[Bug d/88150] Use sections_elf_shared.d on Solaris

[ibuclaw at gdcproject dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88150

--- Comment #10 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
I've got a (horrible?) hack for getting tls_modid from Solaris.

Looking at dlinfo(RTLD_DI_LINKMAP):

https://github.com/illumos/illumos-gate/blob/4e0c5eff9af325c80994e9527b7cb8b3a1ffd1d4/usr/src/cmd/sgs/rtld/common/dlfcns.c#L1927-L1934

The lmp variable returned is originally an Rt_map*, layout is:
---
struct Rt_map
{
    Link_map rt_public;
    const char* rt_pathname;
    c_ulong rt_padstart;
    c_ulong rt_padimlen; 
    c_ulong rt_msize;
    uint rt_flags;
    uint rt_flags1;
    c_ulong rt_tlsmodid;
}
---

Let's do a little test...
---
case PT_TLS: // TLS segment
    assert(!pdso._tlsSize); // is unique per DSO
    static if (OS_Have_Dlpi_Tls_Modid)
    {
        pdso._tlsMod = info.dlpi_tls_modid;
        pdso._tlsSize = phdr.p_memsz;
    }
    else version (Solaris)
    {
        Rt_map* map;
        version (Shared)
            dlinfo(handleForName(info.dlpi_name), RTLD_DI_LINKMAP, &map);
        else
            dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map);
        pdso._tlsMod = map.rt_tlsmodid;
        pdso._tlsSize = phdr.p_memsz;
    }
    else
    {
        pdso._tlsMod = 0;
        pdso._tlsSize = 0;
    }
    break;
---

Inspecting this in gdb
---
(gdb) p map
$1 = (struct Rt_map *) 0xfedb001
(gdb) p *map
$2 = {rt_public = {l_addr = 4275896320, 
    l_name = 0xfc0f02e4
"/mnt/build/i386-pc-solaris2.11/./libphobos/libdruntime/.libs/libgdruntime.so.76",
l_ld = 0xfedd00d4, l_next = 0xfedb0678, l_prev = 0xfef206c8, l_refname = 0x0}, 
  rt_pathname = 0xfc0f0334
"/mnt/build/i386-pc-solaris2.11/libphobos/libdruntime/.libs/libgdruntime.so.76.0.3",
rt_padstart = 4275896320, rt_padimlen = 1272912, rt_msize = 1272912, rt_flags =
272761348, 
  rt_flags1 = 1155, rt_tlsmodid = 2}
---

And there it is, a valid rt_tlsmodid.

Interestingly, Solaris sets the first tlsmodid to zero.

https://github.com/illumos/illumos-gate/blob/8a06b3d6467c15646e663c05086378f16288af85/usr/src/cmd/sgs/rtld/common/tls.c#L52-L60

This is in stark contrast to what elf_shared expects, given that there's an
assert that it is always non-zero if _tlsSize is set.