From 91de4b11eb2d7f9b0abd83837deb510a6f69cd81 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sat, 28 Feb 2015 08:31:36 -0800
Subject: [PATCH] Add -mcopyreloc-in-pie
Ue copy relocation in PIE improves performance. But copy relocation
can't be used to access protected symbols defined in shared libaries
and linker in binutils 2.26 enforces doesn't allow it. GCC doesn't
know if an external definition is protected or not. This option gives
user an option to turn it off to avoid problem at link-time.
gcc/
PR target/65248
* config/i386/i386.c (ix86_option_override_internal): Set
flag_copyreloc_in_pie to HAVE_LD_PIE_COPYRELOC if not set.
(legitimate_pic_address_disp_p): Replace HAVE_LD_PIE_COPYRELOC
with flag_copyreloc_in_pie.
* config/i386/i386.opt (mcopyreloc-in-pie): New.
* doc/invoke.texi: Document -mcopyreloc-in-pie.
gcc/testsuite/
PR target/65248
* gcc.target/i386/pr65248-1.c: New.
* gcc.target/i386/pr65248-2.c: Likewise.
* gcc.target/i386/pr65248-3.c: Likewise.
* gcc.target/i386/pr65248-4.c: Likewise.
---
gcc/config/i386/i386.c | 6 +++++-
gcc/config/i386/i386.opt | 4 ++++
gcc/doc/invoke.texi | 10 +++++++++-
gcc/testsuite/gcc.target/i386/pr65248-1.c | 13 +++++++++++++
gcc/testsuite/gcc.target/i386/pr65248-2.c | 13 +++++++++++++
gcc/testsuite/gcc.target/i386/pr65248-3.c | 16 ++++++++++++++++
gcc/testsuite/gcc.target/i386/pr65248-4.c | 16 ++++++++++++++++
7 files changed, 76 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr65248-1.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr65248-2.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr65248-3.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr65248-4.c
@@ -4248,6 +4248,10 @@ ix86_option_override_internal (bool main_args_p,
#endif
}
+ /* Set the default value for -mcopyreloc-in-pie. */
+ if (opts->x_flag_copyreloc_in_pie == -1)
+ opts->x_flag_copyreloc_in_pie = HAVE_LD_PIE_COPYRELOC;
+
if (!(opts_set->x_target_flags & MASK_VZEROUPPER))
opts->x_target_flags |= MASK_VZEROUPPER;
if (!ix86_tune_features[X86_TUNE_AVX256_UNALIGNED_LOAD_OPTIMAL]
@@ -13230,7 +13234,7 @@ legitimate_pic_address_disp_p (rtx disp)
}
else if (!SYMBOL_REF_FAR_ADDR_P (op0)
&& (SYMBOL_REF_LOCAL_P (op0)
- || (HAVE_LD_PIE_COPYRELOC
+ || (flag_copyreloc_in_pie
&& flag_pie
&& !SYMBOL_REF_WEAK (op0)
&& !SYMBOL_REF_FUNCTION_P (op0)))
@@ -826,6 +826,10 @@ mfentry
Target Report Var(flag_fentry) Init(-1)
Emit profiling counter call at function entry before prologue.
+mcopyreloc-in-pie
+Target Report Var(flag_copyreloc_in_pie) Init(-1)
+Use copy relocations in Position Independent Executable (PIE)
+
mrecord-mcount
Target Report Var(flag_record_mcount) Init(0)
Generate __mcount_loc section with all mcount or __fentry__ calls.
@@ -1078,7 +1078,8 @@ See RS/6000 and PowerPC Options.
-m32 -m64 -mx32 -m16 -mlarge-data-threshold=@var{num} @gol
-msse2avx -mfentry -mrecord-mcount -mnop-mcount -m8bit-idiv @gol
-mavx256-split-unaligned-load -mavx256-split-unaligned-store @gol
--malign-data=@var{type} -mstack-protector-guard=@var{guard}}
+-malign-data=@var{type} -mstack-protector-guard=@var{guard}} @gol
+-mcopyreloc-in-pie
@emph{x86 Windows Options}
@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol
@@ -22704,6 +22705,13 @@ For systems that use the GNU C Library, the default is on.
Specify that the assembler should encode SSE instructions with VEX
prefix. The option @option{-mavx} turns this on by default.
+@item -mcopyreloc-in-pie
+@itemx -mno-copyreloc-in-pie
+@opindex mcopyreloc-in-pie
+Use copy relocations in Position Independent Executable (PIE). It
+requires linker support. This option is turned on by default if GCC
+is configured to use a linker that supports copy relocations in PIE.
+
@item -mfentry
@itemx -mno-fentry
@opindex mfentry
new file mode 100644
@@ -0,0 +1,13 @@
+/* Check that GOTPCREL isn't used to access glob_a. */
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fpie -mcopyreloc-in-pie" } */
+
+extern int glob_a;
+
+int foo ()
+{
+ return glob_a;
+}
+
+/* glob_a should never be accessed with a GOTPCREL. */
+/* { dg-final { scan-assembler-not "glob_a@GOTPCREL" { target { ! ia32 } } } } */
new file mode 100644
@@ -0,0 +1,13 @@
+/* Check that GOTPCREL isn't used to access glob_a. */
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fpie -mno-copyreloc-in-pie" } */
+
+int glob_a;
+
+int foo ()
+{
+ return glob_a;
+}
+
+/* glob_a should never be accessed with a GOTPCREL. */
+/* { dg-final { scan-assembler-not "glob_a@GOTPCREL" { target { ! ia32 } } } } */
new file mode 100644
@@ -0,0 +1,16 @@
+/* Check that GOTPCREL is used to access glob_a. */
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fpie -mno-copyreloc-in-pie" } */
+
+extern int glob_a;
+
+int foo ()
+{
+ if (&glob_a != 0)
+ return glob_a;
+ else
+ return 0;
+}
+
+/* weak glob_a should be accessed with a GOTPCREL. */
+/* { dg-final { scan-assembler "glob_a@GOTPCREL" { target { ! ia32 } } } } */
new file mode 100644
@@ -0,0 +1,16 @@
+/* Check that GOTPCREL is used to access glob_a. */
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fpie -mno-copyreloc-in-pie" } */
+
+extern int glob_a __attribute__((weak));
+
+int foo ()
+{
+ if (&glob_a != 0)
+ return glob_a;
+ else
+ return 0;
+}
+
+/* weak glob_a should be accessed with a GOTPCREL. */
+/* { dg-final { scan-assembler "glob_a@GOTPCREL" { target { ! ia32 } } } } */
--
2.1.0