[PATCH v2] LoongArch: ld: Move .got .got.plt before .data and protect .got with relro

[mengqinggang]

Thank you very much, this patch has been applied.


在 2024/4/8 下午8:14, Xi Ruoyao 写道:
> On Mon, 2024-04-08 at 14:49 +0800, mengqinggang wrote:
>> Move .got .got.plt before .data so .got can be protected with -zrelro.
>> And the first two entries of .got.plt (_dl_runtime_resolve and link map)
>> are placed within the relro region.
>> ---
>> Changes v1 -> v2:
>> - Add --hash-style=both option in data-got.d.
>>
>> v1 link: https://sourceware.org/pipermail/binutils/2024-April/133300.html
> I've rebuilt the entire base system with v1 applied onto 2.42 without
> any problem, so it should be OK.
>
>>   bfd/elfnn-loongarch.c                            |  2 ++
>>   ld/emulparams/elf64loongarch-defs.sh             |  5 ++++-
>>   ld/testsuite/ld-loongarch-elf/data-got.d         | 16 ++++++++++++++++
>>   ld/testsuite/ld-loongarch-elf/data-got.s         |  6 ++++++
>>   .../ld-loongarch-elf/ld-loongarch-elf.exp        |  1 +
>>   5 files changed, 29 insertions(+), 1 deletion(-)
>>   create mode 100644 ld/testsuite/ld-loongarch-elf/data-got.d
>>   create mode 100644 ld/testsuite/ld-loongarch-elf/data-got.s
>>
>> diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
>> index eb70799b06a..e8632905019 100644
>> --- a/bfd/elfnn-loongarch.c
>> +++ b/bfd/elfnn-loongarch.c
>> @@ -127,6 +127,8 @@ struct loongarch_elf_link_hash_table
>>   
>>   #define GOT_ENTRY_SIZE (LARCH_ELF_WORD_BYTES)
>>   
>> +/* Reserve two entries of GOTPLT for ld.so, one is used for PLT
>> +   resolver _dl_runtime_resolve, the other is used for link map.  */
>>   #define GOTPLT_HEADER_SIZE (GOT_ENTRY_SIZE * 2)
>>   
>>   #define elf_backend_want_got_plt 1
>> diff --git a/ld/emulparams/elf64loongarch-defs.sh b/ld/emulparams/elf64loongarch-defs.sh
>> index c793f5d8388..a8147bf71d7 100644
>> --- a/ld/emulparams/elf64loongarch-defs.sh
>> +++ b/ld/emulparams/elf64loongarch-defs.sh
>> @@ -34,6 +34,9 @@ TEXT_START_ADDR=0x120000000
>>   MAXPAGESIZE="CONSTANT (MAXPAGESIZE)"
>>   COMMONPAGESIZE="CONSTANT (COMMONPAGESIZE)"
>>   
>> -SEPARATE_GOTPLT=0
>> +# Put .got before .data
>> +DATA_GOT=" "
>> +# First two entries for PLT resolver _dl_runtime_resolve and link map.
>> +SEPARATE_GOTPLT="SIZEOF (.got.plt) >= 16 ? 16 : 0"
>>   INITIAL_READONLY_SECTIONS=".interp         : { *(.interp) } ${CREATE_PIE-${INITIAL_READONLY_SECTIONS}}"
>>   INITIAL_READONLY_SECTIONS="${RELOCATING+${CREATE_SHLIB-${INITIAL_READONLY_SECTIONS}}}"
>> diff --git a/ld/testsuite/ld-loongarch-elf/data-got.d b/ld/testsuite/ld-loongarch-elf/data-got.d
>> new file mode 100644
>> index 00000000000..a754478a655
>> --- /dev/null
>> +++ b/ld/testsuite/ld-loongarch-elf/data-got.d
>> @@ -0,0 +1,16 @@
>> +# line 11 test the first two entries of .got.plt in relro region
>> +# relro segment size is .dynamic size + .got size + 0x10
>> +# line 13 test .got .got.plt before .got
>> +# line 15 test .got in relro segment
>> +#as:
>> +#ld: -shared -z relro --hash-style=both
>> +#readelf: -l --wide
>> +#skip: loongarch32-*-*
>> +
>> +#...
>> +  GNU_RELRO      0x003c10 0x0000000000007c10 0x0000000000007c10 0x0003f0 0x0003f0 R   0x1
>> +#...
>> +   01     .dynamic .got .got.plt .data
>> +#...
>> +   03     .dynamic .got
>> +#pass
>> diff --git a/ld/testsuite/ld-loongarch-elf/data-got.s b/ld/testsuite/ld-loongarch-elf/data-got.s
>> new file mode 100644
>> index 00000000000..364fcf64c0e
>> --- /dev/null
>> +++ b/ld/testsuite/ld-loongarch-elf/data-got.s
>> @@ -0,0 +1,6 @@
>> +.text
>> +b foo
>> +.section .got
>> +.space 0x2a8, 4
>> +.data
>> +.zero 24
>> diff --git a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
>> index 759acab80d4..c2d616b8d0a 100644
>> --- a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
>> +++ b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
>> @@ -133,6 +133,7 @@ if [istarget "loongarch64-*-*"] {
>>       run_dump_test "tlsdesc-dso"
>>       run_dump_test "desc-norelax"
>>       run_dump_test "desc-relax"
>> +    run_dump_test "data-got"
>>     }
>>   
>>     if [check_pie_support] {