@@ -1,3 +1,5 @@
basic-gcs
libc-gcs
gcs-locking
+gcs-stress
+gcs-stress-thread
@@ -6,7 +6,8 @@
# nolibc.
#
-TEST_GEN_PROGS := basic-gcs libc-gcs gcs-locking
+TEST_GEN_PROGS := basic-gcs libc-gcs gcs-locking gcs-stress
+TEST_GEN_PROGS_EXTENDED := gcs-stress-thread
LDLIBS+=-lpthread
@@ -18,3 +19,6 @@ $(OUTPUT)/basic-gcs: basic-gcs.c
-I../../../../../usr/include \
-std=gnu99 -I../.. -g \
-ffreestanding -Wall $^ -o $@ -lgcc
+
+$(OUTPUT)/gcs-stress-thread: gcs-stress-thread.S
+ $(CC) -nostdlib $^ -o $@
new file mode 100644
new file mode 100644
@@ -0,0 +1,311 @@
+// Program that loops for ever doing lots of recursions and system calls,
+// intended to be used as part of a stress test for GCS context switching.
+//
+// Copyright 2015-2023 Arm Ltd
+
+#include <asm/unistd.h>
+
+#define sa_sz 32
+#define sa_flags 8
+#define sa_handler 0
+#define sa_mask_sz 8
+
+#define si_code 8
+
+#define SIGINT 2
+#define SIGABRT 6
+#define SIGUSR1 10
+#define SIGSEGV 11
+#define SIGUSR2 12
+#define SIGTERM 15
+#define SEGV_CPERR 10
+
+#define SA_NODEFER 1073741824
+#define SA_SIGINFO 4
+#define ucontext_regs 184
+
+#define PR_SET_SHADOW_STACK_STATUS 75
+# define PR_SHADOW_STACK_ENABLE (1UL << 0)
+
+#define GCSPR_EL0 S3_3_C2_C5_1
+
+.macro function name
+ .macro endfunction
+ .type \name, @function
+ .purgem endfunction
+ .endm
+\name:
+.endm
+
+// Print a single character x0 to stdout
+// Clobbers x0-x2,x8
+function putc
+ str x0, [sp, #-16]!
+
+ mov x0, #1 // STDOUT_FILENO
+ mov x1, sp
+ mov x2, #1
+ mov x8, #__NR_write
+ svc #0
+
+ add sp, sp, #16
+ ret
+endfunction
+.globl putc
+
+// Print a NUL-terminated string starting at address x0 to stdout
+// Clobbers x0-x3,x8
+function puts
+ mov x1, x0
+
+ mov x2, #0
+0: ldrb w3, [x0], #1
+ cbz w3, 1f
+ add x2, x2, #1
+ b 0b
+
+1: mov w0, #1 // STDOUT_FILENO
+ mov x8, #__NR_write
+ svc #0
+
+ ret
+endfunction
+.globl puts
+
+// Utility macro to print a literal string
+// Clobbers x0-x4,x8
+.macro puts string
+ .pushsection .rodata.str1.1, "aMS", @progbits, 1
+.L__puts_literal\@: .string "\string"
+ .popsection
+
+ ldr x0, =.L__puts_literal\@
+ bl puts
+.endm
+
+// Print an unsigned decimal number x0 to stdout
+// Clobbers x0-x4,x8
+function putdec
+ mov x1, sp
+ str x30, [sp, #-32]! // Result can't be > 20 digits
+
+ mov x2, #0
+ strb w2, [x1, #-1]! // Write the NUL terminator
+
+ mov x2, #10
+0: udiv x3, x0, x2 // div-mod loop to generate the digits
+ msub x0, x3, x2, x0
+ add w0, w0, #'0'
+ strb w0, [x1, #-1]!
+ mov x0, x3
+ cbnz x3, 0b
+
+ ldrb w0, [x1]
+ cbnz w0, 1f
+ mov w0, #'0' // Print "0" for 0, not ""
+ strb w0, [x1, #-1]!
