PING^4 https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570139.html
One major design goal of PIE was to avoid copy relocations. The original patch for GCC 5 caused problems for many years. On Wed, Aug 18, 2021 at 11:54 PM Fāng-ruì Sòng <mask...@google.com> wrote: > PING^3 https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570139.html > > On Fri, Jun 4, 2021 at 3:04 PM Fāng-ruì Sòng <mask...@google.com> wrote: > > > > PING^2 https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570139.html > > > > On Mon, May 24, 2021 at 9:43 AM Fāng-ruì Sòng <mask...@google.com> > wrote: > > > > > > Ping https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570139.html > > > > > > On Tue, May 11, 2021 at 8:29 PM Fangrui Song <mask...@google.com> > wrote: > > > > > > > > This was introduced in 2014-12 to use local binding for external > symbols > > > > for -fPIE. Now that we have H.J. Lu's GOTPCRELX for years which > mostly > > > > nullify the benefit of HAVE_LD_PIE_COPYRELOC, HAVE_LD_PIE_COPYRELOC > > > > should retire now. > > > > > > > > One design goal of -fPIE was to avoid copy relocations. > > > > HAVE_LD_PIE_COPYRELOC has deviated from the goal. With this change, > the > > > > -fPIE behavior of x86-64 will be closer to x86-32 and other targets. > > > > > > > > --- > > > > > > > > See https://gcc.gnu.org/legacy-ml/gcc/2019-05/msg00215.html for a > list > > > > of fixed and unfixed (e.g. gold incompatibility with protected > > > > https://sourceware.org/bugzilla/show_bug.cgi?id=19823) issues. > > > > > > > > If you prefer a longer write-up, see > > > > > https://maskray.me/blog/2021-01-09-copy-relocations-canonical-plt-entries-and-protected > > > > --- > > > > gcc/config.in | 6 --- > > > > gcc/config/i386/i386.c | 11 +--- > > > > gcc/configure | 52 > ------------------- > > > > gcc/configure.ac | 48 > ----------------- > > > > gcc/doc/sourcebuild.texi | 3 -- > > > > .../gcc.target/i386/pie-copyrelocs-1.c | 14 ----- > > > > .../gcc.target/i386/pie-copyrelocs-2.c | 14 ----- > > > > .../gcc.target/i386/pie-copyrelocs-3.c | 14 ----- > > > > .../gcc.target/i386/pie-copyrelocs-4.c | 17 ------ > > > > gcc/testsuite/lib/target-supports.exp | 47 ----------------- > > > > 10 files changed, 2 insertions(+), 224 deletions(-) > > > > delete mode 100644 gcc/testsuite/gcc.target/i386/pie-copyrelocs-1.c > > > > delete mode 100644 gcc/testsuite/gcc.target/i386/pie-copyrelocs-2.c > > > > delete mode 100644 gcc/testsuite/gcc.target/i386/pie-copyrelocs-3.c > > > > delete mode 100644 gcc/testsuite/gcc.target/i386/pie-copyrelocs-4.c > > > > > > > > diff --git a/gcc/config.in b/gcc/config.in > > > > index e54f59ce0c3..a65bf5d4176 100644 > > > > --- a/gcc/config.in > > > > +++ b/gcc/config.in > > > > @@ -1659,12 +1659,6 @@ > > > > #endif > > > > > > > > > > > > -/* Define 0/1 if your linker supports -pie option with copy reloc. > */ > > > > -#ifndef USED_FOR_TARGET > > > > -#undef HAVE_LD_PIE_COPYRELOC > > > > -#endif > > > > - > > > > - > > > > /* Define if your PowerPC linker has .gnu.attributes long double > support. */ > > > > #ifndef USED_FOR_TARGET > > > > #undef HAVE_LD_PPC_GNU_ATTR_LONG_DOUBLE > > > > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c > > > > index 915f89f571a..5ec3c6fd0c9 100644 > > > > --- a/gcc/config/i386/i386.c > > > > +++ b/gcc/config/i386/i386.c > > > > @@ -10579,11 +10579,7 @@ legitimate_pic_address_disp_p (rtx disp) > > > > return true; > > > > } > > > > else if (!SYMBOL_REF_FAR_ADDR_P (op0) > > > > - && (SYMBOL_REF_LOCAL_P (op0) > > > > - || (HAVE_LD_PIE_COPYRELOC > > > > - && flag_pie > > > > - && !SYMBOL_REF_WEAK (op0) > > > > - && !SYMBOL_REF_FUNCTION_P (op0))) > > > > + && SYMBOL_REF_LOCAL_P (op0) > > > > && ix86_cmodel != CM_LARGE_PIC) > > > > return true; > > > > break; > > > > @@ -22892,10 +22888,7 @@ ix86_atomic_assign_expand_fenv (tree *hold, > tree *clear, tree *update) > > > > static bool > > > > ix86_binds_local_p (const_tree exp) > > > > { > > > > - return default_binds_local_p_3 (exp, flag_shlib != 0, true, true, > > > > - (!flag_pic > > > > - || (TARGET_64BIT > > > > - && HAVE_LD_PIE_COPYRELOC != > 0))); > > > > + return default_binds_local_p_3 (exp, flag_shlib != 0, true, true, > !flag_pic); > > > > } > > > > #endif > > > > > > > > diff --git a/gcc/configure b/gcc/configure > > > > index f03fe888384..c500f5ca11e 100755 > > > > --- a/gcc/configure > > > > +++ b/gcc/configure > > > > @@ -29968,58 +29968,6 @@ fi > > > > { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld_pie" >&5 > > > > $as_echo "$gcc_cv_ld_pie" >&6; } > > > > > > > > -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking linker PIE > support with copy reloc" >&5 > > > > -$as_echo_n "checking linker PIE support with copy reloc... " >&6; } > > > > -gcc_cv_ld_pie_copyreloc=no > > > > -if test $gcc_cv_ld_pie = yes ; then > > > > - if test $in_tree_ld = yes ; then > > > > - if test "$gcc_cv_gld_major_version" -eq 2 -a > "$gcc_cv_gld_minor_version" -ge 25 -o "$gcc_cv_gld_major_version" -gt 2; > then > > > > - gcc_cv_ld_pie_copyreloc=yes > > > > - fi > > > > - elif test x$gcc_cv_as != x -a x$gcc_cv_ld != x ; then > > > > - # Check if linker supports -pie option with copy reloc > > > > - case "$target" in > > > > - i?86-*-linux* | x86_64-*-linux*) > > > > - cat > conftest1.s <<EOF > > > > - .globl a_glob > > > > - .data > > > > - .type a_glob, @object > > > > - .size a_glob, 4 > > > > -a_glob: > > > > - .long 2 > > > > -EOF > > > > - cat > conftest2.s <<EOF > > > > - .text > > > > - .globl main > > > > - .type main, @function > > > > -main: > > > > - movl %eax, a_glob(%rip) > > > > - .size main, .-main > > > > - .globl ptr > > > > - .section .data.rel,"aw",@progbits > > > > - .type ptr, @object > > > > -ptr: > > > > - .quad a_glob > > > > -EOF > > > > - if $gcc_cv_as --64 -o conftest1.o conftest1.s > /dev/null > 2>&1 \ > > > > - && $gcc_cv_ld -shared -melf_x86_64 -o conftest1.so > conftest1.o > /dev/null 2>&1 \ > > > > - && $gcc_cv_as --64 -o conftest2.o conftest2.s > /dev/null > 2>&1 \ > > > > - && $gcc_cv_ld -pie -melf_x86_64 -o conftest conftest2.o > conftest1.so > /dev/null 2>&1; then > > > > - gcc_cv_ld_pie_copyreloc=yes > > > > - fi > > > > - rm -f conftest conftest1.so conftest1.o conftest2.o > conftest1.s conftest2.s > > > > - ;; > > > > - esac > > > > - fi > > > > -fi > > > > - > > > > -cat >>confdefs.h <<_ACEOF > > > > -#define HAVE_LD_PIE_COPYRELOC `if test x"$gcc_cv_ld_pie_copyreloc" > = xyes; then echo 1; else echo 0; fi` > > > > -_ACEOF > > > > - > > > > -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: > $gcc_cv_ld_pie_copyreloc" >&5 > > > > -$as_echo "$gcc_cv_ld_pie_copyreloc" >&6; } > > > > - > > > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking linker > EH-compatible garbage collection of sections" >&5 > > > > $as_echo_n "checking linker EH-compatible garbage collection of > sections... " >&6; } > > > > gcc_cv_ld_eh_gc_sections=no > > > > diff --git a/gcc/configure.ac b/gcc/configure.ac > > > > index e9ba2af548a..d60b22c1708 100644 > > > > --- a/gcc/configure.ac > > > > +++ b/gcc/configure.ac > > > > @@ -5924,54 +5924,6 @@ if test x"$gcc_cv_ld_pie" = xyes; then > > > > fi > > > > AC_MSG_RESULT($gcc_cv_ld_pie) > > > > > > > > -AC_MSG_CHECKING(linker PIE support with copy reloc) > > > > -gcc_cv_ld_pie_copyreloc=no > > > > -if test $gcc_cv_ld_pie = yes ; then > > > > - if test $in_tree_ld = yes ; then > > > > - if