* Check pahole availibity and BPF support of toolchain before starting a Linux kernel build @ 2021-01-11 12:48 Sedat Dilek 2021-01-11 16:05 ` Yonghong Song 0 siblings, 1 reply; 19+ messages in thread From: Sedat Dilek @ 2021-01-11 12:48 UTC (permalink / raw) To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend, KP Singh, Masahiro Yamada Cc: bpf, linux-kbuild Hi BPF maintainers and Mashiro, Debian started to use CONFIG_DEBUG_INFO_BTF=y. My kernel-build fails like this: + info BTFIDS vmlinux + [ != silent_ ] + printf %-7s %s\n BTFIDS vmlinux BTFIDS vmlinux + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux FAILED: load BTF from vmlinux: Invalid argument The root cause is my selfmade LLVM toolchain has no BPF support. $ which llc /home/dileks/src/llvm-toolchain/install/bin/llc $ llc --version LLVM (http://llvm.org/): LLVM version 11.0.1 Optimized build. Default target: x86_64-unknown-linux-gnu Host CPU: sandybridge Registered Targets: x86 - 32-bit X86: Pentium-Pro and above x86-64 - 64-bit X86: EM64T and AMD64 Debian's llc-11 shows me BPF support is built-in. I see the breakag approx. 3 hours after the start of my kernel-build - in the stage "vmlinux". After 2 faulures in my build (2x 3 hours of build-time) I have still no finished Linux v5.11-rc3 kernel. This is a bit frustrating. What about doing pre-checks - means before doing a single line of compilation - to check for: 1. Required binaries 2. Required support of whatever feature in compiler, linker, toolchain etc. Recently, I fell over depmod binary not found in my PATH - in one of the last steps (modfinal) of the kernel build. Any ideas to improve the situation? ( ...and please no RTFM, see links below. ) Thanks. Regards, - Sedat - [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-11 12:48 Check pahole availibity and BPF support of toolchain before starting a Linux kernel build Sedat Dilek @ 2021-01-11 16:05 ` Yonghong Song 2021-01-11 17:56 ` Sedat Dilek 0 siblings, 1 reply; 19+ messages in thread From: Yonghong Song @ 2021-01-11 16:05 UTC (permalink / raw) To: sedat.dilek, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada Cc: bpf, linux-kbuild On 1/11/21 4:48 AM, Sedat Dilek wrote: > Hi BPF maintainers and Mashiro, > > Debian started to use CONFIG_DEBUG_INFO_BTF=y. > > My kernel-build fails like this: > > + info BTFIDS vmlinux > + [ != silent_ ] > + printf %-7s %s\n BTFIDS vmlinux > BTFIDS vmlinux > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > FAILED: load BTF from vmlinux: Invalid argument > > The root cause is my selfmade LLVM toolchain has no BPF support. linux build should depend on LLVM toolchain unless you use LLVM to build kernel. > > $ which llc > /home/dileks/src/llvm-toolchain/install/bin/llc > > $ llc --version > LLVM (http://llvm.org/ ): > LLVM version 11.0.1 > Optimized build. > Default target: x86_64-unknown-linux-gnu > Host CPU: sandybridge > > Registered Targets: > x86 - 32-bit X86: Pentium-Pro and above > x86-64 - 64-bit X86: EM64T and AMD64 > > Debian's llc-11 shows me BPF support is built-in. > > I see the breakag approx. 3 hours after the start of my kernel-build - > in the stage "vmlinux". > After 2 faulures in my build (2x 3 hours of build-time) I have still > no finished Linux v5.11-rc3 kernel. > This is a bit frustrating. You mean "BTFIDS vmlinux" takes more than 3 hours here? Maybe a bug in resolve_btfids due to somehow different ELF format resolve_btfids need to handle? > > What about doing pre-checks - means before doing a single line of > compilation - to check for: > 1. Required binaries > 2. Required support of whatever feature in compiler, linker, toolchain etc. > > Recently, I fell over depmod binary not found in my PATH - in one of > the last steps (modfinal) of the kernel build. > > Any ideas to improve the situation? > ( ...and please no RTFM, see links below. ) > > Thanks. > > Regards, > - Sedat - > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 > [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f > [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm > [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-11 16:05 ` Yonghong Song @ 2021-01-11 17:56 ` Sedat Dilek 2021-01-11 21:03 ` Andrii Nakryiko 0 siblings, 1 reply; 19+ messages in thread From: Sedat Dilek @ 2021-01-11 17:56 UTC (permalink / raw) To: Yonghong Song Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, linux-kbuild, Tom Stellard On Mon, Jan 11, 2021 at 5:05 PM Yonghong Song <yhs@fb.com> wrote: > > > > On 1/11/21 4:48 AM, Sedat Dilek wrote: > > Hi BPF maintainers and Mashiro, > > > > Debian started to use CONFIG_DEBUG_INFO_BTF=y. > > > > My kernel-build fails like this: > > > > + info BTFIDS vmlinux > > + [ != silent_ ] > > + printf %-7s %s\n BTFIDS vmlinux > > BTFIDS vmlinux > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > FAILED: load BTF from vmlinux: Invalid argument > > > > The root cause is my selfmade LLVM toolchain has no BPF support. > > linux build should depend on LLVM toolchain unless you use LLVM to build > kernel. > > > > > $ which llc > > /home/dileks/src/llvm-toolchain/install/bin/llc > > > > $ llc --version > > LLVM (http://llvm.org/ ): > > LLVM version 11.0.1 > > Optimized build. > > Default target: x86_64-unknown-linux-gnu > > Host CPU: sandybridge > > > > Registered Targets: > > x86 - 32-bit X86: Pentium-Pro and above > > x86-64 - 64-bit X86: EM64T and AMD64 > > > > Debian's llc-11 shows me BPF support is built-in. > > > > I see the breakag approx. 3 hours after the start of my kernel-build - > > in the stage "vmlinux". > > After 2 faulures in my build (2x 3 hours of build-time) I have still > > no finished Linux v5.11-rc3 kernel. > > This is a bit frustrating. > > You mean "BTFIDS vmlinux" takes more than 3 hours here? > Maybe a bug in resolve_btfids due to somehow different ELF format > resolve_btfids need to handle? > [ CC Tom ] OMG no. 3 hours up to running scripts/link-vmlinux.sh. In the meantime I have built a LLVM toolchain with BPF support. $ llc --version LLVM (http://llvm.org/): LLVM version 11.0.1 Optimized build. Default target: x86_64-unknown-linux-gnu Host CPU: sandybridge Registered Targets: bpf - BPF (host endian) bpfeb - BPF (big endian) bpfel - BPF (little endian) x86 - 32-bit X86: Pentium-Pro and above x86-64 - 64-bit X86: EM64T and AMD64 Tom reported BTF issues with pahole v1.19 (see [2] and [3]): "I ran into this same bug trying to build the Fedora kernel. The problem is that pahole segfaults at: scripts/link-vmlinux.sh:131. This looks to me like a bug in pahole." pahole ToT (post v1.19) offers some BTF fixes - I have manually build and use it. Building a new Linux-kernel... - Sedat - [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > What about doing pre-checks - means before doing a single line of > > compilation - to check for: > > 1. Required binaries > > 2. Required support of whatever feature in compiler, linker, toolchain etc. > > > > Recently, I fell over depmod binary not found in my PATH - in one of > > the last steps (modfinal) of the kernel build. > > > > Any ideas to improve the situation? > > ( ...and please no RTFM, see links below. ) > > > > Thanks. > > > > Regards, > > - Sedat - > > > > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 > > [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f > > [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm > > [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation > > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-11 17:56 ` Sedat Dilek @ 2021-01-11 21:03 ` Andrii Nakryiko [not found] ` <CA+icZUVrF_LCVhELbNLA7=FzEZK4=jk3QLD9XT2w5bQNo=nnOA@mail.gmail.com> 0 siblings, 1 reply; 19+ messages in thread From: Andrii Nakryiko @ 2021-01-11 21:03 UTC (permalink / raw) To: sedat.dilek, Jiri Olsa Cc: Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On Mon, Jan 11, 2021 at 9:56 AM Sedat Dilek <sedat.dilek@gmail.com> wrote: > > On Mon, Jan 11, 2021 at 5:05 PM Yonghong Song <yhs@fb.com> wrote: > > > > > > > > On 1/11/21 4:48 AM, Sedat Dilek wrote: > > > Hi BPF maintainers and Mashiro, > > > > > > Debian started to use CONFIG_DEBUG_INFO_BTF=y. > > > > > > My kernel-build fails like this: > > > > > > + info BTFIDS vmlinux > > > + [ != silent_ ] > > > + printf %-7s %s\n BTFIDS vmlinux > > > BTFIDS vmlinux > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > The root cause is my selfmade LLVM toolchain has no BPF support. > > > > linux build should depend on LLVM toolchain unless you use LLVM to build > > kernel. > > > > > > > > $ which llc > > > /home/dileks/src/llvm-toolchain/install/bin/llc > > > > > > $ llc --version > > > LLVM (http://llvm.org/ ): > > > LLVM version 11.0.1 > > > Optimized build. > > > Default target: x86_64-unknown-linux-gnu > > > Host CPU: sandybridge > > > > > > Registered Targets: > > > x86 - 32-bit X86: Pentium-Pro and above > > > x86-64 - 64-bit X86: EM64T and AMD64 > > > > > > Debian's llc-11 shows me BPF support is built-in. > > > > > > I see the breakag approx. 3 hours after the start of my kernel-build - > > > in the stage "vmlinux". > > > After 2 faulures in my build (2x 3 hours of build-time) I have still > > > no finished Linux v5.11-rc3 kernel. > > > This is a bit frustrating. > > > > You mean "BTFIDS vmlinux" takes more than 3 hours here? > > Maybe a bug in resolve_btfids due to somehow different ELF format > > resolve_btfids need to handle? > > > > [ CC Tom ] > > OMG no. > > 3 hours up to running scripts/link-vmlinux.sh. > > In the meantime I have built a LLVM toolchain with BPF support. > > $ llc --version > LLVM (http://llvm.org/): > LLVM version 11.0.1 > Optimized build. > Default target: x86_64-unknown-linux-gnu > Host CPU: sandybridge > > Registered Targets: > bpf - BPF (host endian) > bpfeb - BPF (big endian) > bpfel - BPF (little endian) As Yonghong mentioned, you don't need BPF target support in Clang to build the kernel, so the issue is elsewhere. It's somewhere between generated DWARF (we've seen multiple bugs in DWARF over time), pahole's BTF output and resolve_btfids's handling of that BTF. I've CC'ed Jiri, who can help with resolve_btfids. Meanwhile, if you can provide SHA from which you built Clang, kernel config you used, and probably exact invocation of the build you used, it would help reproduce the issue. > x86 - 32-bit X86: Pentium-Pro and above > x86-64 - 64-bit X86: EM64T and AMD64 > > Tom reported BTF issues with pahole v1.19 (see [2] and [3]): > "I ran into this same bug trying to build the Fedora kernel. The > problem is that pahole segfaults at: scripts/link-vmlinux.sh:131. This > looks to me like a bug in pahole." > > pahole ToT (post v1.19) offers some BTF fixes - I have manually build > and use it. > > Building a new Linux-kernel... > > - Sedat - > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 There are no significant bug fixes between pahole 1.19 and master that would solve this problem, so let's try to repro this. > > > > > > > > > What about doing pre-checks - means before doing a single line of > > > compilation - to check for: > > > 1. Required binaries > > > 2. Required support of whatever feature in compiler, linker, toolchain etc. > > > > > > Recently, I fell over depmod binary not found in my PATH - in one of > > > the last steps (modfinal) of the kernel build. > > > > > > Any ideas to improve the situation? > > > ( ...and please no RTFM, see links below. ) > > > > > > Thanks. > > > > > > Regards, > > > - Sedat - > > > > > > > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 > > > [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f > > > [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm > > > [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation > > > ^ permalink raw reply [flat|nested] 19+ messages in thread
