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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.
This commit is contained in:
Maciej W. Rozycki 2018-07-09 21:30:44 +01:00
parent 055303e28f
commit 4b8377e7db
18 changed files with 229 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2018-07-09 Maciej W. Rozycki <macro@mips.com>
* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol): Don't set
`->needs_lazy_stub' if the stubs output section is the absolute
section.
2018-07-09 H.J. Lu <hongjiu.lu@intel.com>
PR ld/23388

3
bfd/elfxx-mips.c
View File

@ -9043,7 +9043,8 @@ _bfd_mips_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
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++;

22
ld/ChangeLog
View File

@ -1,3 +1,25 @@
2018-07-09 Maciej W. Rozycki <macro@mips.com>
* 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.
2018-07-09 Maciej W. Rozycki <macro@mips.com>
* testsuite/lib/ld-lib.exp (run_dump_test): Call `unsupported'

36
ld/testsuite/ld-mips-elf/mips-elf.exp
View File

@ -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"]]
}
}

17
ld/testsuite/ld-mips-elf/stub-dynsym-2.dd Normal file
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@ -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

12
ld/testsuite/ld-mips-elf/stub-dynsym-2.gd Normal file
View File

@ -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

21
ld/testsuite/ld-mips-elf/stub-dynsym-2.ld Normal file
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@ -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) }
}

2
ld/testsuite/ld-mips-elf/stub-dynsym-2.s Normal file
View File

@ -0,0 +1,2 @@
lw $25,%call16(foo)($gp)
lw $25,%call16(bar)($gp)

5
ld/testsuite/ld-mips-elf/stub-dynsym-2.sd Normal file
View File

@ -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

12
ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.gd Normal file
View File

@ -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

22
ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.ld Normal file
View File

@ -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)
}
}

5
ld/testsuite/ld-mips-elf/stub-dynsym-discard-2.sd Normal file
View File

@ -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

16
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.dd Normal file
View File

@ -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

12
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.gd Normal file
View File

@ -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

5
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-2.sd Normal file
View File

@ -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

17
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.dd Normal file
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@ -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

12
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.gd Normal file
View File

@ -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

5
ld/testsuite/ld-mips-elf/stub-dynsym-micromips-insn32-2.sd Normal file
View File

@ -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