On Sun, Jul 21, 2024 at 12:51 AM Tony Ambardar tony.ambardar@gmail.com wrote:
Linking uprobe_multi.c on mips64el fails due to relocation overflows, when the GOT entries required exceeds the default maximum. Add a specific CFLAGS (-mxgot) for uprobe_multi.c on MIPS that allows using a larger GOT and avoids errors such as:
/tmp/ccBTNQzv.o: in function `bench': uprobe_multi.c:49:(.text+0x1d7720): relocation truncated to fit: R_MIPS_GOT_DISP against `uprobe_multi_func_08188' uprobe_multi.c:49:(.text+0x1d7730): relocation truncated to fit: R_MIPS_GOT_DISP against `uprobe_multi_func_08189' ... collect2: error: ld returned 1 exit status
Fixes: 519dfeaf5119 ("selftests/bpf: Add uprobe_multi test program") Signed-off-by: Tony Ambardar tony.ambardar@gmail.com
tools/testing/selftests/bpf/Makefile | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index a9c447c63fee..0b4bfbc0ef68 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -784,9 +784,12 @@ $(OUTPUT)/veristat: $(OUTPUT)/veristat.o $(call msg,BINARY,,$@) $(Q)$(CC) $(CFLAGS) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@
+# Linking uprobe_multi can fail due to relocation overflows on mips. +uprobe_multi.c-CFLAGS := $(if $(filter mips, $(ARCH)),-mxgot)
$(OUTPUT)/uprobe_multi: uprobe_multi.c $(call msg,BINARY,,$@)
$(Q)$(CC) $(CFLAGS) -O0 $(LDFLAGS) $^ $(LDLIBS) -o $@
$(Q)$(CC) $(CFLAGS) $($<-CFLAGS) -O0 $(LDFLAGS) $^ $(LDLIBS) -o $@
this $($<-CFLAGS) approach is fragile, non-obvious and will break. But there is also no need for this, see:
$(OUTPUT)/bench: LDLIBS += -lm
make allows to override envvars on a per-target basis, so all you should need is:
$(OUTPUT)/uprobe_multi: CFLAGS += $(if $(filter mips, $(ARCH)),-mxgot) $(OUTPUT)/uprobe_multi: uprobe_multi.c ... the rest is the same with no change whatsoever ...
EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR) \ prog_tests/tests.h map_tests/tests.h verifier/tests.h \ -- 2.34.1