kernel-yocto: conditionally enable stack protection checking on x86-64

The kernel Makfile uses pkgconfig to check for libelf when enabling
CONFIG_STACK_VALIDATION. We already have libelf in our DEPENDS, but
the kernel Makefiles hardcode 'pkgconfig', so fail to pick up our
pkgconfig-native binary that would report the correct flags and paths
for libelf support.

Rather than patching the kernel Makefile's to use pkgconfig-native,
we can use the KERNEL_EXTRA_ARGS variable to pass the definition of
HOST_LIBELF_LIBS via the kernel build commmand line.

We conditionally set HOST_LIBELF_LIBS based on "stack" being in
a newly introduced variable KERNEL_DEBUG_OPTIONS. The value of
HOST_LIBELF_LIBS is the same as pkgconfig-native would set in a
kernel build (but we cannot call pkgconfig at the point this
variable is set).

(From OE-Core rev: 0ad2b69dace6ac851c1f0bdae6a3c41045fc2d1d)

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/meta/recipes-kernel/linux/linux-yocto.inc b/meta/recipes-kernel/linux/linux-yocto.inc
index 331727d62c..15fc7ff724 100644
--- a/meta/recipes-kernel/linux/linux-yocto.inc
+++ b/meta/recipes-kernel/linux/linux-yocto.inc
@@ -46,6 +46,7 @@ LINUX_VERSION_EXTENSION ??= "-yocto-${LINUX_KERNEL_TYPE}"
 # Pick up shared functions
 inherit kernel
 inherit kernel-yocto
+inherit pkgconfig
 
 B = "${WORKDIR}/linux-${PACKAGE_ARCH}-${LINUX_KERNEL_TYPE}-build"
 
@@ -57,3 +58,6 @@ do_install:append(){
 
 # enable kernel-sample for oeqa/runtime/cases's ksample.py test
 KERNEL_FEATURES:append:qemuall=" features/kernel-sample/kernel-sample.scc"
+
+KERNEL_DEBUG_OPTIONS ?= "stack"
+KERNEL_EXTRA_ARGS:append:x86-64 = "${@bb.utils.contains('KERNEL_DEBUG_OPTIONS', 'stack', 'HOST_LIBELF_LIBS="-L${RECIPE_SYSROOT_NATIVE}/usr/lib/pkgconfig/../../../usr/lib/ -lelf"', '', d)}"