x86-64: Generate branch with PLT32 relocation

Since there is no need to prepare for PLT branch on x86-64, generate
R_X86_64_PLT32, instead of R_X86_64_PC32, if possible, which can be
used as a marker for 32-bit PC-relative branches.

To compile Linux kernel, this patch:

From: "H.J. Lu" <hjl.tools@gmail.com>
Subject: [PATCH] x86: Treat R_X86_64_PLT32 as R_X86_64_PC32

On i386, there are 2 types of PLTs, PIC and non-PIC.  PIE and shared
objects must use PIC PLT.  To use PIC PLT, you need to load
_GLOBAL_OFFSET_TABLE_ into EBX first.  There is no need for that on
x86-64 since x86-64 uses PC-relative PLT.

On x86-64, for 32-bit PC-relative branches, we can generate PLT32
relocation, instead of PC32 relocation, which can also be used as
a marker for 32-bit PC-relative branches.  Linker can always reduce
PLT32 relocation to PC32 if function is defined locally.   Local
functions should use PC32 relocation.  As far as Linux kernel is
concerned, R_X86_64_PLT32 can be treated the same as R_X86_64_PC32
since Linux kernel doesn't use PLT.

is needed.  It is available on hjl/plt32/master branch at

https://github.com/hjl-tools/linux

bfd/

	PR gas/22791
	* elf64-x86-64.c (is_32bit_relative_branch): Removed.
	(elf_x86_64_relocate_section): Check PIC relocations in PIE.
	Remove is_32bit_relative_branch usage.  Disallow PC32 reloc
	against protected function in shared object.

gas/

	PR gas/22791
	* config/tc-i386.c (need_plt32_p): New function.
	(output_jump): Generate BFD_RELOC_X86_64_PLT32 if possible.
	(md_estimate_size_before_relax): Likewise.
	* testsuite/gas/i386/reloc64.d: Updated.
	* testsuite/gas/i386/x86-64-jump.d: Likewise.
	* testsuite/gas/i386/x86-64-mpx-branch-1.d: Likewise.
	* testsuite/gas/i386/x86-64-mpx-branch-2.d: Likewise.
	* testsuite/gas/i386/x86-64-relax-2.d: Likewise.
	* testsuite/gas/i386/x86-64-relax-3.d: Likewise.
	* testsuite/gas/i386/ilp32/reloc64.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-branch.d: Likewise.

ld/

	PR gas/22791
	* testsuite/ld-x86-64/mpx1c.rd: Updated.
	* testsuite/ld-x86-64/pr22791-1.err: New file.
	* testsuite/ld-x86-64/pr22791-1a.c: Likewise.
	* testsuite/ld-x86-64/pr22791-1b.s: Likewise.
	* testsuite/ld-x86-64/pr22791-2.rd: Likewise.
	* testsuite/ld-x86-64/pr22791-2a.s: Likewise.
	* testsuite/ld-x86-64/pr22791-2b.c: Likewise.
	* testsuite/ld-x86-64/pr22791-2c.s: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run PR ld/22791 tests.

10 files changed, 106 insertions, 1 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index c5b35e6..a173b62 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,16 @@
+2018-02-13  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR gas/22791
+	* testsuite/ld-x86-64/mpx1c.rd: Updated.
+	* testsuite/ld-x86-64/pr22791-1.err: New file.
+	* testsuite/ld-x86-64/pr22791-1a.c: Likewise.
+	* testsuite/ld-x86-64/pr22791-1b.s: Likewise.
+	* testsuite/ld-x86-64/pr22791-2.rd: Likewise.
+	* testsuite/ld-x86-64/pr22791-2a.s: Likewise.
+	* testsuite/ld-x86-64/pr22791-2b.c: Likewise.
+	* testsuite/ld-x86-64/pr22791-2c.s: Likewise.
+	* testsuite/ld-x86-64/x86-64.exp: Run PR ld/22791 tests.
+
 2018-02-13  Alan Modra  <amodra@gmail.com>
 
