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[committed] MIPS/BFD: Do not redirect to discarded lazy binding stubs
- From: "Maciej W. Rozycki" <macro at mips dot com>
- To: <binutils at sourceware dot org>
- Date: Mon, 9 Jul 2018 21:31:17 +0100
- Subject: [committed] MIPS/BFD: Do not redirect to discarded lazy binding stubs
Correct a MIPS/BFD linker issue with dynamic symbol and corresponding
GOT entry values being redirected to lazy binding stubs where the stubs
section has been discarded by assigning to the `/DISCARD/' output
section in the linker script used. The issue manifests itself by the
values entered being relative to the absolute section, which is what any
discarded sections are internally assigned in the linker.
For the `stub-dynsym-2.s' piece of code included as a test case with
this change this issue results in the dynamic symbol table and the GOT
looking like:
Symbol table '.dynsym' contains 3 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000010 0 FUNC GLOBAL DEFAULT UND bar
2: 00000000 0 FUNC GLOBAL DEFAULT UND foo
Primary GOT:
Canonical gp value: 00097ff0
Reserved entries:
Address Access Initial Purpose
00090000 -32752(gp) 00000000 Lazy resolver
00090004 -32748(gp) 80000000 Module pointer (GNU extension)
Global entries:
Address Access Initial Sym.Val. Type Ndx Name
00090008 -32744(gp) 00000010 00000010 FUNC UND bar
0009000c -32740(gp) 00000000 00000000 FUNC UND foo
if assembled to regular MIPS code, or:
Symbol table '.dynsym' contains 3 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000d 0 FUNC GLOBAL DEFAULT UND bar
2: 00000001 0 FUNC GLOBAL DEFAULT UND foo
Primary GOT:
Canonical gp value: 00097ff0
Reserved entries:
Address Access Initial Purpose
00090000 -32752(gp) 00000000 Lazy resolver
00090004 -32748(gp) 80000000 Module pointer (GNU extension)
Global entries:
Address Access Initial Sym.Val. Type Ndx Name
00090008 -32744(gp) 0000000d 0000000d FUNC UND bar
0009000c -32740(gp) 00000001 00000001 FUNC UND foo
if assembled to microMIPS code. Symbol values and GOT entries record
the offset into the inexistent stubs section and the ISA bit rather than
zero, which would be the case if a lazy binding stub was not used for
other reasons, such as the value of the symbol being taken for a purpose
other than making a function call (e.g. an R_MIPS_GOT16 relocation).
Correct the issue by refraining from redirecting symbols to lazy binding
stubs if the stubs section is going to be discarded.
bfd/
* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol): Don't set
`->needs_lazy_stub' if the stubs output section is the absolute
section.
ld/
* testsuite/ld-mips-elf/stub-dynsym-2.dd: New test.
* testsuite/ld-mips-elf/stub-dynsym-2.gd: New test.
* testsuite/ld-mips-elf/stub-dynsym-2.sd: New test.
* testsuite/ld-mips-elf/stub-dynsym-discard-2.gd: New test.
* testsuite/ld-mips-elf/stub-dynsym-discard-2.sd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-2.dd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-2.gd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-2.sd: New test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.dd: New
test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.gd: New
test.
* testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.sd: New
test.
* testsuite/ld-mips-elf/stub-dynsym-2.ld: New test linker
script.
