[COMMITTED,BPF] bfd: fix handling of R_BPF_INSN_{32, 64} relocations.

Message ID 87a71r4yuh.fsf@oracle.com
State New
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  • [COMMITTED,BPF] bfd: fix handling of R_BPF_INSN_{32, 64} relocations.
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Commit Message

Just pushed the patch below on behalf of David Faust.
Salud!

Author: David Faust <david.faust@oracle.com>
Date:   Thu May 28 20:53:29 2020 +0200

    bfd: fix handling of R_BPF_INSN_{32,64} relocations.
    
    2020-05-28  David Faust  <david.faust@oracle.com>
    
            * elf64-bpf.c (bpf_elf_relocate_section): Fix handling of
            R_BPF_INSN_{32,64} relocations.

Patch

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 482bf81e68..05452c5d46 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@ 
+2020-05-28  David Faust  <david.faust@oracle.com>
+
+	* elf64-bpf.c (bpf_elf_relocate_section): Fix handling of
+	R_BPF_INSN_{32,64} relocations.
+
 2020-05-28  Stephen Casner  <casner@acm.org>
 
 	* pdp11.c: Implement BRD_RELOC_32 to relocate the low 16 bits of
diff --git a/bfd/elf64-bpf.c b/bfd/elf64-bpf.c
index bf488af81f..641caa1f05 100644
--- a/bfd/elf64-bpf.c
+++ b/bfd/elf64-bpf.c
@@ -64,7 +64,7 @@  static reloc_howto_type bpf_elf_howto_table [] =
 	 MINUS_ONE,		/* dst_mask */
 	 TRUE),			/* pcrel_offset */
 
-  /* 32-immediate in LDDW instruction.  */
+  /* 32-immediate in many instructions. Note: handled manually.  */
   HOWTO (R_BPF_INSN_32,		/* type */
 	 0,			/* rightshift */
 	 2,			/* size (0 = byte, 1 = short, 2 = long) */
@@ -460,6 +460,31 @@  bpf_elf_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
             r = bfd_reloc_ok;
             break;
           }
+        case R_BPF_INSN_32:
+          {
+            /*  Write relocated value */
+            bfd_put (howto->bitsize, input_bfd, relocation,
+                     contents + rel->r_offset + 4);
+
+            r = bfd_reloc_ok;
+            break;
+          }
+        case R_BPF_INSN_64:
+          {
+            /*
+                LDDW instructions are 128 bits long, with a 64-bit immediate.
+                The lower 32 bits of the immediate are in the same position
+                as the imm32 field of other instructions.
+                The upper 32 bits of the immediate are stored at the end of
+                the instruction.
+             */
+            bfd_put (32, input_bfd, (relocation & 0xFFFFFFFF),
+                     contents + rel->r_offset + 4);
+            bfd_put (32, input_bfd, (relocation >> 32),
+                     contents + rel->r_offset + 12);
+            r = bfd_reloc_ok;
+            break;
+          }
         default:
           r = _bfd_final_link_relocate (howto, input_bfd, input_section,
                                         contents, rel->r_offset, relocation,