+
+1: mov x0, x1
+ bl puts
+
+ ldr x30, [sp], #32
+ ret
+endfunction
+.globl putdec
+
+// Print an unsigned decimal number x0 to stdout, followed by a newline
+// Clobbers x0-x5,x8
+function putdecn
+ mov x5, x30
+
+ bl putdec
+ mov x0, #'\n'
+ bl putc
+
+ ret x5
+endfunction
+.globl putdecn
+
+// Fill x1 bytes starting at x0 with 0.
+// Clobbers x1, x2.
+function memclr
+ mov w2, #0
+endfunction
+.globl memclr
+ // fall through to memfill
+
+// Trivial memory fill: fill x1 bytes starting at address x0 with byte w2
+// Clobbers x1
+function memfill
+ cmp x1, #0
+ b.eq 1f
+
+0: strb w2, [x0], #1
+ subs x1, x1, #1
+ b.ne 0b
+
+1: ret
+endfunction
+.globl memfill
+
+// w0: signal number
+// x1: sa_action
+// w2: sa_flags
+// Clobbers x0-x6,x8
+function setsignal
+ str x30, [sp, #-((sa_sz + 15) / 16 * 16 + 16)]!
+
+ mov w4, w0
+ mov x5, x1
+ mov w6, w2
+
+ add x0, sp, #16
+ mov x1, #sa_sz
+ bl memclr
+
+ mov w0, w4
+ add x1, sp, #16
+ str w6, [x1, #sa_flags]
+ str x5, [x1, #sa_handler]
+ mov x2, #0
+ mov x3, #sa_mask_sz
+ mov x8, #__NR_rt_sigaction
+ svc #0
+
+ cbz w0, 1f
+
+ puts "sigaction failure\n"
+ b abort
+
+1: ldr x30, [sp], #((sa_sz + 15) / 16 * 16 + 16)
+ ret
+endfunction
+
+
+function tickle_handler
+ // Perhaps collect GCSPR_EL0 here in future?
+ ret
+endfunction
+
+function terminate_handler
+ mov w21, w0
+ mov x20, x2
+
+ puts "Terminated by signal "
+ mov w0, w21
+ bl putdec
+ puts ", no error\n"
+
+ mov x0, #0
+ mov x8, #__NR_exit
+ svc #0
+endfunction
+
+function segv_handler
+ // stash the siginfo_t *
+ mov x20, x1
+
+ // Disable GCS, we don't want additional faults logging things
+ mov x0, PR_SET_SHADOW_STACK_STATUS
+ mov x1, xzr
+ mov x2, xzr
+ mov x3, xzr
+ mov x4, xzr
+ mov x5, xzr
+ mov x8, #__NR_prctl
+ svc #0
+
+ puts "Got SIGSEGV code "
+
+ ldr x21, [x20, #si_code]
+ mov x0, x21
+ bl putdec
+
+ // GCS faults should have si_code SEGV_CPERR
+ cmp x21, #SEGV_CPERR
+ bne 1f
+
+ puts " (GCS violation)"
+1:
+ mov x0, '\n'
+ bl putc
+ b abort
+endfunction
+
+// Recurse x20 times
+.macro recurse id
+function recurse\id
+ stp x29, x30, [sp, #-16]!
+ mov x29, sp
+
+ cmp x20, 0
+ beq 1f
+ sub x20, x20, 1
+ bl recurse\id
+
+1:
+ ldp x29, x30, [sp], #16
+
+ // Do a syscall immediately prior to returning to try to provoke
+ // scheduling and migration at a point where coherency issues
+ // might trigger.