* testsuite/ld-mips-elf/stub-dynsym-discard-2.ld: New test
linker script.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
---
bfd/elfxx-mips.c | 3 -
ld/testsuite/ld-mips-elf/mips-elf.exp | 36 +++++++++++++
ld/testsuite/ld-mips-elf/stub-dynsym-2.dd | 17 ++++++
ld/testsuite/ld-mips-elf/stub-dynsym-2.gd | 12 ++++
ld/testsuite/ld-mips-elf/stub-dynsym-2.ld | 21 +++++++
ld/testsuite/ld-mips-elf/stub-dynsym-2.s | 2
ld/testsuite/ld-mips-elf/stub-dynsym-2.sd | 5 +
ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.gd | 12 ++++
ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.ld | 22 +++++++
ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.sd | 5 +
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.dd | 16 +++++
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.gd | 12 ++++
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.sd | 5 +
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.dd | 17 ++++++
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.gd | 12 ++++
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.sd | 5 +
16 files changed, 201 insertions(+), 1 deletion(-)
binutils-mips-bfd-lazy-stubs-discard.diff
Index: binutils/bfd/elfxx-mips.c
===================================================================
--- binutils.orig/bfd/elfxx-mips.c 2018-07-06 12:15:39.727666507 +0100
+++ binutils/bfd/elfxx-mips.c 2018-07-06 12:16:06.818626837 +0100
@@ -9043,7 +9043,8 @@ _bfd_mips_elf_adjust_dynamic_symbol (str
the symbol to the stub location. This is required to make
function pointers compare as equal between the normal
executable and the shared library. */
- if (!h->def_regular)
+ if (!h->def_regular
+ && !bfd_is_abs_section (htab->sstubs->output_section))
{
hmips->needs_lazy_stub = TRUE;
htab->lazy_stub_count++;
Index: binutils/ld/testsuite/ld-mips-elf/mips-elf.exp
===================================================================
--- binutils.orig/ld/testsuite/ld-mips-elf/mips-elf.exp 2018-07-06 12:15:39.736741786 +0100
+++ binutils/ld/testsuite/ld-mips-elf/mips-elf.exp 2018-07-06 12:16:06.873551591 +0100
@@ -807,6 +807,42 @@ if { $linux_gnu } {
"stub-dynsym$suffix-1-$dynsym.d"]] \
"stub-dynsym$suffix-1-$dynsym"]]
}
+ run_ld_link_tests [list \
+ [list \
+ "Retained stubs for dynsyms ($isa)" \
+ "-shared -melf32btsmip -T stub-dynsym-2.ld $lflag" "" \
+ "-EB $aflag -32 -KPIC" \
+ [list "stub-dynsym-2.s"] \
+ [list \
+ [list \
+ "objdump" \
+ "-dz -j .MIPS.stubs" \
+ "stub-dynsym$suffix-2.dd"] \
+ [list \
+ "readelf" \
+ "--dyn-syms" \
+ "stub-dynsym$suffix-2.sd"] \
+ [list \
+ "readelf" \
+ "-A" \
+ "stub-dynsym$suffix-2.gd"]] \
+ "stub-dynsym$suffix-2"] \
+ [list \
+ "Discarded stubs for dynsyms ($isa)" \
+ "-shared -melf32btsmip -T stub-dynsym-discard-2.ld $lflag" \
+ "" \
+ "-EB $aflag -32 -KPIC" \
+ [list "stub-dynsym-2.s"] \
+ [list \
+ [list \
+ "readelf" \
+ "--dyn-syms" \
+ "stub-dynsym-discard-2.sd"] \
+ [list \
+ "readelf" \
+ "-A" \
+ "stub-dynsym-discard-2.gd"]] \
+ "stub-dynsym-discard$suffix-2"]]
}
}
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.dd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.dd 2018-07-06 12:16:06.882699773 +0100
@@ -0,0 +1,17 @@
+.*: +file format .*mips.*
+
+Disassembly of section \.MIPS\.stubs:
+
+000800ec <_MIPS_STUBS_>:
+ 800ec: 8f998010 lw t9,-32752\(gp\)
+ 800f0: 03e07825 move t7,ra
