arm64 fixes/updates:

- Work around broken GCC 4.9 handling of "S" asm constraint.
 
 - Suppress W=1 missing prototype warnings.
 
 - Warn the user when a small VA_BITS value cannot map the available
   memory.
 
 - Drop the useless update to per-cpu cycles.
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull more arm64 updates from Catalin Marinas:
 "These are some some trivial updates that mostly fix/clean-up code
  pushed during the merging window:

   - Work around broken GCC 4.9 handling of "S" asm constraint

   - Suppress W=1 missing prototype warnings

   - Warn the user when a small VA_BITS value cannot map the available
     memory

   - Drop the useless update to per-cpu cycles"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Work around broken GCC 4.9 handling of "S" constraint
  arm64: Warn the user when a small VA_BITS value wastes memory
  arm64: entry: suppress W=1 prototype warnings
  arm64: topology: Drop the useless update to per-cpu cycles

arch/arm64/include/asm/exception.h

@@ -31,6 +31,10 @@ static inline u32 disr_to_esr(u64 disr)
 	return esr;
 }
 
+asmlinkage void el1_sync_handler(struct pt_regs *regs);
+asmlinkage void el0_sync_handler(struct pt_regs *regs);
+asmlinkage void el0_sync_compat_handler(struct pt_regs *regs);
+
 asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs);
 asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs);
 asmlinkage void enter_from_user_mode(void);

arch/arm64/include/asm/kvm_asm.h

@@ -200,6 +200,12 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
+#if defined(GCC_VERSION) && GCC_VERSION < 50000
+#define SYM_CONSTRAINT	"i"
+#else
+#define SYM_CONSTRAINT	"S"
+#endif
+
 /*
  * Obtain the PC-relative address of a kernel symbol
  * s: symbol
@@ -216,7 +222,7 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 		typeof(s) *addr;					\
 		asm("adrp	%0, %1\n"				\
 		    "add	%0, %0, :lo12:%1\n"			\
-		    : "=r" (addr) : "S" (&s));				\
+		    : "=r" (addr) : SYM_CONSTRAINT (&s));		\
 		addr;							\
 	})
 

arch/arm64/kernel/topology.c

@@ -314,7 +314,7 @@ void topology_scale_freq_tick(void)
 
 	if (unlikely(core_cnt <= prev_core_cnt ||
 		     const_cnt <= prev_const_cnt))
-		goto store_and_exit;
+		return;
 
 	/*
 	 *	    /\core    arch_max_freq_scale
@@ -331,10 +331,6 @@ void topology_scale_freq_tick(void)
 
 	scale = min_t(unsigned long, scale, SCHED_CAPACITY_SCALE);
 	this_cpu_write(freq_scale, (unsigned long)scale);
-
-store_and_exit:
-	this_cpu_write(arch_core_cycles_prev, core_cnt);
-	this_cpu_write(arch_const_cycles_prev, const_cnt);
 }
 
 #ifdef CONFIG_ACPI_CPPC_LIB

arch/arm64/mm/init.c

@@ -295,6 +295,9 @@ void __init arm64_memblock_init(void)
 	memstart_addr = round_down(memblock_start_of_DRAM(),
 				   ARM64_MEMSTART_ALIGN);
 
+	if ((memblock_end_of_DRAM() - memstart_addr) > linear_region_size)
+		pr_warn("Memory doesn't fit in the linear mapping, VA_BITS too small\n");
+
 	/*
 	 * Remove the memory that we will not be able to cover with the
 	 * linear mapping. Take care not to clip the kernel which may be