bpf: relocation fixes for eBPF ELF backend

The eBPF ELF backend was not properly recording relocation addends
during installation, nor reading and applying them when performing
the final relocation. This lead to various issues with incorrect
relocations.

These issues are fixed with a new howto special function to install
the relocations, and updates to bpf_elf_relocate_section to read and
use the addends as recorded in the input_bfd.

bfd/ChangeLog

2020-08-05  David Faust  <david.faust@oracle.com>

	* elf64-bpf.c (bpf_elf_generic_reloc): New function.
	(bpf_elf_howto_table): Use it here.
	(bpf_elf_relocate_section): Use addends recorded in input_bfd for
	instruction and data relocations.

ld/ChangeLog

2020-08-05  David Faust  <david.faust@oracle.com>

	* testsuite/ld-bpf/call-2.s: New file.
	* testsuite/ld-bpf/call-2.d: Likewise.
	* testsuite/ld-bpf/reloc-data-be.d: Likewise.
	* testsuite/ld-bpf/reloc-data-le.d: Likewise.
	* testsuite/ld-bpf/reloc-data.s: Likewise.
	* testsuite/ld-bpf/reloc-insn-external-be.d: Likewise.
	* testsuite/ld-bpf/reloc-insn-external-le.d: Likewise.
	* testsuite/ld-bpf/reloc-insn-external.s: Likewise.
	* testsuite/ld-bpf/reloc-insn32-be.d: Likewise.
	* testsuite/ld-bpf/reloc-insn32-le.d: Likewise.
	* testsuite/ld-bpf/reloc-insn32.s: Likewise.
	* testsuite/ld-bpf/reloc-insn64-be.d: Likewise.
	* testsuite/ld-bpf/reloc-insn64-le.d: Likewise.
	* testsuite/ld-bpf/reloc-insn64.s: Likewise.