+ 800f4: 0320f809 jalr t9
+ 800f8: 24180002 li t8,2
+ 800fc: 8f998010 lw t9,-32752\(gp\)
+ 80100: 03e07825 move t7,ra
+ 80104: 0320f809 jalr t9
+ 80108: 24180001 li t8,1
+ 8010c: 00000000 nop
+ 80110: 00000000 nop
+ 80114: 00000000 nop
+ 80118: 00000000 nop
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.gd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.gd 2018-07-06 12:16:06.889809768 +0100
@@ -0,0 +1,12 @@
+Primary GOT:
+ Canonical gp value: 00097ff0
+
+ Reserved entries:
+ Address Access Initial Purpose
+ 00090000 -32752\(gp\) 00000000 Lazy resolver
+ 00090004 -32748\(gp\) 80000000 Module pointer \(GNU extension\)
+
+ Global entries:
+ Address Access Initial Sym\.Val\. Type Ndx Name
+ 00090008 -32744\(gp\) 000800fc 000800fc FUNC UND bar
+ 0009000c -32740\(gp\) 000800ec 000800ec FUNC UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.ld
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.ld 2018-07-06 12:16:06.924950522 +0100
@@ -0,0 +1,21 @@
+SECTIONS
+{
+ . = 0x80000;
+ .interp : { *(.interp) }
+ .hash : { *(.hash) }
+ .dynsym : { *(.dynsym) }
+ .dynstr : { *(.dynstr) }
+ .rel.dyn : { *(.rel.dyn) }
+ .MIPS.stubs : { *(.MIPS.stubs) }
+ .text : { *(.text) }
+
+ . = ALIGN (0x10000);
+ HIDDEN (_gp = . + 0x7ff0);
+ .got : { *(.got) }
+
+ .symtab : { *(.symtab) }
+ .strtab : { *(.strtab) }
+ .shstrtab : { *(.shstrtab) }
+
+ /DISCARD/ : { *(.reginfo) *(.MIPS.abiflags) *(.gnu.attributes) }
+}
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.s
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.s 2018-07-06 12:16:06.948281756 +0100
@@ -0,0 +1,2 @@
+ lw $25,%call16(foo)($gp)
+ lw $25,%call16(bar)($gp)
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.sd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-2.sd 2018-07-06 12:16:06.958519166 +0100
@@ -0,0 +1,5 @@
+Symbol table '\.dynsym' contains 3 entries:
+ Num: Value Size Type Bind Vis Ndx Name
+ 0: 00000000 0 NOTYPE LOCAL DEFAULT UND
+ 1: 000800fc 0 FUNC GLOBAL DEFAULT UND bar
+ 2: 000800ec 0 FUNC GLOBAL DEFAULT UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.gd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.gd 2018-07-06 12:16:06.981108400 +0100
@@ -0,0 +1,12 @@
+Primary GOT:
+ Canonical gp value: 00097ff0
+
+ Reserved entries:
+ Address Access Initial Purpose
+ 00090000 -32752\(gp\) 00000000 Lazy resolver
+ 00090004 -32748\(gp\) 80000000 Module pointer \(GNU extension\)
+
+ Global entries:
+ Address Access Initial Sym\.Val\. Type Ndx Name
+ 00090008 -32744\(gp\) 00000000 00000000 FUNC UND bar
+ 0009000c -32740\(gp\) 00000000 00000000 FUNC UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.ld
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.ld 2018-07-06 12:16:06.996292882 +0100
@@ -0,0 +1,22 @@
+SECTIONS
+{
+ . = 0x80000;
+ .interp : { *(.interp) }
+ .hash : { *(.hash) }
+ .dynsym : { *(.dynsym) }
+ .dynstr : { *(.dynstr) }
+ .rel.dyn : { *(.rel.dyn) }
+ .text : { *(.text) }
+
+ . = ALIGN (0x10000);
+ HIDDEN (_gp = . + 0x7ff0);
+ .got : { *(.got) }
+
+ .symtab : { *(.symtab) }
+ .strtab : { *(.strtab) }
+ .shstrtab : { *(.shstrtab) }
+
+ /DISCARD/ : {
+ *(.reginfo) *(.MIPS.abiflags) *(.MIPS.stubs) *(.gnu.attributes)
+ }
+}
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.sd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.sd 2018-07-06 12:16:07.013395836 +0100
