linux-user: don't adjust base of found hole

The pgb_find_hole function goes to the trouble of taking account of
both mmap_min_addr and any offset we've applied to decide the starting
address of a potential hole. This is especially important for
emulating 32bit ARM in a 32bit build as we have applied the offset to
ensure there will be space to map the ARM_COMMPAGE bellow the main
guest map (using wrapped arithmetic).

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/690
Message-Id: <20220105135009.1584676-27-alex.bennee@linaro.org>

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 30dbb00..99829fa 100644 (file)
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2339,8 +2339,7 @@ static uintptr_t pgb_find_hole(uintptr_t guest_loaddr, uintptr_t guest_size,
     brk = (uintptr_t)sbrk(0);
 
     if (!maps) {
-        ret = pgd_find_hole_fallback(guest_size, brk, align, offset);
-        return ret == -1 ? -1 : ret - guest_loaddr;
+        return pgd_find_hole_fallback(guest_size, brk, align, offset);
     }
 
     /* The first hole is before the first map entry. */
@@ -2380,7 +2379,7 @@ static uintptr_t pgb_find_hole(uintptr_t guest_loaddr, uintptr_t guest_size,
 
         /* Record the lowest successful match. */
         if (ret < 0) {
-            ret = align_start - guest_loaddr;
+            ret = align_start;
         }
         /* If this hole contains the identity map, select it. */
         if (align_start <= guest_loaddr &&