diff --git a/softmmu/cpus.c b/softmmu/cpus.c index 071085f840..23bca46b07 100644 --- a/softmmu/cpus.c +++ b/softmmu/cpus.c @@ -352,6 +352,10 @@ static void qemu_init_sigbus(void) { struct sigaction action; + /* + * ALERT: when modifying this, take care that SIGBUS forwarding in + * os_mem_prealloc() will continue working as expected. + */ memset(&action, 0, sizeof(action)); action.sa_flags = SA_SIGINFO; action.sa_sigaction = sigbus_handler; diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 9829149e4b..9efdc74bba 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -35,6 +35,7 @@ #include "sysemu/sysemu.h" #include "trace.h" #include "qapi/error.h" +#include "qemu/error-report.h" #include "qemu/sockets.h" #include "qemu/thread.h" #include @@ -95,6 +96,7 @@ typedef struct MemsetThread MemsetThread; /* used by sigbus_handler() */ static MemsetContext *sigbus_memset_context; +struct sigaction sigbus_oldact; static QemuMutex sigbus_mutex; static QemuMutex page_mutex; @@ -446,7 +448,11 @@ const char *qemu_get_exec_dir(void) return exec_dir; } +#ifdef CONFIG_LINUX +static void sigbus_handler(int signal, siginfo_t *siginfo, void *ctx) +#else /* CONFIG_LINUX */ static void sigbus_handler(int signal) +#endif /* CONFIG_LINUX */ { int i; @@ -459,6 +465,26 @@ static void sigbus_handler(int signal) } } } + +#ifdef CONFIG_LINUX + /* + * We assume that the MCE SIGBUS handler could have been registered. We + * should never receive BUS_MCEERR_AO on any of our threads, but only on + * the main thread registered for PR_MCE_KILL_EARLY. Further, we should not + * receive BUS_MCEERR_AR triggered by action of other threads on one of + * our threads. So, no need to check for unrelated SIGBUS when seeing one + * for our threads. + * + * We will forward to the MCE handler, which will either handle the SIGBUS + * or reinstall the default SIGBUS handler and reraise the SIGBUS. The + * default SIGBUS handler will crash the process, so we don't care. + */ + if (sigbus_oldact.sa_flags & SA_SIGINFO) { + sigbus_oldact.sa_sigaction(signal, siginfo, ctx); + return; + } +#endif /* CONFIG_LINUX */ + warn_report("os_mem_prealloc: unrelated SIGBUS detected and ignored"); } static void *do_touch_pages(void *arg) @@ -628,10 +654,10 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, { static gsize initialized; int ret; - struct sigaction act, oldact; size_t hpagesize = qemu_fd_getpagesize(fd); size_t numpages = DIV_ROUND_UP(memory, hpagesize); bool use_madv_populate_write; + struct sigaction act; /* * Sense on every invocation, as MADV_POPULATE_WRITE cannot be used for @@ -647,10 +673,15 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, qemu_mutex_lock(&sigbus_mutex); memset(&act, 0, sizeof(act)); +#ifdef CONFIG_LINUX + act.sa_sigaction = &sigbus_handler; + act.sa_flags = SA_SIGINFO; +#else /* CONFIG_LINUX */ act.sa_handler = &sigbus_handler; act.sa_flags = 0; +#endif /* CONFIG_LINUX */ - ret = sigaction(SIGBUS, &act, &oldact); + ret = sigaction(SIGBUS, &act, &sigbus_oldact); if (ret) { error_setg_errno(errp, errno, "os_mem_prealloc: failed to install signal handler"); @@ -667,7 +698,7 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, } if (!use_madv_populate_write) { - ret = sigaction(SIGBUS, &oldact, NULL); + ret = sigaction(SIGBUS, &sigbus_oldact, NULL); if (ret) { /* Terminate QEMU since it can't recover from error */ perror("os_mem_prealloc: failed to reinstall signal handler");