2019-11-18 18:07:49 +01:00
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This is for userspace live patching, adding some space into
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shared libs or executable (in the .ulp section) when one of the
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input files contains a section named .ulp.track.
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Index: bfd/elflink.c
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===================================================================
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--- bfd/elflink.c.orig 2019-09-09 15:19:43.000000000 +0200
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2019-11-18 21:47:39 +01:00
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+++ bfd/elflink.c 2019-11-18 21:43:18.000000000 +0100
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2019-11-18 18:53:50 +01:00
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@@ -7070,6 +7070,13 @@ bfd_elf_size_dynamic_sections (bfd *outp
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2019-11-18 18:07:49 +01:00
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s = bfd_get_linker_section (dynobj, ".gnu.version");
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s->flags |= SEC_EXCLUDE;
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}
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+
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2019-11-18 18:53:50 +01:00
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+ if (bed->elf_backend_is_ulp_enabled != NULL
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+ && bed->elf_backend_setup_ulp != NULL
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2019-11-18 21:47:39 +01:00
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+ && (*bed->elf_backend_is_ulp_enabled) (info->input_bfds))
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2019-11-18 18:07:49 +01:00
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+ {
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2019-11-18 18:53:50 +01:00
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+ (*bed->elf_backend_setup_ulp)(info);
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2019-11-18 18:07:49 +01:00
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+ }
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}
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return TRUE;
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}
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Index: bfd/elfxx-x86.c
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===================================================================
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--- bfd/elfxx-x86.c.orig 2019-09-09 15:19:43.000000000 +0200
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2019-11-18 20:52:06 +01:00
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+++ bfd/elfxx-x86.c 2019-11-18 20:50:24.000000000 +0100
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2019-11-18 18:53:50 +01:00
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@@ -31,6 +31,8 @@
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#define ELF64_DYNAMIC_INTERPRETER "/lib/ld64.so.1"
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#define ELFX32_DYNAMIC_INTERPRETER "/lib/ldx32.so.1"
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2019-11-18 18:07:49 +01:00
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2019-11-18 18:53:50 +01:00
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+#define ULP_ENTRY_LEN 16
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+
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bfd_boolean
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_bfd_x86_elf_mkobject (bfd *abfd)
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{
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@@ -952,6 +954,64 @@ _bfd_x86_elf_link_check_relocs (bfd *abf
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2019-11-18 18:07:49 +01:00
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return _bfd_elf_link_check_relocs (abfd, info);
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}
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+/* Check if input bfds are ulp-enabled by containing .ulp.track section */
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+
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+bfd_boolean
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2019-11-18 18:53:50 +01:00
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+_bfd_x86_elf_is_ulp_enabled (struct bfd *input_bfd)
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2019-11-18 18:07:49 +01:00
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+{
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+ while (input_bfd != NULL)
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+ for (; input_bfd != NULL; input_bfd = input_bfd->link.next)
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+ {
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+ if (input_bfd->section_count == 0) continue;
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+ if (bfd_get_section_by_name (input_bfd, ".ulp.track")) return TRUE;
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+ }
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+ return FALSE;
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+}
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+
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+/* To be used by elf_link_hash_traverse when computing the ulp length */
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+
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+static bfd_boolean
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+bfd_x86_elf_link_compute_ulp (struct elf_link_hash_entry *h, void *data)
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+{
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+ unsigned long *ulp_length = (unsigned long *) data;
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+
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+ if (h->dynindx != -1 && h->type == STT_FUNC && !h->def_dynamic)
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+ {
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+ ++(*ulp_length);
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+ }
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+ return TRUE;
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+}
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+
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+/* Fill the user-space live patching section */
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+
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+bfd_boolean
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2019-11-18 18:53:50 +01:00
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+_bfd_x86_elf_setup_ulp (struct bfd_link_info *info)
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2019-11-18 18:07:49 +01:00
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+{
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+ struct elf_x86_link_hash_table *htab;
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+ asection *ulp;
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+ unsigned int ulp_length = 0;
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+
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+ htab = elf_x86_hash_table (info, X86_64_ELF_DATA);
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+
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+ elf_link_hash_traverse (elf_hash_table (info),
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+ bfd_x86_elf_link_compute_ulp,
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+ &ulp_length);
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+
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+ ulp = htab->ulp;
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+
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+ ulp->size = ulp_length * ULP_ENTRY_LEN;
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+
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+ ulp->contents = (bfd_byte *) bfd_malloc (ulp->size);
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+ if (ulp->contents == NULL)
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+ return FALSE;
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+
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+ if (!ulp->contents)
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+ return FALSE;
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+
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+ memset(ulp->contents, 0x00, ulp->size);
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+ return TRUE;
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+}
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+
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/* Set the sizes of the dynamic sections. */
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bfd_boolean
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2019-11-18 18:53:50 +01:00
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@@ -2935,7 +2995,26 @@ error_alignment:
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2019-11-18 18:07:49 +01:00
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htab->plt_second = sec;
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}
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- }
