xen/arm: add missing noreturn attributes

The marked functions never return to their caller, but lack the
`noreturn' attribute.

Functions that never return should be declared with a `noreturn'
attribute.

The lack of `noreturn' causes a violation of MISRA C Rule 17.11 (not
currently accepted in Xen), and also Rule 2.1: "A project shall not
contain unreachable code". Depending on the compiler used and the
compiler optimization used, the lack of `noreturn' might lead to the
presence of unreachable code.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Signed-off-by: Victor Lira <victorm.lira@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/efi/efi-boot.h

@@ -934,7 +934,7 @@ static void __init efi_arch_blexit(void)
         efi_bs->FreePool(memmap);
 }
 
-static void __init efi_arch_halt(void)
+static void noreturn __init efi_arch_halt(void)
 {
     stop_cpu();
 }

xen/arch/arm/include/asm/arm64/traps.h

@@ -6,7 +6,7 @@ void inject_undef64_exception(struct cpu_user_regs *regs);
 void do_sysreg(struct cpu_user_regs *regs,
                const union hsr hsr);
 
-void do_bad_mode(struct cpu_user_regs *regs, int reason);
+void noreturn do_bad_mode(struct cpu_user_regs *regs, int reason);
 
 #endif /* __ASM_ARM64_TRAPS__ */
 /*

xen/arch/arm/include/asm/processor.h

@@ -571,7 +571,7 @@ extern register_t __cpu_logical_map[];
 #endif
 
 #ifndef __ASSEMBLY__
-void panic_PAR(uint64_t par);
+void noreturn panic_PAR(uint64_t par);
 
 /* Debugging functions are declared with external linkage to aid development. */
 void show_registers(const struct cpu_user_regs *regs);

xen/arch/arm/setup.c

@@ -63,7 +63,7 @@ bool __read_mostly acpi_disabled;
 
 domid_t __read_mostly max_init_domid;
 
-static __used void init_done(void)
+static __used void noreturn init_done(void)
 {
     int rc;