@@ -0,0 +1,5 @@
+Symbol table '\.dynsym' contains 3 entries:
+ Num: Value Size Type Bind Vis Ndx Name
+ 0: 00000000 0 NOTYPE LOCAL DEFAULT UND
+ 1: 00000000 0 FUNC GLOBAL DEFAULT UND bar
+ 2: 00000000 0 FUNC GLOBAL DEFAULT UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.dd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.dd 2018-07-06 12:16:07.022449217 +0100
@@ -0,0 +1,16 @@
+.*: +file format .*mips.*
+
+Disassembly of section \.MIPS\.stubs:
+
+000800ec <_MIPS_STUBS_>:
+ 800ec: ff3c 8010 lw t9,-32752\(gp\)
+ 800f0: 0dff move t7,ra
+ 800f2: 45d9 jalr t9
+ 800f4: 3300 0002 li t8,2
+ 800f8: ff3c 8010 lw t9,-32752\(gp\)
+ 800fc: 0dff move t7,ra
+ 800fe: 45d9 jalr t9
+ 80100: 3300 0001 li t8,1
+ 80104: 0000 0000 nop
+ 80108: 0000 0000 nop
+ 8010c: 0000 0000 nop
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.gd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.gd 2018-07-06 12:16:07.034524614 +0100
@@ -0,0 +1,12 @@
+Primary GOT:
+ Canonical gp value: 00097ff0
+
+ Reserved entries:
+ Address Access Initial Purpose
+ 00090000 -32752\(gp\) 00000000 Lazy resolver
+ 00090004 -32748\(gp\) 80000000 Module pointer \(GNU extension\)
+
+ Global entries:
+ Address Access Initial Sym\.Val\. Type Ndx Name
+ 00090008 -32744\(gp\) 000800f9 000800f9 FUNC UND bar
+ 0009000c -32740\(gp\) 000800ed 000800ed FUNC UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.sd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.sd 2018-07-06 12:16:07.063691654 +0100
@@ -0,0 +1,5 @@
+Symbol table '\.dynsym' contains 3 entries:
+ Num: Value Size Type Bind Vis Ndx Name
+ 0: 00000000 0 NOTYPE LOCAL DEFAULT UND
+ 1: 000800f9 0 FUNC GLOBAL DEFAULT UND bar
+ 2: 000800ed 0 FUNC GLOBAL DEFAULT UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.dd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.dd 2018-07-06 12:16:07.077791419 +0100
@@ -0,0 +1,17 @@
+.*: +file format .*mips.*
+
+Disassembly of section \.MIPS\.stubs:
+
+000800ec <_MIPS_STUBS_>:
+ 800ec: ff3c 8010 lw t9,-32752\(gp\)
+ 800f0: 001f 7a90 move t7,ra
+ 800f4: 03f9 0f3c jalr t9
+ 800f8: 3300 0002 li t8,2
+ 800fc: ff3c 8010 lw t9,-32752\(gp\)
+ 80100: 001f 7a90 move t7,ra
+ 80104: 03f9 0f3c jalr t9
+ 80108: 3300 0001 li t8,1
+ 8010c: 0000 0000 nop
+ 80110: 0000 0000 nop
+ 80114: 0000 0000 nop
+ 80118: 0000 0000 nop
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.gd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.gd 2018-07-06 12:16:07.092884623 +0100
@@ -0,0 +1,12 @@
+Primary GOT:
+ Canonical gp value: 00097ff0
+
+ Reserved entries:
+ Address Access Initial Purpose
+ 00090000 -32752\(gp\) 00000000 Lazy resolver
+ 00090004 -32748\(gp\) 80000000 Module pointer \(GNU extension\)
+
+ Global entries:
+ Address Access Initial Sym\.Val\. Type Ndx Name
+ 00090008 -32744\(gp\) 000800fd 000800fd FUNC UND bar
+ 0009000c -32740\(gp\) 000800ed 000800ed FUNC UND foo
Index: binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.sd
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ binutils/ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.sd 2018-07-06 12:16:07.119089076 +0100
@@ -0,0 +1,5 @@
+Symbol table '\.dynsym' contains 3 entries:
+ Num: Value Size Type Bind Vis Ndx Name
+ 0: 00000000 0 NOTYPE LOCAL DEFAULT UND
+ 1: 000800fd 0 FUNC GLOBAL DEFAULT UND bar
+ 2: 000800ed 0 FUNC GLOBAL DEFAULT UND foo