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+
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+ /* create sections to support user-space live patching */
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2019-11-18 20:52:06 +01:00
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+ if (_bfd_x86_elf_is_ulp_enabled(info->input_bfds))
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2019-11-18 18:07:49 +01:00
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+ {
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+ flagword flags = (bed->dynamic_sec_flags
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+ | SEC_ALLOC
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+ | SEC_CODE
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+ | SEC_LOAD
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+ | SEC_READONLY);
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+
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+ sec = bfd_make_section_anyway_with_flags (dynobj, ".ulp", flags);
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+ if (sec == NULL)
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+ info->callbacks->einfo (_("%F%P: failed to create ULP section\n"));
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+
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2020-02-17 15:18:06 +01:00
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+ if (!bfd_set_section_alignment (sec, plt_alignment))
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2019-11-18 18:07:49 +01:00
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+ goto error_alignment;
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+
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+ htab->ulp = sec;
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+ }
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+ }
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if (!info->no_ld_generated_unwind_info)
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{
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Index: bfd/elfxx-x86.h
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===================================================================
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--- bfd/elfxx-x86.h.orig 2019-09-09 15:19:43.000000000 +0200
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2019-11-18 20:52:06 +01:00
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+++ bfd/elfxx-x86.h 2019-11-18 20:48:33.000000000 +0100
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2019-11-18 18:07:49 +01:00
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@@ -447,6 +447,7 @@ struct elf_x86_link_hash_table
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asection *plt_second_eh_frame;
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asection *plt_got;
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asection *plt_got_eh_frame;
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+ asection *ulp;
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/* Parameters describing PLT generation, lazy or non-lazy. */
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struct elf_x86_plt_layout plt;
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2019-11-18 18:53:50 +01:00
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@@ -708,6 +709,12 @@ extern void _bfd_x86_elf_link_fixup_ifun
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(struct bfd_link_info *, struct elf_x86_link_hash_table *,
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struct elf_link_hash_entry *, Elf_Internal_Sym *sym);
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+extern bfd_boolean _bfd_x86_elf_is_ulp_enabled
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2019-11-18 18:07:49 +01:00
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+ (struct bfd *);
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+
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2019-11-18 18:53:50 +01:00
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+extern bfd_boolean _bfd_x86_elf_setup_ulp
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2019-11-18 18:07:49 +01:00
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+ (struct bfd_link_info *);
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+
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2019-11-18 18:53:50 +01:00
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#define bfd_elf64_mkobject \
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_bfd_x86_elf_mkobject
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#define bfd_elf32_mkobject \
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@@ -745,3 +752,7 @@ extern void _bfd_x86_elf_link_fixup_ifun
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_bfd_x86_elf_merge_gnu_properties
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#define elf_backend_fixup_gnu_properties \
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_bfd_x86_elf_link_fixup_gnu_properties
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+#define elf_backend_is_ulp_enabled \
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+ _bfd_x86_elf_is_ulp_enabled
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+#define elf_backend_setup_ulp \
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+ _bfd_x86_elf_setup_ulp
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Index: bfd/elf-bfd.h
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===================================================================
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--- bfd/elf-bfd.h.orig 2019-09-09 15:19:43.000000000 +0200
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2019-11-18 20:52:06 +01:00
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+++ bfd/elf-bfd.h 2019-11-18 20:48:33.000000000 +0100
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2019-11-18 18:53:50 +01:00
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@@ -1423,6 +1423,10 @@ struct elf_backend_data
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(const bfd *ibfd, bfd *obfd, const Elf_Internal_Shdr *isection,
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Elf_Internal_Shdr *osection);
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+ bfd_boolean (*elf_backend_is_ulp_enabled) (bfd *abfd);
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2019-11-18 18:07:49 +01:00
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+
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2019-11-18 18:53:50 +01:00
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+ bfd_boolean (*elf_backend_setup_ulp) (struct bfd_link_info *);
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2019-11-18 18:07:49 +01:00
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+
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2019-11-18 18:53:50 +01:00
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/* Used to handle bad SHF_LINK_ORDER input. */
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void (*link_order_error_handler) (const char *, ...);
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Index: bfd/elfxx-target.h
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===================================================================
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--- bfd/elfxx-target.h.orig 2019-09-09 15:19:43.000000000 +0200
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2019-11-18 20:52:06 +01:00
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+++ bfd/elfxx-target.h 2019-11-18 20:48:33.000000000 +0100
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2019-11-18 18:53:50 +01:00
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@@ -754,6 +754,14 @@
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#define elf_backend_copy_special_section_fields NULL
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#endif
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+#ifndef elf_backend_is_ulp_enabled
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+#define elf_backend_is_ulp_enabled NULL
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+#endif
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+
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+#ifndef elf_backend_setup_ulp
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+#define elf_backend_setup_ulp NULL
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+#endif
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+
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#ifndef elf_backend_compact_eh_encoding
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#define elf_backend_compact_eh_encoding NULL
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#endif
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@@ -867,6 +875,8 @@ static struct elf_backend_data elfNN_bed
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elf_backend_maybe_function_sym,
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elf_backend_get_reloc_section,
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elf_backend_copy_special_section_fields,
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+ elf_backend_is_ulp_enabled,
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+ elf_backend_setup_ulp,
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elf_backend_link_order_error_handler,
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elf_backend_relplt_name,
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ELF_MACHINE_ALT1,
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