[PATCH 2/2] gas: consistently emit diagnostics for non-zero data emission to .bss/.struct

["Jan Beulich" <JBeulich at suse dot com>]

gas/
2015-12-07  Jan Beulich  <jbeulich@suse.com>

	* read.c (in_bss): New.
	(do_align): Use it to also warn for non-zero fill in .bss.
	(do_org): Likewise.
	(s_space): Likewise.
	(s_fill): Error on bad use in .bss/.struct.
	(float_cons): Likewise.
	(emit_leb128_expr): Likewise.
	(emit_expr_with_reloc): Defer handling use inside .struct. Also
	error on non-zero item added to .bss.
	(stringer_append_char): Error on non-zero character.

gas/
2015-12-07  Jan Beulich  <jbeulich@suse.com>

	* gas/elf/bad-bss.d, gas/elf/bad-bss.err: New.
	* gas/elf/bss.d, gas/elf/bss.s: New.
	* gas/elf/elf.exp: Run new tests.

--- 2015-12-07/gas/read.c
+++ 2015-12-07/gas/read.c
@@ -1337,6 +1337,14 @@ convert_to_bignum (expressionS *exp, int
   exp->X_add_number = i;
 }
 
+static bfd_boolean
+in_bss (void)
+{
+  flagword flags = bfd_get_section_flags (stdoutput, now_seg);
+
+  return (flags & SEC_ALLOC) && !(flags & (SEC_LOAD | SEC_HAS_CONTENTS));
+}
+
 /* For most MRI pseudo-ops, the line actually ends at the first
    nonquoted space.  This function looks for that point, stuffs a null
    in, and sets *STOPCP to the character that used to be there, and
@@ -1402,13 +1410,17 @@ s_abort (int ignore ATTRIBUTE_UNUSED)
 static void
 do_align (int n, char *fill, int len, int max)
 {
-  if (now_seg == absolute_section)
+  if (now_seg == absolute_section || in_bss ())
     {
       if (fill != NULL)
 	while (len-- > 0)
 	  if (*fill++ != '\0')
 	    {
-	      as_warn (_("ignoring fill value in absolute section"));
+	      if (now_seg == absolute_section)
+		as_warn (_("ignoring fill value in absolute section"));
+	      else
+		as_warn (_("ignoring fill value in section `%s'"),
+			 segment_name (now_seg));
 	      break;
 	    }
       fill = NULL;
@@ -2207,6 +2219,20 @@ s_fill (int ignore ATTRIBUTE_UNUSED)
 
   if (size && !need_pass_2)
     {
+      if (now_seg == absolute_section)
+	{
+	  if (rep_exp.X_op != O_constant)
+	    as_bad (_("non-constant fill count for absolute section"));
+	  else if (fill && rep_exp.X_add_number != 0)
+	    as_bad (_("attempt to fill absolute section with non-zero value"));
+	  abs_section_offset += rep_exp.X_add_number * size;
+	}
+      else if (fill
+	       && (rep_exp.X_op != O_constant || rep_exp.X_add_number != 0)
+	       && in_bss ())
+	as_bad (_("attempt to fill section `%s' with non-zero value"),
+		segment_name (now_seg));
+
       if (rep_exp.X_op == O_constant)
 	{
 	  p = frag_var (rs_fill, (int) size, (int) size,
@@ -2777,6 +2803,10 @@ do_org (segT segment, expressionS *exp,
       symbolS *sym = exp->X_add_symbol;
       offsetT off = exp->X_add_number * OCTETS_PER_BYTE;
 
+      if (fill && in_bss ())
+	as_warn (_("ignoring fill value in section `%s'"),
+		 segment_name (now_seg));
+
       if (exp->X_op != O_constant && exp->X_op != O_symbol)
 	{
 	  /* Handle complex expressions.  */
@@ -3331,10 +3361,11 @@ s_space (int mult)
       val.X_add_number = 0;
     }
 
-  if (val.X_op != O_constant
-      || val.X_add_number < - 0x80
-      || val.X_add_number > 0xff
-      || (mult != 0 && mult != 1 && val.X_add_number != 0))
+  if ((val.X_op != O_constant
+       || val.X_add_number < - 0x80
+       || val.X_add_number > 0xff
+       || (mult != 0 && mult != 1 && val.X_add_number != 0))
+      && (now_seg != absolute_section && !in_bss ()))
     {
       resolve_expression (&exp);
       if (exp.X_op != O_constant)
@@ -3375,6 +3406,8 @@ s_space (int mult)
 	  /* If we are in the absolute section, just bump the offset.  */
 	  if (now_seg == absolute_section)
 	    {
+	      if (val.X_op != O_constant || val.X_add_number != 0)
+		as_warn (_("ignoring fill value in absolute section"));
 	      abs_section_offset += repeat;
 	      goto getout;
 	    }
@@ -3412,7 +3445,10 @@ s_space (int mult)
 			  make_expr_symbol (&exp), (offsetT) 0, (char *) 0);
 	}
 
