[PATCH] configure: Use lld --image-base for --disable-pie user mode binaries

[Fangrui Song <i@maskray.me>]

For lld, --image-base is the preferred way to set the base address.
lld does not actually implement -Ttext-segment, but treats it as an alias for
-Ttext. -Ttext-segment=0x60000000 combined with --no-rosegment can
create a 1.6GB executable.

Fix the problem by using --image-base for lld. GNU ld and gold will
still get -Ttext-segment. Also delete the ld --verbose fallback introduced
in 2013, which is no longer relevant or correct (the default linker
script has changed).

Signed-off-by: Fangrui Song <i@maskray.me>
---
  configure | 33 ++++++++++++---------------------
  1 file changed, 12 insertions(+), 21 deletions(-)

diff --git a/configure b/configure
index 6099be1d84..2d45af0d09 100755
--- a/configure
+++ b/configure
@@ -6336,43 +6336,34 @@ fi
  
  # Probe for the need for relocating the user-only binary.
  if ( [ "$linux_user" = yes ] || [ "$bsd_user" = yes ] ) && [ "$pie" = no ]; then
-  textseg_addr=
+  image_base=
    case "$cpu" in
      arm | i386 | ppc* | s390* | sparc* | x86_64 | x32)
-      # ??? Rationale for choosing this address
-      textseg_addr=0x60000000
+      # An arbitrary address that makes it unlikely to collide with user
+      # programs.
+      image_base=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
+      image_base=0x60000000
        ;;
    esac
-  if [ -n "$textseg_addr" ]; then
+  if [ -n "$image_base" ]; 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 ! $ld --verbose >/dev/null 2>&1; then
+    image_base_ldflags="-Wl,--image-base=$image_base"
+    if ! compile_prog "" "$image_base_ldflags"; then
+      image_base_ldflags="-Wl,-Ttext-segment=$image_base"
+      if ! compile_prog "" "$image_base_ldflags"; 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." \
+            "supports neither --image-base nor -Ttext-segment. " \
              "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 = $textseg_addr/" > config-host.ld
-      textseg_ldflags="-Wl,-T../config-host.ld"
      fi
    fi
  fi
@@ -7945,7 +7936,7 @@ if test "$gprof" = "yes" ; then
  fi
  
  if test "$target_linux_user" = "yes" || test "$target_bsd_user" = "yes" ; then
-  ldflags="$ldflags $textseg_ldflags"
+  ldflags="$ldflags $image_base_ldflags"
  fi
  
  # Newer kernels on s390 check for an S390_PGSTE program header and
-- 
2.24.0