[xen staging] x86/uaccess: add attribute noreturn to __{get,put}_user_bad()

[patchbot@xxxxxxx]

commit 54557ee9b4ad8f2ed708c3dd222ee0db74d4c83b
Author:     Federico Serafini <federico.serafini@xxxxxxxxxxx>
AuthorDate: Thu Feb 22 11:53:23 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 22 11:53:23 2024 +0100

    x86/uaccess: add attribute noreturn to __{get,put}_user_bad()
    
    __get_user_bad() and __put_user_bad() are undefined symbols used
    to assert the unreachability of a program point:
    a call to one of such functions is optimized away if it is considered
    unreachable by the compiler. Otherwise, a linker error is reported.
    
    In accordance with the purpose of such constructs:
    1) add the attribute noreturn to __get_user_bad() and __put_user_bad();
    2) change return type of __get_user_bad() to void (returning long is a
       leftover from the past).
    
    Point (1) meets the requirements to deviate MISRA C:2012 Rule 16.3
    ("An unconditional break statement shall terminate every switch
    clause") since functions with noreturn attribute are considered
    as allowed terminals for switch clauses.
    
    Point (2) addresses several violations of MISRA C:2012 Rule 17.7
    ("The value returned by a function having non-void return type
    shall be used").
    
    While there also zap "extern".
    
    No functional change.
    
    Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/include/asm/uaccess.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/include/asm/uaccess.h 
b/xen/arch/x86/include/asm/uaccess.h
index 7443519d5b..55bc6932fd 100644
--- a/xen/arch/x86/include/asm/uaccess.h
+++ b/xen/arch/x86/include/asm/uaccess.h
@@ -21,8 +21,8 @@ unsigned int copy_from_guest_ll(void *to, const void __user 
*from, unsigned int
 unsigned int copy_to_unsafe_ll(void *to, const void *from, unsigned int n);
 unsigned int copy_from_unsafe_ll(void *to, const void *from, unsigned int n);
 
-extern long __get_user_bad(void);
-extern void __put_user_bad(void);
+void noreturn __get_user_bad(void);
+void noreturn __put_user_bad(void);
 
 #define UA_KEEP(args...) args
 #define UA_DROP(args...)
--
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