path: root/arch/s390/Makefile
diff options
authorHendrik Brueckner <brueckner@linux.vnet.ibm.com>2017-11-20 11:41:07 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-12-13 10:51:35 +0100
commitbc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513 (patch)
tree8afb21635860b1ba73e8d5be04536b626cbb338b /arch/s390/Makefile
parents390/pci: handle insufficient resources during dma tlb flush (diff)
s390/kernel: emit CFI data in .debug_frame and discard .eh_frame sections
Using perf probe and libdw on kernel modules failed to find CFI data for symbols. The CFI data is stored in the .eh_frame section. The elfutils libdw is not able to extract the CFI data correctly, because the .eh_frame section requires "non-simple" relocations for kernel modules. The suggestion is to avoid these "non-simple" relocations by emitting the CFI data in the .debug_frame section. Let gcc emit respective directives by specifying the -fno-asynchronous-unwind-tables option. Using the .debug_frame section for CFI data, the .eh_frame section becomes unused and, thus, discard it for kernel and modules builds The vDSO requires the .eh_frame section and, hence, emit the CFI data in both, the .eh_frame and .debug_frame sections. See also discussion on elfutils/libdw bugzilla: https://sourceware.org/bugzilla/show_bug.cgi?id=22452 Suggested-by: Mark Wielaard <mark@klomp.org> Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/Makefile')
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index de54cfc6109d..494bb9ad5edf 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -90,6 +90,7 @@ endif
KBUILD_CFLAGS += -mbackchain -msoft-float $(cflags-y)
KBUILD_CFLAGS += -pipe -fno-strength-reduce -Wno-sign-compare
+KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
KBUILD_AFLAGS += $(aflags-y)