RISC-V: Fix that IRELATIVE relocs may be inserted to the wrong place.

For the ifunc symbol, which is referenced by GOT rather than PLT relocs,
we should add the dynamic reloc (usually IRELATIVE) into the .rel.iplt
when generating the static executable.  But if we use riscv_elf_append_rela
to add the dynamic relocs into .rela.iplt, this may cause the overwrite
problem.

The reason is that we don't handle the `reloc_index` of .rela.iplt, but
the riscv_elf_append_rela adds the relocs to the place that are calculated
from the reloc_index (in seqential).  Therefore, we may overwrite the
dynamic relocs when the `reloc_index` of .rela.iplt isn't handled correctly.

One solution is that we can add these dynamic relocs (GOT ifunc) from
the last of .rela.iplt section.  But I'm not sure if it is the best way.

	bfd/
	* elfnn-riscv.c (riscv_elf_link_hash_table): Add last_iplt_index.
	(riscv_elf_size_dynamic_sections): Initialize the last_iplt_index.
	(riscv_elf_relocate_section): Use riscv_elf_append_rela.
	(riscv_elf_finish_dynamic_symbol): If the use_elf_append_rela is
	false, then we should add the dynamic relocs from the last of
	the .rela.iplt, and don't use the riscv_elf_append_rela to add.

	ld/
	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s: New testcase.
	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d: Likewise.
	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd: Likewise.
	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd: Likewise.
	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd: Likewise.
	* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated.

7 files changed, 92 insertions, 0 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 3a9d381..780bb4b 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,5 +1,14 @@
 2020-10-16  Nelson Chu  <nelson.chu@sifive.com>
 
+	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s: New testcase.
+	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d: Likewise.
+	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd: Likewise.
+	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd: Likewise.
+	* testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd: Likewise.
+	* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated.
+
+2020-10-16  Nelson Chu  <nelson.chu@sifive.com>
+
 	* emulparams/elf32lriscv-defs.sh: Add IREL_IN_PLT.
 	* testsuite/ld-ifunc/ifunc.exp: Enable ifunc tests for RISC-V.
 	* testsuite/ld-riscv-elf/ld-riscv-elf.exp (run_dump_test_ifunc):
diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd
new file mode 100644
index 0000000..0de47a4
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd
@@ -0,0 +1,4 @@
+Relocation section '.rela.plt' at .*
+[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_IRELATIVE[ 	]+[0-9a-f]*
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_IRELATIVE[ 	]+[0-9a-f]*
diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd
new file mode 100644
index 0000000..f65d789
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd
@@ -0,0 +1,8 @@
+Relocation section '.rela.got' at .*
+[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_(32|64)[ 	]+foo2\(\)[ 	]+foo2 \+ 0
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_(32|64)[ 	]+foo1\(\)[ 	]+foo1 \+ 0
+#...
+Relocation section '.rela.plt' at .*
+[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_JUMP_SLOT[ 	]+foo1\(\)[ 	]+foo1 \+ 0
diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd
new file mode 100644
index 0000000..32e66f0
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd
@@ -0,0 +1,7 @@
+Relocation section '.rela.got' at .*
+[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_IRELATIVE[ 	]+[0-9a-f]*
+
+Relocation section '.rela.plt' at .*
+[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
+[0-9a-f]+[ 	]+[0-9a-f]+[ 	]+R_RISCV_IRELATIVE[ 	]+[0-9a-f]*
diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d
new file mode 100644
index 0000000..333dea3
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d
@@ -0,0 +1,19 @@
+#...
+Disassembly of section .plt:
+#...
+0+[0-9a-f]+ <(\*ABS\*\+0x[0-9a-f]+@plt|foo@plt|.plt)>:
+#...
+Disassembly of section .text:
+#...
+0+[0-9a-f]+ <foo_resolver>:
+#...
+0+[0-9a-f]+ <bar>:
+.*:[ 	]+[0-9a-f]+[ 	]+auipc[ 	]+.*
+.*:[ 	]+[0-9a-f]+[ 	]+(lw|ld)[ 	]+.*<(_GLOBAL_OFFSET_TABLE_.*|.*)>
+.*:[ 	]+[0-9a-f]+[ 	]+auipc[ 	]+.*
+.*:[ 	]+[0-9a-f]+[ 	]+jalr[ 	]+.*<(.*plt.*)>
+.*:[ 	]+[0-9a-f]+[ 	]+auipc[ 	]+.*
+.*:[ 	]+[0-9a-f]+[ 	]+jalr[ 	]+.*<(.*plt.*)>
+.*:[ 	]+[0-9a-f]+[ 	]+auipc[ 	]+.*
+.*:[ 	]+[0-9a-f]+[ 	]+(lw|ld)[ 	]+.*<(_GLOBAL_OFFSET_TABLE_.*|.*)>
+#...
diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s
new file mode 100644
index 0000000..6c2f8e8
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s
@@ -0,0 +1,38 @@
+	.text
+
+	.type	foo_resolver, @function
+foo_resolver:
+	ret
+	.size	foo_resolver, .-foo_resolver
+
+	.globl	foo1
+	.type	foo1, %gnu_indirect_function
+	.set	foo1, foo_resolver
+
+	.globl	foo2
+	.type	foo2, %gnu_indirect_function
+	.set	foo2, foo_resolver
+
+	.globl	bar
+	.type	bar, @function
+bar:
+.L1:
+	auipc	x1, %got_pcrel_hi (foo1)
+.ifdef __64_bit__
+	ld	x1, %pcrel_lo (.L1) (x1)
+.else
+	lw	x1, %pcrel_lo (.L1) (x1)
+.endif
+
+	call	foo1
+	call	foo1@plt
+
+.L2:
+	auipc	x2, %got_pcrel_hi (foo2)
+.ifdef __64_bit__
+	ld	x2, %pcrel_lo (.L2) (x2)
+.else
+	lw	x2, %pcrel_lo (.L2) (x2)
+.endif
+	ret
+	.size	bar, .-bar
diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
index b82e092..9834041 100644
--- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
+++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
@@ -175,6 +175,13 @@ if [istarget "riscv*-*-*"] {
     run_dump_test_ifunc "ifunc-plt-02" rv64 exe
     run_dump_test_ifunc "ifunc-plt-02" rv64 pie
     run_dump_test_ifunc "ifunc-plt-02" rv64 pic
+    # Check the .rela.iplt overwrite issue.
+    run_dump_test_ifunc "ifunc-plt-got-overwrite" rv32 exe
+    run_dump_test_ifunc "ifunc-plt-got-overwrite" rv32 pie
+    run_dump_test_ifunc "ifunc-plt-got-overwrite" rv32 pic
+    run_dump_test_ifunc "ifunc-plt-got-overwrite" rv64 exe
+    run_dump_test_ifunc "ifunc-plt-got-overwrite" rv64 pie
+    run_dump_test_ifunc "ifunc-plt-got-overwrite" rv64 pic
 
     # Setup shared libraries.
     run_ld_link_tests {