[PATCH 3/5] configure: use TEST_CC to check for -Ttext-segment

[Adhemerval Zanella Netto]

On 06/12/25 10:31, Sam James wrote:
> Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
> 
>> The ld.lld does not support this option; however, it does support a
>> similar option (--image-base=).  If the -Ttext-segment check fails, it
>> also checks for support for --image-base=.
> 
> How similar are they? Identical functionality or not? If identical,
> let's just use it for bfd, as it seems to support it. If not, we need to
> know why it's OK to use it.

They are not strictly identical, the -Ttext-segment does not take in consideration
the ELF header to set the base virtual address; but both are suffice the trigger
the issue from which the test came from [1] (a non-zero load address).

I forgot to check if bfd has support for --image-base, I will change to only
use it instead.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=31799

> 
>> ---
>>  configure    | 41 +++++++++++++++++++++++++++++++++++++++++
>>  configure.ac | 15 +++++++++++----
>>  2 files changed, 52 insertions(+), 4 deletions(-)
>>
>> diff --git a/configure b/configure
>> index 4cfc3daf83..7bf92aab37 100755
>> --- a/configure
>> +++ b/configure
>> @@ -9125,6 +9125,8 @@ libc_linker_feature=no
>>  cat > conftest.c <<EOF
>>  int _start (void) { return 42; }
>>  EOF
>> +saved_CC="$CC"
>> +CC="$TEST_CC"
>>  if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
>>  		  -Wl,-Ttext-segment=$libc_cv_pde_load_address -nostdlib -nostartfiles
>>  		  -fPIC -shared -o conftest.so conftest.c
>> @@ -9149,8 +9151,47 @@ if test $libc_linker_feature = yes; then
>>  else
>>    libc_cv_load_address_ldflag=
>>  fi
>> +CC="$saved_CC"
>>  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5
>>  printf "%s\n" "$libc_linker_feature" >&6; }
>> +if test -z $libc_cv_load_address_ldflag; then
>> +  # ld.lld does not support -Ttext-segment, but supports a similar option
>> +  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for linker that supports --image-base=$libc_cv_pde_load_address" >&5
>> +printf %s "checking for linker that supports --image-base=$libc_cv_pde_load_address... " >&6; }
>> +libc_linker_feature=no
>> +cat > conftest.c <<EOF
>> +int _start (void) { return 42; }
>> +EOF
>> +saved_CC="$CC"
>> +CC="$TEST_CC"
>> +if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
>> +		  -Wl,--image-base=$libc_cv_pde_load_address -nostdlib -nostartfiles
>> +		  -fPIC -shared -o conftest.so conftest.c
>> +		  1>&5'
>> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
>> +  (eval $ac_try) 2>&5
>> +  ac_status=$?
>> +  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
>> +  test $ac_status = 0; }; }
>> +then
>> +  if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -Wl,--image-base=$libc_cv_pde_load_address -nostdlib \
>> +      -nostartfiles -fPIC -shared -o conftest.so conftest.c 2>&1 \
>> +      | grep "warning: --image-base=$libc_cv_pde_load_address ignored" > /dev/null 2>&1; then
>> +    true
>> +  else
>> +    libc_linker_feature=yes
>> +  fi
>> +fi
>> +rm -f conftest*
>> +if test $libc_linker_feature = yes; then
>> +  libc_cv_load_address_ldflag=-Wl,--image-base
>> +else
>> +  libc_cv_load_address_ldflag=
>> +fi
>> +CC="$saved_CC"
>> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5
>> +printf "%s\n" "$libc_linker_feature" >&6; }
>> +fi
>>  config_vars="$config_vars
>>  load-address-ldflag = $libc_cv_load_address_ldflag"
>>  
>> diff --git a/configure.ac b/configure.ac
>> index c7907f48f8..92ad33f37a 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -2043,10 +2043,17 @@ LIBC_CONFIG_VAR([pde-load-address], [$libc_cv_pde_load_address])
>>  # Get the linker command-line option to load executable at a non-zero
>>  # load address.  This is only used by glibc tests to verify that PIE and
>>  # static PIE with non-zero load address work correctly.
>> -LIBC_LINKER_FEATURE([-Ttext-segment=$libc_cv_pde_load_address],
>> -		    [-Wl,-Ttext-segment=$libc_cv_pde_load_address],
>> -		    [libc_cv_load_address_ldflag=-Wl,-Ttext-segment],
>> -		    [libc_cv_load_address_ldflag=])
>> +LIBC_TEST_LINKER_FEATURE([-Ttext-segment=$libc_cv_pde_load_address],
>> +			 [-Wl,-Ttext-segment=$libc_cv_pde_load_address],
>> +			 [libc_cv_load_address_ldflag=-Wl,-Ttext-segment],
>> +			 [libc_cv_load_address_ldflag=])
> 
> I'd really prefer AS_IF for the below test wherever possible but I won't
> insist on it. At some point I'll convert everything where appropriate..
> 
>> +if test -z $libc_cv_load_address_ldflag; then
>> +  # ld.lld does not support -Ttext-segment, but supports a similar option
>> +  LIBC_TEST_LINKER_FEATURE([--image-base=$libc_cv_pde_load_address],
>> +			   [-Wl,--image-base=$libc_cv_pde_load_address],
>> +			   [libc_cv_load_address_ldflag=-Wl,--image-base],
>> +			   [libc_cv_load_address_ldflag=])
>> +fi
>>  LIBC_CONFIG_VAR([load-address-ldflag], [$libc_cv_load_address_ldflag])
>>  
>>  # Check if compiler supports -fno-fp-int-builtin-inexact