We have hit multiple problems checking for a static non-PIE binary using incorrect conditions. In looking into a TLS relaxation that should not have happened we found another. To help avoid this problem in the future (and to make reading the code a lot easier for someone who isn't familiar with the BFD linker flags) we now perform the check for a static PDE with a macro called `static_pde`.
N.b. this macro can only be used after we've created any needed dynamic sections. That happens when loading symbols, which is very early on and hence before any of the places we want to use this macro. However it's still good to note it's not always a valid check.
############### Attachment also inlined for ease of reply ###############
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c index 1b6e80aa20982c294780cc20cd49c1702549a47c..a0898f9e7b9e44ae609bbc0a6eae5eaa830771e2 100644 --- a/bfd/elfnn-aarch64.c +++ b/bfd/elfnn-aarch64.c @@ -292,6 +292,17 @@ (((htab)->root.srelplt == NULL) ? 0 \ : (htab)->root.srelplt->reloc_count * GOT_ENTRY_SIZE (htab))
+/* Macro to check for a static non-PIE binary. Checking for this in incorrect + ways is something that has been the cause of a few bugs throughout Morello + development. Making a macro for the check should help make this easier to + check. + N.b. this macro can only be called after symbols have been loaded by the + generic linker. In practice this is not much of a restriction, since the + check_relocs, size_dynamic_sections, and relocate_section hooks are all done + after that point. */ +#define static_pde(info) (!elf_hash_table (info)->dynamic_sections_created \ + && bfd_link_executable (info)) + /* The only time that we want the value of a symbol but do not want a relocation for it in Morello is when that symbol is undefined weak. In this case we just need the zero capability and there's no point emitting a @@ -7438,7 +7449,7 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto, done so that we can mark that section with __rela_dyn_{start,end} symbols for the runtime to find and initialise relocations with. */ - if (bfd_link_executable (info) && !is_dynamic) + if (static_pde (info)) s = globals->srelcaps;
outrel.r_addend = signed_addend; @@ -9146,8 +9157,7 @@ aarch64_elf_init_got_section (bfd *abfd, struct bfd_link_info *info) }
/* Track capability initialisation for static non-PIE binaries. */ - if (bfd_link_executable (info) && !globals->root.dynamic_sections_created - && globals->srelcaps == NULL) + if (static_pde (info) && globals->srelcaps == NULL) globals->srelcaps = globals->root.srelgot;
if (globals->root.igotplt != NULL) @@ -10288,22 +10298,16 @@ elfNN_aarch64_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf) symbol that we know will not be resolved to anything by the runtime do not need a relocation. */ } - else if (dyn) - { - /* Any capability relocations required in a dynamic binary - should go in the srelgot. N.b. many capability relocations - would be caught by the first clause in this if chain. */ - htab->root.srelgot->size += RELOC_SIZE (htab); - } - else if (bfd_link_executable (info)) - { - /* If we have a capability relocation that is not handled by the - case above then this must be a statically linked executable. - We want capability relocations in a statically linked - executable to go in the srelcaps section. */ - BFD_ASSERT (!bfd_link_pic (info) && !dyn); - htab->srelcaps->size += RELOC_SIZE (htab); - } + else if (!static_pde (info)) + /* Any capability relocations required in something other than a + static PDE should go in the srelgot. N.b. many capability + relocations would be caught by the first clause in this if + chain. */ + htab->root.srelgot->size += RELOC_SIZE (htab); + else + /* We want capability relocations in a statically linked + PDE to go in the srelcaps section. */ + htab->srelcaps->size += RELOC_SIZE (htab); } else { @@ -10646,10 +10650,8 @@ elfNN_aarch64_size_dynamic_sections (bfd *output_bfd, || got_type & GOT_NORMAL) htab->root.srelgot->size += RELOC_SIZE (htab); } - /* Static binary; put relocs into srelcaps. */ - else if (bfd_link_executable (info) - && !htab->root.dynamic_sections_created - && htab->c64_rel) + /* Static non-PIE; put relocs into srelcaps. */ + else if (static_pde (info) && htab->c64_rel) htab->srelcaps->size += RELOC_SIZE (htab); /* Else capability relocation needs to go into srelgot. */ else if (htab->c64_rel) @@ -10678,8 +10680,7 @@ elfNN_aarch64_size_dynamic_sections (bfd *output_bfd, elfNN_aarch64_allocate_local_ifunc_dynrelocs, info);
- if (bfd_link_executable (info) - && !htab->root.dynamic_sections_created + if (static_pde (info) && htab->srelcaps && htab->srelcaps->size > 0) {