Re: [PATCH v2 5/7] configure: Unnest detection of -z, relro and -z, now

[Fangrui Song <i@maskray.me>]

On 2019-12-18, Philippe Mathieu-Daudé wrote:
>On 12/18/19 11:34 PM, Richard Henderson wrote:
>>There is nothing about these options that is related to PIE.
>>Use them unconditionally.
>>
>>Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>>---
>>v2: Do not split into two tests.
>>---
>>  configure | 9 ++++++---
>>  1 file changed, 6 insertions(+), 3 deletions(-)
>>
>>diff --git a/configure b/configure
>>index 7a646ec007..2503288654 100755
>>--- a/configure
>>+++ b/configure
>>@@ -2040,9 +2040,6 @@ if test "$pie" != "no" ; then
>>      QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS"
>>      LDFLAGS="-pie $LDFLAGS"
>>      pie="yes"
>>-    if compile_prog "" "-Wl,-z,relro -Wl,-z,now" ; then
>>-      LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS"
>>-    fi
>>    else
>>      if test "$pie" = "yes"; then
>>        error_exit "PIE not available due to missing toolchain support"
>>@@ -2053,6 +2050,12 @@ if test "$pie" != "no" ; then
>>    fi
>>  fi
>>+# Detect support for PT_GNU_RELRO + DT_BIND_NOW.
>>+# The combination is known as "full relro", because .got is read-only too.
>>+if compile_prog "" "-Wl,-z,relro -Wl,-z,now" ; then
>>+  LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS"
>>+fi
>>+
>>  ##########################################
>>  # __sync_fetch_and_and requires at least -march=i486. Many toolchains
>>  # use i686 as default anyway, but for those that don't, an explicit
>>
>
>Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

One nit, .got is also read-only in partial relro. Full relro makes .got.plt
read-only. (On EM_PPC and EM_PPC64, .got.plt is named .plt (yes,
misnomer)).

Reviewed-by: Fangrui Song <i@maskray.me>