--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018, Breno Leitao, Gustavo Romero, IBM Corp.
+ *
+ * This test raises a SIGUSR1 signal, and toggle the MSR[TS]
+ * fields at the signal handler. With MSR[TS] being set, the kernel will
+ * force a recheckpoint, which may cause a segfault when returning to
+ * user space. Since the test needs to re-run, the segfault needs to be
+ * caught and handled.
+ *
+ * In order to continue the test even after a segfault, the context is
+ * saved prior to the signal being raised, and it is restored when there is
+ * a segmentation fault. This happens for COUNT_MAX times.
+ *
+ * This test never fails (as returning EXIT_FAILURE). It either succeeds,
+ * or crash the kernel (on a buggy kernel).
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <string.h>
+#include <ucontext.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include "tm.h"
+#include "utils.h"
+#include "reg.h"
+
+#define COUNT_MAX 5000 /* Number of interactions */
+
+/*
+ * This test only runs on 64 bits system. Unsetting MSR_TS_S to avoid
+ * compilation issue on 32 bits system. There is no side effect, since the
+ * whole test will be skipped if it is not running on 64 bits system.
+ */
+#ifndef __powerpc64__
+#undef MSR_TS_S
+#define MSR_TS_S 0
+#endif
+
+/* Setting contexts because the test will crash and we want to recover */
+ucontext_t init_context, main_context;
+
+static int count, first_time;
+
+void usr_signal_handler(int signo, siginfo_t *si, void *uc)
+{
+ ucontext_t *ucp = uc;
+ int ret;
+
+ /*
+ * Allocating memory in a signal handler, and never freeing it on
+ * purpose, forcing the heap increase, so, the memory leak is what
+ * we want here.
+ */
+ ucp->uc_link = mmap(NULL, sizeof(ucontext_t),
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+ if (ucp->uc_link == (void *)-1) {
+ perror("Mmap failed");
+ exit(-1);
+ }
+
+ /* Forcing the page to be allocated in a page fault */
+ ret = madvise(ucp->uc_link, sizeof(ucontext_t), MADV_DONTNEED);
+ if (ret) {
+ perror("madvise failed");
+ exit(-1);
+ }
+
+ memcpy(&ucp->uc_link->uc_mcontext, &ucp->uc_mcontext,
+ sizeof(ucp->uc_mcontext));
+
+ /* Forcing to enable MSR[TM] */
+ UCONTEXT_MSR(ucp) |= MSR_TS_S;
+
+ /*
+ * A fork inside a signal handler seems to be more efficient than a
+ * fork() prior to the signal being raised.
+ */
+ if (fork() == 0) {
+ /*
+ * Both child and parent will return, but, child returns
+ * with count set so it will exit in the next segfault.
+ * Parent will continue to loop.
+ */
+ count = COUNT_MAX;
+ }
+
+ /*
+ * If the change above does not hit the bug, it will cause a
+ * segmentation fault, since the ck structures are NULL.
+ */
+}
+
+void seg_signal_handler(int signo, siginfo_t *si, void *uc)
+{
+ if (count == COUNT_MAX) {
+ /* Return to tm_signal_force_msr() and exit */
+ setcontext(&main_context);
+ }
+
+ count++;
+
+ /* Reexecute the test */
+ setcontext(&init_context);
+}
+
+void tm_trap_test(void)
+{
+ struct sigaction usr_sa, seg_sa;
+ stack_t ss;
+
+ usr_sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
+ usr_sa.sa_sigaction = usr_signal_handler;
+
+ seg_sa.sa_flags = SA_SIGINFO;
+ seg_sa.sa_sigaction = seg_signal_handler;
+
+ /*
+ * Set initial context. Will get back here from
+ * seg_signal_handler()
+ */
+ getcontext(&init_context);
+
+ /* Allocated an alternative signal stack area */
+ ss.ss_sp = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+ ss.ss_size = SIGSTKSZ;
+ ss.ss_flags = 0;
+
+ if (ss.ss_sp == (void *)-1) {
+ perror("mmap error\n");
+ exit(-1);
+ }
+
+ /* Force the allocation through a page fault */
+ if (madvise(ss.ss_sp, SIGSTKSZ, MADV_DONTNEED)) {
+ perror("madvise\n");
+ exit(-1);
+ }
+
+ /* Setting an alternative stack to generate a page fault when
+ * the signal is raised.
+ */
+ if (sigaltstack(&ss, NULL)) {
+ perror("sigaltstack\n");
+ exit(-1);
+ }
+
+ /* The signal handler will enable MSR_TS */
+ sigaction(SIGUSR1, &usr_sa, NULL);
+ /* If it does not crash, it will segfault, avoid it to retest */
+ sigaction(SIGSEGV, &seg_sa, NULL);
+
+ raise(SIGUSR1);
+}
+
+int tm_signal_context_force_tm(void)
+{
+ SKIP_IF(!have_htm());
+ /*
+ * Skipping if not running on 64 bits system, since I think it is
+ * not possible to set mcontext's [MSR] with TS, due to it being 32
+ * bits.
+ */
+ SKIP_IF(!is_ppc64le());
+
+ /* Will get back here after COUNT_MAX interactions */
+ getcontext(&main_context);
+
+ if (!first_time++)
+ tm_trap_test();
+
+ return EXIT_SUCCESS;
+}
+
+int main(int argc, char **argv)
+{
+ test_harness(tm_signal_context_force_tm, "tm_signal_context_force_tm");
+}
projects / openwrt / staging / blogic.git / commitdiff