[PATCH] as: Replace the removed symbol with the versioned symbol
H.J. Lu
hjl.tools@gmail.com
Sun Aug 1 15:16:20 GMT 2021
When a symbol removed by .symver is used in relocation and there is one
and only one versioned symbol, don't remove the symbol. Instead, mark
it to be removed and replace the removed symbol used in relocation with
the versioned symbol before generating relocation.
PR gas/28157
* symbols.c (symbol_flags): Add removed.
(symbol_entry_find): Updated.
(symbol_mark_removed): New function.
(symbol_removed_p): Likewise.
* symbols.h (symbol_mark_removed): New prototype.
(symbol_removed_p): Likewise.
* write.c (write_relocs): Call obj_fixup_removed_symbol on
removed fixp->fx_addsy and fixp->fx_subsy if defined.
(set_symtab): Don't add a symbol if symbol_removed_p returns true.
* config/obj-elf.c (elf_frob_symbol): Don't remove the symbol
if it is used on relocation. Instead, mark it as to be removed
and issue an error if the symbol has more than one versioned name.
(elf_fixup_removed_symbol): New function.
* config/obj-elf.h (elf_fixup_removed_symbol): New prototype.
(obj_fixup_removed_symbol): New.
* testsuite/gas/symver/symver11.d: Updated expected error
message.
* testsuite/gas/symver/symver16.d: New file.
* testsuite/gas/symver/symver16.s: Likewise.
---
gas/config/obj-elf.c | 28 ++++++++++++++++++++++++++--
gas/config/obj-elf.h | 5 +++++
gas/symbols.c | 26 +++++++++++++++++++++++++-
gas/symbols.h | 2 ++
gas/testsuite/gas/symver/symver11.d | 2 +-
gas/testsuite/gas/symver/symver16.d | 13 +++++++++++++
gas/testsuite/gas/symver/symver16.s | 16 ++++++++++++++++
gas/write.c | 21 +++++++++++++++------
8 files changed, 103 insertions(+), 10 deletions(-)
create mode 100644 gas/testsuite/gas/symver/symver16.d
create mode 100644 gas/testsuite/gas/symver/symver16.s
diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
index 42a3851e772..a6087a21eb3 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -2705,7 +2705,7 @@ elf_frob_symbol (symbolS *symp, int *puntp)
S_SET_EXTERNAL (symp2);
}
- switch (symbol_get_obj (symp)->visibility)
+ switch (sy_obj->visibility)
{
case visibility_unchanged:
break;
@@ -2716,7 +2716,18 @@ elf_frob_symbol (symbolS *symp, int *puntp)
elfsym->internal_elf_sym.st_other |= STV_HIDDEN;
break;
case visibility_remove:
- symbol_remove (symp, &symbol_rootP, &symbol_lastP);
+ /* Don't remove the symbol if it is used in relocation.
+ Instead, mark it as to be removed and issue an error
+ if the symbol has more than one versioned name. */
+ if (symbol_used_in_reloc_p (symp))
+ {
+ if (sy_obj->versioned_name->next != NULL)
+ as_bad (_("symbol '%s' with multiple versions cannot be used in relocation"),
+ S_GET_NAME (symp));
+ symbol_mark_removed (symp);
+ }
+ else
+ symbol_remove (symp, &symbol_rootP, &symbol_lastP);
break;
case visibility_local:
S_CLEAR_EXTERNAL (symp);
@@ -2734,6 +2745,19 @@ elf_frob_symbol (symbolS *symp, int *puntp)
}
}
+/* Fix up SYMPP which has been marked to be removed by .symver. */
+
+void
+elf_fixup_removed_symbol (symbolS **sympp)
+{
+ symbolS *symp = *sympp;
+ struct elf_obj_sy *sy_obj = symbol_get_obj (symp);
+
+ /* Replace the removed symbol with the versioned symbol. */
+ symp = symbol_find (sy_obj->versioned_name->name);
+ *sympp = symp;
+}
+
struct group_list
{
asection **head; /* Section lists. */
diff --git a/gas/config/obj-elf.h b/gas/config/obj-elf.h
index d1fd3152998..763c58dfcad 100644
--- a/gas/config/obj-elf.h
+++ b/gas/config/obj-elf.h
@@ -273,6 +273,11 @@ extern void elf_frob_symbol (symbolS *, int *);
#define obj_frob_symbol(symp, punt) elf_frob_symbol (symp, &punt)
#endif
+extern void elf_fixup_removed_symbol (symbolS **);
+#ifndef obj_fixup_removed_symbol
+#define obj_fixup_removed_symbol(sympp) elf_fixup_removed_symbol (sympp)
+#endif
+
extern void elf_pop_insert (void);
#ifndef obj_pop_insert
#define obj_pop_insert() elf_pop_insert()
diff --git a/gas/symbols.c b/gas/symbols.c
index 302eb4bd6f7..3cb9425c4ce 100644
--- a/gas/symbols.c
+++ b/gas/symbols.c
@@ -78,6 +78,10 @@ struct symbol_flags
before. It is cleared as soon as any direct reference to the
symbol is present. */
unsigned int weakrefd : 1;
+
+ /* Whether the symbol has been marked to be removed by a .symver
+ directive. */
+ unsigned int removed : 1;
};
/* A pointer in the symbol may point to either a complete symbol
@@ -194,7 +198,7 @@ static void *
