ld: bfd: sframe: fix incorrect r_offset in RELA entries

PR/32666  Incorrect .rela.sframe when using ld -r

Input SFrame sections are merged using _bfd_elf_merge_section_sframe (),
which clubs all SFrame FDEs together in one blob and all SFrame FREs in
another.  This, of course, means the offset of an SFrame FDE in the output
section cannot be simply derived from the output_offset of the sections.

Fix this by providing _bfd_elf_sframe_section_offset () which returns
the new offset of the SFrame FDE in the merged SFrame section.

Unlike EH_Frame sections, which also use the _bfd_elf_section_offset (),
to update the r_offset, SFrame sections additionally need :

          if (o->sec_info_type != SEC_INFO_TYPE_SFRAME)
            irela->r_offset += o->output_offset;

because information in SFrame and EH_Frame sections is organised
differently.  In case of SFrame, the SFrame FDE will not simply sit at
location "o->output_offset + offset of SFrame FDE in o".  Recall that
information layout in an SFrame section is as follows:
   SFrame Header
   SFrame FDE 1
   SFrame FDE 2
   ...
   SFrame FDEn
   SFrame FREs (Frame Row Entries)
Note how the SFrame FDEs and SFrame FREs are clubber together in groups
of their own.

Taking the above into account, the correct offset has already been
calculated via _bfd_elf_section_offset ().  So for SFrame sections, the
r_offset of the RELA should not be offset further by the
o->output_offset (offset of the input SFrame section in the output
SFrame section).

Add a new enum to track the current state of the SFrame input section
during the linking process (SFRAME_SEC_DECODED, SFRAME_SEC_MERGED) for
each input SFrame section.  This is then used to assert an assumption
that _bfd_elf_sframe_section_offset () is being used on an input SFrame
sections which have not been merged (via
_bfd_elf_merge_section_sframe ()) yet.

bfd/
        * elf-bfd.h: New declaration.
        * elf-sframe.c (_bfd_elf_sframe_section_offset): New definition.
        * elf.c (_bfd_elf_section_offset): Adjust offset if SFrame
	section.
        * elflink.c (elf_link_input_bfd): RELA offset adjust be done
	conditionally.

ld/testsuite/
        * ld-x86-64/x86-64.exp: New test.
        * ld-x86-64/sframe-reloc-1.d: New test.

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 5903d857faad2a15afe9320276e6f62275258890..f62570919d540e89eaf1ffb47dab6c8f7e471b91 100644 (file)
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -503,12 +503,21 @@ struct sframe_func_bfdinfo
   unsigned int func_reloc_index;
 };
 
+/* Link state information of the SFrame section.  */
+enum sframe_sec_state
+{
+  SFRAME_SEC_DECODED = 1,
+  SFRAME_SEC_MERGED,
+};
+
 /* SFrame decoder info.
    Contains all information for a decoded .sframe section.  */
 struct sframe_dec_info
 {
   /* Decoder context.  */
   struct sframe_decoder_ctx *sfd_ctx;
+  /* SFrame section state as it progresses through the link process.  */
+  enum sframe_sec_state sfd_state;
   /* Number of function descriptor entries in this .sframe.  */
   unsigned int sfd_fde_count;
   /* Additional information for linking.  */
@@ -2540,6 +2549,8 @@ extern bool _bfd_elf_discard_section_sframe
   (asection *, bool (*) (bfd_vma, void *), struct elf_reloc_cookie *);
 extern bool _bfd_elf_merge_section_sframe
   (bfd *, struct bfd_link_info *, asection *, bfd_byte *);
+extern bfd_vma _bfd_elf_sframe_section_offset
+  (bfd *, struct bfd_link_info *, asection *, bfd_vma);
 extern bool _bfd_elf_write_section_sframe
   (bfd *, struct bfd_link_info *);
 extern bool _bfd_elf_set_section_sframe (bfd *, struct bfd_link_info *);

diff --git a/bfd/elf-sframe.c b/bfd/elf-sframe.c
index a5958464536c963a19bf27051ae87dc87d01eabf..9c7bf09964962342d6e5acc1ab10ee712fd76e63 100644 (file)
--- a/bfd/elf-sframe.c
+++ b/bfd/elf-sframe.c
@@ -213,10 +213,11 @@ _bfd_elf_parse_sframe (bfd *abfd,
   /* Decode the buffer and keep decoded contents for later use.
      Relocations are performed later, but are such that the section's
      size is unaffected.  */
-  sfd_info = bfd_alloc (abfd, sizeof (*sfd_info));
+  sfd_info = bfd_zalloc (abfd, sizeof (*sfd_info));
   sf_size = sec->size;
 
   sfd_info->sfd_ctx = sframe_decode ((const char*)sfbuf, sf_size, &decerr);
+  sfd_info->sfd_state = SFRAME_SEC_DECODED;
   sfd_ctx = sfd_info->sfd_ctx;
   if (!sfd_ctx)
     /* Free'ing up any memory held by decoder context is done by
@@ -507,12 +508,72 @@ _bfd_elf_merge_section_sframe (bfd *abfd,
            }
        }
     }
+  sfd_info->sfd_state = SFRAME_SEC_MERGED;
   /* Free the SFrame decoder context.  */
   sframe_decoder_free (&sfd_ctx);
 
