[PATCH v1] LoongArch: Do not relax against __[start|stop]_SECNAME symbol

[Lulu Cai]

Hi Nick,


   This patch fixes a relaxation bug for LoongArch and needs to be 
applied to 2.44 branch and the mainline source.

   link: https://sourceware.org/pipermail/binutils/2025-January/138943.html

   Thanks.

On 1/22/2025 5:00 PM, Lulu Cai wrote:
> The value of the __[start|stop]_SECNAME symbol will be set after
> loongarch_elf_relax_section. If relaxation is done against the
> __[start|stop]_SECNAME symbol, the correct symbol value cannot
> be obtained.
> ---
>   bfd/elfnn-loongarch.c                      |  5 ++++-
>   ld/testsuite/ld-loongarch-elf/relax.exp    |  2 ++
>   ld/testsuite/ld-loongarch-elf/start_stop.d | 13 +++++++++++++
>   ld/testsuite/ld-loongarch-elf/start_stop.s | 10 ++++++++++
>   4 files changed, 29 insertions(+), 1 deletion(-)
>   create mode 100644 ld/testsuite/ld-loongarch-elf/start_stop.d
>   create mode 100644 ld/testsuite/ld-loongarch-elf/start_stop.s
>
> diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
> index efa57184e44..dfb760dbf22 100644
> --- a/bfd/elfnn-loongarch.c
> +++ b/bfd/elfnn-loongarch.c
> @@ -5636,10 +5636,13 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
>   	}
>         else
>   	{
> +	  /* Do not relax __[start|stop]_SECNAME, since the symbol value
> +	     is not set yet.  */
>   	  if (h != NULL
>   	      && ((h->type == STT_GNU_IFUNC
>   		   && r_type != R_LARCH_CALL36)
> -		  || bfd_is_abs_section (h->root.u.def.section)))
> +		  || bfd_is_abs_section (h->root.u.def.section)
> +		  || h->start_stop))
>   	    continue;
>   
>   	  /* The GOT entry of tls symbols must in current execute file or
> diff --git a/ld/testsuite/ld-loongarch-elf/relax.exp b/ld/testsuite/ld-loongarch-elf/relax.exp
> index 81924cd35cb..5c17a2ef403 100644
> --- a/ld/testsuite/ld-loongarch-elf/relax.exp
> +++ b/ld/testsuite/ld-loongarch-elf/relax.exp
> @@ -484,4 +484,6 @@ if [istarget loongarch64-*-*] {
>   	      "uleb128" \
>   	  ] \
>         ]
> +
> +  run_dump_test "start_stop"
>   }
> diff --git a/ld/testsuite/ld-loongarch-elf/start_stop.d b/ld/testsuite/ld-loongarch-elf/start_stop.d
> new file mode 100644
> index 00000000000..b887dcc2eb7
> --- /dev/null
> +++ b/ld/testsuite/ld-loongarch-elf/start_stop.d
> @@ -0,0 +1,13 @@
> +#ld: -z norelro -pie -e0
> +#objdump: -d
> +
> +.*:     file format .*
> +
> +
> +Disassembly of section sec1:
> +
> +[0-9a-f]+ <_start>:
> + [0-9a-f]+:	[0-9a-f]+ 	pcalau12i   	\$a0, .*
> + [0-9a-f]+:	[0-9a-f]+ 	ld.d        	\$a0, \$a0, .*
> + [0-9a-f]+:	[0-9a-f]+ 	pcalau12i   	\$a0, .*
> + [0-9a-f]+:	[0-9a-f]+ 	ld.d        	\$a0, \$a0, .*
> diff --git a/ld/testsuite/ld-loongarch-elf/start_stop.s b/ld/testsuite/ld-loongarch-elf/start_stop.s
> new file mode 100644
> index 00000000000..f50bc603abb
> --- /dev/null
> +++ b/ld/testsuite/ld-loongarch-elf/start_stop.s
> @@ -0,0 +1,10 @@
> +	.section	sec1,"ax",@progbits
> +	.globl	_start
> +	.type   _start, @function
> +_start:
> +	la.got	$a0,__start_sec1
> +	la.got	$a0,__stop_sec1
> +	.size   _start, .-_start
> +
> +	.hidden	__start_sec1
> +	.hidden	__stop_sec1