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authorHendrik Brueckner <brueckner@linux.vnet.ibm.com>2017-11-20 13:41:07 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-12-13 12:51:35 +0300
commitbc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513 (patch)
tree8afb21635860b1ba73e8d5be04536b626cbb338b /arch/s390/kernel/vdso32
parenta5f1005517534aeb1fac20180badfbf0896c183c (diff)
downloadlinux-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/vdso32')
-rw-r--r--arch/s390/kernel/vdso32/Makefile3
-rw-r--r--arch/s390/kernel/vdso32/clock_getres.S1
-rw-r--r--arch/s390/kernel/vdso32/clock_gettime.S1
-rw-r--r--arch/s390/kernel/vdso32/getcpu.S1
-rw-r--r--arch/s390/kernel/vdso32/gettimeofday.S1
5 files changed, 7 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
diff --git a/arch/s390/kernel/vdso32/clock_getres.S b/arch/s390/kernel/vdso32/clock_getres.S
index f61df5253c23..6aeddf8e4bc7 100644
--- a/arch/s390/kernel/vdso32/clock_getres.S
+++ b/arch/s390/kernel/vdso32/clock_getres.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
diff --git a/arch/s390/kernel/vdso32/clock_gettime.S b/arch/s390/kernel/vdso32/clock_gettime.S
index 2d6ec3abe095..d0ac32c413e2 100644
--- a/arch/s390/kernel/vdso32/clock_gettime.S
+++ b/arch/s390/kernel/vdso32/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
diff --git a/arch/s390/kernel/vdso32/getcpu.S b/arch/s390/kernel/vdso32/getcpu.S
index 5477a2c112fb..539d92a2c61b 100644
--- a/arch/s390/kernel/vdso32/getcpu.S
+++ b/arch/s390/kernel/vdso32/getcpu.S
@@ -8,6 +8,7 @@
*/
#include <asm/vdso.h>
#include <asm/asm-offsets.h>
+#include <asm/dwarf.h>
.text
.align 4
diff --git a/arch/s390/kernel/vdso32/gettimeofday.S b/arch/s390/kernel/vdso32/gettimeofday.S
index aa8bf13a2edb..435f819c3e65 100644
--- a/arch/s390/kernel/vdso32/gettimeofday.S
+++ b/arch/s390/kernel/vdso32/gettimeofday.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