test "$gcc_cv_gld_major_version" -eq 2 -a > "$gcc_cv_gld_minor_version" -ge 25 -o "$gcc_cv_gld_major_version" -gt 2; > then > > > > - gcc_cv_ld_pie_copyreloc=yes > > > > - fi > > > > - elif test x$gcc_cv_as != x -a x$gcc_cv_ld != x ; then > > > > - # Check if linker supports -pie option with copy reloc > > > > - case "$target" in > > > > - i?86-*-linux* | x86_64-*-linux*) > > > > - cat > conftest1.s <<EOF > > > > - .globl a_glob > > > > - .data > > > > - .type a_glob, @object > > > > - .size a_glob, 4 > > > > -a_glob: > > > > - .long 2 > > > > -EOF > > > > - cat > conftest2.s <<EOF > > > > - .text > > > > - .globl main > > > > - .type main, @function > > > > -main: > > > > - movl %eax, a_glob(%rip) > > > > - .size main, .-main > > > > - .globl ptr > > > > - .section .data.rel,"aw",@progbits > > > > - .type ptr, @object > > > > -ptr: > > > > - .quad a_glob > > > > -EOF > > > > - if $gcc_cv_as --64 -o conftest1.o conftest1.s > /dev/null > 2>&1 \ > > > > - && $gcc_cv_ld -shared -melf_x86_64 -o conftest1.so > conftest1.o > /dev/null 2>&1 \ > > > > - && $gcc_cv_as --64 -o conftest2.o conftest2.s > /dev/null > 2>&1 \ > > > > - && $gcc_cv_ld -pie -melf_x86_64 -o conftest conftest2.o > conftest1.so > /dev/null 2>&1; then > > > > - gcc_cv_ld_pie_copyreloc=yes > > > > - fi > > > > - rm -f conftest conftest1.so conftest1.o conftest2.o > conftest1.s conftest2.s > > > > - ;; > > > > - esac > > > > - fi > > > > -fi > > > > -AC_DEFINE_UNQUOTED(HAVE_LD_PIE_COPYRELOC, > > > > - [`if test x"$gcc_cv_ld_pie_copyreloc" = xyes; then echo 1; else > echo 0; fi`], > > > > - [Define 0/1 if your linker supports -pie option with copy reloc.]) > > > > -AC_MSG_RESULT($gcc_cv_ld_pie_copyreloc) > > > > - > > > > AC_MSG_CHECKING(linker EH-compatible garbage collection of sections) > > > > gcc_cv_ld_eh_gc_sections=no > > > > if test $in_tree_ld = yes ; then > > > > diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi > > > > index 3a1d6536833..1c8019ea04c 100644 > > > > --- a/gcc/doc/sourcebuild.texi > > > > +++ b/gcc/doc/sourcebuild.texi > > > > @@ -2383,9 +2383,6 @@ Target supports FPU instructions. > > > > @item non_strict_align > > > > Target does not require strict alignment. > > > > > > > > -@item pie_copyreloc > > > > -The x86-64 target linker supports PIE with copy reloc. > > > > - > > > > @item rdrand > > > > Target supports x86 @code{rdrand} instruction. > > > > > > > > diff --git a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-1.c > b/gcc/testsuite/gcc.target/i386/pie-copyrelocs-1.c > > > > deleted file mode 100644 > > > > index 7af851bde9b..00000000000 > > > > --- a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-1.c > > > > +++ /dev/null > > > > @@ -1,14 +0,0 @@ > > > > -/* Check that GOTPCREL isn't used to access glob_a. */ > > > > -/* { dg-do compile { target *-*-linux* } } */ > > > > -/* { dg-require-effective-target pie_copyreloc } */ > > > > -/* { dg-options "-O2 -fpie" } */ > > > > - > > > > -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 } } } } */ > > > > diff --git a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-2.c > b/gcc/testsuite/gcc.target/i386/pie-copyrelocs-2.c > > > > deleted file mode 100644 > > > > index 19cb97e882c..00000000000 > > > > --- a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-2.c > > > > +++ /dev/null > > > > @@ -1,14 +0,0 @@ > > > > -/* Check that GOTPCREL isn't used to access glob_a. */ > > > > -/* { dg-do compile { target *-*-linux* } } */ > > > > -/* { dg-require-effective-target pie_copyreloc } */ > > > > -/* { dg-options "-O2 -fpie" } */ > > > > - > > > > -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 } } } } */ > > > > diff --git a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-3.c > b/gcc/testsuite/gcc.target/i386/pie-copyrelocs-3.c > > > > deleted file mode 100644 > > > > index c2fa8968e77..00000000000 > > > > --- a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-3.c > > > > +++ /dev/null > > > > @@ -1,14 +0,0 @@ > > > > -/* Check that PLT is used to access glob_a. */ > > > > -/* { dg-do compile { target *-*-linux* } } */ > > > > -/* { dg-require-effective-target pie_copyreloc } */ > > > > -/* { dg-options "-O2 -fpie" } */ > > > > - > > > > -extern int glob_a (void); > > > > - > > > > -int foo () > > > > -{ > > > > - return glob_a (); > > > > -} > > > > - > > > > -/* glob_a should be accessed with a PLT. */ > > > > -/* { dg-final { scan-assembler "glob_a@PLT" { target { ! ia32 } } > } } */ > > > > diff --git a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-4.c > b/gcc/testsuite/gcc.target/i386/pie-copyrelocs-4.c > > > > deleted file mode 100644 > > > > index 413cdf381c3..00000000000 > > > > --- a/gcc/testsuite/gcc.target/i386/pie-copyrelocs-4.c > > > > +++ /dev/null > > > > @@ -1,17 +0,0 @@ > > > > -/* Check that GOTPCREL is used to access glob_a. */ > > > > -/* { dg-do compile { target *-*-linux* } } */ > > > > -/* { dg-require-effective-target pie_copyreloc } */ > > > > -/* { dg-options "-O2 -fpie" } */ > > > > - > > > > -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 > } } } } */ > > > > diff --git a/gcc/testsuite/lib/target-supports.exp > b/gcc/testsuite/lib/target-supports.exp > > > > index 5700c231065..6f922ebf2ab 100644 > > > > --- a/gcc/testsuite/lib/target-supports.exp > > > > +++ b/gcc/testsuite/lib/target-supports.exp > > > > @@ -10133,53 +10133,6 @@ proc > scan-ltrans-tree-dump-dem-not_required_options {} { > > > > return "-flto-partition=one" > > > > } > > > > > > > > -# Return 1 if the x86-64 target supports PIE with copy reloc, 0 > > > > -# otherwise. Cache the result. > > > > - > > > > -proc check_effective_target_pie_copyreloc { } { > > > > - global tool > > > > - global GCC_UNDER_TEST > > > > - > > > > - if { !([istarget i?86-*-*] || [istarget x86_64-*-*]) } { > > > > - return 0 > > > > - } > > > > - > > > > - # Need auto-host.h to check linker support. > > > > - if { ![file exists ../../auto-host.h ] } { > > > > - return 0 > > > > - } > > > > - > > > > - return [check_cached_effective_target pie_copyreloc { > > > > - # Set up and compile to see if linker supports PIE with copy > > > > - # reloc. Include the current process ID in the file names to > > > > - # prevent conflicts with invocations for multiple testsuites. > > > > - > > > > - set src pie[pid].c > > > > - set obj pie[pid].o > > > > - > > > > - set f [open $src "w"] > > > > - puts $f "#include \"../../auto-host.h\"" > > > > - puts $f "#if HAVE_LD_PIE_COPYRELOC == 0" > > > > - puts $f "# error Linker does not support PIE with copy > reloc." > > > > - puts $f "#endif" > > > > - close $f > > > > - > > > > - verbose "check_effective_target_pie_copyreloc compiling > testfile $src" 2 > > > > - set lines [${tool}_target_compile $src $obj object ""] > > > > - > > > > - file delete $src > > > > - file delete $obj > > > > - > > > > - if [string match "" $lines] then { > > > > - verbose "check_effective_target_pie_copyreloc testfile > compilation passed" 2 > > > > - return 1 > > > > - } else { > > > > - verbose "check_effective_target_pie_copyreloc testfile > compilation failed" 2 > > > > - return 0 > > > > - } > > > > - }] > > > > -} > > > > - > > > > # Return 1 if the x86 target supports R_386_GOT32X relocation, 0 > > > > # otherwise. Cache the result. > > > > > > > > -- > > > > 2.31.1.607.g51e8a6a459-goog > > > > > > > > > > > > > -- > > > 宋方睿 > > > > > > > > -- > > 宋方睿 > > > > -- > 宋方睿 > -- 宋方睿