symbol_entry_find (htab_t table, const char *name)
{
hashval_t hash = htab_hash_string (name);
- symbol_entry_t needle = { { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
+ symbol_entry_t needle = { { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
hash, name, 0, 0, 0 } };
return htab_find_with_hash (table, &needle, hash);
}
@@ -2807,6 +2811,26 @@ symbol_written_p (symbolS *s)
return s->flags.written;
}
+/* Mark a symbol as to be removed. */
+
+void
+symbol_mark_removed (symbolS *s)
+{
+ if (s->flags.local_symbol)
+ return;
+ s->flags.removed = 1;
+}
+
+/* Return whether a symbol has been marked to be removed. */
+
+int
+symbol_removed_p (symbolS *s)
+{
+ if (s->flags.local_symbol)
+ return 0;
+ return s->flags.removed;
+}
+
/* Mark a symbol has having been resolved. */
void
diff --git a/gas/symbols.h b/gas/symbols.h
index 91f69882a7e..317252c7fa1 100644
--- a/gas/symbols.h
+++ b/gas/symbols.h
@@ -193,6 +193,8 @@ extern int symbol_mri_common_p (symbolS *);
extern void symbol_mark_written (symbolS *);
extern void symbol_clear_written (symbolS *);
extern int symbol_written_p (symbolS *);
+extern void symbol_mark_removed (symbolS *);
+extern int symbol_removed_p (symbolS *);
extern void symbol_mark_resolved (symbolS *);
extern int symbol_resolved_p (symbolS *);
extern int symbol_section_p (symbolS *);
diff --git a/gas/testsuite/gas/symver/symver11.d b/gas/testsuite/gas/symver/symver11.d
index caa76e167da..10f8ef810b2 100644
--- a/gas/testsuite/gas/symver/symver11.d
+++ b/gas/testsuite/gas/symver/symver11.d
@@ -1,2 +1,2 @@
#name: symver symver11
-#error: .*symbol cannot be used on reloc
+#error: .*: symbol 'foo' with multiple versions cannot be used in relocation
diff --git a/gas/testsuite/gas/symver/symver16.d b/gas/testsuite/gas/symver/symver16.d
new file mode 100644
index 00000000000..cdf0ddde57d
--- /dev/null
+++ b/gas/testsuite/gas/symver/symver16.d
@@ -0,0 +1,13 @@
+#name: symver symver16
+#readelf: -srW
+
+#...
+Relocation section .*
+#...
+[0-9a-f]+[ \t]+[0-9a-f]+[ \t]+R_.*[ \t]+[0-9a-f]+[ \t]+foo@@VERS_1.*
+#...
+[0-9a-f]+[ \t]+[0-9a-f]+[ \t]+R_.*[ \t]+[0-9a-f]+[ \t]+bar@VERS_1.*
+#...
+ +[0-9]+: 0+ +1 +OBJECT +GLOBAL +DEFAULT +[0-9]+ +foo@@VERS_1
+ +[0-9]+: 0+1 +1 +OBJECT +GLOBAL +DEFAULT +[0-9]+ +bar@VERS_1
+#pass
diff --git a/gas/testsuite/gas/symver/symver16.s b/gas/testsuite/gas/symver/symver16.s
new file mode 100644
index 00000000000..df330fd4f25
--- /dev/null
+++ b/gas/testsuite/gas/symver/symver16.s
@@ -0,0 +1,16 @@
+ .data
+ .type foo,%object
+foo:
+ .byte 0
+ .size foo,.-foo
+ .globl foo
+ .symver foo,foo@@VERS_1,remove
+ .globl bar
+ .symver bar,bar@VERS_1,remove
+ .type bar,%object
+bar:
+ .byte 0
+ .size bar,.-bar
+ .balign 8
+ .dc.a foo
+ .dc.a bar
diff --git a/gas/write.c b/gas/write.c
index 253dfc476f8..e2c7bf29249 100644
--- a/gas/write.c
+++ b/gas/write.c
@@ -1289,6 +1289,13 @@ write_relocs (bfd *abfd ATTRIBUTE_UNUSED, asection *sec,
as_bad_where (fixp->fx_file, fixp->fx_line,
_("internal error: fixup not contained within frag"));
+#ifdef obj_fixup_removed_symbol
+ if (fixp->fx_addsy && symbol_removed_p (fixp->fx_addsy))
+ obj_fixup_removed_symbol (&fixp->fx_addsy);
+ if (fixp->fx_subsy && symbol_removed_p (fixp->fx_subsy))
+ obj_fixup_removed_symbol (&fixp->fx_subsy);
+#endif
+
#ifndef RELOC_EXPANSION_POSSIBLE
*reloc = tc_gen_reloc (sec, fixp);
#else
@@ -1755,9 +1762,10 @@ set_symtab (void)
two. Generate unused section symbols only if needed. */
nsyms = 0;
for (symp = symbol_rootP; symp; symp = symbol_next (symp))
- if (bfd_keep_unused_section_symbols (stdoutput)
- || !symbol_section_p (symp)
- || symbol_used_in_reloc_p (symp))
+ if (!symbol_removed_p (symp)
+ && (bfd_keep_unused_section_symbols (stdoutput)
+ || !symbol_section_p (symp)
+ || symbol_used_in_reloc_p (symp)))
nsyms++;
if (nsyms)
@@ -1768,9 +1776,10 @@ set_symtab (void)
asympp = (asymbol **) bfd_alloc (stdoutput, amt);
symp = symbol_rootP;
for (i = 0; i < nsyms; symp = symbol_next (symp))
- if (bfd_keep_unused_section_symbols (stdoutput)
- || !symbol_section_p (symp)
- || symbol_used_in_reloc_p (symp))
+ if (!symbol_removed_p (symp)
+ && (bfd_keep_unused_section_symbols (stdoutput)
+ || !symbol_section_p (symp)
+ || symbol_used_in_reloc_p (symp)))
{
asympp[i] = symbol_get_bfdsym (symp);
if (asympp[i]->flags != BSF_SECTION_SYM
--
2.31.1
More information about the Binutils
mailing list