linux-kernel - [tip:x86/cache 29/38] arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c:363:1: warning: unsupported size for integer register

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Date:   Wed, 20 Jun 2018 08:49:09 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Reinette Chatre <reinette.chatre@...el.com>
Cc:     kbuild-all@...org, linux-kernel@...r.kernel.org,
        tipbuild@...or.com, Thomas Gleixner <tglx@...utronix.de>
Subject: [tip:x86/cache 29/38]
 arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c:363:1: warning: unsupported size
 for integer register

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/cache
head:   f61050aefc0ca1c0b3e93114eadd0a910a66202b
commit: 0438fb1aebf428efcdce64ef4ec610e93e0006f9 [29/38] x86/intel_rdt: Pseudo-lock region creation/removal core
config: i386-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
        git checkout 0438fb1aebf428efcdce64ef4ec610e93e0006f9
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

   arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c: In function 'pseudo_lock_fn':
>> arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c:363:1: warning: unsupported size for integer register
    }
    ^
>> arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c:363:1: warning: unsupported size for integer register

vim +363 arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c

   280	
   281		/*
   282		 * Make sure none of the allocated memory is cached. If it is we
   283		 * will get a cache hit in below loop from outside of pseudo-locked
   284		 * region.
   285		 * wbinvd (as opposed to clflush/clflushopt) is required to
   286		 * increase likelihood that allocated cache portion will be filled
   287		 * with associated memory.
   288		 */
   289		native_wbinvd();
   290	
   291		/*
   292		 * Always called with interrupts enabled. By disabling interrupts
   293		 * ensure that we will not be preempted during this critical section.
   294		 */
   295		local_irq_disable();
   296	
   297		/*
   298		 * Call wrmsr and rdmsr as directly as possible to avoid tracing
   299		 * clobbering local register variables or affecting cache accesses.
   300		 *
   301		 * Disable the hardware prefetcher so that when the end of the memory
   302		 * being pseudo-locked is reached the hardware will not read beyond
   303		 * the buffer and evict pseudo-locked memory read earlier from the
   304		 * cache.
   305		 */
   306		__wrmsr(MSR_MISC_FEATURE_CONTROL, prefetch_disable_bits, 0x0);
   307		closid_p = this_cpu_read(pqr_state.cur_closid);
   308		rmid_p = this_cpu_read(pqr_state.cur_rmid);
   309		mem_r = plr->kmem;
   310		size = plr->size;
   311		line_size = plr->line_size;
   312		/*
   313		 * Critical section begin: start by writing the closid associated
   314		 * with the capacity bitmask of the cache region being
   315		 * pseudo-locked followed by reading of kernel memory to load it
   316		 * into the cache.
   317		 */
   318		__wrmsr(IA32_PQR_ASSOC, rmid_p, rdtgrp->closid);
   319		/*
   320		 * Cache was flushed earlier. Now access kernel memory to read it
   321		 * into cache region associated with just activated plr->closid.
   322		 * Loop over data twice:
   323		 * - In first loop the cache region is shared with the page walker
   324		 *   as it populates the paging structure caches (including TLB).
   325		 * - In the second loop the paging structure caches are used and
   326		 *   cache region is populated with the memory being referenced.
   327		 */
   328		for (i = 0; i < size; i += PAGE_SIZE) {
   329			/*
   330			 * Add a barrier to prevent speculative execution of this
   331			 * loop reading beyond the end of the buffer.
   332			 */
   333			rmb();
   334			asm volatile("mov (%0,%1,1), %%eax\n\t"
   335				:
   336				: "r" (mem_r), "r" (i)
   337				: "%eax", "memory");
   338		}
   339		for (i = 0; i < size; i += line_size) {
   340			/*
   341			 * Add a barrier to prevent speculative execution of this
   342			 * loop reading beyond the end of the buffer.
   343			 */
   344			rmb();
   345			asm volatile("mov (%0,%1,1), %%eax\n\t"
   346				:
   347				: "r" (mem_r), "r" (i)
   348				: "%eax", "memory");
   349		}
   350		/*
   351		 * Critical section end: restore closid with capacity bitmask that
   352		 * does not overlap with pseudo-locked region.
   353		 */
   354		__wrmsr(IA32_PQR_ASSOC, rmid_p, closid_p);
   355	
   356		/* Re-enable the hardware prefetcher(s) */
   357		wrmsr(MSR_MISC_FEATURE_CONTROL, 0x0, 0x0);
   358		local_irq_enable();
   359	
   360		plr->thread_done = 1;
   361		wake_up_interruptible(&plr->lock_thread_wq);
   362		return 0;
 > 363	}
   364	

---
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