+ mov x8, #__NR_getpid
+ svc #0
+
+ ret
+endfunction
+.endm
+
+// Generate and use two copies so we're changing the GCS contents
+recurse 1
+recurse 2
+
+.globl _start
+function _start
+ // Run with GCS
+ mov x0, PR_SET_SHADOW_STACK_STATUS
+ mov x1, PR_SHADOW_STACK_ENABLE
+ mov x2, xzr
+ mov x3, xzr
+ mov x4, xzr
+ mov x5, xzr
+ mov x8, #__NR_prctl
+ svc #0
+ cbz x0, 1f
+ puts "Failed to enable GCS\n"
+ b abort
+1:
+
+ mov w0, #SIGTERM
+ adr x1, terminate_handler
+ mov w2, #SA_SIGINFO
+ bl setsignal
+
+ mov w0, #SIGUSR1
+ adr x1, tickle_handler
+ mov w2, #SA_SIGINFO
+ orr w2, w2, #SA_NODEFER
+ bl setsignal
+
+ mov w0, #SIGSEGV
+ adr x1, segv_handler
+ mov w2, #SA_SIGINFO
+ orr w2, w2, #SA_NODEFER
+ bl setsignal
+
+ puts "Running\n"
+
+loop:
+ // Small recursion depth so we're frequently flipping between
+ // the two recursors and changing what's on the stack
+ mov x20, #5
+ bl recurse1
+ mov x20, #5
+ bl recurse2
+ b loop
+endfunction
+
+abort:
+ mov x0, #255
+ mov x8, #__NR_exit
+ svc #0
new file mode 100644
@@ -0,0 +1,530 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022-3 ARM Limited.
+ */
+
+#define _GNU_SOURCE
+#define _POSIX_C_SOURCE 199309L
+
+#include <errno.h>
+#include <getopt.h>
+#include <poll.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/auxv.h>
+#include <sys/epoll.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <asm/hwcap.h>
+
+#include "../../kselftest.h"
+
+struct child_data {
+ char *name, *output;
+ pid_t pid;
+ int stdout;
+ bool output_seen;
+ bool exited;
+ int exit_status;
+ int exit_signal;
+};
+
+static int epoll_fd;
+static struct child_data *children;
+static struct epoll_event *evs;
+static int tests;
+static int num_children;
+static bool terminate;
+
+static int startup_pipe[2];
+
+static int num_processors(void)
+{
+ long nproc = sysconf(_SC_NPROCESSORS_CONF);
+ if (nproc < 0) {
+ perror("Unable to read number of processors\n");
+ exit(EXIT_FAILURE);
+ }
+
+ return nproc;
+}
+
+static void start_thread(struct child_data *child)
+{
+ int ret, pipefd[2], i;
+ struct epoll_event ev;
+
+ ret = pipe(pipefd);
+ if (ret != 0)
+ ksft_exit_fail_msg("Failed to create stdout pipe: %s (%d)\n",
+ strerror(errno), errno);
+
+ child->pid = fork();
+ if (child->pid == -1)
+ ksft_exit_fail_msg("fork() failed: %s (%d)\n",
+ strerror(errno), errno);
+
+ if (!child->pid) {
+ /*
+ * In child, replace stdout with the pipe, errors to
+ * stderr from here as kselftest prints to stdout.
+ */
+ ret = dup2(pipefd[1], 1);
+ if (ret == -1) {
+ fprintf(stderr, "dup2() %d\n", errno);
+ exit(EXIT_FAILURE);
+ }
+
+ /*
+ * Duplicate the read side of the startup pipe to
+ * FD 3 so we can close everything else.
+ */
+ ret = dup2(startup_pipe[0], 3);
+ if (ret == -1) {
+ fprintf(stderr, "dup2() %d\n", errno);
+ exit(EXIT_FAILURE);
+ }
+
+ /*
+ * Very dumb mechanism to clean open FDs other than
+ * stdio. We don't want O_CLOEXEC for the pipes...
+ */
+ for (i = 4; i < 8192; i++)
+ close(i);
+
+ /*
+ * Read from the startup pipe, there should be no data
+ * and we should block until it is closed. We just
+ * carry on on error since this isn't super critical.
+ */
+ ret = read(3, &i, sizeof(i));
+ if (ret < 0)
+ fprintf(stderr, "read(startp pipe) failed: %s (%d)\n",
+ strerror(errno), errno);
+ if (ret > 0)
+ fprintf(stderr, "%d bytes of data on startup pipe\n",
+ ret);
+ close(3);
+
+ ret = execl("gcs-stress-thread", "gcs-stress-thread", NULL);
+ fprintf(stderr, "execl(gcs-stress-thread) failed: %d (%s)\n",
+ errno, strerror(errno));
+
+ exit(EXIT_FAILURE);
+ } else {
+ /*
+ * In parent, remember the child and close our copy of the
+ * write side of stdout.
