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: - enrich subtest_basic_usdt test case to cover SIB addressing usdt argument spec handling logic Signed-off-by: Jiawei Zhao <[email protected]> --- tools/testing/selftests/bpf/prog_tests/usdt.c | 30 +++++++++++++++++++ tools/testing/selftests/bpf/progs/test_usdt.c | 28 +++++++++++++++++ 2 files changed, 58 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c b/tools/testing/selftests/bpf/prog_tests/usdt.c index 9057e983cc54..56990d4b5861 100644 --- a/tools/testing/selftests/bpf/prog_tests/usdt.c +++ b/tools/testing/selftests/bpf/prog_tests/usdt.c @@ -25,6 +25,10 @@ unsigned short test_usdt0_semaphore SEC(".probes"); unsigned short test_usdt3_semaphore SEC(".probes"); unsigned short test_usdt12_semaphore SEC(".probes"); +#if defined(__x86_64__) || defined(__i386__) +unsigned short test_usdt_sib_semaphore SEC(".probes"); +#endif + static void __always_inline trigger_func(int x) { long y = 42; @@ -40,6 +44,22 @@ static void __always_inline trigger_func(int x) { } } +#if defined(__x86_64__) || defined(__i386__) +static __attribute__((optimize("O1"))) void trigger_sib_spec(void) +{ + /* Base address + offset + (index * scale) */ + /* Force SIB addressing with inline assembly */ + asm volatile( + "# probe point with memory access\n" + STAP_PROBE_ASM(test, usdt_sib, -2@(%%rdx,%%rax,2)) + "# end probe point" + : + : "d"(nums), "a"(0) + : "memory" + ); +} +#endif + static void subtest_basic_usdt(void) { LIBBPF_OPTS(bpf_usdt_opts, opts); @@ -156,6 +176,16 @@ static void subtest_basic_usdt(void) ASSERT_EQ(bss->usdt3_args[1], 42, "usdt3_arg2"); ASSERT_EQ(bss->usdt3_args[2], (uintptr_t)&bla, "usdt3_arg3"); + #if defined(__x86_64__) || defined(__i386__) + trigger_sib_spec(); + ASSERT_EQ(bss->usdt_sib_called, 1, "usdt_sib_called"); + ASSERT_EQ(bss->usdt_sib_cookie, 0, "usdt_sib_cookie"); + ASSERT_EQ(bss->usdt_sib_arg_cnt, 1, "usdt_sib_arg_cnt"); + ASSERT_EQ(bss->usdt_sib_arg, nums[0], "usdt_sib_arg"); + ASSERT_EQ(bss->usdt_sib_arg_ret, 0, "usdt_sib_arg_ret"); + ASSERT_EQ(bss->usdt_sib_arg_size, sizeof(nums[0]), "usdt_sib_arg_size"); + #endif + cleanup: test_usdt__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/test_usdt.c b/tools/testing/selftests/bpf/progs/test_usdt.c index 096488f47fbc..8b499732e6a8 100644 --- a/tools/testing/selftests/bpf/progs/test_usdt.c +++ b/tools/testing/selftests/bpf/progs/test_usdt.c @@ -107,4 +107,32 @@ int BPF_USDT(usdt12, int a1, int a2, long a3, long a4, unsigned a5, return 0; } + +int usdt_sib_called; +u64 usdt_sib_cookie; +int usdt_sib_arg_cnt; +int usdt_sib_arg_ret; +u64 usdt_sib_arg; +int usdt_sib_arg_size; + +SEC("usdt//proc/self/exe:test:usdt_sib") +int usdt_sib(struct pt_regs *ctx) +{ + long tmp; + + if (my_pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + __sync_fetch_and_add(&usdt_sib_called, 1); + + usdt_sib_cookie = bpf_usdt_cookie(ctx); + usdt_sib_arg_cnt = bpf_usdt_arg_cnt(ctx); + + usdt_sib_arg_ret = bpf_usdt_arg(ctx, 0, &tmp); + usdt_sib_arg = (short)tmp; + usdt_sib_arg_size = bpf_usdt_arg_size(ctx, 0); + + return 0; +} + char _license[] SEC("license") = "GPL"; -- 2.43.0
