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[PATCH] GAS: Keep symbols in their own section [PR27566]

Xiao Zeng zengxiao@eswincomputing.com
Tue Oct 22 09:38:18 GMT 2024 
PR27566 is categorized under ld:
<https://sourceware.org/bugzilla/show_bug.cgi?id=27566>
but the root cause of this issue is in gas.

The following assembly example is provided:
        .section        .rodata
        .globl Sym
        .type  Sym, @object
        .set   Sym, . + 0x1200
        .size	Sym, 8

readelf reads ELF information:
Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
  [ 4] .rodata           PROGBITS        0000000000000000 000040 001208 00   A  0   0  1

Symbol table '.symtab' contains 7 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     6: 0000000000001200     8 OBJECT  GLOBAL DEFAULT    4 Sym

The Sym belongs to the .rodata section, but the size of .rodata is 0.

        PR gas/27566
	* write.c (size_seg): Update section size.
	* testsuite/gas/elf/elf.exp: New test.
	* testsuite/gas/elf/pr27566.d: New file.
	* testsuite/gas/elf/pr27566.s: Likewise.

Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com>
---
 gas/testsuite/gas/elf/elf.exp   |  1 +
 gas/testsuite/gas/elf/pr27566.d | 11 +++++++++++
 gas/testsuite/gas/elf/pr27566.s |  5 +++++
 gas/write.c                     |  7 +++++++
 4 files changed, 24 insertions(+)
 create mode 100644 gas/testsuite/gas/elf/pr27566.d
 create mode 100644 gas/testsuite/gas/elf/pr27566.s

diff --git a/gas/testsuite/gas/elf/elf.exp b/gas/testsuite/gas/elf/elf.exp
index c828c3af25c..6a69acbc109 100644
--- a/gas/testsuite/gas/elf/elf.exp
+++ b/gas/testsuite/gas/elf/elf.exp
@@ -387,4 +387,5 @@ if { [is_elf_format] } then {
     run_dump_test "bignums" $dump_opts
     run_dump_test "section-symbol-redef"
     run_dump_test "pr27228"
+    run_dump_test "pr27566"
 }
diff --git a/gas/testsuite/gas/elf/pr27566.d b/gas/testsuite/gas/elf/pr27566.d
new file mode 100644
index 00000000000..75268cefb20
--- /dev/null
+++ b/gas/testsuite/gas/elf/pr27566.d
@@ -0,0 +1,11 @@
+#as:
+#name: Keep symbols in their own section (PR 27566)
+#readelf: -S --wide
+
+There are [0-9]+ section headers, starting at offset 0x[0-9a-f]+:
+
+Section Headers:
+ +\[Nr\] Name +Type +Addr(ess|) +Off +Size +ES +Flg +Lk +Inf +Al
+#...
+ *\[ [1-9]\] *\.rodata +PROGBITS +0*0 +0[0-9a-f]* +0*1208 .*
+#pass
diff --git a/gas/testsuite/gas/elf/pr27566.s b/gas/testsuite/gas/elf/pr27566.s
new file mode 100644
index 00000000000..4232df21494
--- /dev/null
+++ b/gas/testsuite/gas/elf/pr27566.s
@@ -0,0 +1,5 @@
+        .section        .rodata
+        .globl Sym
+        .type  Sym, @object
+        .set   Sym, . + 0x1200
+        .size	Sym, 8
diff --git a/gas/write.c b/gas/write.c
index 18cf18fc830..7f69d7aad44 100644
--- a/gas/write.c
+++ b/gas/write.c
@@ -559,6 +559,7 @@ size_seg (bfd *abfd ATTRIBUTE_UNUSED, asection *sec, void *xxx ATTRIBUTE_UNUSED)
   segment_info_type *seginfo;
   int x;
   valueT size, newsize;
+  symbolS *symp;
 
   subseg_change (sec, 0);
 
@@ -577,6 +578,12 @@ size_seg (bfd *abfd ATTRIBUTE_UNUSED, asection *sec, void *xxx ATTRIBUTE_UNUSED)
   else
     size = 0;
 
+  /* Keep symbols in their own section.  */
+  for (symp = symbol_rootP; symp; symp = symbol_next (symp))
+    if (S_GET_SEGMENT (symp) == sec
+	&& size < (S_GET_VALUE (symp) + S_GET_SIZE (symp)))
+      size = S_GET_VALUE (symp) + S_GET_SIZE (symp);
+
   flags = bfd_section_flags (sec);
   if (size == 0 && bfd_section_size (sec) != 0 &&
     (flags & SEC_HAS_CONTENTS) != 0)
-- 
2.17.1
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