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ld: optionally emit _etext last, before .data

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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.
This commit is contained in:
Hans-Peter Nilsson
2020-07-19 06:08:07 +02:00
parent e10a07b32d
commit 4609ada49f
4 changed files with 21 additions and 4 deletions
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6
ld/ChangeLog
View File

@@ -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.

4
ld/emulparams/elf64mmix.sh
View File

@@ -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 :
{

13
ld/scripttempl/elf.sc
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@@ -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}};}}}

2
ld/testsuite/ld-mmix/sec-1.d
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@@ -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