path: root/package/musl/Config.in
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authorGravatar Romain Naour <romain.naour@gmail.com>2018-09-08 16:41:39 +0200
committerGravatar Thomas Petazzoni <thomas.petazzoni@bootlin.com>2018-11-04 12:49:25 +0100
commit435613ef298d49788d82f7bb2e06f944d69d890b (patch)
tree6110416978492439949c477f5ee53275a6a177af /package/musl/Config.in
parent03d52226e2f02d642bf3d44ca299cc190cb0b253 (diff)
toolchain: disable SSP support if CFI support in binutils is missing
As reported by [1], SSP support is missing in the Buildroot toolchain for microblaze even if it's requested by selecting BR2_TOOLCHAIN_HAS_SSP config option. In Buildroot, we are using libssp provided by the C library (glibc, musl, uClibc-ng) when available. We are not using libssp from gcc. So for a microblaze glibc based toolchain, the SSP support is enabled unconditionally by a select BR2_TOOLCHAIN_HAS_SSP. BR2_microblazeel=y BR2_TOOLCHAIN_BUILDROOT_GLIBC=y BR2_KERNEL_HEADERS_4_14=y BR2_BINUTILS_VERSION_2_30_X=y BR2_GCC_VERSION_8_X=y BR2_TOOLCHAIN_BUILDROOT_CXX=y While building the toolchain, we are building host-binutils which provide "as" (assembler) and host-gcc-initial wich provide a minimal cross gcc (C only cross-compiler without any C library). When SSP support is requested, gcc_cv_libc_provides_ssp=yes is added to the make command line (see [2] for full details) With this setting, the SSP support is requested but it's not available in the end and the toochain build succeed. When the microblaze toolchain is imported to Biuldroot (2018.05) as external toolchain with BR2_TOOLCHAIN_EXTERNAL_HAS_SSP set, the build stop with : "SSP support not available in this toolchain, please disable BR2_TOOLCHAIN_EXTERNAL_HAS_SSP" The test is doing the following command line: echo 'void main(){}' | [...]/host/bin/microblazeel-linux-gcc.br_real -Werror -fstack-protector -x c - -o [...]/build/.br-toolchain-test.tmp cc1: error: -fstack-protector not supported for this target [-Werror] When we look at the gcc-final log file (config.log) we can see this error several time when using the minimal gcc (from host-gcc-initial). So Why the minimal gcc doesn't support SSP? When we look at the gcc-initial log file (config.log) we can see an error with 'as': configure:23194: checking assembler for cfi directives configure:23209: [...]microblazeel-buildroot-linux-gnu/bin/as -o conftest.o conftest.s >&5 conftest.s: Assembler messages: conftest.s:2: Error: CFI is not supported for this target conftest.s:3: Error: CFI is not supported for this target conftest.s:4: Error: CFI is not supported for this target conftest.s:5: Error: CFI is not supported for this target conftest.s:6: Error: CFI is not supported for this target conftest.s:7: Error: CFI is not supported for this target configure:23212: $? = 1 configure: failed program was .text .cfi_startproc .cfi_offset 0, 0 .cfi_same_value 1 .cfi_def_cfa 1, 2 .cfi_escape 1, 2, 3, 4, 5 .cfi_endproc This is the only relevant difference compared to a nios2 toolchain where libssp is enabled and available (nios2 is an example). "CFI" stand for "Control Flow Integrity" and it seems that SSP support requires CFI target support (see [3] for some explanation). The SSP support seems to depends on CFI support, but the toolchain infrastructure is not detailed enough to handle the CFI dependency. The NiosII toolchains built with binutils < 2.30 are also affected by this issue. This patch improve the toolchain infrastructure by adding a new BR2_PACKAGE_HOST_BINUTILS_SUPPORTS_CFI blind option Disable SSP support for microblaze entirely. Disable SSP support for nios2 only with Binutils < 2.30. Fixes: https://gitlab.com/free-electrons/toolchains-builder/-/jobs/72006389 [1] https://gitlab.com/free-electrons/toolchains-builder/issues/1 [2] https://git.buildroot.net/buildroot/tree/package/gcc/gcc.mk?h=2018.05#n275 [3] https://grsecurity.net/rap_faq.php Signed-off-by: Romain Naour <romain.naour@gmail.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> [Thomas: adjust how the BR2_PACKAGE_HOST_BINUTILS_SUPPORTS_CFI option is expressed.] Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Diffstat (limited to 'package/musl/Config.in')
1 files changed, 2 insertions, 1 deletions
diff --git a/package/musl/Config.in b/package/musl/Config.in
index bedc50cd45..67e9e78a14 100644
--- a/package/musl/Config.in
+++ b/package/musl/Config.in
@@ -4,6 +4,7 @@ config BR2_PACKAGE_MUSL
# SSP broken on i386/ppc: http://www.openwall.com/lists/musl/2016/12/04/2
- select BR2_TOOLCHAIN_HAS_SSP if !(BR2_i386 || BR2_powerpc)
+ && !(BR2_i386 || BR2_powerpc)
# Compatibility headers: cdefs.h, queue.h