arch/sh/mm/cache-sh4.c:275:30: warning: variable 'end' set but not used

From: kernel test robot
Date: Sat Sep 23 2023 - 17:32:58 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 3aba70aed91f2b283f7952be152ad76ec5c34975
commit: ccbb5239d495923cb24b84a73eb814626c5bfa57 sh: remove -Werror from Makefiles
date: 3 years, 1 month ago
config: sh-randconfig-m041-20221209 (https://download.01.org/0day-ci/archive/20230924/202309240556.UgGAK6iq-lkp@xxxxxxxxx/config)
compiler: sh4-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230924/202309240556.UgGAK6iq-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309240556.UgGAK6iq-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

In file included from include/linux/gfp.h:6,
from include/linux/mm.h:10,
from arch/sh/mm/cache-sh4.c:14:
include/linux/mmzone.h: In function '__nr_to_section':
include/linux/mmzone.h:1213:13: warning: the comparison will always evaluate as 'true' for the address of 'mem_section' will never be NULL [-Waddress]
1213 | if (!mem_section[SECTION_NR_TO_ROOT(nr)])
| ^
include/linux/mmzone.h:1199:27: note: 'mem_section' declared here
1199 | extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
| ^~~~~~~~~~~
arch/sh/mm/cache-sh4.c: In function 'sh4_flush_cache_range':
>> arch/sh/mm/cache-sh4.c:275:30: warning: variable 'end' set but not used [-Wunused-but-set-variable]
275 | unsigned long start, end;
| ^~~
>> arch/sh/mm/cache-sh4.c:275:23: warning: variable 'start' set but not used [-Wunused-but-set-variable]
275 | unsigned long start, end;
| ^~~~~
arch/sh/mm/cache-sh4.c: At top level:
>> arch/sh/mm/cache-sh4.c:373:13: warning: no previous prototype for 'sh4_cache_init' [-Wmissing-prototypes]
373 | void __init sh4_cache_init(void)
| ^~~~~~~~~~~~~~
--
In file included from include/linux/gfp.h:6,
from include/linux/mm.h:10,
from arch/sh/mm/flush-sh4.c:2:
include/linux/mmzone.h: In function '__nr_to_section':
include/linux/mmzone.h:1213:13: warning: the comparison will always evaluate as 'true' for the address of 'mem_section' will never be NULL [-Waddress]
1213 | if (!mem_section[SECTION_NR_TO_ROOT(nr)])
| ^
include/linux/mmzone.h:1199:27: note: 'mem_section' declared here
1199 | extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
| ^~~~~~~~~~~
arch/sh/mm/flush-sh4.c: At top level:
>> arch/sh/mm/flush-sh4.c:106:13: warning: no previous prototype for 'sh4__flush_region_init' [-Wmissing-prototypes]
106 | void __init sh4__flush_region_init(void)
| ^~~~~~~~~~~~~~~~~~~~~~