   return true;
 }
 
+/* Adjust an address in the .sframe section.  Given OFFSET within
+   SEC, this returns the new offset in the merged .sframe section,
+   or -1 if the address refers to an FDE which has been removed.
+
+   PS: This function assumes that _bfd_elf_merge_section_sframe has
+   not been called on the input section SEC yet.  Note how it uses
+   sframe_encoder_get_num_fidx () to figure out the offset of FDE
+   in the output section.  */
+
+bfd_vma
+_bfd_elf_sframe_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED,
+                               struct bfd_link_info *info,
+                               asection *sec,
+                               bfd_vma offset)
+{
+  struct sframe_dec_info *sfd_info;
+  struct sframe_enc_info *sfe_info;
+  sframe_decoder_ctx *sfd_ctx;
+  sframe_encoder_ctx *sfe_ctx;
+  struct elf_link_hash_table *htab;
+
+  unsigned int sec_fde_idx, out_fde_idx;
+  unsigned int i, sfe_num_fdes;
+
+  if (sec->sec_info_type != SEC_INFO_TYPE_SFRAME)
+    return offset;
+
+  sfd_info = (struct sframe_dec_info *) elf_section_data (sec)->sec_info;
+  sfd_ctx = sfd_info->sfd_ctx;
+
+  BFD_ASSERT (sfd_info->sfd_state == SFRAME_SEC_DECODED);
+
+  /* Identify the index of the FDE (at OFFSET) in the input section.  */
+  sec_fde_idx = ((offset - sframe_decoder_get_hdr_size (sfd_ctx))
+                / sizeof (sframe_func_desc_entry));
+
+  if (sframe_decoder_func_deleted_p (sfd_info, sec_fde_idx))
+    return (bfd_vma) -1;
+
+  htab = elf_hash_table (info);
+  sfe_info = &(htab->sfe_info);
+  sfe_ctx = sfe_info->sfe_ctx;
+  sfe_num_fdes = sframe_encoder_get_num_fidx (sfe_ctx);
+
+  /* The index of this FDE in the output section depends on number of deleted
+     functions (between index 0 and sec_fde_idx), if any.  */
+  out_fde_idx = 0;
+  for (i = 0; i < sec_fde_idx; i++)
+    {
+      if (!sframe_decoder_func_deleted_p (sfd_info, i))
+       out_fde_idx++;
+    }
+  /* The actual index of the FDE in the output SFrame section.  */
+  out_fde_idx += sfe_num_fdes;
+
+  return (sframe_decoder_get_hdr_size (sfd_ctx)
+         + out_fde_idx * sizeof (sframe_func_desc_entry));
+}
+
 /* Write out the .sframe section.  This must be called after
    _bfd_elf_merge_section_sframe has been called on all input
    .sframe sections.  */

diff --git a/bfd/elf.c b/bfd/elf.c
index 3f8bc838bfb34b367c500b916046a090b4015143..3d65486ad5ba655f740490dabf1fe4195c47a88f 100644 (file)
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -13491,6 +13491,9 @@ _bfd_elf_section_offset (bfd *abfd,
     case SEC_INFO_TYPE_EH_FRAME:
       return _bfd_elf_eh_frame_section_offset (abfd, info, sec, offset);
 
+    case SEC_INFO_TYPE_SFRAME:
+      return _bfd_elf_sframe_section_offset (abfd, info, sec, offset);
+
     default:
       if ((sec->flags & SEC_ELF_REVERSE_COPY) != 0)
        {

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 13993527e3e4cfc28b9b9fa670a8f8dd8c7f0e9e..895fbb0206e1f4b41a3fd1166d59f90fd2f1e977 100644 (file)
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -11974,7 +11974,11 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
                      continue;
                    }
 
-                 irela->r_offset += o->output_offset;
+                 /* All SFrame FDEs from input sections are clubbed together
+                    in the beginning of the output section.  RELA offsets are
+                    already up to date.  PR ld/32666.  */
+                 if (o->sec_info_type != SEC_INFO_TYPE_SFRAME)
+                   irela->r_offset += o->output_offset;
 
                  /* Relocs in an executable have to be virtual addresses.  */
                  if (!bfd_link_relocatable (flinfo->info))

diff --git a/ld/testsuite/ld-x86-64/sframe-reloc-1.d b/ld/testsuite/ld-x86-64/sframe-reloc-1.d
new file mode 100644 (file)
index 0000000..308f94b
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/sframe-reloc-1.d
@@ -0,0 +1,34 @@
+#as: --gsframe
+#source: sframe-foo.s
+#source: sframe-bar.s
+#objdump: --sframe=.sframe
+#ld: -r --no-rosegment
+#name: SFrame simple link - relocatable
+
+.*: +file format .*
+
+Contents of the SFrame section .sframe:
+  Header :
+
+    Version: SFRAME_VERSION_2
+    Flags: SFRAME_F_FDE_SORTED
+    CFA fixed RA offset: \-8
+    Num FDEs: 2
+    Num FREs: 8
+
+  Function Index :
+
+
+    func idx \[0\]: pc = 0x0, size = 53 bytes
+    STARTPC +CFA +FP +RA +
+    0+0000 +sp\+8 +u +f +
+    0+0001 +sp\+16 +c-16 +f +
+    0+0004 +fp\+16 +c-16 +f +
+    0+0034 +sp\+8 +c-16 +f +
+
+    func idx \[1\]: pc = 0x35, size = 37 bytes
+    STARTPC +CFA +FP +RA +
+    0+0035 +sp\+8 +u +f +
+    0+0036 +sp\+16 +c-16 +f +
+    0+0039 +fp\+16 +c-16 +f +
+    0+0059 +sp\+8 +c-16 +f +

diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 01d6459b5d79c03de4587e009284cb1433361fad..eed06af80df1cdf9ff144da843ec0dbf88ec7899 100644 (file)
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -566,6 +566,7 @@ run_dump_test "pr32591-4-x32"
 
 if { ![skip_sframe_tests] } {
     run_dump_test "sframe-simple-1"
+    run_dump_test "sframe-reloc-1"
     run_dump_test "sframe-plt-1"
     run_dump_test "sframe-ibt-plt-1"
     run_dump_test "sframe-pltgot-1"