[Xen-devel] [PATCH 1/2] xen/compiler: Replace opencoded __attribute__((noreturn))

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Make a formal define for noreturn in compiler.h, and replace opencoded
uses of __attribute__((noreturn)).

There is a stale statement in sh_skip_sync(); BUG() now contains
unreachable(), removing the justification for having "return 0".

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>

---

I have compile tested this for both arm32 and arm64
---
 xen/arch/arm/early_printk.c        |    2 +-
 xen/arch/x86/crash.c               |    2 +-
 xen/arch/x86/mm/shadow/common.c    |    1 -
 xen/arch/x86/shutdown.c            |    2 +-
 xen/include/asm-arm/early_printk.h |    4 ++--
 xen/include/xen/compiler.h         |    2 ++
 xen/include/xen/lib.h              |    2 +-
 xen/include/xen/sched.h            |    4 ++--
 8 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/early_printk.c b/xen/arch/arm/early_printk.c
index 058d044..00ec72a 100644
--- a/xen/arch/arm/early_printk.c
+++ b/xen/arch/arm/early_printk.c
@@ -52,7 +52,7 @@ void __init early_printk(const char *fmt, ...)
     va_end(args);
 }
 
-void __attribute__((noreturn)) __init
+void noreturn __init
 early_panic(const char *fmt, ...)
 {
     va_list args;
diff --git a/xen/arch/x86/crash.c b/xen/arch/x86/crash.c
index 01fd906..836babb 100644
--- a/xen/arch/x86/crash.c
+++ b/xen/arch/x86/crash.c
@@ -36,7 +36,7 @@ static unsigned int crashing_cpu;
 static DEFINE_PER_CPU_READ_MOSTLY(bool_t, crash_save_done);
 
 /* This becomes the NMI handler for non-crashing CPUs, when Xen is crashing. */
-void __attribute__((noreturn)) do_nmi_crash(struct cpu_user_regs *regs)
+void noreturn do_nmi_crash(struct cpu_user_regs *regs)
 {
     int cpu = smp_processor_id();
 
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 0bfa595..c1a416c 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -875,7 +875,6 @@ static int sh_skip_sync(struct vcpu *v, mfn_t gl1mfn)
     SHADOW_ERROR("gmfn %#lx was OOS but not shadowed as an l1.\n",
                  mfn_x(gl1mfn));
     BUG();
-    return 0; /* BUG() is no longer __attribute__((noreturn)). */
 }
 
 
diff --git a/xen/arch/x86/shutdown.c b/xen/arch/x86/shutdown.c
index 6eba271..6143c40 100644
--- a/xen/arch/x86/shutdown.c
+++ b/xen/arch/x86/shutdown.c
@@ -85,7 +85,7 @@ static inline void kb_wait(void)
             break;
 }
 
-static void __attribute__((noreturn)) __machine_halt(void *unused)
+static void noreturn __machine_halt(void *unused)
 {
     local_irq_disable();
     for ( ; ; )
diff --git a/xen/include/asm-arm/early_printk.h 
b/xen/include/asm-arm/early_printk.h
index 707bbf7..3cb8dab 100644
--- a/xen/include/asm-arm/early_printk.h
+++ b/xen/include/asm-arm/early_printk.h
@@ -26,7 +26,7 @@
 
 void early_printk(const char *fmt, ...)
     __attribute__((format (printf, 1, 2)));
-void early_panic(const char *fmt, ...) __attribute__((noreturn))
+void early_panic(const char *fmt, ...) noreturn
     __attribute__((format (printf, 1, 2)));
 
 #else
@@ -35,7 +35,7 @@ static inline  __attribute__((format (printf, 1, 2))) void
 early_printk(const char *fmt, ...)
 {}
 
-static inline void  __attribute__((noreturn))
+static inline void noreturn
 __attribute__((format (printf, 1, 2))) early_panic(const char *fmt, ...)
 {while(1);}
 
diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index 7d6805c..c80398d 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -14,6 +14,8 @@
 #define always_inline __inline__ __attribute__ ((always_inline))
 #define noinline      __attribute__((noinline))
 
+#define noreturn      __attribute__((noreturn))
+
 #if (!defined(__clang__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 5))
 #define unreachable() do {} while (1)
 #else
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index 5b258fd..814fcb4 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -8,7 +8,7 @@
 #include <xen/string.h>
 #include <asm/bug.h>
 
-void __bug(char *file, int line) __attribute__((noreturn));
+void __bug(char *file, int line) noreturn;
 void __warn(char *file, int line);
 
 #define BUG_ON(p)  do { if (unlikely(p)) BUG();  } while (0)
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index cbdf377..0d2a442 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -578,7 +578,7 @@ void __domain_crash(struct domain *d);
  * Mark current domain as crashed and synchronously deschedule from the local
  * processor. This function never returns.
  */
-void __domain_crash_synchronous(void) __attribute__((noreturn));
+void __domain_crash_synchronous(void) noreturn;
 #define domain_crash_synchronous() do {                                   \
     printk("domain_crash_sync called from %s:%d\n", __FILE__, __LINE__);  \
     __domain_crash_synchronous();                                         \
@@ -589,7 +589,7 @@ void __domain_crash_synchronous(void) 
__attribute__((noreturn));
  * the crash occured.  If addr is 0, look up address from last extable
  * redirection.
  */
-void asm_domain_crash_synchronous(unsigned long addr) 
__attribute__((noreturn));
+void asm_domain_crash_synchronous(unsigned long addr) noreturn;
 
 #define set_current_state(_s) do { current->state = (_s); } while (0)
 void scheduler_init(void);
-- 
1.7.10.4


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