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Re: [PATCH] gold: Ignore definition from a dynamic object for __start/__stop
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Cary Coutant <ccoutant at gmail dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Wed, 8 Nov 2017 16:01:46 -0800
- Subject: Re: [PATCH] gold: Ignore definition from a dynamic object for __start/__stop
- Authentication-results: sourceware.org; auth=none
- References: <20171018132021.GA4627@gmail.com> <CAJimCsEYhYtcPosB6vjsUsp02G69KKgn3MZ9=a=5XUowcx6diA@mail.gmail.com> <CAMe9rOoC=tOzrQJwdY=esUJpyE4n5d19NKLRutk066F9SJHMtg@mail.gmail.com> <CAJimCsFQiqTWALj4F8Ko7b_PhNuyFUqc8PmUW-5KGpD-kDD5eA@mail.gmail.com> <CAMe9rOqiJ4s9+oWM6XpL=r3cawTDR+o1Myn9nargOiN+_pNq9g@mail.gmail.com> <CAMe9rOq0TrC=2Rtqr+bVktdOrdH5zzz04Mw_ojTieub9sGmZVA@mail.gmail.com> <CAJimCsGSUr=+H3oc2zbOm2Ln0_WDGY_G0RDbCiuiWtW-fkcChQ@mail.gmail.com>
On Wed, Nov 8, 2017 at 3:50 PM, Cary Coutant <ccoutant@gmail.com> wrote:
> + // Skip if the old definition is from a regular object.
> + if (!oldsym->is_from_dynobj())
> + return NULL;
> +
> + // If the symbol has the hidden or internal visibility, ignore
> + // definition and reference from a dynamic object.
> + if ((visibility == elfcpp::STV_HIDDEN
> + || visibility == elfcpp::STV_INTERNAL)
> + && !oldsym->in_reg())
>
> s/the hidden/hidden/
>
> The last if statement really just ignores the symbol if it hasn't been
> referenced in a regular object. The first if statement takes care of
> the case where the definition was in a dynamic object.
>
> OK with updated comment.
>
This is what I am checking in.
H.J.
From 33f692f6bffedfb5477eacbf82eb80ed8090b5fb Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 8 Nov 2017 15:56:54 -0800
Subject: [PATCH] gold: Ignore def/ref from a dynamic object for special
symbols
Since special symbol must be defined in a regular object, definition
from a dynamic object should be ignored. If special symbol has the
hidden or internal visibility, reference from a dynamic object should
also be ignored. Also __start and __stop symbols in a dynamic object
shouldn't be preempted.
PR gold/22291
* layout.cc (Layout::define_section_symbols): Use STV_PROTECTED
for __start and __stop symbols.
* symtab.cc (Symbol_table::define_special_symbol): Add an
argument, visibility. Ignore definition and reference from
a dynamic object, depending on visibility.
(Symbol_table::do_define_in_output_data): Pass visibility to
define_special_symbol.
(Symbol_table::do_define_in_output_segment): Likewise.
(Symbol_table::do_define_as_constant): Likewise.
(Symbol_table::add_undefined_symbol_from_command_line): Pass
STV_DEFAULT to define_special_symbol.
* symtab.h (Symbol_table::define_special_symbol): Add an
argument, visibility.
---
gold/ChangeLog | 17 +++++++++++++++++
gold/layout.cc | 4 ++--
gold/symtab.cc | 48 +++++++++++++++++++++++++++++++++++++++---------
gold/symtab.h | 3 ++-
4 files changed, 60 insertions(+), 12 deletions(-)
diff --git a/gold/ChangeLog b/gold/ChangeLog
index c4c171d785..bd842a67d8 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,20 @@
+2017-11-08 H.J. Lu <hongjiu.lu@intel.com>
+
+ PR gold/22291
+ * layout.cc (Layout::define_section_symbols): Use STV_PROTECTED
+ for __start and __stop symbols.
+ * symtab.cc (Symbol_table::define_special_symbol): Add an
+ argument, visibility. Ignore definition and reference from
+ a dynamic object, depending on visibility.
+ (Symbol_table::do_define_in_output_data): Pass visibility to
+ define_special_symbol.
+ (Symbol_table::do_define_in_output_segment): Likewise.
+ (Symbol_table::do_define_as_constant): Likewise.
+ (Symbol_table::add_undefined_symbol_from_command_line): Pass
+ STV_DEFAULT to define_special_symbol.
+ * symtab.h (Symbol_table::define_special_symbol): Add an
+ argument, visibility.