14 files changed, 189 insertions, 0 deletions

diff --git a/ld/testsuite/ld-bpf/call-2.d b/ld/testsuite/ld-bpf/call-2.d
new file mode 100644
index 0000000..3d09095
--- /dev/null
+++ b/ld/testsuite/ld-bpf/call-2.d
@@ -0,0 +1,20 @@
+#as: --EL
+#source: call-2.s
+#source: bar.s
+#objdump: -dr
+#ld: -EL
+#name: CALL with disp32 reloc and addend
+
+.*: +file format .*bpf.*
+
+Disassembly of section .text:
+
+[0-9a-f]+ <.*>:
+ *[0-9a-f]+:	b7 01 00 00 01 00 00 00 	mov %r1,1
+ *[0-9a-f]+:	85 10 00 00 02 00 00 00 	call 2
+ *[0-9a-f]+:	95 00 00 00 00 00 00 00 	exit
+
+[0-9a-f]+ <bar>:
+ *[0-9a-f]+:	bf 21 00 00 00 00 00 00 	mov %r1,%r2
+ *[0-9a-f]+:	bf 13 00 00 00 00 00 00 	mov %r3,%r1
+ *[0-9a-f]+:	95 00 00 00 00 00 00 00 	exit
diff --git a/ld/testsuite/ld-bpf/call-2.s b/ld/testsuite/ld-bpf/call-2.s
new file mode 100644
index 0000000..e2a5b90
--- /dev/null
+++ b/ld/testsuite/ld-bpf/call-2.s
@@ -0,0 +1,3 @@
+    mov %r1, 1
+    call bar + 0x1
+    exit
diff --git a/ld/testsuite/ld-bpf/reloc-data-be.d b/ld/testsuite/ld-bpf/reloc-data-be.d
new file mode 100644
index 0000000..4d793e2
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-data-be.d
@@ -0,0 +1,11 @@
+#as: --EB
+#source: reloc-data.s
+#objdump: -s
+#ld: -Tdata=0x20 -EB
+#name: data relocs BE
+
+.*:     file format .*-bpfbe
+
+Contents of section \.data:
+ 0020 666f6f00 62617200 00000000 00000020  .*
+ 0030 00000028 003034                      .*
diff --git a/ld/testsuite/ld-bpf/reloc-data-le.d b/ld/testsuite/ld-bpf/reloc-data-le.d
new file mode 100644
index 0000000..97cb1b3
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-data-le.d
@@ -0,0 +1,11 @@
+#as: --EL
+#source: reloc-data.s
+#objdump: -s
+#ld: -Tdata=0x20 -EL
+#name: data relocs LE
+
+.*:     file format .*-bpfle
+
+Contents of section \.data:
+ 0020 666f6f00 62617200 20000000 00000000  .*
+ 0030 28000000 300034                      .*
diff --git a/ld/testsuite/ld-bpf/reloc-data.s b/ld/testsuite/ld-bpf/reloc-data.s
new file mode 100644
index 0000000..431ef5a
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-data.s
@@ -0,0 +1,16 @@
+    .data
+foo:
+    .string "foo"
+
+    .global bar
+bar:
+    .string "bar"
+
+d64:
+    .quad foo
+d32:
+    .word d64
+d16:
+    .half d32
+d8:
+    .byte d16
diff --git a/ld/testsuite/ld-bpf/reloc-insn-external-be.d b/ld/testsuite/ld-bpf/reloc-insn-external-be.d
new file mode 100644
index 0000000..032d364
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn-external-be.d
@@ -0,0 +1,16 @@
+#as: --EB
+#source: reloc-data.s
+#source: reloc-insn-external.s
+#objdump: -dr
+#ld: -Tdata=0x20 -EB
+#name: reloc insn external BE
+
+.*: +file format .*bpfbe
+
+Disassembly of section .text:
+
+[0-9a-f]+ <.*>:
+ *[0-9a-f]+:	18 10 00 00 00 00 00 28[ 	]*lddw %r1,0x28
+ *[0-9a-f]+:	00 00 00 00 00 00 00 00[ 	]*
+ *[0-9a-f]+:	b7 20 00 00 00 00 00 26[ 	]*mov %r2,0x26
+ *[0-9a-f]+:	61 34 00 24 00 00 00 00[ 	]*ldxw %r3,\[%r4\+0x24\]
diff --git a/ld/testsuite/ld-bpf/reloc-insn-external-le.d b/ld/testsuite/ld-bpf/reloc-insn-external-le.d
new file mode 100644
index 0000000..d351376
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn-external-le.d
@@ -0,0 +1,16 @@
+#as: --EL
+#source: reloc-data.s
+#source: reloc-insn-external.s
+#objdump: -dr
+#ld: -Tdata=0x20 -EL
+#name: reloc insn external LE
+
+.*: +file format .*bpfle
+
+Disassembly of section .text:
+
+[0-9a-f]+ <.*>:
+ *[0-9a-f]+:	18 01 00 00 28 00 00 00[ 	]*lddw %r1,0x28
+ *[0-9a-f]+:	00 00 00 00 00 00 00 00[ 	]*
+ *[0-9a-f]+:	b7 02 00 00 26 00 00 00[ 	]*mov %r2,0x26
