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bfd: aarch64: Refactor stub sizing code

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elfNN_aarch64_size_stubs has grown big, so factor out the call stub
related code before adding new logic there.
This commit is contained in:
Szabolcs Nagy
2023-01-30 12:57:54 +00:00
parent 2f79f2e767
commit 557a2f2822
1 changed files with 279 additions and 273 deletions
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552
bfd/elfnn-aarch64.c
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@@ -4265,12 +4265,285 @@ _bfd_aarch64_erratum_843419_scan (bfd *input_bfd, asection *section,
}
/* Determine and set the size of the stub section for a final link.
/* Add stub entries for calls.
The basic idea here is to examine all the relocations looking for
PC-relative calls to a target that is unreachable with a "bl"
instruction. */
static bool
_bfd_aarch64_add_call_stub_entries (bool *stub_changed, bfd *output_bfd,
struct bfd_link_info *info)
{
struct elf_aarch64_link_hash_table *htab = elf_aarch64_hash_table (info);
bfd *input_bfd;
for (input_bfd = info->input_bfds; input_bfd != NULL;
input_bfd = input_bfd->link.next)
{
Elf_Internal_Shdr *symtab_hdr;
asection *section;
Elf_Internal_Sym *local_syms = NULL;
if (!is_aarch64_elf (input_bfd)
|| (input_bfd->flags & BFD_LINKER_CREATED) != 0)
continue;
/* We'll need the symbol table in a second. */
symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr;
if (symtab_hdr->sh_info == 0)
continue;
/* Walk over each section attached to the input bfd. */
for (section = input_bfd->sections;
section != NULL; section = section->next)
{
Elf_Internal_Rela *internal_relocs, *irelaend, *irela;
/* If there aren't any relocs, then there's nothing more to do. */
if ((section->flags & SEC_RELOC) == 0
|| section->reloc_count == 0
|| (section->flags & SEC_CODE) == 0)
continue;
/* If this section is a link-once section that will be
discarded, then don't create any stubs. */
if (section->output_section == NULL
|| section->output_section->owner != output_bfd)
continue;
/* Get the relocs. */
internal_relocs
= _bfd_elf_link_read_relocs (input_bfd, section, NULL,
NULL, info->keep_memory);
if (internal_relocs == NULL)
goto error_ret_free_local;
/* Now examine each relocation. */
irela = internal_relocs;
irelaend = irela + section->reloc_count;
for (; irela < irelaend; irela++)
{
unsigned int r_type, r_indx;
enum elf_aarch64_stub_type stub_type;
struct elf_aarch64_stub_hash_entry *stub_entry;
asection *sym_sec;
bfd_vma sym_value;
bfd_vma destination;
struct elf_aarch64_link_hash_entry *hash;
const char *sym_name;
char *stub_name;
const asection *id_sec;
unsigned char st_type;
bfd_size_type len;
r_type = ELFNN_R_TYPE (irela->r_info);
r_indx = ELFNN_R_SYM (irela->r_info);
if (r_type >= (unsigned int) R_AARCH64_end)
{
bfd_set_error (bfd_error_bad_value);
error_ret_free_internal:
if (elf_section_data (section)->relocs == NULL)
free (internal_relocs);
goto error_ret_free_local;
}
/* Only look for stubs on unconditional branch and
branch and link instructions. */
if (r_type != (unsigned int) AARCH64_R (CALL26)
&& r_type != (unsigned int) AARCH64_R (JUMP26))
continue;
/* Now determine the call target, its name, value,
section. */
sym_sec = NULL;
sym_value = 0;
destination = 0;
hash = NULL;
sym_name = NULL;
if (r_indx < symtab_hdr->sh_info)
{
/* It's a local symbol. */
Elf_Internal_Sym *sym;
Elf_Internal_Shdr *hdr;
if (local_syms == NULL)
{
local_syms
= (Elf_Internal_Sym *) symtab_hdr->contents;
if (local_syms == NULL)
local_syms
= bfd_elf_get_elf_syms (input_bfd, symtab_hdr,
symtab_hdr->sh_info, 0,
NULL, NULL, NULL);
if (local_syms == NULL)
goto error_ret_free_internal;
}
sym = local_syms + r_indx;
hdr = elf_elfsections (input_bfd)[sym->st_shndx];
sym_sec = hdr->bfd_section;
if (!sym_sec)
