From: linux@dominikbrodowski.net (Dominik Brodowski)
Subject: [Linux-kselftest-mirror] [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none
Date: Sun, 11 Feb 2018 12:10:10 +0100 [thread overview]
Message-ID: <20180211111013.16888-3-linux@dominikbrodowski.net> (raw)
Message-ID: <20180211111010.MjMhAZRYQgevNbQv-6W35zbhOETXojmBvLbWlzZt7Lk@z> (raw)
In-Reply-To: <20180211111013.16888-1-linux@dominikbrodowski.net>
The vDSO selftest tries to execute a vsyscall unconditionally, even if it
is not present on the test system (e.g. if booted with vsyscall=none or
with CONFIG_LEGACY_VSYSCALL_NONE=y set. Fix this by copying (and tweaking)
the vsyscall check from test_vsyscall.c
CC: Andrew Lutomirski <luto at kernel.org>
Signed-off-by: Dominik Brodowski <linux at dominikbrodowski.net>
---
tools/testing/selftests/x86/test_vdso.c | 50 ++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 7 deletions(-)
diff --git a/tools/testing/selftests/x86/test_vdso.c b/tools/testing/selftests/x86/test_vdso.c
index 29973cde06d3..558c8207e7b9 100644
--- a/tools/testing/selftests/x86/test_vdso.c
+++ b/tools/testing/selftests/x86/test_vdso.c
@@ -28,18 +28,52 @@
int nerrs = 0;
+typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
+
+getcpu_t vgetcpu;
+getcpu_t vdso_getcpu;
+
+static void *vsyscall_getcpu(void)
+{
#ifdef __x86_64__
-# define VSYS(x) (x)
+ FILE *maps;
+ char line[128];
+ bool found = false;
+
+ maps = fopen("/proc/self/maps", "r");
+ if (!maps) /* might still be present, but ignore it here, as we test vDSO not vsyscall */
+ return NULL;
+
+ while (fgets(line, sizeof(line), maps)) {
+ char r, x;
+ void *start, *end;
+ char name[128];
+ if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
+ &start, &end, &r, &x, name) != 5)
+ continue;
+
+ if (strcmp(name, "[vsyscall]"))
+ continue;
+
+ /* assume entries are OK, as we test vDSO here not vsyscall */
+ found = true;
+ break;
+ }
+
+ fclose(maps);
+
+ if (!found) {
+ printf("Warning: failed to find vsyscall getcpu\n");
+ return NULL;
+ }
+ return (void *) (0xffffffffff600800);
#else
-# define VSYS(x) 0
+ return NULL;
#endif
+}
-typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
-
-const getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
-getcpu_t vdso_getcpu;
-void fill_function_pointers()
+static void fill_function_pointers()
{
void *vdso = dlopen("linux-vdso.so.1",
RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
@@ -54,6 +88,8 @@ void fill_function_pointers()
vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
if (!vdso_getcpu)
printf("Warning: failed to find getcpu in vDSO\n");
+
+ vgetcpu = (getcpu_t) vsyscall_getcpu();
}
static long sys_getcpu(unsigned * cpu, unsigned * node,
--
2.16.1
--
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next prev parent reply other threads:[~2018-02-11 11:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-11 11:10 [Linux-kselftest-mirror] [PATCH 0/5] selftests/x86: fixes for !CONFIG_IA32_EMULATION and vsyscall=none linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 1/5] selftests/x86: 5lvl test has been moved linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` linux [this message]
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none Dominik Brodowski
2018-02-11 11:21 ` mingo
2018-02-11 11:21 ` Ingo Molnar
2018-02-11 12:17 ` linux
2018-02-11 12:17 ` Dominik Brodowski
2018-02-11 13:00 ` linux
2018-02-11 13:00 ` Dominik Brodowski
2018-02-11 18:24 ` mingo
2018-02-11 18:24 ` Ingo Molnar
2018-02-11 20:59 ` [Linux-kselftest-mirror] [PATCH] selftests/x86: clarify that there is no buffer overflow on sscanf usage linux
2018-02-11 20:59 ` Dominik Brodowski
2018-02-12 17:58 ` shuah
2018-02-12 17:58 ` Shuah Khan
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 3/5] selftests/x86: do not rely on int $0x80 in test_mremap_vdso.c linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 4/5] selftests/x86: do not rely on int $0x80 in single_step_syscall.c linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 5/5] selftests/x86: disable tests requiring 32bit support on pure 64bit systems linux
2018-02-11 11:10 ` Dominik Brodowski
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