linux-user/aarch64: Reset target data on MADV_DONTNEED

aarch64 stores MTE tags in target_date, and they should be reset by
MADV_DONTNEED.

Signed-off-by: Vitaly Buka <vitalybuka@google.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220711220028.2467290-1-vitalybuka@google.com>
[lv: fix code style issues]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

accel/tcg/translate-all.c

@@ -2314,6 +2314,32 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
     }
 }
 
+void page_reset_target_data(target_ulong start, target_ulong end)
+{
+    target_ulong addr, len;
+
+    /*
+     * 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(end - 1 <= GUEST_ADDR_MAX);
+    assert(start < end);
+    assert_memory_lock();
+
+    start = start & TARGET_PAGE_MASK;
+    end = TARGET_PAGE_ALIGN(end);
+
+    for (addr = start, len = end - start;
+         len != 0;
+         len -= TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {
+        PageDesc *p = page_find_alloc(addr >> TARGET_PAGE_BITS, 1);
+
+        g_free(p->target_data);
+        p->target_data = NULL;
+    }
+}
+
 void *page_get_target_data(target_ulong address)
 {
     PageDesc *p = page_find(address >> TARGET_PAGE_BITS);

include/exec/cpu-all.h

@@ -271,6 +271,7 @@ int walk_memory_regions(void *, walk_memory_regions_fn);
 
 int page_get_flags(target_ulong address);
 void page_set_flags(target_ulong start, target_ulong end, int flags);
+void page_reset_target_data(target_ulong start, target_ulong end);
 int page_check_range(target_ulong start, target_ulong len, int flags);
 
 /**

linux-user/mmap.c

@@ -894,6 +894,9 @@ abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice)
     if (advice == MADV_DONTNEED &&
         can_passthrough_madv_dontneed(start, end)) {
         ret = get_errno(madvise(g2h_untagged(start), len, MADV_DONTNEED));
+        if (ret == 0) {
+            page_reset_target_data(start, start + len);
+        }
     }
     mmap_unlock();