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| author | Hendrik Brueckner <brueckner@linux.vnet.ibm.com> | 2017-11-20 11:41:07 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-12-13 10:51:35 +0100 |
| commit | bc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513 (patch) | |
| tree | 8afb21635860b1ba73e8d5be04536b626cbb338b /arch/s390/kernel/vdso32/Makefile | |
| parent | s390/pci: handle insufficient resources during dma tlb flush (diff) | |
| download | linux-bc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513.tar.xz linux-bc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513.zip | |
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/kernel/vdso32/Makefile')
| -rw-r--r-- | arch/s390/kernel/vdso32/Makefile | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/kernel/vdso32/Makefile b/arch/s390/kernel/vdso32/Makefile index 308564b9bf68..c5c856f320bc 100644 --- a/arch/s390/kernel/vdso32/Makefile +++ b/arch/s390/kernel/vdso32/Makefile @@ -10,6 +10,9 @@ obj-vdso32 = gettimeofday.o clock_getres.o clock_gettime.o note.o getcpu.o targets := $(obj-vdso32) vdso32.so vdso32.so.dbg obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32)) +KBUILD_AFLAGS += -DBUILD_VDSO +KBUILD_CFLAGS += -DBUILD_VDSO + KBUILD_AFLAGS_31 := $(filter-out -m64,$(KBUILD_AFLAGS)) KBUILD_AFLAGS_31 += -m31 -s |