ppc476 gas warn on data in code sections

	* config/tc-ppc.c (warn_476, last_insn, last_seg, last_subseg):
	New static vars.
	(md_longopts, md_parse_option, md_show_usage): Add --ppc476-workaround.
	(ppc_elf_cons_fix_check): New function.
	(md_assemble): Set last_insn, last_seg, last_subseg.
	(ppc_byte, md_apply_fix): Handle warn_476.
	* config/tc-ppc.h (TC_CONS_FIX_CHECK): Define.
	(ppc_elf_cons_fix_check): Declare.
	* read.c (cons_worker): Invoke TC_CONS_FIX_CHECK.

4 files changed, 87 insertions, 1 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 36242a8..b6e2b84 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,5 +1,17 @@
 2014-04-09  Alan Modra  <amodra@gmail.com>
 
+	* config/tc-ppc.c (warn_476, last_insn, last_seg, last_subseg):
+	New static vars.
+	(md_longopts, md_parse_option, md_show_usage): Add --ppc476-workaround.
+	(ppc_elf_cons_fix_check): New function.
+	(md_assemble): Set last_insn, last_seg, last_subseg.
+	(ppc_byte, md_apply_fix): Handle warn_476.
+	* config/tc-ppc.h (TC_CONS_FIX_CHECK): Define.
+	(ppc_elf_cons_fix_check): Declare.
+	* read.c (cons_worker): Invoke TC_CONS_FIX_CHECK.
+
+2014-04-09  Alan Modra  <amodra@gmail.com>
+
 	* gas/config/tc-alpha.h (TC_CONS_FIX_NEW): Add RELOC parameter.
 	* gas/config/tc-arc.c (arc_cons_fix_new): Add reloc parameter.
 	* gas/config/tc-arc.h (arc_cons_fix_new): Update prototype.
diff --git a/gas/config/tc-ppc.c b/gas/config/tc-ppc.c
index 5cfe1db..2c8ce6a 100644
--- a/gas/config/tc-ppc.c
+++ b/gas/config/tc-ppc.c
@@ -211,6 +211,12 @@ enum {
   has_large_toc_reloc = 1,
   has_small_toc_reloc = 2
 } toc_reloc_types;
+
+/* Warn on emitting data to code sections.  */
+int warn_476;
+unsigned long last_insn;
+segT last_seg;
+subsegT last_subseg;
 
 /* The target specific pseudo-ops which we support.  */
 
@@ -1065,6 +1071,8 @@ const char *const md_shortopts = "um:";
 #define OPTION_NOPS (OPTION_MD_BASE + 0)
 const struct option md_longopts[] = {
   {"nops", required_argument, NULL, OPTION_NOPS},
+  {"ppc476-workaround", no_argument, &warn_476, 1},
+  {"no-ppc476-workaround", no_argument, &warn_476, 0},
   {NULL, no_argument, NULL, 0}
 };
 const size_t md_longopts_size = sizeof (md_longopts);
@@ -1243,6 +1251,9 @@ md_parse_option (int c, char *arg)
       }
       break;
 
+    case 0:
+      break;
+
     default:
       return 0;
     }
@@ -1316,7 +1327,8 @@ PowerPC options:\n\
 -Qy, -Qn                ignored\n"));
 #endif
   fprintf (stream, _("\
--nops=count             when aligning, more than COUNT nops uses a branch\n"));
+-nops=count             when aligning, more than COUNT nops uses a branch\n\
+-ppc476-workaround      warn if emitting data to code sections\n"));
 }
 
 /* Set ppc_cpu if it is not already set.  */
@@ -2056,6 +2068,37 @@ ppc_elf_parse_cons (expressionS *exp, unsigned int nbytes)
   return BFD_RELOC_NONE;
 }
 
+/* Warn when emitting data to code sections, unless we are emitting
+   a relocation that ld --ppc476-workaround uses to recognise data
+   *and* there was an unconditional branch prior to the data.  */
+
+void
+ppc_elf_cons_fix_check (expressionS *exp ATTRIBUTE_UNUSED,
+			unsigned int nbytes, fixS *fix)
+{
+  if (warn_476
+      && (now_seg->flags & SEC_CODE) != 0
+      && (nbytes != 4
+	  || fix == NULL
+	  || !(fix->fx_r_type == BFD_RELOC_32
+	       || fix->fx_r_type == BFD_RELOC_CTOR
+	       || fix->fx_r_type == BFD_RELOC_32_PCREL)
+	  || !(last_seg == now_seg && last_subseg == now_subseg)
+	  || !((last_insn & (0x3f << 26)) == (18u << 26)
+	       || ((last_insn & (0x3f << 26)) == (16u << 26)
+		   && (last_insn & (0x14 << 21)) == (0x14 << 21))
+	       || ((last_insn & (0x3f << 26)) == (19u << 26)
+		   && (last_insn & (0x3ff << 1)) == (16u << 1)
+		   && (last_insn & (0x14 << 21)) == (0x14 << 21)))))
+    {
+      /* Flag that we've warned.  */
+      if (fix != NULL)
+	fix->fx_tcbit = 1;
+
+      as_warn (_("data in executable section"));
+    }
+}
+
 /* Solaris pseduo op to change to the .rodata section.  */
 static void
 ppc_elf_rdata (int xxx)
@@ -3345,6 +3388,9 @@ md_assemble (char *str)
   frag_now->insn_addr = addr_mod;
   frag_now->has_code = 1;
   md_number_to_chars (f, insn, insn_length);
+  last_insn = insn;
+  last_seg = now_seg;
+  last_subseg = now_subseg;
 