/* This is an undefined symbol. It can never
be resolved. */
continue;
if (ELF_ST_TYPE (sym->st_info) != STT_SECTION)
sym_value = sym->st_value;
destination = (sym_value + irela->r_addend
+ sym_sec->output_offset
+ sym_sec->output_section->vma);
st_type = ELF_ST_TYPE (sym->st_info);
sym_name
= bfd_elf_string_from_elf_section (input_bfd,
symtab_hdr->sh_link,
sym->st_name);
}
else
{
int e_indx;
e_indx = r_indx - symtab_hdr->sh_info;
hash = ((struct elf_aarch64_link_hash_entry *)
elf_sym_hashes (input_bfd)[e_indx]);
while (hash->root.root.type == bfd_link_hash_indirect
|| hash->root.root.type == bfd_link_hash_warning)
hash = ((struct elf_aarch64_link_hash_entry *)
hash->root.root.u.i.link);
if (hash->root.root.type == bfd_link_hash_defined
|| hash->root.root.type == bfd_link_hash_defweak)
{
struct elf_aarch64_link_hash_table *globals =
elf_aarch64_hash_table (info);
sym_sec = hash->root.root.u.def.section;
sym_value = hash->root.root.u.def.value;
/* For a destination in a shared library,
use the PLT stub as target address to
decide whether a branch stub is
needed. */
if (globals->root.splt != NULL && hash != NULL
&& hash->root.plt.offset != (bfd_vma) - 1)
{
sym_sec = globals->root.splt;
sym_value = hash->root.plt.offset;
if (sym_sec->output_section != NULL)
destination = (sym_value
+ sym_sec->output_offset
+ sym_sec->output_section->vma);
}
else if (sym_sec->output_section != NULL)
destination = (sym_value + irela->r_addend
+ sym_sec->output_offset
+ sym_sec->output_section->vma);
}
else if (hash->root.root.type == bfd_link_hash_undefined
|| (hash->root.root.type
== bfd_link_hash_undefweak))
{
/* For a shared library, use the PLT stub as
target address to decide whether a long
branch stub is needed.
For absolute code, they cannot be handled. */
struct elf_aarch64_link_hash_table *globals =
elf_aarch64_hash_table (info);
if (globals->root.splt != NULL && hash != NULL
&& hash->root.plt.offset != (bfd_vma) - 1)
{
sym_sec = globals->root.splt;
sym_value = hash->root.plt.offset;
if (sym_sec->output_section != NULL)
destination = (sym_value
+ sym_sec->output_offset
+ sym_sec->output_section->vma);
}
else
continue;
}
else
{
bfd_set_error (bfd_error_bad_value);
goto error_ret_free_internal;
}
st_type = ELF_ST_TYPE (hash->root.type);
sym_name = hash->root.root.root.string;
}
/* Determine what (if any) linker stub is needed. */
stub_type = aarch64_type_of_stub (section, irela, sym_sec,
st_type, destination);
if (stub_type == aarch64_stub_none)
continue;
/* Support for grouping stub sections. */
id_sec = htab->stub_group[section->id].link_sec;
/* Get the name of this stub. */
stub_name = elfNN_aarch64_stub_name (id_sec, sym_sec, hash,
irela);
if (!stub_name)
goto error_ret_free_internal;
stub_entry =
aarch64_stub_hash_lookup (&htab->stub_hash_table,
stub_name, false, false);
if (stub_entry != NULL)
{
/* The proper stub has already been created. */
free (stub_name);
/* Always update this stub's target since it may have
changed after layout. */
stub_entry->target_value = sym_value + irela->r_addend;
continue;
}
stub_entry = _bfd_aarch64_add_stub_entry_in_group
(stub_name, section, htab);
if (stub_entry == NULL)
{
free (stub_name);
goto error_ret_free_internal;
}
stub_entry->target_value = sym_value + irela->r_addend;
stub_entry->target_section = sym_sec;
stub_entry->stub_type = stub_type;
stub_entry->h = hash;
stub_entry->st_type = st_type;
if (sym_name == NULL)
sym_name = "unnamed";
len = sizeof (STUB_ENTRY_NAME) + strlen (sym_name);
stub_entry->output_name = bfd_alloc (htab->stub_bfd, len);
if (stub_entry->output_name == NULL)
{
free (stub_name);
goto error_ret_free_internal;
}
snprintf (stub_entry->output_name, len, STUB_ENTRY_NAME,
sym_name);
*stub_changed = true;
}
/* We're done with the internal relocs, free them. */
if (elf_section_data (section)->relocs == NULL)
