selftests/powerpc: Add ptrace hw breakpoint test

This test the ptrace hw breakpoints via PTRACE_SET_DEBUGREG and
PPC_PTRACE_SETHWDEBUG.  This test was use to find the bugs fixed by
these recent commits:

  4f7c06e2 powerpc/ptrace: Fix setting 512B aligned breakpoints with PTRACE_SET_DEBUGREG
  cd6ef7ee powerpc/ptrace: Fix enforcement of DAWR constraints
Signed-off-by: Michael Neuling <mikey@neuling.org>
[mpe: Add SPDX tag, clang format it]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/ptrace/.gitignore

@@ -8,3 +8,4 @@ ptrace-vsx
 ptrace-tm-vsx
 ptrace-tm-spd-vsx
 ptrace-tm-spr
+ptrace-hwbreak

tools/testing/selftests/powerpc/ptrace/Makefile

 # SPDX-License-Identifier: GPL-2.0
 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-tm-spd-vsx ptrace-tm-spr ptrace-hwbreak
 
 include ../../lib.mk
 

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

+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Ptrace test for hw breakpoints
+ *
+ * Based on tools/testing/selftests/breakpoints/breakpoint_test.c
+ *
+ * This test forks and the parent then traces the child doing various
+ * types of ptrace enabled breakpoints
+ *
+ * Copyright (C) 2018 Michael Neuling, IBM Corporation.
+ */
+
+#include <sys/ptrace.h>
+#include <unistd.h>
+#include <stddef.h>
+#include <sys/user.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include "ptrace.h"
+
+/* Breakpoint access modes */
+enum {
+	BP_X = 1,
+	BP_RW = 2,
+	BP_W = 4,
+};
+
+static pid_t child_pid;
+static struct ppc_debug_info dbginfo;
+
+static void get_dbginfo(void)
+{
+	int ret;
+
+	ret = ptrace(PPC_PTRACE_GETHWDBGINFO, child_pid, NULL, &dbginfo);
+	if (ret) {
+		perror("Can't get breakpoint info\n");
+		exit(-1);
+	}
+}
+
+static bool hwbreak_present(void)
+{
+	return (dbginfo.num_data_bps != 0);
+}
+
+static bool dawr_present(void)
+{
+	return !!(dbginfo.features & PPC_DEBUG_FEATURE_DATA_BP_DAWR);
+}
+
+static void set_breakpoint_addr(void *addr)
+{
+	int ret;
+
+	ret = ptrace(PTRACE_SET_DEBUGREG, child_pid, 0, addr);
+	if (ret) {
+		perror("Can't set breakpoint addr\n");
+		exit(-1);
+	}
+}
+
+static int set_hwbreakpoint_addr(void *addr, int range)
+{
+	int ret;
+
+	struct ppc_hw_breakpoint info;
+
+	info.version = 1;
+	info.trigger_type = PPC_BREAKPOINT_TRIGGER_RW;
+	info.addr_mode = PPC_BREAKPOINT_MODE_EXACT;
+	if (range > 0)
+		info.addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE;
+	info.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
+	info.addr = (__u64)addr;
+	info.addr2 = (__u64)addr + range;
+	info.condition_value = 0;
+
+	ret = ptrace(PPC_PTRACE_SETHWDEBUG, child_pid, 0, &info);
+	if (ret < 0) {
+		perror("Can't set breakpoint\n");
+		exit(-1);
+	}
+	return ret;
+}
+
+static int del_hwbreakpoint_addr(int watchpoint_handle)
+{
+	int ret;
+
+	ret = ptrace(PPC_PTRACE_DELHWDEBUG, child_pid, 0, watchpoint_handle);
+	if (ret < 0) {
+		perror("Can't delete hw breakpoint\n");
+		exit(-1);
+	}
+	return ret;
+}
+
+#define DAWR_LENGTH_MAX 512
+
+/* Dummy variables to test read/write accesses */
+static unsigned long long
+	dummy_array[DAWR_LENGTH_MAX / sizeof(unsigned long long)]
+	__attribute__((aligned(512)));
+static unsigned long long *dummy_var = dummy_array;
+
+static void write_var(int len)
+{
+	long long *plval;
+	char *pcval;
+	short *psval;
+	int *pival;
+
+	switch (len) {
+	case 1:
+		pcval = (char *)dummy_var;
+		*pcval = 0xff;
+		break;
+	case 2:
+		psval = (short *)dummy_var;
+		*psval = 0xffff;
+		break;
+	case 4:
+		pival = (int *)dummy_var;
+		*pival = 0xffffffff;
+		break;
+	case 8:
+		plval = (long long *)dummy_var;
+		*plval = 0xffffffffffffffffLL;
+		break;
+	}
+}
+
+static void read_var(int len)
+{
+	char cval __attribute__((unused));
+	short sval __attribute__((unused));
+	int ival __attribute__((unused));
+	long long lval __attribute__((unused));
+
+	switch (len) {
+	case 1:
+		cval = *(char *)dummy_var;
+		break;
+	case 2:
+		sval = *(short *)dummy_var;
+		break;
+	case 4:
+		ival = *(int *)dummy_var;
+		break;
+	case 8:
+		lval = *(long long *)dummy_var;
+		break;
+	}
+}
+
+/*
+ * Do the r/w accesses to trigger the breakpoints. And run
+ * the usual traps.
+ */
+static void trigger_tests(void)
+{
+	int len, ret;
