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
crypto/asymmetric_keys/x509_cert_parser.o: warning: objtool: x509_note_pkey_algo()+0xa4: sibling call from callable instruction with modified stack frame
drivers/infiniband/hw/bnxt_re/qplib_fp.o: warning: objtool: bnxt_qplib_poll_cq()+0x106: sibling call from callable instruction with modified stack frame
It's likely that this is the complete set at the moment, I saw each one multiple times, but did not see any others. I'll reply with the respective object files for your reference, in case these are so far unknown to you. There are only a handful of randconfig warnings we see overall in the kernel these days (at least on x86 and arm64), so even if they are false-positive, it would be great to get rid of the output so we can do randconfig testing on 4.14.y and treat any output from 'make -s' as a regression. I did not check
The third one has been fixed upstream with
99ce7962d52d ("objtool: Fix switch-table detection")
... so we should put that one into stable.
I don't recall seeing the other two, I'll look into them.
With gcc-8, things are looking very differently, and we still get an endless supply of similar warnings.
Yeah, I haven't forgotten about GCC 8, it just fell off my plate thanks to spectre/meltdown. It's still on my TODO list...