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 <p...@kamp.de>
---
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
