File add-ulp-section.diff of Package cross-i386-binutils.16991
This is for userspace live patching, adding some space into
shared libs or executable (in the .ulp section) when one of the
input files contains a section named .ulp.track.
Index: binutils-2.35/bfd/elf-bfd.h
===================================================================
--- binutils-2.35.orig/bfd/elf-bfd.h 2020-07-24 11:12:19.000000000 +0200
+++ binutils-2.35/bfd/elf-bfd.h 2020-08-10 16:30:46.555219071 +0200
@@ -1476,6 +1476,10 @@ struct elf_backend_data
(const bfd *ibfd, bfd *obfd, const Elf_Internal_Shdr *isection,
Elf_Internal_Shdr *osection);
+ bfd_boolean (*elf_backend_is_ulp_enabled) (bfd *abfd);
+
+ bfd_boolean (*elf_backend_setup_ulp) (struct bfd_link_info *);
+
/* Used to handle bad SHF_LINK_ORDER input. */
void (*link_order_error_handler) (const char *, ...);
Index: binutils-2.35/bfd/elflink.c
===================================================================
--- binutils-2.35.orig/bfd/elflink.c 2020-07-24 11:12:19.000000000 +0200
+++ binutils-2.35/bfd/elflink.c 2020-08-10 16:30:46.565219071 +0200
@@ -7197,6 +7197,13 @@ bfd_elf_size_dynamic_sections (bfd *outp
s = bfd_get_linker_section (dynobj, ".gnu.version");
s->flags |= SEC_EXCLUDE;
}
+
+ if (bed->elf_backend_is_ulp_enabled != NULL
+ && bed->elf_backend_setup_ulp != NULL
+ && (*bed->elf_backend_is_ulp_enabled) (info->input_bfds))
+ {
+ (*bed->elf_backend_setup_ulp)(info);
+ }
}
return TRUE;
}
Index: binutils-2.35/bfd/elfxx-target.h
===================================================================
--- binutils-2.35.orig/bfd/elfxx-target.h 2020-07-24 11:12:19.000000000 +0200
+++ binutils-2.35/bfd/elfxx-target.h 2020-08-10 16:30:46.565219071 +0200
@@ -768,6 +768,14 @@
#define elf_backend_copy_special_section_fields _bfd_elf_copy_special_section_fields
#endif
+#ifndef elf_backend_is_ulp_enabled
+#define elf_backend_is_ulp_enabled NULL
+#endif
+
+#ifndef elf_backend_setup_ulp
+#define elf_backend_setup_ulp NULL
+#endif
+
#ifndef elf_backend_compact_eh_encoding
#define elf_backend_compact_eh_encoding NULL
#endif
@@ -900,6 +908,8 @@ static struct elf_backend_data elfNN_bed
elf_backend_maybe_function_sym,
elf_backend_get_reloc_section,
elf_backend_copy_special_section_fields,
+ elf_backend_is_ulp_enabled,
+ elf_backend_setup_ulp,
elf_backend_link_order_error_handler,
elf_backend_relplt_name,
ELF_MACHINE_ALT1,
Index: binutils-2.35/bfd/elfxx-x86.c
===================================================================
--- binutils-2.35.orig/bfd/elfxx-x86.c 2020-07-24 11:12:19.000000000 +0200
+++ binutils-2.35/bfd/elfxx-x86.c 2020-08-10 16:30:46.565219071 +0200
@@ -31,6 +31,8 @@
#define ELF64_DYNAMIC_INTERPRETER "/lib/ld64.so.1"
#define ELFX32_DYNAMIC_INTERPRETER "/lib/ldx32.so.1"
+#define ULP_ENTRY_LEN 16
+
bfd_boolean
_bfd_x86_elf_mkobject (bfd *abfd)
{
@@ -984,6 +986,64 @@ _bfd_elf_x86_valid_reloc_p (asection *in
return valid_p;
}
+/* Check if input bfds are ulp-enabled by containing .ulp.track section */
+
+bfd_boolean
+_bfd_x86_elf_is_ulp_enabled (struct bfd *input_bfd)
+{