vim +/end +275 arch/sh/mm/cache-sh4.c

^1da177e4c3f41 Linus Torvalds 2005-04-16 261
^1da177e4c3f41 Linus Torvalds 2005-04-16 262 /*
^1da177e4c3f41 Linus Torvalds 2005-04-16 263 * Write back and invalidate D-caches.
^1da177e4c3f41 Linus Torvalds 2005-04-16 264 *
^1da177e4c3f41 Linus Torvalds 2005-04-16 265 * START, END: Virtual Address (U0 address)
^1da177e4c3f41 Linus Torvalds 2005-04-16 266 *
^1da177e4c3f41 Linus Torvalds 2005-04-16 267 * NOTE: We need to flush the _physical_ page entry.
^1da177e4c3f41 Linus Torvalds 2005-04-16 268 * Flushing the cache lines for U0 only isn't enough.
^1da177e4c3f41 Linus Torvalds 2005-04-16 269 * We need to flush for P1 too, which may contain aliases.
^1da177e4c3f41 Linus Torvalds 2005-04-16 270 */
f26b2a562b46ab Paul Mundt 2009-08-21 271 static void sh4_flush_cache_range(void *args)
^1da177e4c3f41 Linus Torvalds 2005-04-16 272 {
f26b2a562b46ab Paul Mundt 2009-08-21 273 struct flusher_data *data = args;
f26b2a562b46ab Paul Mundt 2009-08-21 274 struct vm_area_struct *vma;
f26b2a562b46ab Paul Mundt 2009-08-21 @275 unsigned long start, end;
f26b2a562b46ab Paul Mundt 2009-08-21 276
f26b2a562b46ab Paul Mundt 2009-08-21 277 vma = data->vma;
f26b2a562b46ab Paul Mundt 2009-08-21 278 start = data->addr1;
f26b2a562b46ab Paul Mundt 2009-08-21 279 end = data->addr2;
f26b2a562b46ab Paul Mundt 2009-08-21 280
e7b8b7f16edc9b Paul Mundt 2009-08-15 281 if (cpu_context(smp_processor_id(), vma->vm_mm) == NO_CONTEXT)
e7b8b7f16edc9b Paul Mundt 2009-08-15 282 return;
e7b8b7f16edc9b Paul Mundt 2009-08-15 283
b638d0b921dc95 Richard Curnow 2006-09-27 284 /*
b638d0b921dc95 Richard Curnow 2006-09-27 285 * If cache is only 4k-per-way, there are never any 'aliases'. Since
b638d0b921dc95 Richard Curnow 2006-09-27 286 * the cache is physically tagged, the data can just be left in there.
b638d0b921dc95 Richard Curnow 2006-09-27 287 */
7ec9d6f8c0e693 Paul Mundt 2007-09-21 288 if (boot_cpu_data.dcache.n_aliases == 0)
b638d0b921dc95 Richard Curnow 2006-09-27 289 return;
b638d0b921dc95 Richard Curnow 2006-09-27 290
a252710fc5b63b Paul Mundt 2006-09-27 291 flush_dcache_all();
b638d0b921dc95 Richard Curnow 2006-09-27 292
654d364e26c797 Paul Mundt 2009-09-09 293 if (vma->vm_flags & VM_EXEC)
^1da177e4c3f41 Linus Torvalds 2005-04-16 294 flush_icache_all();
^1da177e4c3f41 Linus Torvalds 2005-04-16 295 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 296
b638d0b921dc95 Richard Curnow 2006-09-27 297 /**
a7a7c0e1d12bcf Valentin Sitdikov 2009-10-16 298 * __flush_cache_one
b638d0b921dc95 Richard Curnow 2006-09-27 299 *
b638d0b921dc95 Richard Curnow 2006-09-27 300 * @addr: address in memory mapped cache array
b638d0b921dc95 Richard Curnow 2006-09-27 301 * @phys: P1 address to flush (has to match tags if addr has 'A' bit
b638d0b921dc95 Richard Curnow 2006-09-27 302 * set i.e. associative write)
b638d0b921dc95 Richard Curnow 2006-09-27 303 * @exec_offset: set to 0x20000000 if flush has to be executed from P2
b638d0b921dc95 Richard Curnow 2006-09-27 304 * region else 0x0
b638d0b921dc95 Richard Curnow 2006-09-27 305 *
b638d0b921dc95 Richard Curnow 2006-09-27 306 * The offset into the cache array implied by 'addr' selects the
b638d0b921dc95 Richard Curnow 2006-09-27 307 * 'colour' of the virtual address range that will be flushed. The
b638d0b921dc95 Richard Curnow 2006-09-27 308 * operation (purge/write-back) is selected by the lower 2 bits of
b638d0b921dc95 Richard Curnow 2006-09-27 309 * 'phys'.
b638d0b921dc95 Richard Curnow 2006-09-27 310 */
a7a7c0e1d12bcf Valentin Sitdikov 2009-10-16 311 static void __flush_cache_one(unsigned long addr, unsigned long phys,
b638d0b921dc95 Richard Curnow 2006-09-27 312 unsigned long exec_offset)
b638d0b921dc95 Richard Curnow 2006-09-27 313 {
b638d0b921dc95 Richard Curnow 2006-09-27 314 int way_count;
b638d0b921dc95 Richard Curnow 2006-09-27 315 unsigned long base_addr = addr;
b638d0b921dc95 Richard Curnow 2006-09-27 316 struct cache_info *dcache;
b638d0b921dc95 Richard Curnow 2006-09-27 317 unsigned long way_incr;