+ */
+ close(pipefd[1]);
+ child->stdout = pipefd[0];
+ child->output = NULL;
+ child->exited = false;
+ child->output_seen = false;
+
+ ev.events = EPOLLIN | EPOLLHUP;
+ ev.data.ptr = child;
+
+ ret = asprintf(&child->name, "Thread-%d", child->pid);
+ if (ret == -1)
+ ksft_exit_fail_msg("asprintf() failed\n");
+
+ ret = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, child->stdout, &ev);
+ if (ret < 0) {
+ ksft_exit_fail_msg("%s EPOLL_CTL_ADD failed: %s (%d)\n",
+ child->name, strerror(errno), errno);
+ }
+ }
+
+ ksft_print_msg("Started %s\n", child->name);
+ num_children++;
+}
+
+static bool child_output_read(struct child_data *child)
+{
+ char read_data[1024];
+ char work[1024];
+ int ret, len, cur_work, cur_read;
+
+ ret = read(child->stdout, read_data, sizeof(read_data));
+ if (ret < 0) {
+ if (errno == EINTR)
+ return true;
+
+ ksft_print_msg("%s: read() failed: %s (%d)\n",
+ child->name, strerror(errno),
+ errno);
+ return false;
+ }
+ len = ret;
+
+ child->output_seen = true;
+
+ /* Pick up any partial read */
+ if (child->output) {
+ strncpy(work, child->output, sizeof(work) - 1);
+ cur_work = strnlen(work, sizeof(work));
+ free(child->output);
+ child->output = NULL;
+ } else {
+ cur_work = 0;
+ }
+
+ cur_read = 0;
+ while (cur_read < len) {
+ work[cur_work] = read_data[cur_read++];
+
+ if (work[cur_work] == '\n') {
+ work[cur_work] = '\0';
+ ksft_print_msg("%s: %s\n", child->name, work);
+ cur_work = 0;
+ } else {
+ cur_work++;
+ }
+ }
+
+ if (cur_work) {
+ work[cur_work] = '\0';
+ ret = asprintf(&child->output, "%s", work);
+ if (ret == -1)
+ ksft_exit_fail_msg("Out of memory\n");
+ }
+
+ return false;
+}
+
+static void child_output(struct child_data *child, uint32_t events,
+ bool flush)
+{
+ bool read_more;
+
+ if (events & EPOLLIN) {
+ do {
+ read_more = child_output_read(child);
+ } while (read_more);
+ }
+
+ if (events & EPOLLHUP) {
+ close(child->stdout);
+ child->stdout = -1;
+ flush = true;
+ }
+
+ if (flush && child->output) {
+ ksft_print_msg("%s: %s<EOF>\n", child->name, child->output);
+ free(child->output);
+ child->output = NULL;
+ }
+}
+
+static void child_tickle(struct child_data *child)
+{
+ if (child->output_seen && !child->exited)
+ kill(child->pid, SIGUSR1);
+}
+
+static void child_stop(struct child_data *child)
+{
+ if (!child->exited)
+ kill(child->pid, SIGTERM);
+}
+
+static void child_cleanup(struct child_data *child)
+{
+ pid_t ret;
+ int status;
+ bool fail = false;
+
+ if (!child->exited) {
+ do {
+ ret = waitpid(child->pid, &status, 0);
+ if (ret == -1 && errno == EINTR)
+ continue;
+
+ if (ret == -1) {
+ ksft_print_msg("waitpid(%d) failed: %s (%d)\n",
+ child->pid, strerror(errno),
+ errno);
+ fail = true;
+ break;
+ }
+
+ if (WIFEXITED(status)) {
+ child->exit_status = WEXITSTATUS(status);
+ child->exited = true;
+ }
+
+ if (WIFSIGNALED(status)) {
+ child->exit_signal = WTERMSIG(status);
+ ksft_print_msg("%s: Exited due to signal %d\n",
+ child->name);
+ fail = true;
+ child->exited = true;