+
2017-11-08 James Clarke <jrtc27@jrtc27.com>
PR gold/22266
diff --git a/gold/layout.cc b/gold/layout.cc
index 15c54344de..351c4b4d4f 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -2252,7 +2252,7 @@ Layout::define_section_symbols(Symbol_table* symtab)
0, // symsize
elfcpp::STT_NOTYPE,
elfcpp::STB_GLOBAL,
- elfcpp::STV_DEFAULT,
+ elfcpp::STV_PROTECTED,
0, // nonvis
false, // offset_is_from_end
true); // only_if_ref
@@ -2265,7 +2265,7 @@ Layout::define_section_symbols(Symbol_table* symtab)
0, // symsize
elfcpp::STT_NOTYPE,
elfcpp::STB_GLOBAL,
- elfcpp::STV_DEFAULT,
+ elfcpp::STV_PROTECTED,
0, // nonvis
true, // offset_is_from_end
true); // only_if_ref
diff --git a/gold/symtab.cc b/gold/symtab.cc
index 7ebcd6b568..d1f71e02d0 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -1761,6 +1761,7 @@ template<int size, bool big_endian>
Sized_symbol<size>*
Symbol_table::define_special_symbol(const char** pname, const char** pversion,
bool only_if_ref,
+ elfcpp::STV visibility,
Sized_symbol<size>** poldsym,
bool* resolve_oldsym, bool is_forced_local)
{
@@ -1799,8 +1800,21 @@ Symbol_table::define_special_symbol(const char** pname, const char** pversion,
oldsym = this->lookup(*pname, *pversion);
if (oldsym == NULL && is_default_version)
oldsym = this->lookup(*pname, NULL);
- if (oldsym == NULL || !oldsym->is_undefined())
+ if (oldsym == NULL)
return NULL;
+ if (!oldsym->is_undefined())
+ {
+ // Skip if the old definition is from a regular object.
+ if (!oldsym->is_from_dynobj())
+ return NULL;
+
+ // If the symbol has hidden or internal visibility, ignore
+ // definition and reference from a dynamic object.
+ if ((visibility == elfcpp::STV_HIDDEN
+ || visibility == elfcpp::STV_INTERNAL)
+ && !oldsym->in_reg())
+ return NULL;
+ }
*pname = oldsym->name();
if (is_default_version)
@@ -1975,7 +1989,9 @@ Symbol_table::do_define_in_output_data(
{
#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
sym = this->define_special_symbol<size, true>(&name, &version,
- only_if_ref, &oldsym,
+ only_if_ref,
+ visibility,
+ &oldsym,
&resolve_oldsym,
is_forced_local);
#else
@@ -1986,7 +2002,9 @@ Symbol_table::do_define_in_output_data(
{
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
sym = this->define_special_symbol<size, false>(&name, &version,
- only_if_ref, &oldsym,
+ only_if_ref,
+ visibility,
+ &oldsym,
&resolve_oldsym,
is_forced_local);
#else
@@ -2094,7 +2112,9 @@ Symbol_table::do_define_in_output_segment(
{
#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
sym = this->define_special_symbol<size, true>(&name, &version,
- only_if_ref, &oldsym,
+ only_if_ref,
+ visibility,
+ &oldsym,
&resolve_oldsym,
is_forced_local);
#else
@@ -2105,7 +2125,9 @@ Symbol_table::do_define_in_output_segment(
{
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
sym = this->define_special_symbol<size, false>(&name, &version,
- only_if_ref, &oldsym,
+ only_if_ref,
+ visibility,
+ &oldsym,
&resolve_oldsym,
is_forced_local);
#else
@@ -2211,7 +2233,9 @@ Symbol_table::do_define_as_constant(
{
#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
sym = this->define_special_symbol<size, true>(&name, &version,
- only_if_ref, &oldsym,
+ only_if_ref,
+ visibility,
+ &oldsym,
&resolve_oldsym,
is_forced_local);
#else
@@ -2222,7 +2246,9 @@ Symbol_table::do_define_as_constant(
{
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
sym = this->define_special_symbol<size, false>(&name, &version,
- only_if_ref, &oldsym,
+ only_if_ref,
+ visibility,
+ &oldsym,
&resolve_oldsym,
is_forced_local);
#else
@@ -2449,7 +2475,9 @@ Symbol_table::add_undefined_symbol_from_command_line(const char* name)
{
#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
sym = this->define_special_symbol<size, true>(&name, &version,
- false, &oldsym,
+ false,
+ elfcpp::STV_DEFAULT,
+ &oldsym,
&resolve_oldsym,
false);
#else
@@ -2460,7 +2488,9 @@ Symbol_table::add_undefined_symbol_from_command_line(const char* name)
{
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
sym = this->define_special_symbol<size, false>(&name, &version,
- false, &oldsym,
+ false,
+ elfcpp::STV_DEFAULT,
+ &oldsym,
&resolve_oldsym,
false);
#else
diff --git a/gold/symtab.h b/gold/symtab.h
index a67d5eb90d..edf1c1729c 100644
--- a/gold/symtab.h
+++ b/gold/symtab.h
@@ -1830,7 +1830,8 @@ class Symbol_table
template<int size, bool big_endian>
Sized_symbol<size>*
define_special_symbol(const char** pname, const char** pversion,
- bool only_if_ref, Sized_symbol<size>** poldsym,
+ bool only_if_ref, elfcpp::STV visibility,
+ Sized_symbol<size>** poldsym,
bool* resolve_oldsym, bool is_forced_local);
// Define a symbol in an Output_data, sized version.
--
2.13.6