selftests: arm64: add test for unaligned/inexact watchpoint handling

ARM64 hardware expects 64bit aligned address for watchpoint invocation.
However, it provides byte selection method to select any number of
consecutive byte set within the range of 1-8.

This patch adds support to test all such byte selection option for
different memory write sizes.

Patch also adds a test for handling the case when the cpu does not
report an address which exactly matches one of the regions we have
been watching (which is a situation permitted by the spec if an
instruction accesses both watched and unwatched regions). The test
was failing on a MSM8996pro before this patch series and is
passing now.

Signed-off-by: Pavel Labath <labath@google.com>
Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 240 insertions, 1 deletions

diff --git a/tools/testing/selftests/breakpoints/Makefile b/tools/testing/selftests/breakpoints/Makefile
index 74e533fd4bc5..61b79e8df1f4 100644
--- a/tools/testing/selftests/breakpoints/Makefile
+++ b/tools/testing/selftests/breakpoints/Makefile
@@ -5,6 +5,9 @@ ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
 ifeq ($(ARCH),x86)
 TEST_PROGS := breakpoint_test
 endif
+ifeq ($(ARCH),aarch64)
+TEST_PROGS := breakpoint_test_arm64
+endif
 
 TEST_PROGS += step_after_suspend_test
 
@@ -13,4 +16,4 @@ all: $(TEST_PROGS)
 include ../lib.mk
 
 clean:
-        rm -fr breakpoint_test step_after_suspend_test
+        rm -fr breakpoint_test breakpoint_test_arm64 step_after_suspend_test
diff --git a/tools/testing/selftests/breakpoints/breakpoint_test_arm64.c b/tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
new file mode 100644
index 000000000000..3897e996541e
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
@@ -0,0 +1,236 @@
+/*
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Original Code by Pavel Labath <labath@google.com>
+ *
+ * Code modified by Pratyush Anand <panand@redhat.com>
+ * for testing different byte select for each access size.
+ *
+ */
+
+#define _GNU_SOURCE
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/ptrace.h>
+#include <sys/param.h>
+#include <sys/uio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <elf.h>
+#include <errno.h>
+#include <signal.h>
+
+#include "../kselftest.h"
+
+static volatile uint8_t var[96] __attribute__((__aligned__(32)));
+
+static void child(int size, int wr)
+{
+        volatile uint8_t *addr = &var[32 + wr];
+
+        if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+                perror("ptrace(PTRACE_TRACEME) failed");
+                _exit(1);
+        }
+
+        if (raise(SIGSTOP) != 0) {
+                perror("raise(SIGSTOP) failed");
+                _exit(1);
+        }
+
+        if ((uintptr_t) addr % size) {
+                perror("Wrong address write for the given size\n");
+                _exit(1);
+        }
+        switch (size) {
+        case 1:
+                *addr = 47;
+                break;
+        case 2:
+                *(uint16_t *)addr = 47;
+                break;
+        case 4:
+                *(uint32_t *)addr = 47;
+                break;
+        case 8:
+                *(uint64_t *)addr = 47;
+                break;
+        case 16:
+                __asm__ volatile ("stp x29, x30, %0" : "=m" (addr[0]));
+                break;
+        case 32:
+                __asm__ volatile ("stp q29, q30, %0" : "=m" (addr[0]));
+                break;
+        }
+
+        _exit(0);
+}
+
+static bool set_watchpoint(pid_t pid, int size, int wp)
+{
+        const volatile uint8_t *addr = &var[32 + wp];
+        const int offset = (uintptr_t)addr % 8;
+        const unsigned int byte_mask = ((1 << size) - 1) << offset;
+        const unsigned int type = 2; /* Write */
+        const unsigned int enable = 1;
+        const unsigned int control = byte_mask << 5 | type << 3 | enable;
+        struct user_hwdebug_state dreg_state;
+        struct iovec iov;
+
+        memset(&dreg_state, 0, sizeof(dreg_state));
+        dreg_state.dbg_regs[0].addr = (uintptr_t)(addr - offset);
+        dreg_state.dbg_regs[0].ctrl = control;
+        iov.iov_base = &dreg_state;
+        iov.iov_len = offsetof(struct user_hwdebug_state, dbg_regs) +
+                                sizeof(dreg_state.dbg_regs[0]);
+        if (ptrace(PTRACE_SETREGSET, pid, NT_ARM_HW_WATCH, &iov) == 0)
+                return true;
