When using GCC on x86-64 to compile an usdt prog with -O1 or higher optimization, the compiler will generate SIB addressing mode for global array and PC-relative addressing mode for global variable, e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)".
In this patch: - force -O2 optimization for usdt.test.o to generate SIB addressing usdt argument spec. - change the global variable t1 to a local variable, to avoid compiler generating PC-relative addressing mode for it.
Signed-off-by: Jiawei Zhao phoenix500526@163.com --- tools/testing/selftests/bpf/Makefile | 5 +++++ tools/testing/selftests/bpf/prog_tests/usdt.c | 18 ++++++++++++------ 2 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 910d8d6402ef..f53c86023334 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -759,6 +759,11 @@ TRUNNER_BPF_BUILD_RULE := $$(error no BPF objects should be built) TRUNNER_BPF_CFLAGS := $(eval $(call DEFINE_TEST_RUNNER,test_maps))
+# Force usdt.c to use -O2 optimization to generate SIB addressing +$(OUTPUT)/usdt.test.o: CFLAGS:=$(subst O0,O2,$(CFLAGS)) +$(OUTPUT)/cpuv4/usdt.test.o: CFLAGS:=$(subst O0,O2,$(CFLAGS)) +$(OUTPUT)/no_alu32/usdt.test.o: CFLAGS:=$(subst O0,O2,$(CFLAGS)) + # Define test_verifier test runner. # It is much simpler than test_maps/test_progs and sufficiently different from # them (e.g., test.h is using completely pattern), that it's worth just diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c b/tools/testing/selftests/bpf/prog_tests/usdt.c index 495d66414b57..86f354d25aef 100644 --- a/tools/testing/selftests/bpf/prog_tests/usdt.c +++ b/tools/testing/selftests/bpf/prog_tests/usdt.c @@ -14,10 +14,15 @@ static volatile int idx = 2; static volatile __u64 bla = 0xFEDCBA9876543210ULL; static volatile short nums[] = {-1, -2, -3, -4};
-static volatile struct { - int x; - signed char y; -} t1 = { 1, -127 }; +/* + * TODO: At O2 optimization level, t1's USDT argument spec becomes -1@4+t1(%rip). + * Since libbpf doesn't support RIP addressing mode yet, this causes "unrecognized register" errors. + * This test will be re-enabled once libbpf supports RIP addressing mode. + */ +// static volatile struct { +// int x; +// signed char y; +// } t1 = { 1, -127 };
#define SEC(name) __attribute__((section(name), used))
@@ -27,6 +32,7 @@ unsigned short test_usdt12_semaphore SEC(".probes");
static void __always_inline trigger_func(int x) { long y = 42; + signed char t1 = -127;
if (test_usdt0_semaphore) STAP_PROBE(test, usdt0); @@ -36,7 +42,7 @@ static void __always_inline trigger_func(int x) { STAP_PROBE12(test, usdt12, x, x + 1, y, x + y, 5, y / 7, bla, &bla, -9, nums[x], - nums[idx], t1.y); + nums[idx], t1); } }
@@ -106,7 +112,7 @@ static void subtest_basic_usdt(void) ASSERT_EQ(bss->usdt12_args[8], -9, "usdt12_arg9"); ASSERT_EQ(bss->usdt12_args[9], nums[1], "usdt12_arg10"); ASSERT_EQ(bss->usdt12_args[10], nums[idx], "usdt12_arg11"); - ASSERT_EQ(bss->usdt12_args[11], t1.y, "usdt12_arg12"); + ASSERT_EQ(bss->usdt12_args[11], -127, "usdt12_arg12");
int usdt12_expected_arg_sizes[12] = { 4, 4, 8, 8, 4, 8, 8, 8, 4, 2, 2, 1 };