-      if (p)
+      if ((val.X_op != O_constant || val.X_add_number != 0) && in_bss ())
+	as_warn (_("ignoring fill value in section `%s'"),
+		 segment_name (now_seg));
+      else if (p)
 	*p = val.X_add_number;
     }
 
@@ -4213,15 +4249,6 @@ emit_expr_with_reloc (expressionS *exp,
 
   op = exp->X_op;
 
-  /* Allow `.word 0' in the absolute section.  */
-  if (now_seg == absolute_section)
-    {
-      if (op != O_constant || exp->X_add_number != 0)
-	as_bad (_("attempt to store value in absolute section"));
-      abs_section_offset += nbytes;
-      return;
-    }
-
   /* Handle a negative bignum.  */
   if (op == O_uminus
       && exp->X_add_number == 0
@@ -4271,6 +4298,20 @@ emit_expr_with_reloc (expressionS *exp,
       op = O_constant;
     }
 
+  /* Allow `.word 0' in the absolute section.  */
+  if (now_seg == absolute_section)
+    {
+      if (op != O_constant || exp->X_add_number != 0)
+	as_bad (_("attempt to store value in absolute section"));
+      abs_section_offset += nbytes;
+      return;
+    }
+
+  /* Allow `.word 0' in BSS style sections.  */
+  if ((op != O_constant || exp->X_add_number != 0) && in_bss ())
+    as_bad (_("attempt to store non-zero value in section `%s'"),
+	    segment_name (now_seg));
+
   p = frag_more ((int) nbytes);
 
   if (reloc != TC_PARSE_CONS_RETURN_NONE)
@@ -4854,6 +4895,21 @@ float_cons (/* Clobbers input_line-point
       return;
     }
 
+  if (now_seg == absolute_section)
+    {
+      as_bad (_("attempt to store float in absolute section"));
+      ignore_rest_of_line ();
+      return;
+    }
+
+  if (in_bss ())
+    {
+      as_bad (_("attempt to store float in section `%s'"),
+	      segment_name (now_seg));
+      ignore_rest_of_line ();
+      return;
+    }
+
 #ifdef md_flush_pending_output
   md_flush_pending_output ();
 #endif
@@ -5186,6 +5242,18 @@ emit_leb128_expr (expressionS *exp, int
       op = O_big;
     }
 
+  if (now_seg == absolute_section)
+    {
+      if (op != O_constant || exp->X_add_number != 0)
+	as_bad (_("attempt to store value in absolute section"));
+      abs_section_offset++;
+      return;
+    }
+
+  if ((op != O_constant || exp->X_add_number != 0) && in_bss ())
+    as_bad (_("attempt to store non-zero value in section `%s'"),
+	    segment_name (now_seg));
+
   /* Let check_eh_frame know that data is being emitted.  nbytes == -1 is
      a signal that this is leb128 data.  It shouldn't optimize this away.  */
   nbytes = (unsigned int) -1;
@@ -5255,6 +5323,10 @@ s_leb128 (int sign)
 static void
 stringer_append_char (int c, int bitsize)
 {
+  if (c && in_bss ())
+    as_bad (_("attempt to store non-empty string in section `%s'"),
+	    segment_name (now_seg));
+
   if (!target_big_endian)
     FRAG_APPEND_1_CHAR (c);
 
