[OE-core] [PATCH 2/4] gcc: Update default Power GCC settings to use secure-plt

[Mark Hatle]

The gcc default, bss-plt, will cause errors when using the prelinker.  All
other distributions that I am aware of are using the the secure-plt.  For an
explanation of the differences, the gcc docs:

  Current PowerPC GCC accepts a `-msecure-plt' option that generates code
  capable of using a newer PLT and GOT layout that has the security
  advantage of no executable section ever needing to be writable and no
  writable section ever being executable. PowerPC ld will generate this
  layout, including stubs to access the PLT, if all input files (including
  startup and static libraries) were compiled with `-msecure-plt'.
  `--bss-plt' forces the old BSS PLT (and GOT layout) which can give
  slightly better performance.

The security of the new PLT and ability to run the prelinker outweigh
any performance penalty.

The secure-plt is enabled by default.  The old bss-plt can be enabled by
selecting 'bssplt' in the DISTRO_FEATURES.

[Yocto #7991]

Signed-off-by: Mark Hatle <mark.hatle at windriver.com>
---
 meta/recipes-devtools/gcc/gcc-common.inc           | 5 +++++
 meta/recipes-devtools/gcc/gcc-configure-common.inc | 1 +
 meta/recipes-devtools/gcc/gcc-cross-initial.inc    | 1 +
 3 files changed, 7 insertions(+)

diff --git a/meta/recipes-devtools/gcc/gcc-common.inc b/meta/recipes-devtools/gcc/gcc-common.inc
index d63c07f..6f2f224 100644
--- a/meta/recipes-devtools/gcc/gcc-common.inc
+++ b/meta/recipes-devtools/gcc/gcc-common.inc
@@ -25,6 +25,11 @@ def get_gcc_mips_plt_setting(bb, d):
         return "--with-mips-plt"
     return ""
 
+def get_gcc_ppc_plt_settings(bb, d):
+    if d.getVar('TRANSLATED_TARGET_ARCH', True) in [ 'powerpc' ] and not bb.utils.contains('DISTRO_FEATURES', 'bssplt', True, False, d):
+        return "--enable-secureplt"
+    return ""
+
 def get_long_double_setting(bb, d):
     if d.getVar('TRANSLATED_TARGET_ARCH', True) in [ 'powerpc', 'powerpc64' ] and d.getVar('TCLIBC', True) in [ 'uclibc', 'glibc' ]:
         return "--with-long-double-128"
diff --git a/meta/recipes-devtools/gcc/gcc-configure-common.inc b/meta/recipes-devtools/gcc/gcc-configure-common.inc
index a14be73..cee6f4a 100644
--- a/meta/recipes-devtools/gcc/gcc-configure-common.inc
+++ b/meta/recipes-devtools/gcc/gcc-configure-common.inc
@@ -47,6 +47,7 @@ EXTRA_OECONF = "\
     ${EXTRA_OECONF_GCC_FLOAT} \
     ${EXTRA_OECONF_PATHS} \
     ${@get_gcc_mips_plt_setting(bb, d)} \
+    ${@get_gcc_ppc_plt_settings(bb, d)} \
     ${@get_long_double_setting(bb, d)} \
     ${@get_gcc_multiarch_setting(bb, d)} \
 "
diff --git a/meta/recipes-devtools/gcc/gcc-cross-initial.inc b/meta/recipes-devtools/gcc/gcc-cross-initial.inc
index 7197447..c0fa139 100644
--- a/meta/recipes-devtools/gcc/gcc-cross-initial.inc
+++ b/meta/recipes-devtools/gcc/gcc-cross-initial.inc
@@ -26,6 +26,7 @@ EXTRA_OECONF = "\
     ${EXTRA_OECONF_INITIAL} \
     ${@bb.utils.contains('DISTRO_FEATURES', 'ld-is-gold', '--with-ld=${STAGING_BINDIR_TOOLCHAIN}/${TARGET_PREFIX}ld.bfd', '', d)} \
     ${EXTRA_OECONF_GCC_FLOAT} \
+    ${@get_gcc_ppc_plt_settings(bb, d)} \
 "
 
 EXTRA_OECONF += "--with-native-system-header-dir=${SYSTEMHEADERS}"
-- 
1.9.3