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S390: Fix tst-ptrace-singleblock if kernel does not support PTRACE_SINGLEBLOCK. 

The request PTRACE_SINGLEBLOCK was introduced in Linux 3.15.  Thus the ptrace call
will fail on older kernels.
Thus the test is now testing PTRACE_SINGLEBLOCK with data argument pointing to a
buffer on stack which is assumed to fail.  If the request would be interpreted as
PTRACE_GETREGS, then the ptrace call will not fail and the regs are written to buf.

If we run with a kernel with support for PTRACE_SINGLEBLOCK a ptrace call with
data=NULL, returns zero with no error.  If we run with a kernel without support for
PTRACE_SINGLEBLOCK a ptrace call with data=NULL reports an error.
In the latter case, the test is just continuing with PTRACE_CONT.

ChangeLog:

	* sysdeps/unix/sysv/linux/s390/tst-ptrace-singleblock.c:
	Support running on kernels without PTRACE_SINGLEBLOCK.
This commit is contained in:
Stefan Liebler 2017-07-11 10:37:03 +02:00
parent 38eea35ca7
commit 2c80445787
2 changed files with 57 additions and 2 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2017-07-11 Stefan Liebler <stli@linux.vnet.ibm.com>
* sysdeps/unix/sysv/linux/s390/tst-ptrace-singleblock.c:
Support running on kernels without PTRACE_SINGLEBLOCK.
2017-07-10 H.J. Lu <hongjiu.lu@intel.com>
[BZ #21742]

54
sysdeps/unix/sysv/linux/s390/tst-ptrace-singleblock.c
View File

@ -26,6 +26,8 @@
#include <elf.h>
#include <support/xunistd.h>
#include <support/check.h>
#include <string.h>
#include <errno.h>
/* Ensure that we use the PTRACE_SINGLEBLOCK definition from glibc ptrace.h
in tracer_func. We need the kernel ptrace.h for structs ptrace_area
@ -63,6 +65,10 @@ tracer_func (int pid)
gregset_t regs2;
int status;
int ret;
#define MAX_CHARS_IN_BUF 4096
char buf[MAX_CHARS_IN_BUF + 1];
size_t buf_count;
while (1)
{
@ -104,11 +110,55 @@ tracer_func (int pid)
The s390 kernel has no support for PTRACE_GETREGS!
Thus glibc ptrace.h is adjusted to match kernel ptrace.h.
The glibc sys/ptrace.h header contains the identifier
PTRACE_SINGLEBLOCK in enum __ptrace_request. In contrast, the kernel
asm/ptrace.h header defines PTRACE_SINGLEBLOCK.
This test ensures, that PTRACE_SINGLEBLOCK defined in glibc
works as expected. If the kernel would interpret it as
PTRACE_GETREGS, then the tracee will not make any progress
and this testcase will time out. */
TEST_VERIFY_EXIT (ptrace (req_singleblock, pid, NULL, NULL) == 0);
and this testcase will time out or the ptrace call will fail with
different errors. */
/* Ptrace request 12 is first done with data argument pointing to
a buffer:
-If request 12 is interpreted as PTRACE_GETREGS, it will store the regs
to buffer without an error.
-If request 12 is interpreted as PTRACE_SINGLEBLOCK, it will fail
as data argument is used as signal-number and the address of
buf is no valid signal.
-If request 12 is not implemented, it will also fail.
Here the test expects that the buffer is untouched and an error is
returned. */
memset (buf, 'a', MAX_CHARS_IN_BUF);
ret = ptrace (req_singleblock, pid, NULL, buf);
buf [MAX_CHARS_IN_BUF] = '\0';
buf_count = strspn (buf, "a");
TEST_VERIFY_EXIT (buf_count == MAX_CHARS_IN_BUF);
TEST_VERIFY_EXIT (ret == -1);
/* If request 12 is interpreted as PTRACE_GETREGS, the first ptrace
call will touch the buffer which is detected by this test. */
errno = 0;
ret = ptrace (req_singleblock, pid, NULL, NULL);
if (ret == 0)
{
/* The kernel has support for PTRACE_SINGLEBLOCK ptrace request. */
TEST_VERIFY_EXIT (errno == 0);
}
else
{
/* The kernel (< 3.15) has no support for PTRACE_SINGLEBLOCK ptrace
request. */
TEST_VERIFY_EXIT (errno == EIO);
TEST_VERIFY_EXIT (ret == -1);
/* Just continue tracee until it exits normally. */
TEST_VERIFY_EXIT (ptrace (PTRACE_CONT, pid, NULL, NULL) == 0);
}
}
}