+ }
+ } while (!child->exited);
+ }
+
+ if (!child->output_seen) {
+ ksft_print_msg("%s no output seen\n", child->name);
+ fail = true;
+ }
+
+ if (child->exit_status != 0) {
+ ksft_print_msg("%s exited with error code %d\n",
+ child->name, child->exit_status);
+ fail = true;
+ }
+
+ ksft_test_result(!fail, "%s\n", child->name);
+}
+
+static void handle_child_signal(int sig, siginfo_t *info, void *context)
+{
+ int i;
+ bool found = false;
+
+ for (i = 0; i < num_children; i++) {
+ if (children[i].pid == info->si_pid) {
+ children[i].exited = true;
+ children[i].exit_status = info->si_status;
+ found = true;
+ break;
+ }
+ }
+
+ if (!found)
+ ksft_print_msg("SIGCHLD for unknown PID %d with status %d\n",
+ info->si_pid, info->si_status);
+}
+
+static void handle_exit_signal(int sig, siginfo_t *info, void *context)
+{
+ int i;
+
+ /* If we're already exiting then don't signal again */
+ if (terminate)
+ return;
+
+ ksft_print_msg("Got signal, exiting...\n");
+
+ terminate = true;
+
+ /*
+ * This should be redundant, the main loop should clean up
+ * after us, but for safety stop everything we can here.
+ */
+ for (i = 0; i < num_children; i++)
+ child_stop(&children[i]);
+}
+
+/* Handle any pending output without blocking */
+static void drain_output(bool flush)
+{
+ int ret = 1;
+ int i;
+
+ while (ret > 0) {
+ ret = epoll_wait(epoll_fd, evs, tests, 0);
+ if (ret < 0) {
+ if (errno == EINTR)
+ continue;
+ ksft_print_msg("epoll_wait() failed: %s (%d)\n",
+ strerror(errno), errno);
+ }
+
+ for (i = 0; i < ret; i++)
+ child_output(evs[i].data.ptr, evs[i].events, flush);
+ }
+}
+
+static const struct option options[] = {
+ { "timeout", required_argument, NULL, 't' },
+ { }
+};
+
+int main(int argc, char **argv)
+{
+ int seen_children;
+ bool all_children_started = false;
+ int gcs_threads;
+ int timeout = 10;
+ int ret, cpus, i, c;
+ struct sigaction sa;
+
+ while ((c = getopt_long(argc, argv, "t:", options, NULL)) != -1) {
+ switch (c) {
+ case 't':
+ ret = sscanf(optarg, "%d", &timeout);
+ if (ret != 1)
+ ksft_exit_fail_msg("Failed to parse timeout %s\n",
+ optarg);
+ break;
+ default:
+ ksft_exit_fail_msg("Unknown argument\n");
+ }
+ }
+
+ cpus = num_processors();
+ tests = 0;
+
+ if (getauxval(AT_HWCAP2) & HWCAP2_GCS) {
+ /* One extra thread, trying to trigger migrations */
+ gcs_threads = cpus + 1;
+ tests += gcs_threads;
+ } else {
+ gcs_threads = 0;
+ }
+
+ ksft_print_header();
+ ksft_set_plan(tests);
+
+ ksft_print_msg("%d CPUs, %d GCS threads\n",
+ cpus, gcs_threads);
+
+ if (!tests)
+ ksft_exit_skip("No tests scheduled\n");
+
+ if (timeout > 0)
+ ksft_print_msg("Will run for %ds\n", timeout);
+ else
+ ksft_print_msg("Will run until terminated\n");
+
+ children = calloc(sizeof(*children), tests);
+ if (!children)
+ ksft_exit_fail_msg("Unable to allocate child data\n");
+
+ ret = epoll_create1(EPOLL_CLOEXEC);
+ if (ret < 0)
+ ksft_exit_fail_msg("epoll_create1() failed: %s (%d)\n",
+ strerror(errno), ret);
