Re: [PATCH] LoongArch: Disallow TLS transition when a section contains TLS_IE64 or TLS_DESC64 reloc

[Xi Ruoyao <xry111@xry111.site>]

On Fri, 2024-01-26 at 16:12 +0800, Xi Ruoyao wrote:
> On Fri, 2024-01-26 at 09:43 +0800, mengqinggang wrote:
> > Hi,
> > 
> > For TLS transition, we want to change to that the instructions that can be
> > converted must have a R_LARCH_RELAX relocation.

So we need something like

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index b62bb424644..63aa7e254b5 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -818,7 +818,10 @@ loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
       int need_dynreloc = 0;
       int only_need_pcrel = 0;
 
-      r_type = loongarch_tls_transition (info, r_type, h, abfd, r_symndx);
+      if (rel + 1 != relocs + sec->reloc_count
+	  && ELFNN_R_TYPE (rel[1].r_info) == R_LARCH_RELAX)
+	r_type = loongarch_tls_transition (info, r_type, h, abfd, r_symndx);
+
       switch (r_type)
 	{
 	case R_LARCH_GOT_PC_HI20:
@@ -2789,7 +2792,12 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 
       BFD_ASSERT (!resolved_local || defined_local);
 
-      relaxed_r_type = loongarch_tls_transition (info, r_type, h, input_bfd, r_symndx);
+      relaxed_r_type = r_type;
+      if (rel + 1 != relend
+	  && ELFNN_R_TYPE (rel[1].r_info) == R_LARCH_RELAX)
+	relaxed_r_type = loongarch_tls_transition (info, r_type, h,
+						   input_bfd, r_symndx);
+
       if (relaxed_r_type != r_type)
       {
 	howto = loongarch_elf_rtype_to_howto (input_bfd, relaxed_r_type);

and this is missing in the master branch?

> > After 32ee2b4b71c78d3dc0c0b1f87f25fe5df8786b71 commit, the gas not
> > emit R_LARCH_RELAX for two register macros.
> 
> But with master branch at e14f7abaf81d5d0aa7898570024286de8c188817:
> 
> $ cat t.s
> .globl _start
> _start:
>   la.tls.ie $a0, $a1, foo
> 
> .section .tdata
> foo: .word 114514
> $ gas/as-new t.s -o t.o
> $ ld/ld-new t.o
> [1]    7202 segmentation fault (core dumped)  ld/ld-new t.o
> 
> 

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University