@@ -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
@@ -497,3 +497,42 @@ pid_t qemu_fork(Error **errp)
}
return pid;
}
+
+void *qemu_alloc_stack(size_t sz)
+{
+ void *ptr, *guardpage;
+ size_t pagesz = getpagesize();
+
+ /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
+ sz = MAX(sz, sysconf(_SC_THREAD_STACK_MIN));
+ /* assert that the stack size is a multiple of the page size */
+ assert(!(sz % pagesz));
+
+ 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 = MAX(sz, sysconf(_SC_THREAD_STACK_MIN));
+ munmap(stack, sz);
+}
the allocated stack will be adjusted to the minimum supported stack size by the OS. Additionally an architecture dependent guard page is added to the stack to catch stack overflows. Suggested-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Lieven <pl@kamp.de> --- include/sysemu/os-posix.h | 23 +++++++++++++++++++++++ util/oslib-posix.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 62 insertions(+)