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selftests/powerpc: New PTRACE_SYSEMU test 

This patch adds a new test for the new PTRACE_SYSEMU ptrace request.

This test also relies on PTRACE_GETREGS and PTRACE_SETREGS requests to
run properly, since the trace instruction (gettid() syscall) is being
modified at run-time (by PTRACE_SETREGS) and re-executed three times.
PTRACE_GETREGS is being used to check that the registers are still
sane.

This test basically creates a child process that executes syscalls
and the parent process check if it is being traced appropriately.  The
parent process guarantees that the SYSCALLs are being traced, with
PTRACE_SYSEMU, and ptrace stops the child application before a syscall is
executed. The way the tests validates it, is by guaranteeing that the
system calls arguments, as argv[0] (r3) which is the same register that
will have the syscall return value on powerpc, are not being corrupted on
PTRACE_SYSEMU with a return value, i.e, it continues to have the current
arguments instead, meaning that the registers where not clobbered.

This test is basically the same test for x86 located at
tools/testing/selftests/x86/ptrace_syscall.c, limited to test PTRACE_SYSEMU
request, and ported to PowerPC.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Breno Leitao 2018-09-20 13:45:07 -03:00 committed by Michael Ellerman
parent 5521eb4bca
commit fc35ef12dc
2 changed files with 229 additions and 1 deletions
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2
tools/testing/selftests/powerpc/ptrace/Makefile
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@ -2,7 +2,7 @@
TEST_PROGS := ptrace-gpr ptrace-tm-gpr ptrace-tm-spd-gpr \
ptrace-tar ptrace-tm-tar ptrace-tm-spd-tar ptrace-vsx ptrace-tm-vsx \
ptrace-tm-spd-vsx ptrace-tm-spr ptrace-hwbreak ptrace-pkey core-pkey \
perf-hwbreak
perf-hwbreak ptrace-syscall
include ../../lib.mk

