diff options
Diffstat (limited to 'tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c')
| -rw-r--r-- | tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c b/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c new file mode 100644 index 000000000000..31717625f318 --- /dev/null +++ b/tools/testing/selftests/powerpc/tm/tm-signal-context-force-tm.c @@ -0,0 +1,184 @@ +// 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"); +} |