+Kees On Wed, Feb 14, 2018 at 04:45:25PM -0600, Josh Poimboeuf wrote: > On Wed, Feb 14, 2018 at 04:24:12PM -0600, Josh Poimboeuf wrote: > > On Wed, Feb 14, 2018 at 04:11:15PM +0100, Arnd Bergmann wrote: > > > Hi Josh, > > > > > > I recently did some randconfig testing with a plain 4.14-stable kernel > > > and gcc-7.3.0, and came across three distinct objtool warnings: > > > > > > drivers/misc/lkdtm_bugs.o: warning: objtool: > > > lkdtm_CORRUPT_LIST_ADD()+0x15: return with modified stack frame > > While this is probably an objtool bug, the code is very odd: > > 00000000000001a8 <lkdtm_CORRUPT_LIST_ADD>: > 1a8: e8 00 00 00 00 callq 1ad <lkdtm_CORRUPT_LIST_ADD+0x5> > 1a9: R_X86_64_PC32 __fentry__-0x4 > 1ad: 55 push %rbp > 1ae: 48 89 e5 mov %rsp,%rbp > 1b1: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp > 1b5: 48 83 ec 20 sub $0x20,%rsp > 1b9: 48 89 ec mov %rbp,%rsp > 1bc: 5d pop %rbp > 1bd: c3 retq > > The function just allocates/aligns its stack space and then returns. It > seems like GCC was too smart for its own good here, as the function > doesn't test what it's supposed to. Can you share the config for this > one? lkdtm is a "interesting" module in that it tries to do bad things to test for various stuff. Kees, does the above look like it is doing the correct thing? thanks, greg k-h