-msp430-elf/initarray-warn.ld
@ -0,0 +1,46 @@
+/* Script for ld testsuite */
+OUTPUT_ARCH(msp430)
+ENTRY(_start)
+
+SECTIONS
+{
+  .text :
+  {
+    PROVIDE (_start = .);
+    . = ALIGN(2);
+    *(.text .stub .text.* .gnu.linkonce.t.* .text:*)
+  }
+
+  .rodata :
+  {
+    *(.rodata.* .rodata)
+    . = ALIGN(2);
+    PROVIDE (__preinit_array_start = .);
+    KEEP (*(SORT(.preinit_array.*)))
+    KEEP (*(.preinit_array))
+    PROVIDE (__preinit_array_end = .);
+    . = ALIGN(2);
+    . += 1;
+    PROVIDE (__init_array_start = .);
+    KEEP (*(SORT(.init_array.*)))
+    KEEP (*(.init_array))
+    PROVIDE (__init_array_end = .);
+    . = ALIGN(2);
+    PROVIDE (__fini_array_start = .);
+    KEEP (*(SORT(.fini_array.*)))
+    KEEP (*(.fini_array))
+    PROVIDE (__fini_array_end = .);
+  }
+
+  .data :
+  {
+    . = ALIGN(2);
+    *(.data.* .data)
+  }
+
+  .bss :
+  {
+    . = ALIGN(2);
+    *(.bss.* .bss)
+  }
+}
--- a/ld/testsuite/ld-msp430-elf/initarray-warn.r
+++ b/ld/testsuite/ld-msp430-elf/initarray-warn.r
@ -0,0 +1 @@
+.*warning: "__init_array_start" symbol \(initarray-warn.ld\) is not word aligned
--- a/ld/testsuite/ld-msp430-elf/initarray.s
+++ b/ld/testsuite/ld-msp430-elf/initarray.s
@ -0,0 +1,21 @@
+.text
+	.section	.preinit_array,"aw"
+	.short 42
+
+	.section	.init_array,"aw"
+	.short 43
+
+	.section	.fini_array,"aw"
+	.short 44
+
+.text
+	.global	main
+	.type	main, @function
+main:
+	MOV #__preinit_array_start, R8
+	MOV #__init_array_start, R9
+	MOV #__fini_array_start, R10
+  CALL @R8
+  CALL @R9
+  CALL @R10
+	RET
--- a/ld/testsuite/ld-msp430-elf/msp430-elf.exp
+++ b/ld/testsuite/ld-msp430-elf/msp430-elf.exp
@ -163,6 +163,19 @@ set msp430warntests {
        {{ld warn-no-lower-data.r}} "warn-no-lower-data"}
 }

+set msp430arraytests {
+    { "Warn when __preinit_array_start is not word aligned" "-T preinitarray-warn.ld" "" ""
+        {initarray.s} {{ld preinitarray-warn.r}} "preinitarray-warn"}
+    { "Warn when __init_array_start is not word aligned" "-T initarray-warn.ld" "" ""
+        {initarray.s} {{ld initarray-warn.r}} "initarray-warn"}
+    { "Warn when __fini_array_start is not word aligned" "-T finiarray-warn.ld" "" ""
+        {initarray.s} {{ld finiarray-warn.r}} "finiarray-warn"}
+    { "Don't warn when __{preinit,init,fini}_array_start are word aligned" "-T initarray-nowarn.ld" "" ""
+        {initarray.s} {{ld initarray-nowarn.r}} "initarray-nowarn"}
+}
+
+run_ld_link_tests $msp430arraytests
+
 # Don't run further tests when msp430 ISA is selected
 if {[string match "*-mcpu=msp430 *" [board_info [target_info name] multilib_flags]]
  || [string match "*-mcpu=msp430" [board_info [target_info name] multilib_flags]]} {
--- a/ld/testsuite/ld-msp430-elf/preinitarray-warn.ld
+++ b/ld/testsuite/ld-msp430-elf/preinitarray-warn.ld
@ -0,0 +1,46 @@
+/* Script for ld testsuite */
+OUTPUT_ARCH(msp430)
+ENTRY(_start)
+
+SECTIONS
+{
+  .text :
+  {
+    PROVIDE (_start = .);
+    . = ALIGN(2);
+    *(.text .stub .text.* .gnu.linkonce.t.* .text:*)
+  }
+
+  .rodata :
+  {
+    *(.rodata.* .rodata)
+    . = ALIGN(2);
+    . += 1;
+    PROVIDE (__preinit_array_start = .);
+    KEEP (*(SORT(.preinit_array.*)))
+    KEEP (*(.preinit_array))
+    PROVIDE (__preinit_array_end = .);
+    . = ALIGN(2);
+    PROVIDE (__init_array_start = .);
+    KEEP (*(SORT(.init_array.*)))
+    KEEP (*(.init_array))
+    PROVIDE (__init_array_end = .);
+    . = ALIGN(2);
+    PROVIDE (__fini_array_start = .);
+    KEEP (*(SORT(.fini_array.*)))
+    KEEP (*(.fini_array))
+    PROVIDE (__fini_array_end = .);
+  }
+
+  .data :
+  {
+    . = ALIGN(2);
+    *(.data.* .data)
+  }
+
+  .bss :
+  {
+    . = ALIGN(2);
+    *(.bss.* .bss)
+  }
+}
--- a/ld/testsuite/ld-msp430-elf/preinitarray-warn.r
+++ b/ld/testsuite/ld-msp430-elf/preinitarray-warn.r
@ -0,0 +1 @@
+.*warning: "__preinit_array_start" symbol \(preinitarray-warn.ld\) is not word aligned
			`@ -0,0 +1 @@`
			`.*warning: "__fini_array_start" symbol \(finiarray-warn.ld\) is not word aligned`
			`@ -0,0 +1 @@`
			`.*warning: "__init_array_start" symbol \(initarray-warn.ld\) is not word aligned`
			`@ -0,0 +1 @@`
			`.*warning: "__preinit_array_start" symbol \(preinitarray-warn.ld\) is not word aligned`