+ *[0-9a-f]+:	61 43 24 00 00 00 00 00[ 	]*ldxw %r3,\[%r4\+0x24\]
diff --git a/ld/testsuite/ld-bpf/reloc-insn-external.s b/ld/testsuite/ld-bpf/reloc-insn-external.s
new file mode 100644
index 0000000..be12813
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn-external.s
@@ -0,0 +1,5 @@
+
+    lddw %r1, bar + 4
+    mov %r2, bar + 2
+
+    ldxw %r3, [%r4 + bar]
diff --git a/ld/testsuite/ld-bpf/reloc-insn32-be.d b/ld/testsuite/ld-bpf/reloc-insn32-be.d
new file mode 100644
index 0000000..27d592d
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn32-be.d
@@ -0,0 +1,19 @@
+#as: --EB
+#source: reloc-insn32.s
+#objdump: -d
+#ld: -Tdata=0xdabeef -EB
+#name: reloc INSN32 BE
+
+.*: +file format .*bpfbe
+
+Disassembly of section .text:
+
+[0-9a-f]+ <main>:
+ *[0-9a-f]+:	b7 10 00 00 00 da be f3[ 	]*mov %r1,0xdabef3
+ *[0-9a-f]+:	16 10 00 02 00 da be f3[ 	]*jeq32 %r1,0xdabef3,2
+ *[0-9a-f]+:	38 00 00 00 00 da be ff[ 	]*ldabsdw 0xdabeff
+ *[0-9a-f]+:	95 00 00 00 00 00 00 00[ 	]*exit
+
+[0-9a-f]+ <baz>:
+ *[0-9a-f]+:	07 10 00 00 00 da be ef[ 	]*add %r1,0xdabeef
+ *[0-9a-f]+:	62 20 00 08 00 da be f7[ 	]*stw \[%r2\+8\],0xdabef7
diff --git a/ld/testsuite/ld-bpf/reloc-insn32-le.d b/ld/testsuite/ld-bpf/reloc-insn32-le.d
new file mode 100644
index 0000000..bdbb45f
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn32-le.d
@@ -0,0 +1,19 @@
+#as: --EL
+#source: reloc-insn32.s
+#objdump: -d
+#ld: -Tdata=0xdabeef -EL
+#name: reloc INSN32 LE
+
+.*: +file format .*bpfle
+
+Disassembly of section .text:
+
+[0-9a-f]+ <main>:
+ *[0-9a-f]+:	b7 01 00 00 f3 be da 00[ 	]*mov %r1,0xdabef3
+ *[0-9a-f]+:	16 01 02 00 f3 be da 00[ 	]*jeq32 %r1,0xdabef3,2
+ *[0-9a-f]+:	38 00 00 00 ff be da 00[ 	]*ldabsdw 0xdabeff
+ *[0-9a-f]+:	95 00 00 00 00 00 00 00[ 	]*exit
+
+[0-9a-f]+ <baz>:
+ *[0-9a-f]+:	07 01 00 00 ef be da 00[ 	]*add %r1,0xdabeef
+ *[0-9a-f]+:	62 02 08 00 f7 be da 00[ 	]*stw \[%r2\+8\],0xdabef7
diff --git a/ld/testsuite/ld-bpf/reloc-insn32.s b/ld/testsuite/ld-bpf/reloc-insn32.s
new file mode 100644
index 0000000..a53a0dc
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn32.s
@@ -0,0 +1,20 @@
+    .data
+foo:
+    .string "foo"
+bar:
+    .string "bar"
+d64:
+    .dword bar
+d32:
+    .word d64
+
+    .text
+main:
+    mov %r1, bar
+    jeq32 %r1, bar, baz
+    ldabsdw d32
+    exit
+
+baz:
+    add %r1, foo
+    stw [%r2 + 8], d64
diff --git a/ld/testsuite/ld-bpf/reloc-insn64-be.d b/ld/testsuite/ld-bpf/reloc-insn64-be.d
new file mode 100644
index 0000000..ca74e33
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn64-be.d
@@ -0,0 +1,12 @@
+#as: --EB
+#source: reloc-insn64.s
+#objdump: -s
+#ld: -Tdata=0xdeadbeef1234 -EB
+#name: reloc INSN64 big-endian
+
+.*:     file format .*-bpfbe
+
+#...
+Contents of section \.text:
+[ 	][0-9a-f]+ 18100000 beef1238 00000000 0000dead .*
+#pass
diff --git a/ld/testsuite/ld-bpf/reloc-insn64-le.d b/ld/testsuite/ld-bpf/reloc-insn64-le.d
new file mode 100644
index 0000000..63dcce3
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn64-le.d
@@ -0,0 +1,12 @@
+#as: --EL
+#source: reloc-insn64.s
+#objdump: -s
+#ld: -Tdata=0xdeadbeef1234 -EL
+#name: reloc INSN64 little-endian
+
+.*:     file format .*-bpfle
+
+#...
+Contents of section \.text:
+[ 	][0-9a-f]+ 18010000 3812efbe 00000000 adde0000 .*
+#pass
diff --git a/ld/testsuite/ld-bpf/reloc-insn64.s b/ld/testsuite/ld-bpf/reloc-insn64.s
new file mode 100644
index 0000000..8cb1d9f
--- /dev/null
+++ b/ld/testsuite/ld-bpf/reloc-insn64.s
@@ -0,0 +1,9 @@
+    .data
+x:
+    .string "foo"
+y:
+    .string "bar"
+
+    .text
+main:
+    lddw %r1, y