The SIGSYS handler in sud_benchmark returns by hand: it loads __NR_rt_sigreturn, runs leaveq to drop its frame, adjusts the stack and issues the syscall. leaveq restores the stack from the frame pointer, so the sequence only works in a function that has one.
gcc omits the frame pointer from -O1 up, so the handler restores a stack that is not the signal frame and rt_sigreturn resumes at a bogus address: Caught sys_ff00 Segmentation fault The Makefile passes no -O, so a default build gets -O0 and works. A distribution building the selftests with its own optimisation flags does not: -O1 and -O2 both fault, and both pass again with -fno-omit-frame-pointer. Ask for the frame pointer, which is what the assembly needs. sud_test does not use it and is unaffected. Signed-off-by: Eva Kurchatova <[email protected]> --- tools/testing/selftests/syscall_user_dispatch/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/syscall_user_dispatch/Makefile b/tools/testing/selftests/syscall_user_dispatch/Makefile index 03c120270953..249d9ed30c5c 100644 --- a/tools/testing/selftests/syscall_user_dispatch/Makefile +++ b/tools/testing/selftests/syscall_user_dispatch/Makefile @@ -3,7 +3,7 @@ top_srcdir = ../../../.. INSTALL_HDR_PATH = $(top_srcdir)/usr LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/ -CFLAGS += -Wall -I$(LINUX_HDR_PATH) +CFLAGS += -Wall -fno-omit-frame-pointer -I$(LINUX_HDR_PATH) TEST_GEN_PROGS := sud_test sud_benchmark include ../lib.mk -- 2.55.0
