[PATCH 2/2] selftests/x86: Add test_vdso to test getcpu

From: Andy Lutomirski
Date: Wed Nov 16 2016 - 13:23:42 EST


I'll eventually add tests for more vdso functions here.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/test_vdso.c | 123 ++++++++++++++++++++++++++++++++
2 files changed, 124 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/test_vdso.c

diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index a89f80a5b711..8c1cb423cfe6 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -6,7 +6,7 @@ include ../lib.mk

TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall test_mremap_vdso \
check_initial_reg_state sigreturn ldt_gdt iopl \
- protection_keys
+ protection_keys test_vdso
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
diff --git a/tools/testing/selftests/x86/test_vdso.c b/tools/testing/selftests/x86/test_vdso.c
new file mode 100644
index 000000000000..65d7a2bf7e14
--- /dev/null
+++ b/tools/testing/selftests/x86/test_vdso.c
@@ -0,0 +1,123 @@
+/*
+ * ldt_gdt.c - Test cases for LDT and GDT access
+ * Copyright (c) 2011-2015 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <time.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <dlfcn.h>
+#include <string.h>
+#include <errno.h>
+#include <sched.h>
+#include <stdbool.h>
+
+#ifndef SYS_getcpu
+# ifdef __x86_64__
+# define SYS_getcpu 309
+# else
+# define SYS_getcpu 318
+# endif
+#endif
+
+int nerrs = 0;
+
+#ifdef __x86_64__
+# define VSYS(x) (x)
+#else
+# define VSYS(x) 0
+#endif
+
+typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
+
+const getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
+getcpu_t vdso_getcpu;
+
+void fill_function_pointers()
+{
+ void *vdso = dlopen("linux-vdso.so.1",
+ RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+ if (!vdso)
+ vdso = dlopen("linux-gate.so.1",
+ RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+ if (!vdso) {
+ printf("[WARN]\tfailed to find vDSO\n");
+ return;
+ }
+
+ vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
+ if (!vdso_getcpu)
+ printf("Warning: failed to find getcpu in vDSO\n");
+}
+
+static long sys_getcpu(unsigned * cpu, unsigned * node,
+ void* cache)
+{
+ return syscall(__NR_getcpu, cpu, node, cache);
+}
+
+static void test_getcpu(void)
+{
+ printf("[RUN]\tTesting getcpu...\n");
+
+ for (int cpu = 0; ; cpu++) {
+ cpu_set_t cpuset;
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu, &cpuset);
+ if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+ return;
+
+ unsigned cpu_sys, cpu_vdso, cpu_vsys,
+ node_sys, node_vdso, node_vsys;
+ long ret_sys, ret_vdso = 1, ret_vsys = 1;
+ unsigned node;
+
+ ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
+ if (vdso_getcpu)
+ ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
+ if (vgetcpu)
+ ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
+
+ if (!ret_sys)
+ node = node_sys;
+ else if (!ret_vdso)
+ node = node_vdso;
+ else if (!ret_vsys)
+ node = node_vsys;
+
+ bool ok = true;
+ if (!ret_sys && (cpu_sys != cpu || node_sys != node))
+ ok = false;
+ if (!ret_vdso && (cpu_vdso != cpu || node_vdso != node))
+ ok = false;
+ if (!ret_vsys && (cpu_vsys != cpu || node_vsys != node))
+ ok = false;
+
+ printf("[%s]\tCPU %u:", ok ? "OK" : "FAIL", cpu);
+ if (!ret_sys)
+ printf(" syscall: cpu %u, node %u", cpu_sys, node_sys);
+ if (!ret_vdso)
+ printf(" vdso: cpu %u, node %u", cpu_vdso, node_vdso);
+ if (!ret_vsys)
+ printf(" vsyscall: cpu %u, node %u", cpu_vsys,
+ node_vsys);
+ printf("\n");
+
+ if (!ok)
+ nerrs++;
+ }
+}
+
+int main(int argc, char **argv)
+{
+ fill_function_pointers();
+
+ test_getcpu();
+
+ return nerrs ? 1 : 0;
+}
--
2.7.4