free (internal_relocs);
}
}
return true;
error_ret_free_local:
return false;
}
/* Determine and set the size of the stub section for a final link. */
bool
elfNN_aarch64_size_stubs (bfd *output_bfd,
bfd *stub_bfd,
@@ -4282,7 +4555,6 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
{
bfd_size_type stub_group_size;
bool stubs_always_before_branch;
bool stub_changed = false;
struct elf_aarch64_link_hash_table *htab = elf_aarch64_hash_table (info);
unsigned int num_erratum_835769_fixes = 0;
@@ -4357,285 +4629,19 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
(*htab->layout_sections_again) ();
}
while (1)
for (;;)
{
bfd *input_bfd;
bool stub_changed = false;
for (input_bfd = info->input_bfds;
input_bfd != NULL; input_bfd = input_bfd->link.next)
{
Elf_Internal_Shdr *symtab_hdr;
asection *section;
Elf_Internal_Sym *local_syms = NULL;
if (!is_aarch64_elf (input_bfd)
|| (input_bfd->flags & BFD_LINKER_CREATED) != 0)
continue;
/* We'll need the symbol table in a second. */
symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr;
if (symtab_hdr->sh_info == 0)
continue;
/* Walk over each section attached to the input bfd. */
for (section = input_bfd->sections;
section != NULL; section = section->next)
{
Elf_Internal_Rela *internal_relocs, *irelaend, *irela;
/* If there aren't any relocs, then there's nothing more
to do. */
if ((section->flags & SEC_RELOC) == 0
|| section->reloc_count == 0
|| (section->flags & SEC_CODE) == 0)
continue;
/* If this section is a link-once section that will be
discarded, then don't create any stubs. */
if (section->output_section == NULL
|| section->output_section->owner != output_bfd)
continue;
/* Get the relocs. */
internal_relocs
= _bfd_elf_link_read_relocs (input_bfd, section, NULL,
NULL, info->keep_memory);
if (internal_relocs == NULL)
goto error_ret_free_local;
/* Now examine each relocation. */
irela = internal_relocs;
irelaend = irela + section->reloc_count;
for (; irela < irelaend; irela++)
{
unsigned int r_type, r_indx;
enum elf_aarch64_stub_type stub_type;
struct elf_aarch64_stub_hash_entry *stub_entry;
asection *sym_sec;
bfd_vma sym_value;
bfd_vma destination;
struct elf_aarch64_link_hash_entry *hash;
const char *sym_name;
char *stub_name;
const asection *id_sec;
unsigned char st_type;
bfd_size_type len;
r_type = ELFNN_R_TYPE (irela->r_info);
r_indx = ELFNN_R_SYM (irela->r_info);
if (r_type >= (unsigned int) R_AARCH64_end)
{
bfd_set_error (bfd_error_bad_value);
error_ret_free_internal:
if (elf_section_data (section)->relocs == NULL)
free (internal_relocs);
goto error_ret_free_local;
}
/* Only look for stubs on unconditional branch and
branch and link instructions. */
if (r_type != (unsigned int) AARCH64_R (CALL26)
&& r_type != (unsigned int) AARCH64_R (JUMP26))
continue;
/* Now determine the call target, its name, value,
section. */
sym_sec = NULL;
sym_value = 0;
destination = 0;
hash = NULL;
sym_name = NULL;
if (r_indx < symtab_hdr->sh_info)
{
/* It's a local symbol. */
Elf_Internal_Sym *sym;
Elf_Internal_Shdr *hdr;
if (local_syms == NULL)
{
local_syms
= (Elf_Internal_Sym *) symtab_hdr->contents;
if (local_syms == NULL)
local_syms
= bfd_elf_get_elf_syms (input_bfd, symtab_hdr,
symtab_hdr->sh_info, 0,
NULL, NULL, NULL);
if (local_syms == NULL)
goto error_ret_free_internal;
}
sym = local_syms + r_indx;
hdr = elf_elfsections (input_bfd)[sym->st_shndx];
sym_sec = hdr->bfd_section;
if (!sym_sec)
/* This is an undefined symbol. It can never
be resolved. */
continue;
if (ELF_ST_TYPE (sym->st_info) != STT_SECTION)
sym_value = sym->st_value;
destination = (sym_value + irela->r_addend
+ sym_sec->output_offset
+ sym_sec->output_section->vma);
st_type = ELF_ST_TYPE (sym->st_info);
sym_name
= bfd_elf_string_from_elf_section (input_bfd,
symtab_hdr->sh_link,
sym->st_name);
}
else
{
int e_indx;