+
+	ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);
+	if (ret) {
+		perror("Can't be traced?\n");
+		return;
+	}
+
+	/* Wake up father so that it sets up the first test */
+	kill(getpid(), SIGUSR1);
+
+	/* Test write watchpoints */
+	for (len = 1; len <= sizeof(long); len <<= 1)
+		write_var(len);
+
+	/* Test read/write watchpoints (on read accesses) */
+	for (len = 1; len <= sizeof(long); len <<= 1)
+		read_var(len);
+
+	/* Test when breakpoint is unset */
+
+	/* Test write watchpoints */
+	for (len = 1; len <= sizeof(long); len <<= 1)
+		write_var(len);
+
+	/* Test read/write watchpoints (on read accesses) */
+	for (len = 1; len <= sizeof(long); len <<= 1)
+		read_var(len);
+}
+
+static void check_success(const char *msg)
+{
+	const char *msg2;
+	int status;
+
+	/* Wait for the child to SIGTRAP */
+	wait(&status);
+
+	msg2 = "Failed";
+
+	if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) {
+		msg2 = "Child process hit the breakpoint";
+	}
+
+	printf("%s Result: [%s]\n", msg, msg2);
+}
+
+static void launch_watchpoints(char *buf, int mode, int len,
+			       struct ppc_debug_info *dbginfo, bool dawr)
+{
+	const char *mode_str;
+	unsigned long data = (unsigned long)(dummy_var);
+	int wh, range;
+
+	data &= ~0x7UL;
+
+	if (mode == BP_W) {
+		data |= (1UL << 1);
+		mode_str = "write";
+	} else {
+		data |= (1UL << 0);
+		data |= (1UL << 1);
+		mode_str = "read";
+	}
+
+	/* Set DABR_TRANSLATION bit */
+	data |= (1UL << 2);
+
+	/* use PTRACE_SET_DEBUGREG breakpoints */
+	set_breakpoint_addr((void *)data);
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+	sprintf(buf, "Test %s watchpoint with len: %d ", mode_str, len);
+	check_success(buf);
+	/* Unregister hw brkpoint */
+	set_breakpoint_addr(NULL);
+
+	data = (data & ~7); /* remove dabr control bits */
+
+	/* use PPC_PTRACE_SETHWDEBUG breakpoint */
+	if (!(dbginfo->features & PPC_DEBUG_FEATURE_DATA_BP_RANGE))
+		return; /* not supported */
+	wh = set_hwbreakpoint_addr((void *)data, 0);
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+	sprintf(buf, "Test %s watchpoint with len: %d ", mode_str, len);
+	check_success(buf);
+	/* Unregister hw brkpoint */
+	del_hwbreakpoint_addr(wh);
+
+	/* try a wider range */
+	range = 8;
+	if (dawr)
+		range = 512 - ((int)data & (DAWR_LENGTH_MAX - 1));
+	wh = set_hwbreakpoint_addr((void *)data, range);
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+	sprintf(buf, "Test %s watchpoint with len: %d ", mode_str, len);
+	check_success(buf);
+	/* Unregister hw brkpoint */
+	del_hwbreakpoint_addr(wh);
+}
+
+/* Set the breakpoints and check the child successfully trigger them */
+static int launch_tests(bool dawr)
+{
+	char buf[1024];
+	int len, i, status;
+
+	struct ppc_debug_info dbginfo;
+
+	i = ptrace(PPC_PTRACE_GETHWDBGINFO, child_pid, NULL, &dbginfo);
+	if (i) {
+		perror("Can't set breakpoint info\n");
+		exit(-1);
+	}
+	if (!(dbginfo.features & PPC_DEBUG_FEATURE_DATA_BP_RANGE))
+		printf("WARNING: Kernel doesn't support PPC_PTRACE_SETHWDEBUG\n");
+
+	/* Write watchpoint */
+	for (len = 1; len <= sizeof(long); len <<= 1)
+		launch_watchpoints(buf, BP_W, len, &dbginfo, dawr);
+
+	/* Read-Write watchpoint */
+	for (len = 1; len <= sizeof(long); len <<= 1)
+		launch_watchpoints(buf, BP_RW, len, &dbginfo, dawr);
+
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+
+	/*
+	 * Now we have unregistered the breakpoint, access by child
+	 * should not cause SIGTRAP.
+	 */
+
+	wait(&status);
+
+	if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) {
+		printf("FAIL: Child process hit the breakpoint, which is not expected\n");
+		ptrace(PTRACE_CONT, child_pid, NULL, 0);
+		return TEST_FAIL;
+	}
+
+	if (WIFEXITED(status))
+		printf("Child exited normally\n");
+
+	return TEST_PASS;
+}
+
+static int ptrace_hwbreak(void)
+{
+	pid_t pid;
+	int ret;
+	bool dawr;
+
+	pid = fork();
+	if (!pid) {
+		trigger_tests();
+		return 0;
+	}
+
+	wait(NULL);
+
+	child_pid = pid;
+
+	get_dbginfo();
+	SKIP_IF(!hwbreak_present());
+	dawr = dawr_present();
+
+	ret = launch_tests(dawr);
+
+	wait(NULL);
+
+	return ret;
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	return test_harness(ptrace_hwbreak, "ptrace-hwbreak");
+}