We're about to start validating PAGE_EXEC, which means
that we've got to mark the commpage executable.  We had
been placing the commpage outside of reserved_va, which
was incorrect and lead to an abort.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/arm/target_cpu.h | 4 ++--
 linux-user/elfload.c        | 6 +++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/linux-user/arm/target_cpu.h b/linux-user/arm/target_cpu.h
index 709d19bc9e..89ba274cfc 100644
--- a/linux-user/arm/target_cpu.h
+++ b/linux-user/arm/target_cpu.h
@@ -34,9 +34,9 @@ static inline unsigned long arm_max_reserved_va(CPUState *cs)
     } else {
         /*
          * We need to be able to map the commpage.
-         * See validate_guest_space in linux-user/elfload.c.
+         * See init_guest_commpage in linux-user/elfload.c.
          */
-        return 0xffff0000ul;
+        return 0xfffffffful;
     }
 }
 #define MAX_RESERVED_VA  arm_max_reserved_va
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index ce902dbd56..3e3dc02499 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -398,7 +398,8 @@ enum {
 
 static bool init_guest_commpage(void)
 {
-    void *want = g2h_untagged(HI_COMMPAGE & -qemu_host_page_size);
+    abi_ptr commpage = HI_COMMPAGE & -qemu_host_page_size;
+    void *want = g2h_untagged(commpage);
     void *addr = mmap(want, qemu_host_page_size, PROT_READ | PROT_WRITE,
                       MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
 
@@ -417,6 +418,9 @@ static bool init_guest_commpage(void)
         perror("Protecting guest commpage");
         exit(EXIT_FAILURE);
     }
+
+    page_set_flags(commpage, commpage + qemu_host_page_size,
+                   PAGE_READ | PAGE_EXEC | PAGE_VALID);
     return true;
 }
 
-- 
2.34.1