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Fix the bfd linker's generation of call stubs for large AArch64 binaries with BTI enabled.

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Resolves: #2241902
This commit is contained in:
Nick Clifton 2023-11-07 12:17:50 +00:00
parent c3cd6c8351
commit 1fe93dadad
2 changed files with 147 additions and 1 deletions
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139
binutils-aarch64-big-bti-programs.patch Normal file
View File

@ -0,0 +1,139 @@
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 4592bd6da27..4faf642b422 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -3675,7 +3675,7 @@ group_sections (struct elf_aarch64_link_hash_table *htab,
/* True if the inserted stub does not break BTI compatibility. */
static bool
-aarch64_bti_stub_p (bfd *input_bfd,
+aarch64_bti_stub_p (struct bfd_link_info *info,
struct elf_aarch64_stub_hash_entry *stub_entry)
{
/* Stubs without indirect branch are BTI compatible. */
@@ -3685,12 +3685,22 @@ aarch64_bti_stub_p (bfd *input_bfd,
/* Return true if the target instruction is compatible with BR x16. */
+ struct elf_aarch64_link_hash_table *globals = elf_aarch64_hash_table (info);
asection *section = stub_entry->target_section;
bfd_byte loc[4];
file_ptr off = stub_entry->target_value;
bfd_size_type count = sizeof (loc);
- if (!bfd_get_section_contents (input_bfd, section, loc, off, count))
+ /* PLT code is not generated yet, so treat it specially.
+ Note: Checking elf_aarch64_obj_tdata.plt_type & PLT_BTI is not
+ enough because it only implies BTI in the PLT0 and tlsdesc PLT
+ entries. Normal PLT entries don't have BTI in a shared library
+ (because such PLT is normally not called indirectly and adding
+ the BTI when a stub targets a PLT would change the PLT layout
+ and it's too late for that here). */
+ if (section == globals->root.splt)
+ memcpy (loc, globals->plt_entry, count);
+ else if (!bfd_get_section_contents (section->owner, section, loc, off, count))
return false;
uint32_t insn = bfd_getl32 (loc);
@@ -4637,11 +4647,24 @@ _bfd_aarch64_add_call_stub_entries (bool *stub_changed, bfd *output_bfd,
/* A stub with indirect jump may break BTI compatibility, so
insert another stub with direct jump near the target then. */
- if (need_bti && !aarch64_bti_stub_p (input_bfd, stub_entry))
+ if (need_bti && !aarch64_bti_stub_p (info, stub_entry))
{
+ id_sec_bti = htab->stub_group[sym_sec->id].link_sec;
+
+ /* If the stub with indirect jump and the BTI stub are in
+ the same stub group: change the indirect jump stub into
+ a BTI stub since a direct branch can reach the target.
+ The BTI landing pad is still needed in case another
+ stub indirectly jumps to it. */
+ if (id_sec_bti == id_sec)
+ {
+ stub_entry->stub_type = aarch64_stub_bti_direct_branch;
+ goto skip_double_stub;
+ }
+
stub_entry->double_stub = true;
htab->has_double_stub = true;
- id_sec_bti = htab->stub_group[sym_sec->id].link_sec;
+
stub_name_bti =
elfNN_aarch64_stub_name (id_sec_bti, sym_sec, hash, irela);
if (!stub_name_bti)
@@ -4653,33 +4676,41 @@ _bfd_aarch64_add_call_stub_entries (bool *stub_changed, bfd *output_bfd,
stub_entry_bti =
aarch64_stub_hash_lookup (&htab->stub_hash_table,
stub_name_bti, false, false);
- if (stub_entry_bti == NULL)
- stub_entry_bti =
- _bfd_aarch64_add_stub_entry_in_group (stub_name_bti,
- sym_sec, htab);
- if (stub_entry_bti == NULL)
+ if (stub_entry_bti != NULL)
+ BFD_ASSERT (stub_entry_bti->stub_type
+ == aarch64_stub_bti_direct_branch);
+ else
{
- free (stub_name);
- free (stub_name_bti);
- goto error_ret_free_internal;
- }
-
- stub_entry_bti->target_value = sym_value + irela->r_addend;
- stub_entry_bti->target_section = sym_sec;
- stub_entry_bti->stub_type = aarch64_stub_bti_direct_branch;
- stub_entry_bti->h = hash;
- stub_entry_bti->st_type = st_type;
+ stub_entry_bti =
+ _bfd_aarch64_add_stub_entry_in_group (stub_name_bti,
+ sym_sec, htab);
+ if (stub_entry_bti == NULL)
+ {
+ free (stub_name);
+ free (stub_name_bti);
+ goto error_ret_free_internal;
+ }
- len = sizeof (BTI_STUB_ENTRY_NAME) + strlen (sym_name);
- stub_entry_bti->output_name = bfd_alloc (htab->stub_bfd, len);
- if (stub_entry_bti->output_name == NULL)
- {
- free (stub_name);
- free (stub_name_bti);
- goto error_ret_free_internal;
+ stub_entry_bti->target_value =
+ sym_value + irela->r_addend;
+ stub_entry_bti->target_section = sym_sec;
+ stub_entry_bti->stub_type =
+ aarch64_stub_bti_direct_branch;
+ stub_entry_bti->h = hash;
+ stub_entry_bti->st_type = st_type;
+
+ len = sizeof (BTI_STUB_ENTRY_NAME) + strlen (sym_name);
+ stub_entry_bti->output_name = bfd_alloc (htab->stub_bfd,
+ len);
+ if (stub_entry_bti->output_name == NULL)
+ {
+ free (stub_name);
+ free (stub_name_bti);
+ goto error_ret_free_internal;
+ }
+ snprintf (stub_entry_bti->output_name, len,
+ BTI_STUB_ENTRY_NAME, sym_name);
}
- snprintf (stub_entry_bti->output_name, len,
- BTI_STUB_ENTRY_NAME, sym_name);
/* Update the indirect call stub to target the BTI stub. */
stub_entry->target_value = 0;
@@ -4688,7 +4719,7 @@ _bfd_aarch64_add_call_stub_entries (bool *stub_changed, bfd *output_bfd,
stub_entry->h = NULL;
stub_entry->st_type = STT_FUNC;
}
-
+skip_double_stub:
*stub_changed = true;
}

