Objcopy seems to consider tbss part of PTLOAD

[vijay Shankar]

Take the following example

reprod.c

int __thread a;
int b,c,k=100,n=400;
int my_start()
{
b = 500;
return a*a*b*k*n;
}

 

l.ld

ENTRY(my_start)
SECTIONS
{
  .text (VMA_START) : AT(VMA_START + LMA_START)
   {
      *(.text.*)
   }
  . = ALIGN(16);
 
  .data :
  {
    *(.data)
  }
  . = ALIGN(16);
 
  .tdata : {
    *(.tdata) *(.tdata.*)
  }
  . = ALIGN(16);
  .tbss : {
    *(.tbss) *(.tbss.*)
  }
  . = ALIGN(16);
.sdata :
  {BYTE(0x00)
    *(.sdata) *(.sdata.*)
  }
  . = ALIGN(16);
}

clang reprod.c -ffreestanding -c -o reprod.img

ld.lld --defsym VMA_START=0xffffffff80100000 --defsym LMA_START=0x4800000 -T l.ld reprod.img -o reprod.img

objcopy --change-section-lma .*-0xffffffff80000000 reprod.img

objcopy --adjust-start -0xffffffff80000000 reprod.img

 

lld dosen't seem to consider tbss section to have proper lma

 

of lld

  TLS            0x0000000000002058 0xffffffff80100060 (vma) 0xffffffff80100060 (lma)

                 0x0000000000000000 0x0000000000000004  R      0x4

   03     .tbss

Ld Linker

  TLS            0x0000000000100098 0xffffffff801000a0 (vma) 0xffffffffc81000a0 (lma)

                 0x0000000000000000 0x0000000000000004  R      0x4

 

Since this is my first time looking at bfd code i might be misunderstanding things

Looks like the macro ELF_SECTION_IN_SEGMENT_1 checks if a section belongs to a segment based on vma
and considers tbss part of LOAD segment.

   && (!(check_vma)                            \

       || ((sec_hdr)->sh_flags & SHF_ALLOC) == 0            \

       || ((sec_hdr)->sh_addr >= (segment)->p_vaddr            \

       && (!(strict)                        \

           || ((sec_hdr)->sh_addr - (segment)->p_vaddr        \

           <= (segment)->p_memsz - 1))                \

       && (((sec_hdr)->sh_addr - (segment)->p_vaddr            \

        + ELF_SECTION_SIZE(sec_hdr, segment))            \

           <= (segment)->p_memsz)))   

 

and later when it assigns file offsets, it seems to fail after sorting segments.

    qsort (sorted_seg_map, alloc, sizeof (*sorted_seg_map),

       elf_sort_segments);

sorted segment order:

 

Im not sure if the fix needs to go into objcopy ie add appropriate checks to ELF_SECTION_IN_SEGMENT_1 or make lld emit lma proper. either of both Im ready to do the needful, please guide me on this.

Thank you.