Commit fc35ef12 authored by Breno Leitao's avatar Breno Leitao Committed by Michael Ellerman
Browse files

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: default avatarBreno Leitao <leitao@debian.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 5521eb4b

tools/testing/selftests/powerpc/ptrace/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

tools/testing/selftests/powerpc/ptrace/ptrace-syscall.c

0 → 100644
+228 −0
Original line number Diff line number Diff line 
// 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");

}

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