ld: optionally emit _etext last, before .data

So, here's my suggestion for making _init .. __etext cover .text +
.rodata (including things like the read-only exception tables) for
elf64mmix.  A quick web search gives that __etext (and friends) isn't
well defined, so each target can interpret the "end of text segment"
to their own liking.  It seems likely this change is also a better fit
than the default for other ports, at least those with .rodata after
.text in the same segment.

The presence of a separate rodata-segment is optional (and not true
for elf64mmix).  This is reflected in the name as SEPARATE_TEXT /
SEPARATE_CODE isn't considered, to keep it simple; each target has to
make sure their settings of variables make sense.

ld:
	* scripttempl/elf.sc (ETEXT_LAST_IN_RODATA_SEGMENT): New variable.
	* emulparams/elf64mmix.sh (ETEXT_LAST_IN_RODATA_SEGMENT): Define.
	* testsuite/ld-mmix/sec-1.d: Adjust.

4 files changed, 21 insertions, 4 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 51a4e9c..37a94aa 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,9 @@
+2020-07-19  Hans-Peter Nilsson  <hp@bitrange.com>
+
+	* scripttempl/elf.sc (ETEXT_LAST_IN_RODATA_SEGMENT): New variable.
+	* emulparams/elf64mmix.sh (ETEXT_LAST_IN_RODATA_SEGMENT): Define.
+	* testsuite/ld-mmix/sec-1.d: Adjust.
+
 2020-07-19  Alan Modra  <amodra@gmail.com>
 
 	* emultempl/ppc64elf.em (power10-stubs): Accept optional "auto" arg.
diff --git a/ld/emulparams/elf64mmix.sh b/ld/emulparams/elf64mmix.sh
index dffc6cc..75e24be 100644
--- a/ld/emulparams/elf64mmix.sh
+++ b/ld/emulparams/elf64mmix.sh
@@ -44,6 +44,10 @@ ${RELOCATING+
  PROVIDE (Main = DEFINED (Main) ? Main : (DEFINED (_start) ? _start : _start.));
 }"
 
+# We need a symbol at the end of the read-only data, which is
+# colocated with the code.  We make __etext fit.
+ETEXT_LAST_IN_RODATA_SEGMENT=" "
+
 OTHER_SECTIONS='
  .MMIX.reg_contents :
  {
diff --git a/ld/scripttempl/elf.sc b/ld/scripttempl/elf.sc
index 0b8b32a..eb74743 100644
--- a/ld/scripttempl/elf.sc
+++ b/ld/scripttempl/elf.sc
@@ -62,6 +62,9 @@
 #	OTHER_SYMBOLS - symbols to place right at the end of the script.
 #	ETEXT_NAME - name of a symbol for the end of the text section,
 #		normally etext.
+#	ETEXT_LAST_IN_RODATA_SEGMENT - emit ETEXT_NAME after all sections in
+#		the read-only data segment (which may or may not be equal to
+#		the code segment), instead of after just the code parts.
 #	SEPARATE_CODE - if set, .text and similar sections containing
 #		actual machine instructions must be in wholly disjoint
 #		pages from any other data, including headers
@@ -526,9 +529,9 @@ cat <<EOF
     KEEP (*(SORT_NONE(.fini)))
     ${RELOCATING+${FINI_END}}
   } ${FILL}
-  ${RELOCATING+PROVIDE (__${ETEXT_NAME} = .);}
-  ${RELOCATING+PROVIDE (_${ETEXT_NAME} = .);}
-  ${RELOCATING+PROVIDE (${ETEXT_NAME} = .);}
+  ${RELOCATING+${ETEXT_LAST_IN_RODATA_SEGMENT-PROVIDE (__${ETEXT_NAME} = .);}}
+  ${RELOCATING+${ETEXT_LAST_IN_RODATA_SEGMENT-PROVIDE (_${ETEXT_NAME} = .);}}
+  ${RELOCATING+${ETEXT_LAST_IN_RODATA_SEGMENT-PROVIDE (${ETEXT_NAME} = .);}}
   ${RELOCATING+${TEXT_SEGMENT_ALIGN}}
 EOF
 
@@ -574,6 +577,10 @@ cat <<EOF
   .exception_ranges ${RELOCATING-0} : ONLY_IF_RO { *(.exception_ranges${RELOCATING+*}) }
   ${TEXT_PLT+${PLT_NEXT_DATA+${PLT} ${OTHER_PLT_SECTIONS}}}
 
+  ${RELOCATING+${ETEXT_LAST_IN_RODATA_SEGMENT+PROVIDE (__${ETEXT_NAME} = .);}}
+  ${RELOCATING+${ETEXT_LAST_IN_RODATA_SEGMENT+PROVIDE (_${ETEXT_NAME} = .);}}
+  ${RELOCATING+${ETEXT_LAST_IN_RODATA_SEGMENT+PROVIDE (${ETEXT_NAME} = .);}}
+
   ${RELOCATING+/* Adjust the address for the data segment.  We want to adjust up to
      the same address within the page on the next page up.  */}
   ${CREATE_SHLIB-${CREATE_PIE-${RELOCATING+. = ${DATA_ADDR-${DATA_SEGMENT_ALIGN}};}}}
diff --git a/ld/testsuite/ld-mmix/sec-1.d b/ld/testsuite/ld-mmix/sec-1.d
index 5e31b3f..6f82c8e 100644
--- a/ld/testsuite/ld-mmix/sec-1.d
+++ b/ld/testsuite/ld-mmix/sec-1.d
@@ -24,7 +24,7 @@ Idx Name          Size      VMA               LMA               File off  Algn
 
 SYMBOL TABLE:
 #...
-0+1d g +\*ABS\* _etext
+0+30 g +\*ABS\* _etext
 #...
 2000000000000013 g +\*ABS\* __bss_start
 2000000000000013 g +\*ABS\* _edata