b638d0b921dc95 Richard Curnow 2006-09-27 318 unsigned long a, ea, p;
b638d0b921dc95 Richard Curnow 2006-09-27 319 unsigned long temp_pc;
b638d0b921dc95 Richard Curnow 2006-09-27 320
7ec9d6f8c0e693 Paul Mundt 2007-09-21 321 dcache = &boot_cpu_data.dcache;
b638d0b921dc95 Richard Curnow 2006-09-27 322 /* Write this way for better assembly. */
b638d0b921dc95 Richard Curnow 2006-09-27 323 way_count = dcache->ways;
b638d0b921dc95 Richard Curnow 2006-09-27 324 way_incr = dcache->way_incr;
b638d0b921dc95 Richard Curnow 2006-09-27 325
b638d0b921dc95 Richard Curnow 2006-09-27 326 /*
b638d0b921dc95 Richard Curnow 2006-09-27 327 * Apply exec_offset (i.e. branch to P2 if required.).
b638d0b921dc95 Richard Curnow 2006-09-27 328 *
b638d0b921dc95 Richard Curnow 2006-09-27 329 * FIXME:
b638d0b921dc95 Richard Curnow 2006-09-27 330 *
b638d0b921dc95 Richard Curnow 2006-09-27 331 * If I write "=r" for the (temp_pc), it puts this in r6 hence
b638d0b921dc95 Richard Curnow 2006-09-27 332 * trashing exec_offset before it's been added on - why? Hence
b638d0b921dc95 Richard Curnow 2006-09-27 333 * "=&r" as a 'workaround'
b638d0b921dc95 Richard Curnow 2006-09-27 334 */
b638d0b921dc95 Richard Curnow 2006-09-27 335 asm volatile("mov.l 1f, %0\n\t"
b638d0b921dc95 Richard Curnow 2006-09-27 336 "add %1, %0\n\t"
b638d0b921dc95 Richard Curnow 2006-09-27 337 "jmp @%0\n\t"
b638d0b921dc95 Richard Curnow 2006-09-27 338 "nop\n\t"
b638d0b921dc95 Richard Curnow 2006-09-27 339 ".balign 4\n\t"
b638d0b921dc95 Richard Curnow 2006-09-27 340 "1: .long 2f\n\t"
b638d0b921dc95 Richard Curnow 2006-09-27 341 "2:\n" : "=&r" (temp_pc) : "r" (exec_offset));
b638d0b921dc95 Richard Curnow 2006-09-27 342
b638d0b921dc95 Richard Curnow 2006-09-27 343 /*
b638d0b921dc95 Richard Curnow 2006-09-27 344 * We know there will be >=1 iteration, so write as do-while to avoid
b638d0b921dc95 Richard Curnow 2006-09-27 345 * pointless nead-of-loop check for 0 iterations.
b638d0b921dc95 Richard Curnow 2006-09-27 346 */
b638d0b921dc95 Richard Curnow 2006-09-27 347 do {
b638d0b921dc95 Richard Curnow 2006-09-27 348 ea = base_addr + PAGE_SIZE;
b638d0b921dc95 Richard Curnow 2006-09-27 349 a = base_addr;
b638d0b921dc95 Richard Curnow 2006-09-27 350 p = phys;
b638d0b921dc95 Richard Curnow 2006-09-27 351
b638d0b921dc95 Richard Curnow 2006-09-27 352 do {
b638d0b921dc95 Richard Curnow 2006-09-27 353 *(volatile unsigned long *)a = p;
b638d0b921dc95 Richard Curnow 2006-09-27 354 /*
b638d0b921dc95 Richard Curnow 2006-09-27 355 * Next line: intentionally not p+32, saves an add, p
b638d0b921dc95 Richard Curnow 2006-09-27 356 * will do since only the cache tag bits need to
b638d0b921dc95 Richard Curnow 2006-09-27 357 * match.
b638d0b921dc95 Richard Curnow 2006-09-27 358 */
b638d0b921dc95 Richard Curnow 2006-09-27 359 *(volatile unsigned long *)(a+32) = p;
b638d0b921dc95 Richard Curnow 2006-09-27 360 a += 64;
b638d0b921dc95 Richard Curnow 2006-09-27 361 p += 64;
b638d0b921dc95 Richard Curnow 2006-09-27 362 } while (a < ea);
b638d0b921dc95 Richard Curnow 2006-09-27 363
b638d0b921dc95 Richard Curnow 2006-09-27 364 base_addr += way_incr;
b638d0b921dc95 Richard Curnow 2006-09-27 365 } while (--way_count != 0);
b638d0b921dc95 Richard Curnow 2006-09-27 366 }
b638d0b921dc95 Richard Curnow 2006-09-27 367
37443ef3f0406e Paul Mundt 2009-08-15 368 extern void __weak sh4__flush_region_init(void);
37443ef3f0406e Paul Mundt 2009-08-15 369
37443ef3f0406e Paul Mundt 2009-08-15 370 /*
37443ef3f0406e Paul Mundt 2009-08-15 371 * SH-4 has virtually indexed and physically tagged cache.
37443ef3f0406e Paul Mundt 2009-08-15 372 */
37443ef3f0406e Paul Mundt 2009-08-15 @373 void __init sh4_cache_init(void)

:::::: The code at line 275 was first introduced by commit
:::::: f26b2a562b46ab186c8383993ab1332673ac4a47 sh: Make cache flushers SMP-aware.

:::::: TO: Paul Mundt <lethal@xxxxxxxxxxxx>
:::::: CC: Paul Mundt <lethal@xxxxxxxxxxxx>

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