bpf: fix relocation addend incorrect symbol value

Relocations installed by the BPF ELF backend were sometimes incorrectly
adding the symbol value to the relocation entry addend, when the correct
relocation value was already stored in the addend. This could lead to a
relocation effectively adding the symbol value twice.

Fix that by making bpf_elf_generic_reloc () more similar to the flow of
bfd_install_relocation in the case where howto->install_addend is set,
which is how it ought to behave.

bfd/
	* bpf-reloc.def (R_BPF_64_ABS32, R_BPF_64_ABS64)
	(R_BPF_64_NODYLD32): Set partial_inplace to true.
	* elf64-bpf.c (bpf_elf_generic_reloc): Do not include the value
	of the symbol when installing relocation. Copy some additional
	logic from bfd_elf_generic_reloc.

gas/
	* testsuite/gas/bpf/bpf.exp: Run new test.
	* testsuite/gas/bpf/elf-relo-1.d: New.
	* testsuite/gas/bpf/elf-relo-1.s: New.

3 files changed, 63 insertions, 0 deletions

diff --git a/gas/testsuite/gas/bpf/bpf.exp b/gas/testsuite/gas/bpf/bpf.exp
index 44b050e..dae8bd9 100644
--- a/gas/testsuite/gas/bpf/bpf.exp
+++ b/gas/testsuite/gas/bpf/bpf.exp
@@ -83,4 +83,7 @@ if {[istarget bpf*-*-*]} {
 
     # Test that parser does not create undefined symbols
     run_dump_test asm-extra-sym-1
+
+    # Test relocation installation
+    run_dump_test elf-relo-1
 }
diff --git a/gas/testsuite/gas/bpf/elf-relo-1.d b/gas/testsuite/gas/bpf/elf-relo-1.d
new file mode 100644
index 0000000..4a1c794
--- /dev/null
+++ b/gas/testsuite/gas/bpf/elf-relo-1.d
@@ -0,0 +1,35 @@
+#as: -EL -mdialect=normal
+#objdump: -tdr
+#source elf-relo-1.s
+#name: eBPF ELF relocations 1
+
+.*: +file format elf64-bpfle
+
+SYMBOL TABLE:
+0000000000000000 l    d  .text	0000000000000000 .text
+0000000000000000 l    d  .data	0000000000000000 .data
+0000000000000000 l    d  .bss	0000000000000000 .bss
+0000000000000006 l       .data	0000000000000000 bar
+0000000000000000 l     F .text	0000000000000000 baz
+0000000000000030 l     F .text	0000000000000000 qux
+0000000000000004 g       .data	0000000000000000 foo
+0000000000000000         \*UND\*	0000000000000000 somefunc
+
+
+
+Disassembly of section .text:
+
+0+ <baz>:
+   0:	18 01 00 00 00 00 00 00 	lddw %r1,0
+   8:	00 00 00 00 00 00 00 00 
+			0: R_BPF_64_64	foo
+  10:	b7 02 00 00 06 00 00 00 	mov %r2,6
+			14: R_BPF_64_ABS32	.data
+  18:	18 03 00 00 30 00 00 00 	lddw %r3,48
+  20:	00 00 00 00 00 00 00 00 
+			18: R_BPF_64_64	.text
+  28:	85 10 00 00 ff ff ff ff 	call -1
+			28: R_BPF_64_32	somefunc
+
+0+30 <qux>:
+  30:	95 00 00 00 00 00 00 00 	exit
diff --git a/gas/testsuite/gas/bpf/elf-relo-1.s b/gas/testsuite/gas/bpf/elf-relo-1.s
new file mode 100644
index 0000000..23424e0
--- /dev/null
+++ b/gas/testsuite/gas/bpf/elf-relo-1.s
@@ -0,0 +1,25 @@
+    .global foo
+    .data
+    .byte 1
+    .byte 2
+    .byte 3
+    .byte 4
+foo:
+    .byte 5
+    .byte 6
+bar:
+    .byte 7
+    .byte 8
+
+    .text
+    .align 3
+    .type baz, @function
+baz:
+    lddw    %r1, foo
+    mov     %r2, bar
+    lddw    %r3, qux
+    call    somefunc
+
+    .type qux, @function
+qux:
+    exit