[Qemu-devel] [PATCH v2] linux-user: fix mmap_find_vma_reserved()

[Laurent Vivier <laurent@vivier.eu>]

The value given by mmap_find_vma_reserved() is used with mmap(),
so it is needed to be aligned with the host page size.

Since commit 18e80c55bb, reserved_va is only aligned to TARGET_PAGE_SIZE,
and it works well if this size is greater or equal to the host page size.

But ppc64 hosts have 64kB page size and when we start a 4kiB page size
guest (like i386), it fails when it tries to mmap the stack:

    mmap stack: Invalid argument

Fixes: 18e80c55bb (linux-user: Tidy and enforce reserved_va initialization)
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---

Notes:
    v2:
      fix typo s/has/as/

 linux-user/main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/linux-user/main.c b/linux-user/main.c
index 52b5a618fe..15299e9dd7 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -689,6 +689,11 @@ int main(int argc, char **argv, char **envp)
     target_environ = envlist_to_environ(envlist, NULL);
     envlist_free(envlist);
 
+    /* reserved_va must be aligned with the host page size
+     * as it is used with mmap()
+     */
+    reserved_va &= qemu_host_page_mask;
+
     /*
      * Now that page sizes are configured in tcg_exec_init() we can do
      * proper page alignment for guest_base.
-- 
2.17.1