include/exec: Change reserved_va semantics to last byte

Change the semantics to be the last byte of the guest va, rather
than the following byte.  This avoids some overflow conditions.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 7 insertions, 7 deletions

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index dfae967..f1370a7 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -208,7 +208,7 @@ static bool init_guest_commpage(void)
      * has specified -R reserved_va, which would trigger an assert().
      */
     if (reserved_va != 0 &&
-        TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE >= reserved_va) {
+        TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE - 1 > reserved_va) {
         error_report("Cannot allocate vsyscall page");
         exit(EXIT_FAILURE);
     }
@@ -2504,7 +2504,7 @@ static void pgb_have_guest_base(const char *image_name, abi_ulong guest_loaddr,
         if (guest_hiaddr > reserved_va) {
             error_report("%s: requires more than reserved virtual "
                          "address space (0x%" PRIx64 " > 0x%lx)",
-                         image_name, (uint64_t)guest_hiaddr + 1, reserved_va);
+                         image_name, (uint64_t)guest_hiaddr, reserved_va);
             exit(EXIT_FAILURE);
         }
     } else {
@@ -2525,7 +2525,7 @@ static void pgb_have_guest_base(const char *image_name, abi_ulong guest_loaddr,
     if (reserved_va) {
         guest_loaddr = (guest_base >= mmap_min_addr ? 0
                         : mmap_min_addr - guest_base);
-        guest_hiaddr = reserved_va - 1;
+        guest_hiaddr = reserved_va;
     }
 
     /* Reserve the address space for the binary, or reserved_va. */
@@ -2755,7 +2755,7 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
     if (guest_hiaddr > reserved_va) {
         error_report("%s: requires more than reserved virtual "
                      "address space (0x%" PRIx64 " > 0x%lx)",
-                     image_name, (uint64_t)guest_hiaddr + 1, reserved_va);
+                     image_name, (uint64_t)guest_hiaddr, reserved_va);
         exit(EXIT_FAILURE);
     }
 
@@ -2768,17 +2768,17 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
     /* Reserve the memory on the host. */
     assert(guest_base != 0);
     test = g2h_untagged(0);
-    addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
+    addr = mmap(test, reserved_va + 1, PROT_NONE, flags, -1, 0);
     if (addr == MAP_FAILED || addr != test) {
         error_report("Unable to reserve 0x%lx bytes of virtual address "
                      "space at %p (%s) for use as guest address space (check your "
                      "virtual memory ulimit setting, min_mmap_addr or reserve less "
-                     "using -R option)", reserved_va, test, strerror(errno));
+                     "using -R option)", reserved_va + 1, test, strerror(errno));
         exit(EXIT_FAILURE);
     }
 
     qemu_log_mask(CPU_LOG_PAGE, "%s: base @ %p for %lu bytes\n",
-                  __func__, addr, reserved_va);
+                  __func__, addr, reserved_va + 1);
 }
 
 void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,