228
tools/testing/selftests/powerpc/ptrace/ptrace-syscall.c Normal file
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@ -0,0 +1,228 @@
// SPDX-License-Identifier: GPL-2.0
/*
* A ptrace test for testing PTRACE_SYSEMU, PTRACE_SETREGS and
* PTRACE_GETREG. This test basically create a child process that executes
* syscalls and the parent process check if it is being traced appropriated.
*
* This test is heavily based on tools/testing/selftests/x86/ptrace_syscall.c
* test, and it was adapted to run on Powerpc by
* Breno Leitao <leitao@debian.org>
*/
#define _GNU_SOURCE
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/syscall.h>
#include <sys/user.h>
#include <unistd.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <err.h>
#include <string.h>
#include <sys/auxv.h>
#include "utils.h"
/* Bitness-agnostic defines for user_regs_struct fields. */
#define user_syscall_nr gpr[0]
#define user_arg0 gpr[3]
#define user_arg1 gpr[4]
#define user_arg2 gpr[5]
#define user_arg3 gpr[6]
#define user_arg4 gpr[7]
#define user_arg5 gpr[8]
#define user_ip nip
#define PTRACE_SYSEMU 0x1d
static int nerrs;
static void wait_trap(pid_t chld)
{
siginfo_t si;
if (waitid(P_PID, chld, &si, WEXITED|WSTOPPED) != 0)
err(1, "waitid");
if (si.si_pid != chld)
errx(1, "got unexpected pid in event\n");
if (si.si_code != CLD_TRAPPED)
errx(1, "got unexpected event type %d\n", si.si_code);
}
static void test_ptrace_syscall_restart(void)
{
int status;
struct pt_regs regs;
pid_t chld;
printf("[RUN]\tptrace-induced syscall restart\n");
chld = fork();
if (chld < 0)
err(1, "fork");
/*
* Child process is running 4 syscalls after ptrace.
*
* 1) getpid()
* 2) gettid()
* 3) tgkill() -> Send SIGSTOP
* 4) gettid() -> Where the tests will happen essentially
*/
if (chld == 0) {
if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
err(1, "PTRACE_TRACEME");
pid_t pid = getpid(), tid = syscall(SYS_gettid);
printf("\tChild will make one syscall\n");
syscall(SYS_tgkill, pid, tid, SIGSTOP);
syscall(SYS_gettid, 10, 11, 12, 13, 14, 15);
_exit(0);
}
/* Parent process below */
/* Wait for SIGSTOP sent by tgkill above. */
if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status))
err(1, "waitpid");
printf("[RUN]\tSYSEMU\n");
if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
err(1, "PTRACE_SYSEMU");
wait_trap(chld);
if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
err(1, "PTRACE_GETREGS");
/*
* Ptrace trapped prior to executing the syscall, thus r3 still has
* the syscall number instead of the sys_gettid() result
*/
if (regs.user_syscall_nr != SYS_gettid ||
regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
regs.user_arg4 != 14 || regs.user_arg5 != 15) {
printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
(unsigned long)regs.user_syscall_nr,
(unsigned long)regs.user_arg0,
(unsigned long)regs.user_arg1,
(unsigned long)regs.user_arg2,
(unsigned long)regs.user_arg3,
(unsigned long)regs.user_arg4,
(unsigned long)regs.user_arg5);
nerrs++;
} else {
printf("[OK]\tInitial nr and args are correct\n"); }
printf("[RUN]\tRestart the syscall (ip = 0x%lx)\n",
(unsigned long)regs.user_ip);
/*
* Rewind to retry the same syscall again. This will basically test
* the rewind process together with PTRACE_SETREGS and PTRACE_GETREGS.
*/
regs.user_ip -= 4;
if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
err(1, "PTRACE_SETREGS");
if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
err(1, "PTRACE_SYSEMU");
wait_trap(chld);
if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
err(1, "PTRACE_GETREGS");
if (regs.user_syscall_nr != SYS_gettid ||
regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
regs.user_arg4 != 14 || regs.user_arg5 != 15) {
printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
(unsigned long)regs.user_syscall_nr,
(unsigned long)regs.user_arg0,
(unsigned long)regs.user_arg1,
(unsigned long)regs.user_arg2,
(unsigned long)regs.user_arg3,
(unsigned long)regs.user_arg4,
(unsigned long)regs.user_arg5);
nerrs++;
} else {
printf("[OK]\tRestarted nr and args are correct\n");
}
printf("[RUN]\tChange nr and args and restart the syscall (ip = 0x%lx)\n",
(unsigned long)regs.user_ip);
/*
* Inject a new syscall (getpid) in the same place the previous
* syscall (gettid), rewind and re-execute.
*/
regs.user_syscall_nr = SYS_getpid;
regs.user_arg0 = 20;
regs.user_arg1 = 21;
regs.user_arg2 = 22;
regs.user_arg3 = 23;
regs.user_arg4 = 24;
regs.user_arg5 = 25;
regs.user_ip -= 4;
if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
err(1, "PTRACE_SETREGS");
if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
err(1, "PTRACE_SYSEMU");
wait_trap(chld);
if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
err(1, "PTRACE_GETREGS");
/* Check that ptrace stopped at the new syscall that was
* injected, and guarantee that it haven't executed, i.e, user_args
* contain the arguments and not the syscall return value, for
* instance.
*/
if (regs.user_syscall_nr != SYS_getpid
|| regs.user_arg0 != 20 || regs.user_arg1 != 21
|| regs.user_arg2 != 22 || regs.user_arg3 != 23
|| regs.user_arg4 != 24 || regs.user_arg5 != 25) {
printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
(unsigned long)regs.user_syscall_nr,
(unsigned long)regs.user_arg0,
(unsigned long)regs.user_arg1,
(unsigned long)regs.user_arg2,
(unsigned long)regs.user_arg3,
(unsigned long)regs.user_arg4,
(unsigned long)regs.user_arg5);
nerrs++;
} else {
printf("[OK]\tReplacement nr and args are correct\n");
}
if (ptrace(PTRACE_CONT, chld, 0, 0) != 0)
err(1, "PTRACE_CONT");
if (waitpid(chld, &status, 0) != chld)
err(1, "waitpid");
/* Guarantee that the process executed properly, returning 0 */
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
printf("[FAIL]\tChild failed\n");
nerrs++;
} else {
printf("[OK]\tChild exited cleanly\n");
}
}
int ptrace_syscall(void)
{
test_ptrace_syscall_restart();
return nerrs;
}
int main(void)
{
return test_harness(ptrace_syscall, "ptrace_syscall");
}