diff mbox series

[v2,09/24] linux-user: Implement MAP_FIXED_NOREPLACE

Message ID 20230707204054.8792-12-richard.henderson@linaro.org
State Superseded
Headers show
Series linux-user: mmap range fixes | expand

Commit Message

Richard Henderson July 7, 2023, 8:40 p.m. UTC 
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/mmap.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 12275593a1..b2e130e700 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -508,7 +508,7 @@  abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
      * If the user is asking for the kernel to find a location, do that
      * before we truncate the length for mapping files below.
      */
-    if (!(flags & MAP_FIXED)) {
+    if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) {
         host_len = len + offset - host_offset;
         host_len = HOST_PAGE_ALIGN(host_len);
         start = mmap_find_vma(real_start, host_len, TARGET_PAGE_SIZE);
@@ -550,7 +550,7 @@  abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
         }
     }
 
-    if (!(flags & MAP_FIXED)) {
+    if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) {
         unsigned long host_start;
         void *p;
 
@@ -599,6 +599,13 @@  abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
             goto fail;
         }
 
+        /* Validate that the chosen range is empty. */
+        if ((flags & MAP_FIXED_NOREPLACE)
+            && !page_check_range_empty(start, end - 1)) {
+            errno = EEXIST;
+            goto fail;
+        }
+
         /*
          * worst case: we cannot map the file because the offset is not
          * aligned, so we read it
@@ -614,7 +621,8 @@  abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
                 goto fail;
             }
             retaddr = target_mmap(start, len, target_prot | PROT_WRITE,
-                                  MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
+                                  (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))
+                                  | MAP_PRIVATE | MAP_ANONYMOUS,
                                   -1, 0);
             if (retaddr == -1) {
                 goto fail;