 #ifdef OBJ_ELF
   dwarf2_emit_insn (insn_length);
@@ -3502,6 +3548,8 @@ ppc_section_flags (flagword flags, bfd_vma attr ATTRIBUTE_UNUSED, int type)
 static void
 ppc_byte (int ignore ATTRIBUTE_UNUSED)
 {
+  int count = 0;
+
   if (*input_line_pointer != '\"')
     {
       cons (1);
@@ -3525,8 +3573,11 @@ ppc_byte (int ignore ATTRIBUTE_UNUSED)
 	}
 
       FRAG_APPEND_1_CHAR (c);
+      ++count;
     }
 
+  if (warn_476 && count != 0 && (now_seg->flags & SEC_CODE) != 0)
+    as_warn (_("data in executable section"));
   demand_empty_rest_of_line ();
 }
 
@@ -6924,6 +6975,16 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg)
       if (fixP->fx_size && APPLY_RELOC)
 	md_number_to_chars (fixP->fx_frag->fr_literal + fixP->fx_where,
 			    fieldval, fixP->fx_size);
+      if (warn_476
+	  && (seg->flags & SEC_CODE) != 0
+	  && fixP->fx_size == 4
+	  && fixP->fx_done
+	  && !fixP->fx_tcbit
+	  && (fixP->fx_r_type == BFD_RELOC_32
+	      || fixP->fx_r_type == BFD_RELOC_CTOR
+	      || fixP->fx_r_type == BFD_RELOC_32_PCREL))
+	as_warn_where (fixP->fx_file, fixP->fx_line,
+		       _("data in executable section"));
     }
 
   /* We are only able to convert some relocs to pc-relative.  */
diff --git a/gas/config/tc-ppc.h b/gas/config/tc-ppc.h
index a5e69ca..3cd9bf1 100644
--- a/gas/config/tc-ppc.h
+++ b/gas/config/tc-ppc.h
@@ -235,6 +235,10 @@ extern int ppc_fix_adjustable (struct fix *);
   ppc_elf_parse_cons (EXP, NBYTES)
 extern bfd_reloc_code_real_type ppc_elf_parse_cons (expressionS *,
 						    unsigned int);
+#define TC_CONS_FIX_CHECK(EXP, NBYTES, FIX) \
+  ppc_elf_cons_fix_check (EXP, NBYTES, FIX)
+extern void ppc_elf_cons_fix_check (expressionS *, unsigned int, struct fix *);
+
 #define tc_frob_file_before_adjust ppc_frob_file_before_adjust
 extern void ppc_frob_file_before_adjust (void);
 
diff --git a/gas/read.c b/gas/read.c
index 306f7ec..066783c 100644
--- a/gas/read.c
+++ b/gas/read.c
@@ -3918,6 +3918,12 @@ cons_worker (int nbytes,	/* 1=.byte, 2=.word, 4=.long.  */
   do
     {
       TC_PARSE_CONS_RETURN_TYPE ret = TC_PARSE_CONS_RETURN_NONE;
+#ifdef TC_CONS_FIX_CHECK
+      fixS **cur_fix = &frchain_now->fix_tail;
+
+      if (*cur_fix != NULL)
+	cur_fix = &(*cur_fix)->fx_next;
+#endif
 
 #ifdef TC_M68K
       if (flag_m68k_mri)
@@ -3942,6 +3948,9 @@ cons_worker (int nbytes,	/* 1=.byte, 2=.word, 4=.long.  */
 	    as_fatal (_("rva without symbol"));
 	}
       emit_expr_with_reloc (&exp, (unsigned int) nbytes, ret);
+#ifdef TC_CONS_FIX_CHECK
+      TC_CONS_FIX_CHECK (&exp, nbytes, *cur_fix);
+#endif
       ++c;
     }
   while (*input_line_pointer++ == ',');