+
+        if (errno == EIO) {
+                printf("ptrace(PTRACE_SETREGSET, NT_ARM_HW_WATCH) "
+                        "not supported on this hardware\n");
+                ksft_exit_skip();
+        }
+        perror("ptrace(PTRACE_SETREGSET, NT_ARM_HW_WATCH) failed");
+        return false;
+}
+
+static bool run_test(int wr_size, int wp_size, int wr, int wp)
+{
+        int status;
+        siginfo_t siginfo;
+        pid_t pid = fork();
+        pid_t wpid;
+
+        if (pid < 0) {
+                perror("fork() failed");
+                return false;
+        }
+        if (pid == 0)
+                child(wr_size, wr);
+
+        wpid = waitpid(pid, &status, __WALL);
+        if (wpid != pid) {
+                perror("waitpid() failed");
+                return false;
+        }
+        if (!WIFSTOPPED(status)) {
+                printf("child did not stop\n");
+                return false;
+        }
+        if (WSTOPSIG(status) != SIGSTOP) {
+                printf("child did not stop with SIGSTOP\n");
+                return false;
+        }
+
+        if (!set_watchpoint(pid, wp_size, wp))
+                return false;
+
+        if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+                perror("ptrace(PTRACE_SINGLESTEP) failed");
+                return false;
+        }
+
+        alarm(3);
+        wpid = waitpid(pid, &status, __WALL);
+        if (wpid != pid) {
+                perror("waitpid() failed");
+                return false;
+        }
+        alarm(0);
+        if (WIFEXITED(status)) {
+                printf("child did not single-step\t");
+                return false;
+        }
+        if (!WIFSTOPPED(status)) {
+                printf("child did not stop\n");
+                return false;
+        }
+        if (WSTOPSIG(status) != SIGTRAP) {
+                printf("child did not stop with SIGTRAP\n");
+                return false;
+        }
+        if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+                perror("ptrace(PTRACE_GETSIGINFO)");
+                return false;
+        }
+        if (siginfo.si_code != TRAP_HWBKPT) {
+                printf("Unexpected si_code %d\n", siginfo.si_code);
+                return false;
+        }
+
+        kill(pid, SIGKILL);
+        wpid = waitpid(pid, &status, 0);
+        if (wpid != pid) {
+                perror("waitpid() failed");
+                return false;
+        }
+        return true;
+}
+
+static void sigalrm(int sig)
+{
+}
+
+int main(int argc, char **argv)
+{
+        int opt;
+        bool succeeded = true;
+        struct sigaction act;
+        int wr, wp, size;
+        bool result;
+
+        act.sa_handler = sigalrm;
+        sigemptyset(&act.sa_mask);
+        act.sa_flags = 0;
+        sigaction(SIGALRM, &act, NULL);
+        for (size = 1; size <= 32; size = size*2) {
+                for (wr = 0; wr <= 32; wr = wr + size) {
+                        for (wp = wr - size; wp <= wr + size; wp = wp + size) {
+                                printf("Test size = %d write offset = %d watchpoint offset = %d\t", size, wr, wp);
+                                result = run_test(size, MIN(size, 8), wr, wp);
+                                if ((result && wr == wp) || (!result && wr != wp)) {
+                                        printf("[OK]\n");
+                                        ksft_inc_pass_cnt();
+                                } else {
+                                        printf("[FAILED]\n");
+                                        ksft_inc_fail_cnt();
+                                        succeeded = false;
+                                }
+                        }
+                }
+        }
+
+        for (size = 1; size <= 32; size = size*2) {
+                printf("Test size = %d write offset = %d watchpoint offset = -8\t", size, -size);
+
+                if (run_test(size, 8, -size, -8)) {
+                        printf("[OK]\n");
+                        ksft_inc_pass_cnt();
+                } else {
+                        printf("[FAILED]\n");
+                        ksft_inc_fail_cnt();
+                        succeeded = false;
+                }
+        }
+
+        ksft_print_cnts();
+        if (succeeded)
+                ksft_exit_pass();
+        else
+                ksft_exit_fail();
+}