 	PR 22836
diff --git a/ld/testsuite/ld-x86-64/mpx1c.rd b/ld/testsuite/ld-x86-64/mpx1c.rd
index d3b292c..d66524c 100644
--- a/ld/testsuite/ld-x86-64/mpx1c.rd
+++ b/ld/testsuite/ld-x86-64/mpx1c.rd
@@ -1,3 +1,3 @@
 #...
-[0-9a-f ]+R_X86_64_PC32 +0+ +.*
+[0-9a-f ]+R_X86_64_PLT32 +0+ +.*
 #...
diff --git a/ld/testsuite/ld-x86-64/pr22791-1.err b/ld/testsuite/ld-x86-64/pr22791-1.err
new file mode 100644
index 0000000..5500fa5
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-1.err
@@ -0,0 +1,2 @@
+.*relocation R_X86_64_PC32 against symbol `foo' can not be used when making a PIE object; recompile with -fPIC
+#...
diff --git a/ld/testsuite/ld-x86-64/pr22791-1a.c b/ld/testsuite/ld-x86-64/pr22791-1a.c
new file mode 100644
index 0000000..cd0130c
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-1a.c
@@ -0,0 +1,4 @@
+void
+foo (void)
+{
+}
diff --git a/ld/testsuite/ld-x86-64/pr22791-1b.s b/ld/testsuite/ld-x86-64/pr22791-1b.s
new file mode 100644
index 0000000..9751db4
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-1b.s
@@ -0,0 +1,6 @@
+	.text
+	.globl	main
+	.type	main, @function
+main:
+	movl	foo(%rip), %eax
+	.size	main, .-main
diff --git a/ld/testsuite/ld-x86-64/pr22791-2.rd b/ld/testsuite/ld-x86-64/pr22791-2.rd
new file mode 100644
index 0000000..70deb30
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-2.rd
@@ -0,0 +1,6 @@
+#failif
+#...
+.*\(TEXTREL\).*
+#...
+[0-9a-f ]+R_X86_64_NONE.*
+#...
diff --git a/ld/testsuite/ld-x86-64/pr22791-2a.s b/ld/testsuite/ld-x86-64/pr22791-2a.s
new file mode 100644
index 0000000..0a85502
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-2a.s
@@ -0,0 +1,8 @@
+	.text
+	.p2align 4,,15
+	.globl	foo
+	.type	foo, @function
+foo:
+	jmp	bar
+	.size	foo, .-foo
+	.section	.note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/pr22791-2b.c b/ld/testsuite/ld-x86-64/pr22791-2b.c
new file mode 100644
index 0000000..79ef27c
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-2b.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+void
+bar (void)
+{
+  puts ("PASS");
+}
diff --git a/ld/testsuite/ld-x86-64/pr22791-2c.s b/ld/testsuite/ld-x86-64/pr22791-2c.s
new file mode 100644
index 0000000..1460d1b
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22791-2c.s
@@ -0,0 +1,12 @@
+	.text
+	.p2align 4,,15
+	.globl	main
+	.type	main, @function
+main:
+	subq	$8, %rsp
+	call	foo
+	xorl	%eax, %eax
+	addq	$8, %rsp
+	ret
+	.size	main, .-main
+	.section	.note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index af3afcc..a649de8 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -1152,6 +1152,44 @@ if { [isnative] && [which $CC] != 0 } {
 	     {readelf -lW pr22393-3b.rd}} \
 	    "pr22393-3-static" \
 	] \
+	[list \
+	    "Build pr22791-1.so" \
+	    "-shared" \
+	    "-fPIC" \
+	    { pr22791-1a.c } \
+	    {} \
+	    "pr22791-1.so" \
+	] \
+	[list \
+	    "Build pr22791-1" \
+	    "-pie -Wl,--no-as-needed tmpdir/pr22791-1.so" \
+	    "$NOPIE_CFLAGS" \
+	    { pr22791-1b.s } \
+	    {{error_output "pr22791-1.err"}} \
+	    "pr22791-1" \
+	] \
+	[list \
+	    "Build pr22791-2a.o" \
+	    "" \
+	    "$NOPIE_CFLAGS" \
+	    { pr22791-2a.s } \
+	] \
+	[list \
+	    "Build pr22791-2.so" \
+	    "-shared tmpdir/pr22791-2a.o" \
+	    "-fPIC" \
+	    { pr22791-2b.c } \
+	    {{readelf -drW pr22791-2.rd}} \
+	    "pr22791-2.so" \
+	] \
+	[list \
+	    "Build pr22791-2" \
+	    "-pie -Wl,--no-as-needed tmpdir/pr22791-2.so" \
+	    "$NOPIE_CFLAGS" \
+	    { pr22791-2c.s } \
+	    {{readelf -drW pr22791-2.rd}} \
+	    "pr22791-2" \
+	] \
     ]
 
     if  {[istarget "x86_64-*-linux*-gnux32"]} {
@@ -1477,6 +1515,15 @@ if { [isnative] && [which $CC] != 0 } {
 	    "pr22393-3-static" \
 	    "pass.out" \
 	] \
+	[list \
+	    "Run pr22791-2" \
+	    "-pie -Wl,--no-as-needed tmpdir/pr22791-2.so" \
+	    "" \
+	    { pr22791-2c.s } \
+	    "pr22791-2" \
+	    "pass.out" \
+	    "$NOPIE_CFLAGS" \
+	] \
     ]
 
     # Run-time tests which require working ifunc attribute support.