[xen staging] EFI: address a violation of MISRA C Rule 13.6

[patchbot@xxxxxxx]

commit 6f621f23bc3eb76fd8440d69ef4ed6bec0fb2eff
Author:     Federico Serafini <federico.serafini@xxxxxxxxxxx>
AuthorDate: Mon Sep 30 14:49:15 2024 +0200
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxx>
CommitDate: Fri Oct 4 14:23:15 2024 -0700

    EFI: address a violation of MISRA C Rule 13.6
    
    guest_handle_ok()'s expansion contains a sizeof() involving its
    first argument which is guest_handle_cast().
    The expansion of the latter, in turn, contains a variable
    initialization.
    
    Since MISRA considers the initialization (even of a local variable)
    a side effect, the chain of expansions mentioned above violates
    MISRA C:2012 Rule 13.6 (The operand of the `sizeof' operator shall not
    contain any expression which has potential side effect).
    
    Refactor the code to address the rule violation.
    
    Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Acked-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 xen/common/efi/runtime.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index d03e5c90ce..acf08dcaa3 100644
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -250,14 +250,20 @@ int efi_get_info(uint32_t idx, union xenpf_efi_info *info)
         info->cfg.addr = __pa(efi_ct);
         info->cfg.nent = efi_num_ct;
         break;
+
     case XEN_FW_EFI_VENDOR:
+    {
+        XEN_GUEST_HANDLE_PARAM(CHAR16) vendor_name =
+            guest_handle_cast(info->vendor.name, CHAR16);
+
         if ( !efi_fw_vendor )
             return -EOPNOTSUPP;
+
         info->vendor.revision = efi_fw_revision;
         n = info->vendor.bufsz / sizeof(*efi_fw_vendor);
-        if ( !guest_handle_okay(guest_handle_cast(info->vendor.name,
-                                                  CHAR16), n) )
+        if ( !guest_handle_okay(vendor_name, n) )
             return -EFAULT;
+
         for ( i = 0; i < n; ++i )
         {
             if ( __copy_to_guest_offset(info->vendor.name, i,
@@ -267,6 +273,8 @@ int efi_get_info(uint32_t idx, union xenpf_efi_info *info)
                 break;
         }
         break;
+    }
+
     case XEN_FW_EFI_MEM_INFO:
         for ( i = 0; i < efi_memmap_size; i += efi_mdesc_size )
         {
--
generated by git-patchbot for /home/xen/git/xen.git#staging