9
binutils.spec
View File

@ -2,7 +2,7 @@
Summary: A GNU collection of binary utilities Summary: A GNU collection of binary utilities
Name: binutils%{?_with_debug:-debug} Name: binutils%{?_with_debug:-debug}
Version: 2.41 Version: 2.41
Release: 11%{?dist} Release: 12%{?dist}
License: GPL-3.0-or-later AND (GPL-3.0-or-later WITH Bison-exception-2.2) AND (LGPL-2.0-or-later WITH GCC-exception-2.0) AND BSD-3-Clause AND GFDL-1.3-or-later AND GPL-2.0-or-later LGPL-2.1-or-later AND LGPL-2.0-or-later License: GPL-3.0-or-later AND (GPL-3.0-or-later WITH Bison-exception-2.2) AND (LGPL-2.0-or-later WITH GCC-exception-2.0) AND BSD-3-Clause AND GFDL-1.3-or-later AND GPL-2.0-or-later LGPL-2.1-or-later AND LGPL-2.0-or-later
URL: https://sourceware.org/binutils URL: https://sourceware.org/binutils
@ -282,6 +282,10 @@ Patch22: binutils-x86-64-v3.patch
# Lifetime: Fixed in 2.42 # Lifetime: Fixed in 2.42
Patch23: binutils-big-merge.patch Patch23: binutils-big-merge.patch
# Purpose: Fix linker generated call veneers for large AArch64 programs with BTI enabled.
# Lifetime: Fixed in 2.42
Patch24: binutils-aarch64-big-bti-programs.patch
#---------------------------------------------------------------------------- #----------------------------------------------------------------------------
Provides: bundled(libiberty) Provides: bundled(libiberty)
@ -1287,6 +1291,9 @@ exit 0
#---------------------------------------------------------------------------- #----------------------------------------------------------------------------
%changelog %changelog
* Tue Nov 07 2023 Nick Clifton <nickc@redhat.com> - 2.41-12
- Fix the bfd linker's generation of call stubs for large AArch64 binaries with BTI enabled. (#2241902)
* Tue Nov 07 2023 Nick Clifton <nickc@redhat.com> - 2.41-11 * Tue Nov 07 2023 Nick Clifton <nickc@redhat.com> - 2.41-11
- Fix merging strings when linking really big programs. - Fix merging strings when linking really big programs.