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| author | Hendrik Brueckner <brueckner@linux.vnet.ibm.com> | 2017-11-20 13:41:07 +0300 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-12-13 12:51:35 +0300 |
| commit | bc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513 (patch) | |
| tree | 8afb21635860b1ba73e8d5be04536b626cbb338b /arch/s390/kernel/vdso64/clock_gettime.S | |
| parent | a5f1005517534aeb1fac20180badfbf0896c183c (diff) | |
| download | linux-bc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513.tar.xz | |
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/vdso64/clock_gettime.S')
| -rw-r--r-- | arch/s390/kernel/vdso64/clock_gettime.S | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S index 6046b3bfca46..deccd793b279 100644 --- a/arch/s390/kernel/vdso64/clock_gettime.S +++ b/arch/s390/kernel/vdso64/clock_gettime.S @@ -9,6 +9,7 @@ #include <asm/vdso.h> #include <asm/asm-offsets.h> #include <asm/unistd.h> +#include <asm/dwarf.h> .text .align 4 |