e_indx = r_indx - symtab_hdr->sh_info;
hash = ((struct elf_aarch64_link_hash_entry *)
elf_sym_hashes (input_bfd)[e_indx]);
while (hash->root.root.type == bfd_link_hash_indirect
|| hash->root.root.type == bfd_link_hash_warning)
hash = ((struct elf_aarch64_link_hash_entry *)
hash->root.root.u.i.link);
if (hash->root.root.type == bfd_link_hash_defined
|| hash->root.root.type == bfd_link_hash_defweak)
{
struct elf_aarch64_link_hash_table *globals =
elf_aarch64_hash_table (info);
sym_sec = hash->root.root.u.def.section;
sym_value = hash->root.root.u.def.value;
/* For a destination in a shared library,
use the PLT stub as target address to
decide whether a branch stub is
needed. */
if (globals->root.splt != NULL && hash != NULL
&& hash->root.plt.offset != (bfd_vma) - 1)
{
sym_sec = globals->root.splt;
sym_value = hash->root.plt.offset;
if (sym_sec->output_section != NULL)
destination = (sym_value
+ sym_sec->output_offset
+
sym_sec->output_section->vma);
}
else if (sym_sec->output_section != NULL)
destination = (sym_value + irela->r_addend
+ sym_sec->output_offset
+ sym_sec->output_section->vma);
}
else if (hash->root.root.type == bfd_link_hash_undefined
|| (hash->root.root.type
== bfd_link_hash_undefweak))
{
/* For a shared library, use the PLT stub as
target address to decide whether a long
branch stub is needed.
For absolute code, they cannot be handled. */
struct elf_aarch64_link_hash_table *globals =
elf_aarch64_hash_table (info);
if (globals->root.splt != NULL && hash != NULL
&& hash->root.plt.offset != (bfd_vma) - 1)
{
sym_sec = globals->root.splt;
sym_value = hash->root.plt.offset;
if (sym_sec->output_section != NULL)
destination = (sym_value
+ sym_sec->output_offset
+
sym_sec->output_section->vma);
}
else
continue;
}
else
{
bfd_set_error (bfd_error_bad_value);
goto error_ret_free_internal;
}
st_type = ELF_ST_TYPE (hash->root.type);
sym_name = hash->root.root.root.string;
}
/* Determine what (if any) linker stub is needed. */
stub_type = aarch64_type_of_stub (section, irela, sym_sec,
st_type, destination);
if (stub_type == aarch64_stub_none)
continue;
/* Support for grouping stub sections. */
id_sec = htab->stub_group[section->id].link_sec;
/* Get the name of this stub. */
stub_name = elfNN_aarch64_stub_name (id_sec, sym_sec, hash,
irela);
if (!stub_name)
goto error_ret_free_internal;
stub_entry =
aarch64_stub_hash_lookup (&htab->stub_hash_table,
stub_name, false, false);
if (stub_entry != NULL)
{
/* The proper stub has already been created. */
free (stub_name);
/* Always update this stub's target since it may have
changed after layout. */
stub_entry->target_value = sym_value + irela->r_addend;
continue;
}
stub_entry = _bfd_aarch64_add_stub_entry_in_group
(stub_name, section, htab);
if (stub_entry == NULL)
{
free (stub_name);
goto error_ret_free_internal;
}
stub_entry->target_value = sym_value + irela->r_addend;
stub_entry->target_section = sym_sec;
stub_entry->stub_type = stub_type;
stub_entry->h = hash;
stub_entry->st_type = st_type;
if (sym_name == NULL)
sym_name = "unnamed";
len = sizeof (STUB_ENTRY_NAME) + strlen (sym_name);
stub_entry->output_name = bfd_alloc (htab->stub_bfd, len);
if (stub_entry->output_name == NULL)
{
free (stub_name);
goto error_ret_free_internal;
}
snprintf (stub_entry->output_name, len, STUB_ENTRY_NAME,
sym_name);
stub_changed = true;
}
/* We're done with the internal relocs, free them. */
if (elf_section_data (section)->relocs == NULL)
free (internal_relocs);
}
}
if (!_bfd_aarch64_add_call_stub_entries (&stub_changed, output_bfd, info))
return false;
if (!stub_changed)
break;
return true;
_bfd_aarch64_resize_stubs (htab);
/* Ask the linker to do its stuff. */
(*htab->layout_sections_again) ();
stub_changed = false;
}
return true;
error_ret_free_local:
return false;
}
/* Build all the stubs associated with the current output file. The