Messages in this thread | | | Date | Tue, 19 Dec 2023 01:16:46 +0000 | From | Carlos Llamas <> | Subject | Re: [PATCH] scripts/decode_stacktrace.sh: optionally use LLVM utilities |
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On Tue, Dec 19, 2023 at 12:23:18AM +0000, Justin Stitt wrote: > Hi, > > On Fri, Sep 29, 2023 at 03:48:17AM +0000, Carlos Llamas wrote: > > GNU's addr2line can have problems parsing a vmlinux built with LLVM, > > particularly when LTO was used. In order to decode the traces correctly > > this patch adds the ability to switch to LLVM's utilities readelf and > > addr2line. The same approach is followed by Will in [1]. > > > > Before: > > $ scripts/decode_stacktrace.sh vmlinux < kernel.log > > [17716.240635] Call trace: > > [17716.240646] skb_cow_data (??:?) > > [17716.240654] esp6_input (ld-temp.o:?) > > [17716.240666] xfrm_input (ld-temp.o:?) > > [17716.240674] xfrm6_rcv (??:?) > > [...] > > Perhaps it is due to where I am dumping the stack, but I am getting good > stack traces on mainline (with a LLVM-built kernel) without this patch.
Maybe you have set CROSS_COMPILE=llvm- in your environment? This is an alternative workaround. I write more about this in the commit log.
> > With that being said, applying this patch still has good stack traces > and it makes sense if it helps others. > > > > > After: > > $ LLVM=1 scripts/decode_stacktrace.sh vmlinux < kernel.log > > [17716.240635] Call trace: > > [17716.240646] skb_cow_data (include/linux/skbuff.h:2172 net/core/skbuff.c:4503) > > [17716.240654] esp6_input (net/ipv6/esp6.c:977) > > [17716.240666] xfrm_input (net/xfrm/xfrm_input.c:659) > > [17716.240674] xfrm6_rcv (net/ipv6/xfrm6_input.c:172) > > [...] > > > > Note that one could set CROSS_COMPILE=llvm- instead to hack around this > > issue. However, doing so can break the decodecode routine as it will > > force the selection of other LLVM utilities down the line e.g. llvm-as. > > > > [1] https://lore.kernel.org/all/20230914131225.13415-3-will@kernel.org/ > > > > Cc: Will Deacon <will@kernel.org> > > Cc: John Stultz <jstultz@google.com> > > Cc: Masahiro Yamada <masahiroy@kernel.org> > > Signed-off-by: Carlos Llamas <cmllamas@google.com> > > Tested-by: Justin Stitt <justinstitt@google.com> > > Note that this patch is similar: https://lore.kernel.org/all/20231215-llvm-decode-stacktrace-v1-1-201cb86f4879@quicinc.com/
Ha, I see. Elliot's patch help revive this thread. Cool!
-- Thanks, Carlos Llamas
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