accel/tcg: Pass last not end to page_set_flags

Pass the address of the last byte to be changed, rather than
the first address past the last byte.  This avoids overflow
when the last page of the address space is involved.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1528
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 7 insertions, 9 deletions

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 7b37fd2..035f809 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -480,24 +480,22 @@ static bool pageflags_set_clear(target_ulong start, target_ulong last,
  * The flag PAGE_WRITE_ORG is positioned automatically depending
  * on PAGE_WRITE.  The mmap_lock should already be held.
  */
-void page_set_flags(target_ulong start, target_ulong end, int flags)
+void page_set_flags(target_ulong start, target_ulong last, int flags)
 {
-    target_ulong last;
     bool reset = false;
     bool inval_tb = false;
 
     /* This function should never be called with addresses outside the
        guest address space.  If this assert fires, it probably indicates
        a missing call to h2g_valid.  */
-    assert(start < end);
-    assert(end - 1 <= GUEST_ADDR_MAX);
+    assert(start <= last);
+    assert(last <= GUEST_ADDR_MAX);
     /* Only set PAGE_ANON with new mappings. */
     assert(!(flags & PAGE_ANON) || (flags & PAGE_RESET));
     assert_memory_lock();
 
-    start = start & TARGET_PAGE_MASK;
-    end = TARGET_PAGE_ALIGN(end);
-    last = end - 1;
+    start &= TARGET_PAGE_MASK;
+    last |= ~TARGET_PAGE_MASK;
 
     if (!(flags & PAGE_VALID)) {
         flags = 0;
@@ -510,7 +508,7 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
     }
 
     if (!flags || reset) {
-        page_reset_target_data(start, end);
+        page_reset_target_data(start, last + 1);
         inval_tb |= pageflags_unset(start, last);
     }
     if (flags) {
@@ -518,7 +516,7 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
                                         ~(reset ? 0 : PAGE_STICKY));
     }
     if (inval_tb) {
-        tb_invalidate_phys_range(start, end);
+        tb_invalidate_phys_range(start, last + 1);
     }
 }