From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45660) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bN0Sz-0007aB-M5 for qemu-devel@nongnu.org; Tue, 12 Jul 2016 12:23:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bN0Su-0003bU-0K for qemu-devel@nongnu.org; Tue, 12 Jul 2016 12:23:24 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:34828 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bN0St-0003bA-MP for qemu-devel@nongnu.org; Tue, 12 Jul 2016 12:23:19 -0400 From: Peter Lieven Date: Tue, 12 Jul 2016 18:23:01 +0200 Message-Id: <1468340586-19304-2-git-send-email-pl@kamp.de> In-Reply-To: <1468340586-19304-1-git-send-email-pl@kamp.de> References: <1468340586-19304-1-git-send-email-pl@kamp.de> Subject: [Qemu-devel] [PATCH V5 1/6] oslib-posix: add helpers for stack alloc and free List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com, pbonzini@redhat.com, mst@redhat.com, dgilbert@redhat.com, peter.maydell@linaro.org, eblake@redhat.com, rth@twiddle.net, armbru@redhat.com, Peter Lieven the allocated stack will be adjusted to the minimum supported stack size by the OS and rounded up to be a multiple of the system pagesize. Additionally an architecture dependent guard page is added to the stack to catch stack overflows. Signed-off-by: Peter Lieven --- include/sysemu/os-posix.h | 23 +++++++++++++++++++++++ util/oslib-posix.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 69 insertions(+) diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h index 9c7dfdf..7630665 100644 --- a/include/sysemu/os-posix.h +++ b/include/sysemu/os-posix.h @@ -60,4 +60,27 @@ int qemu_utimens(const char *path, const qemu_timespec *times); bool is_daemonized(void); +/** + * qemu_alloc_stack: + * @sz: size of required stack in bytes + * + * Allocate memory that can be used as a stack, for instance for + * coroutines. If the memory cannot be allocated, this function + * will abort (like g_malloc()). + * + * The allocated stack must be freed with qemu_free_stack(). + * + * Returns: pointer to (the lowest address of) the stack memory. + */ +void *qemu_alloc_stack(size_t sz); + +/** + * qemu_free_stack: + * @stack: stack to free + * @sz: size of stack in bytes + * + * Free a stack allocated via qemu_alloc_stack(). + */ +void qemu_free_stack(void *stack, size_t sz); + #endif diff --git a/util/oslib-posix.c b/util/oslib-posix.c index e2e1d4d..2303ca6 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -497,3 +497,49 @@ pid_t qemu_fork(Error **errp) } return pid; } + +static size_t adjust_stack_size(size_t sz) +{ +#ifdef _SC_THREAD_STACK_MIN + /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ + sz = MAX(MAX(sysconf(_SC_THREAD_STACK_MIN), 0), sz); +#endif + /* adjust stack size to a multiple of the page size */ + sz = ROUND_UP(sz, getpagesize()); + return sz; +} + +void *qemu_alloc_stack(size_t sz) +{ + void *ptr, *guardpage; + size_t pagesz = getpagesize(); + sz = adjust_stack_size(sz); + + ptr = mmap(NULL, sz, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (ptr == MAP_FAILED) { + abort(); + } + +#if defined(HOST_IA64) + /* separate register stack */ + guardpage = ptr + (((sz - pagesz) / 2) & ~pagesz); +#elif defined(HOST_HPPA) + /* stack grows up */ + guardpage = ptr + sz - pagesz; +#else + /* stack grows down */ + guardpage = ptr; +#endif + if (mprotect(guardpage, pagesz, PROT_NONE) != 0) { + abort(); + } + + return ptr; +} + +void qemu_free_stack(void *stack, size_t sz) +{ + sz = adjust_stack_size(sz); + munmap(stack, sz); +} -- 1.9.1