--- 2015-12-07/gas/testsuite/gas/elf/bad-bss.d
+++ 2015-12-07/gas/testsuite/gas/elf/bad-bss.d
@@ -0,0 +1,4 @@
+#name: bad .bss / .struct data allocation directives
+#source: bss.s
+#error-output: bad-bss.err
+#target: i?86-*-* x86_64-*-* ia64-*-* arm-*-* aarch64-*-*
--- 2015-12-07/gas/testsuite/gas/elf/bad-bss.err
+++ 2015-12-07/gas/testsuite/gas/elf/bad-bss.err
@@ -0,0 +1,63 @@
+.*bss\.s: Assembler messages:
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store float in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-empty string in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-empty string in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to fill section .\.bss. with non-zero value
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss.
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store float in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-empty string in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-empty string in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to fill section .\.bss\.local. with non-zero value
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.bss\.local.
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store float in section .\.private.
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-empty string in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-empty string in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to fill section .\.private. with non-zero value
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Error: attempt to store non-zero value in section .\.private.
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Warning: zero assumed.*
+.*bss\.s:[1-9][0-9]*: Error: attempt to store value in absolute section
+.*bss\.s:[1-9][0-9]*: Error: attempt to store value in absolute section
+.*bss\.s:[1-9][0-9]*: Error: attempt to store value in absolute section
+.*bss\.s:[1-9][0-9]*: Error: attempt to store float in absolute section
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in absolute section
+.*bss\.s:[1-9][0-9]*: Error: attempt to fill absolute section with non-zero value
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in absolute section
+.*bss\.s:[1-9][0-9]*: Warning: ignoring fill value in absolute section
+.*bss\.s:[1-9][0-9]*: Error: attempt to store value in absolute section
+.*bss\.s:[1-9][0-9]*: Error: attempt to store value in absolute section
--- 2015-12-07/gas/testsuite/gas/elf/bss.d
+++ 2015-12-07/gas/testsuite/gas/elf/bss.d
@@ -0,0 +1,24 @@
+#name: good .bss / .struct data allocation directives
+#as: --defsym okay=1
+#warning: Warning: zero assumed
+#readelf: -sSW
+#target: i?86-*-* x86_64-*-* ia64-*-* arm-*-* aarch64-*-*
+
+There are [1-9][0-9]* section headers, starting at offset 0x[0-9a-f]*:
+
+Section Headers:
+#...
+ *\[ [1-9]\] *\.bss        +NOBITS +0*0 +0[0-9a-f]* 0*(28|40) +0*0 +WA +0 +0 +32
+ *\[ [1-9]\] *\.bss\.local +NOBITS +0*0 +0[0-9a-f]* 0*(28|40) +0*0 +WA +0 +0 +32
+ *\[ [1-9]\] *\.private    +NOBITS +0*0 +0[0-9a-f]* 0*(28|40) +0*0 +WA +0 +0 +32
+#...
+Symbol table '\.symtab' contains [1-9][0-9]* entries:
+#...
+ *[0-9]*: 0*28 *0 NOTYPE *LOCAL *DEFAULT *[1-9] endof_bss
+#...
+ *[0-9]*: 0*28 *0 NOTYPE *LOCAL *DEFAULT *[1-9] endof_bss_local
+#...
+ *[0-9]*: 0*28 *0 NOTYPE *LOCAL *DEFAULT *[1-9] endof_private
+#...
+ *[0-9]*: 0*27 *0 NOTYPE *LOCAL *DEFAULT *ABS endof_struct
+#pass
--- 2015-12-07/gas/testsuite/gas/elf/bss.s
+++ 2015-12-07/gas/testsuite/gas/elf/bss.s
@@ -0,0 +1,56 @@
+	.macro	bss name
+
+	.long	0
+	.long	,
+
+	.balign	32
+
+	.ifnes "\name", "struct"
+	.ascii	""
+	.asciz	""
+	.endif
+
+	.fill	1, 1
+	.org	.+1
+	.skip	1
+	.sleb128
+	.sleb128 0
+	.uleb128
+	.uleb128 0
+
+	.ifndef okay
+
+	.long	1
+	.long	.
+	.long	x
+	.float	0.0
+
+	.balign	32, -1
+
+	.ifnes "\name", "struct"
+	.ascii	"0"
+	.asciz	"0"
+	.endif
+
+	.fill	1, 1, -1
+	.org	.+1, -1
+	.skip	1, -1
+	.sleb128 -1
+	.uleb128 1
+
+	.endif
+
+endof_\name:
+	.endm
+
+	.bss
+	bss	bss
+
+	.section .bss.local, "aw"
+	bss	bss_local
+
+	.section .private, "aw", %nobits
+	bss	private
+
+	.struct
+	bss	struct
--- 2015-12-07/gas/testsuite/gas/elf/elf.exp
+++ 2015-12-07/gas/testsuite/gas/elf/elf.exp
@@ -204,6 +204,8 @@ if { [is_elf_format] } then {
     run_dump_test "dwarf2-2"
     run_dump_test "dwarf2-3"
     run_dump_test "dwarf2-4"
+    run_dump_test "bss"
+    run_dump_test "bad-bss"
     run_dump_test "bad-section-flag"
     run_dump_test "bad-size"
     run_dump_test "bad-group"

Attachment: binutils-master-bss-alloc-directives.patch
Description: Text document