On Wed, Dec 30, 2020 at 5:28 AM Jiri Olsa <jo...@redhat.com> wrote: > > On Wed, Dec 30, 2020 at 10:03:37AM +0100, Jiri Olsa wrote: > > On Tue, Dec 29, 2020 at 11:28:35PM +0000, Qais Yousef wrote: > > > Hi Jiri > > > > > > On 12/29/20 18:34, Jiri Olsa wrote: > > > > On Tue, Dec 29, 2020 at 03:13:52PM +0000, Qais Yousef wrote: > > > > > Hi > > > > > > > > > > When I enable CONFIG_DEBUG_INFO_BTF I get the following error in the > > > > > BTFIDS > > > > > stage > > > > > > > > > > FAILED unresolved symbol udp6_sock > > > > > > > > > > I cross compile for arm64. My .config is attached. > > > > > > > > > > I managed to reproduce the problem on v5.9 and v5.10. Plus 5.11-rc1. > > > > > > > > > > Have you seen this before? I couldn't find a specific report about > > > > > this > > > > > problem. > > > > > > > > > > Let me know if you need more info. > > > > > > > > hi, > > > > this looks like symptom of the gcc DWARF bug we were > > > > dealing with recently: > > > > > > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060 > > > > > > > > https://lore.kernel.org/lkml/CAE1WUT75gu9G62Q9uAALGN6vLX=o7vz9uhqtvwnbuv81dgm...@mail.gmail.com/#r > > > > > > > > what pahole/gcc version are you using? > > > > > > I'm on gcc 9.3.0 > > > > > > aarch64-linux-gnu-gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0 > > > > > > I was on pahole v1.17. I moved to v1.19 but I still see the same problem. > > > > I can reproduce with your .config, but make 'defconfig' works, > > so I guess it's some config option issue, I'll check later today > > so your .config has > CONFIG_CRYPTO_DEV_BCM_SPU=y > > and that defines 'struct device_private' which > clashes with the same struct defined in drivers/base/base.h > > so several networking structs will be doubled, like net_device: > > $ bpftool btf dump file ../vmlinux.config | grep net_device\' | grep > STRUCT > [2731] STRUCT 'net_device' size=2240 vlen=133 > [113981] STRUCT 'net_device' size=2240 vlen=133 > > each is using different 'struct device_private' when it's unwinded > > and that will confuse BTFIDS logic, becase we have multiple structs > with the same name, and we can't be sure which one to pick > > perhaps we should check on this in pahole and warn earlier with > better error message.. I'll check, but I'm not sure if pahole can > survive another hastab ;-) > > Andrii, any ideas on this? ;-)
It's both unavoidable and correct from the C type system's perspective, so there is nothing for pahole to warn about. We used to have (for a long time) a similar clash with two completely different ring_buffer structs. Eventually they just got renamed to avoid duplication of related structs (task_struct and tons of other). But both BTF dedup and CO-RE relocation algorithms are designed to handle this correctly, so perhaps BTFIDS should be able to handle this as well? > > easy fix is the patch below that renames the bcm's structs, > it makes the kernel to compile.. but of course the new name > is probably wrong and we should push this through that code > authors In this case, I think renaming generic device_private name is a good thing regardless. > > jirka > > > --- [...]
