| Message ID | 20191218031920.6414-2-richard.henderson@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | configure: Improve PIE and other linkage | expand |
On 18/12/2019 04.19, Richard Henderson wrote: > This adjustment was random and unnecessary. The user mode > startup code in probe_guest_base() will choose a value for > guest_base that allows the host qemu binary to not conflict > with the guest binary. > > With modern distributions, this isn't even used, as the default > is PIE, which does the same job in a more portable way. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > configure | 47 ----------------------------------------------- > 1 file changed, 47 deletions(-) > > diff --git a/configure b/configure > index 84b413dbfc..255ac432af 100755 > --- a/configure > +++ b/configure > @@ -6292,49 +6292,6 @@ if test "$cpu" = "s390x" ; then > fi > fi > > -# Probe for the need for relocating the user-only binary. > -if ( [ "$linux_user" = yes ] || [ "$bsd_user" = yes ] ) && [ "$pie" = no ]; then > - textseg_addr= > - case "$cpu" in > - arm | i386 | ppc* | s390* | sparc* | x86_64 | x32) > - # ??? Rationale for choosing this address > - textseg_addr=0x60000000 > - ;; > - mips) > - # A 256M aligned address, high in the address space, with enough > - # room for the code_gen_buffer above it before the stack. > - textseg_addr=0x60000000 > - ;; > - esac > - if [ -n "$textseg_addr" ]; then > - cat > $TMPC <<EOF > - int main(void) { return 0; } > -EOF > - textseg_ldflags="-Wl,-Ttext-segment=$textseg_addr" > - if ! compile_prog "" "$textseg_ldflags"; then > - # In case ld does not support -Ttext-segment, edit the default linker > - # script via sed to set the .text start addr. This is needed on FreeBSD > - # at least. > - if ! $ld --verbose >/dev/null 2>&1; then > - error_exit \ > - "We need to link the QEMU user mode binaries at a" \ > - "specific text address. Unfortunately your linker" \ > - "doesn't support either the -Ttext-segment option or" \ > - "printing the default linker script with --verbose." \ > - "If you don't want the user mode binaries, pass the" \ > - "--disable-user option to configure." > - fi > - > - $ld --verbose | sed \ > - -e '1,/==================================================/d' \ > - -e '/==================================================/,$d' \ > - -e "s/[.] = [0-9a-fx]* [+] SIZEOF_HEADERS/. = $textseg_addr + SIZEOF_HEADERS/" \ > - -e "s/__executable_start = [0-9a-fx]*/__executable_start = $textseg_addr/" > config-host.ld > - textseg_ldflags="-Wl,-T../config-host.ld" config-host.ld is mentioned one more time in the main "Makefile" ... I think you could remove it from there now, too. With such a hunk added: Reviewed-by: Thomas Huth <thuth@redhat.com>
On 12/17/19 8:59 PM, Thomas Huth wrote: > config-host.ld is mentioned one more time in the main "Makefile" ... I > think you could remove it from there now, too. Done, thanks. r~
diff --git a/configure b/configure index 84b413dbfc..255ac432af 100755 --- a/configure +++ b/configure @@ -6292,49 +6292,6 @@ if test "$cpu" = "s390x" ; then fi fi -# Probe for the need for relocating the user-only binary. -if ( [ "$linux_user" = yes ] || [ "$bsd_user" = yes ] ) && [ "$pie" = no ]; then - textseg_addr= - case "$cpu" in - arm | i386 | ppc* | s390* | sparc* | x86_64 | x32) - # ??? Rationale for choosing this address - textseg_addr=0x60000000 - ;; - mips) - # A 256M aligned address, high in the address space, with enough - # room for the code_gen_buffer above it before the stack. - textseg_addr=0x60000000 - ;; - esac - if [ -n "$textseg_addr" ]; then - cat > $TMPC <<EOF - int main(void) { return 0; } -EOF - textseg_ldflags="-Wl,-Ttext-segment=$textseg_addr" - if ! compile_prog "" "$textseg_ldflags"; then - # In case ld does not support -Ttext-segment, edit the default linker - # script via sed to set the .text start addr. This is needed on FreeBSD - # at least. - if ! $ld --verbose >/dev/null 2>&1; then - error_exit \ - "We need to link the QEMU user mode binaries at a" \ - "specific text address. Unfortunately your linker" \ - "doesn't support either the -Ttext-segment option or" \ - "printing the default linker script with --verbose." \ - "If you don't want the user mode binaries, pass the" \ - "--disable-user option to configure." - fi - - $ld --verbose | sed \ - -e '1,/==================================================/d' \ - -e '/==================================================/,$d' \ - -e "s/[.] = [0-9a-fx]* [+] SIZEOF_HEADERS/. = $textseg_addr + SIZEOF_HEADERS/" \ - -e "s/__executable_start = [0-9a-fx]*/__executable_start = $textseg_addr/" > config-host.ld - textseg_ldflags="-Wl,-T../config-host.ld" - fi - fi -fi - # Check that the C++ compiler exists and works with the C compiler. # All the QEMU_CXXFLAGS are based on QEMU_CFLAGS. Keep this at the end to don't miss any other that could be added. if has $cxx; then @@ -7897,10 +7854,6 @@ if test "$gprof" = "yes" ; then fi fi -if test "$target_linux_user" = "yes" || test "$target_bsd_user" = "yes" ; then - ldflags="$ldflags $textseg_ldflags" -fi - # Newer kernels on s390 check for an S390_PGSTE program header and # enable the pgste page table extensions in that case. This makes # the vm.allocate_pgste sysctl unnecessary. We enable this program
This adjustment was random and unnecessary. The user mode startup code in probe_guest_base() will choose a value for guest_base that allows the host qemu binary to not conflict with the guest binary. With modern distributions, this isn't even used, as the default is PIE, which does the same job in a more portable way. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- configure | 47 ----------------------------------------------- 1 file changed, 47 deletions(-)