Hi Nicholas, I love your patch! Yet something to improve:
[auto build test ERROR on powerpc/next] [also build test ERROR on v4.19-rc3 next-20180913] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Nicholas-Piggin/SLB-miss-conversion-to-C-and-SLB-optimisations/20180917-015458 base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next config: powerpc-defconfig (attached as .config) compiler: powerpc64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree GCC_VERSION=7.2.0 make.cross ARCH=powerpc Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings Note: the linux-review/Nicholas-Piggin/SLB-miss-conversion-to-C-and-SLB-optimisations/20180917-015458 HEAD b26bd44c74488169a0fd19eef43ea3db189a207d builds fine. It only hurts bisectibility. All errors (new ones prefixed by >>): arch/powerpc/mm/slb.c: In function 'switch_slb': >> arch/powerpc/mm/slb.c:258:4: error: 'slbie_data' may be used uninitialized >> in this function [-Werror=maybe-uninitialized] asm volatile("slbie %0" : : "r" (slbie_data)); ^~~ cc1: all warnings being treated as errors vim +/slbie_data +258 arch/powerpc/mm/slb.c 465ccab9 arch/powerpc/mm/slb.c will schmidt 2007-10-31 224 ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 225 /* Flush all user entries from the segment table of the current processor. */ ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 226 void switch_slb(struct task_struct *tsk, struct mm_struct *mm) ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 227 { 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 228 unsigned long offset; ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 229 unsigned long pc = KSTK_EIP(tsk); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 230 unsigned long stack = KSTK_ESP(tsk); de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 231 unsigned long exec_base; ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 232 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 233 /* 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 234 * We need interrupts hard-disabled here, not just soft-disabled, 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 235 * so that a PMU interrupt can't occur, which might try to access 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 236 * user memory (to get a stack trace) and possible cause an SLB miss 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 237 * which would update the slb_cache/slb_cache_ptr fields in the PACA. 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 238 */ 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 239 hard_irq_disable(); 9c1e1052 arch/powerpc/mm/slb.c Paul Mackerras 2009-08-17 240 offset = get_paca()->slb_cache_ptr; 44ae3ab3 arch/powerpc/mm/slb.c Matt Evans 2011-04-06 241 if (!mmu_has_feature(MMU_FTR_NO_SLBIE_B) && f66bce5e arch/powerpc/mm/slb.c Olof Johansson 2007-10-16 242 offset <= SLB_CACHE_ENTRIES) { 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 243 unsigned long slbie_data; ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 244 int i; 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 245 ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 246 asm volatile("isync" : : : "memory"); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 247 for (i = 0; i < offset; i++) { 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 248 slbie_data = (unsigned long)get_paca()->slb_cache[i] 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 249 << SID_SHIFT; /* EA */ 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 250 slbie_data |= user_segment_size(slbie_data) 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 251 << SLBIE_SSIZE_SHIFT; 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 252 slbie_data |= SLBIE_C; /* C set for user addresses */ 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 253 asm volatile("slbie %0" : : "r" (slbie_data)); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 254 } ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 255 ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 256 /* Workaround POWER5 < DD2.1 issue */ 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 257 if (!cpu_has_feature(CPU_FTR_ARCH_207S) && offset == 1) 1189be65 arch/powerpc/mm/slb.c Paul Mackerras 2007-10-11 @258 asm volatile("slbie %0" : : "r" (slbie_data)); 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 259 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 260 asm volatile("isync" : : : "memory"); 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 261 } else { 6697d605 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 262 __slb_flush_and_rebolt(); c15c9670 arch/powerpc/mm/slb.c Nicholas Piggin 2018-09-15 263 } ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 264 ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 265 get_paca()->slb_cache_ptr = 0; 52b1e665 arch/powerpc/mm/slb.c Aneesh Kumar K.V 2017-03-22 266 copy_mm_to_paca(mm); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 267 ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 268 /* ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 269 * preload some userspace segments into the SLB. de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 270 * Almost all 32 and 64bit PowerPC executables are linked at de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 271 * 0x10000000 so it makes sense to preload this segment. ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 272 */ de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 273 exec_base = 0x10000000; ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 274 5eb9bac0 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 275 if (is_kernel_addr(pc) || is_kernel_addr(stack) || de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 276 is_kernel_addr(exec_base)) ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 277 return; ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 278 5eb9bac0 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 279 slb_allocate(pc); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 280 5eb9bac0 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 281 if (!esids_match(pc, stack)) ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 282 slb_allocate(stack); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 283 de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 284 if (!esids_match(pc, exec_base) && de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 285 !esids_match(stack, exec_base)) de4376c2 arch/powerpc/mm/slb.c Anton Blanchard 2009-07-13 286 slb_allocate(exec_base); ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 287 } ^1da177e arch/ppc64/mm/slb.c Linus Torvalds 2005-04-16 288 :::::: The code at line 258 was first introduced by commit :::::: 1189be6508d45183013ddb82b18f4934193de274 [POWERPC] Use 1TB segments :::::: TO: Paul Mackerras <pau...@samba.org> :::::: CC: Paul Mackerras <pau...@samba.org> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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