+ epoll_fd = ret;
+
+ /* Create a pipe which children will block on before execing */
+ ret = pipe(startup_pipe);
+ if (ret != 0)
+ ksft_exit_fail_msg("Failed to create startup pipe: %s (%d)\n",
+ strerror(errno), errno);
+
+ /* Get signal handers ready before we start any children */
+ memset(&sa, 0, sizeof(sa));
+ sa.sa_sigaction = handle_exit_signal;
+ sa.sa_flags = SA_RESTART | SA_SIGINFO;
+ sigemptyset(&sa.sa_mask);
+ ret = sigaction(SIGINT, &sa, NULL);
+ if (ret < 0)
+ ksft_print_msg("Failed to install SIGINT handler: %s (%d)\n",
+ strerror(errno), errno);
+ ret = sigaction(SIGTERM, &sa, NULL);
+ if (ret < 0)
+ ksft_print_msg("Failed to install SIGTERM handler: %s (%d)\n",
+ strerror(errno), errno);
+ sa.sa_sigaction = handle_child_signal;
+ ret = sigaction(SIGCHLD, &sa, NULL);
+ if (ret < 0)
+ ksft_print_msg("Failed to install SIGCHLD handler: %s (%d)\n",
+ strerror(errno), errno);
+
+ evs = calloc(tests, sizeof(*evs));
+ if (!evs)
+ ksft_exit_fail_msg("Failed to allocated %d epoll events\n",
+ tests);
+
+ for (i = 0; i < gcs_threads; i++)
+ start_thread(&children[i]);
+
+ /*
+ * All children started, close the startup pipe and let them
+ * run.
+ */
+ close(startup_pipe[0]);
+ close(startup_pipe[1]);
+
+ timeout *= 10;
+ for (;;) {
+ /* Did we get a signal asking us to exit? */
+ if (terminate)
+ break;
+
+ /*
+ * Timeout is counted in 100ms with no output, the
+ * tests print during startup then are silent when
+ * running so this should ensure they all ran enough
+ * to install the signal handler, this is especially
+ * useful in emulation where we will both be slow and
+ * likely to have a large set of VLs.
+ */
+ ret = epoll_wait(epoll_fd, evs, tests, 100);
+ if (ret < 0) {
+ if (errno == EINTR)
+ continue;
+ ksft_exit_fail_msg("epoll_wait() failed: %s (%d)\n",
+ strerror(errno), errno);
+ }
+
+ /* Output? */
+ if (ret > 0) {
+ for (i = 0; i < ret; i++) {
+ child_output(evs[i].data.ptr, evs[i].events,
+ false);
+ }
+ continue;
+ }
+
+ /* Otherwise epoll_wait() timed out */
+
+ /*
+ * If the child processes have not produced output they
+ * aren't actually running the tests yet.
+ */
+ if (!all_children_started) {
+ seen_children = 0;
+
+ for (i = 0; i < num_children; i++)
+ if (children[i].output_seen ||
+ children[i].exited)
+ seen_children++;
+
+ if (seen_children != num_children) {
+ ksft_print_msg("Waiting for %d children\n",
+ num_children - seen_children);
+ continue;
+ }
+
+ all_children_started = true;
+ }
+
+ ksft_print_msg("Sending signals, timeout remaining: %d00ms\n",
+ timeout);
+
+ for (i = 0; i < num_children; i++)
+ child_tickle(&children[i]);
+
+ /* Negative timeout means run indefinitely */
+ if (timeout < 0)
+ continue;
+ if (--timeout == 0)
+ break;
+ }
+
+ ksft_print_msg("Finishing up...\n");
+ terminate = true;
+
+ for (i = 0; i < tests; i++)
+ child_stop(&children[i]);
+
+ drain_output(false);
+
+ for (i = 0; i < tests; i++)
+ child_cleanup(&children[i]);
+
+ drain_output(true);
+
+ ksft_finished();
+}