+ while (input_bfd != NULL)
+ for (; input_bfd != NULL; input_bfd = input_bfd->link.next)
+ {
+ if (input_bfd->section_count == 0) continue;
+ if (bfd_get_section_by_name (input_bfd, ".ulp.track")) return TRUE;
+ }
+ return FALSE;
+}
+
+/* To be used by elf_link_hash_traverse when computing the ulp length */
+
+static bfd_boolean
+bfd_x86_elf_link_compute_ulp (struct elf_link_hash_entry *h, void *data)
+{
+ unsigned long *ulp_length = (unsigned long *) data;
+
+ if (h->dynindx != -1 && h->type == STT_FUNC && !h->def_dynamic)
+ {
+ ++(*ulp_length);
+ }
+ return TRUE;
+}
+
+/* Fill the user-space live patching section */
+
+bfd_boolean
+_bfd_x86_elf_setup_ulp (struct bfd_link_info *info)
+{
+ struct elf_x86_link_hash_table *htab;
+ asection *ulp;
+ unsigned int ulp_length = 0;
+
+ htab = elf_x86_hash_table (info, X86_64_ELF_DATA);
+
+ elf_link_hash_traverse (elf_hash_table (info),
+ bfd_x86_elf_link_compute_ulp,
+ &ulp_length);
+
+ ulp = htab->ulp;
+
+ ulp->size = ulp_length * ULP_ENTRY_LEN;
+
+ ulp->contents = (bfd_byte *) bfd_malloc (ulp->size);
+ if (ulp->contents == NULL)
+ return FALSE;
+
+ if (!ulp->contents)
+ return FALSE;
+
+ memset(ulp->contents, 0x00, ulp->size);
+ return TRUE;
+}
+
/* Set the sizes of the dynamic sections. */
bfd_boolean
@@ -2855,7 +2915,26 @@ _bfd_x86_elf_link_setup_gnu_properties
htab->plt_second = sec;
}
- }
+
+ /* create sections to support user-space live patching */
+ if (_bfd_x86_elf_is_ulp_enabled(info->input_bfds))
+ {
+ flagword flags = (bed->dynamic_sec_flags
+ | SEC_ALLOC
+ | SEC_CODE
+ | SEC_LOAD
+ | SEC_READONLY);
+
+ sec = bfd_make_section_anyway_with_flags (dynobj, ".ulp", flags);
+ if (sec == NULL)
+ info->callbacks->einfo (_("%F%P: failed to create ULP section\n"));
+
+ if (!bfd_set_section_alignment (sec, plt_alignment))
+ goto error_alignment;
+
+ htab->ulp = sec;
+ }
+ }
if (!info->no_ld_generated_unwind_info)
{
Index: binutils-2.35/bfd/elfxx-x86.h
===================================================================
--- binutils-2.35.orig/bfd/elfxx-x86.h 2020-07-24 11:12:19.000000000 +0200
+++ binutils-2.35/bfd/elfxx-x86.h 2020-08-10 16:30:46.565219071 +0200
@@ -449,6 +449,7 @@ struct elf_x86_link_hash_table
asection *plt_second_eh_frame;
asection *plt_got;
asection *plt_got_eh_frame;
+ asection *ulp;
/* Parameters describing PLT generation, lazy or non-lazy. */
struct elf_x86_plt_layout plt;
@@ -687,6 +688,12 @@ extern void _bfd_x86_elf_link_fixup_ifun
(struct bfd_link_info *, struct elf_x86_link_hash_table *,
struct elf_link_hash_entry *, Elf_Internal_Sym *sym);
+extern bfd_boolean _bfd_x86_elf_is_ulp_enabled
+ (struct bfd *);
+
+extern bfd_boolean _bfd_x86_elf_setup_ulp
+ (struct bfd_link_info *);
+
#define bfd_elf64_mkobject \
_bfd_x86_elf_mkobject
#define bfd_elf32_mkobject \
@@ -724,3 +731,7 @@ extern void _bfd_x86_elf_link_fixup_ifun
_bfd_x86_elf_merge_gnu_properties
#define elf_backend_fixup_gnu_properties \
_bfd_x86_elf_link_fixup_gnu_properties
+#define elf_backend_is_ulp_enabled \
+ _bfd_x86_elf_is_ulp_enabled
+#define elf_backend_setup_ulp \
+ _bfd_x86_elf_setup_ulp