[parent not found: <CA+icZUVrF_LCVhELbNLA7=FzEZK4=jk3QLD9XT2w5bQNo=nnOA@mail.gmail.com>]
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build [not found] ` <CA+icZUVrF_LCVhELbNLA7=FzEZK4=jk3QLD9XT2w5bQNo=nnOA@mail.gmail.com> @ 2021-01-11 22:31 ` Jiri Olsa 2021-01-11 22:34 ` Tom Stellard 2021-01-14 14:13 ` Sedat Dilek 2021-01-12 0:57 ` Yonghong Song 1 sibling, 2 replies; 19+ messages in thread From: Jiri Olsa @ 2021-01-11 22:31 UTC (permalink / raw) To: Sedat Dilek Cc: Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: SNIP > > > > > > Building a new Linux-kernel... > > > > > > - Sedat - > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > There are no significant bug fixes between pahole 1.19 and master that > > would solve this problem, so let's try to repro this. > > > > You are right pahole fom latest Git does not solve the issue. > > + info BTFIDS vmlinux > + [ != silent_ ] > + printf %-7s %s\n BTFIDS vmlinux > BTFIDS vmlinux > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > FAILED: load BTF from vmlinux: Invalid argument hm, is there a .BTF section in vmlinux? is this working over vmlinux: $ bpftool btf dump file ./vmlinux do you have a verbose build output? I'd think pahole scream first.. jirka ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-11 22:31 ` Jiri Olsa @ 2021-01-11 22:34 ` Tom Stellard 2021-01-12 10:46 ` Jiri Olsa 2021-01-14 14:13 ` Sedat Dilek 1 sibling, 1 reply; 19+ messages in thread From: Tom Stellard @ 2021-01-11 22:34 UTC (permalink / raw) To: Jiri Olsa, Sedat Dilek Cc: Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On 1/11/21 2:31 PM, Jiri Olsa wrote: > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > SNIP > >>>> >>>> Building a new Linux-kernel... >>>> >>>> - Sedat - >>>> >>>> [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ >>>> [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 >>>> [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 >>> >>> There are no significant bug fixes between pahole 1.19 and master that >>> would solve this problem, so let's try to repro this. >>> >> >> You are right pahole fom latest Git does not solve the issue. >> >> + info BTFIDS vmlinux >> + [ != silent_ ] >> + printf %-7s %s\n BTFIDS vmlinux >> BTFIDS vmlinux >> + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux >> FAILED: load BTF from vmlinux: Invalid argument > > hm, is there a .BTF section in vmlinux? > > is this working over vmlinux: > $ bpftool btf dump file ./vmlinux > > do you have a verbose build output? I'd think pahole scream first.. > It does. For me, pahole segfaults at scripts/link-vmlinux.sh:131. This is pretty easy for me to reproduce. I have logs, what other information would be helpful? How about a pahole backtrace? -Tom > jirka > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-11 22:34 ` Tom Stellard @ 2021-01-12 10:46 ` Jiri Olsa 2021-01-12 13:10 ` Jiri Olsa 0 siblings, 1 reply; 19+ messages in thread From: Jiri Olsa @ 2021-01-12 10:46 UTC (permalink / raw) To: Tom Stellard Cc: Sedat Dilek, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On Mon, Jan 11, 2021 at 02:34:04PM -0800, Tom Stellard wrote: > On 1/11/21 2:31 PM, Jiri Olsa wrote: > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > SNIP > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > - Sedat - > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > + info BTFIDS vmlinux > > > + [ != silent_ ] > > > + printf %-7s %s\n BTFIDS vmlinux > > > BTFIDS vmlinux > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > FAILED: load BTF from vmlinux: Invalid argument > > > > hm, is there a .BTF section in vmlinux? > > > > is this working over vmlinux: > > $ bpftool btf dump file ./vmlinux > > > > do you have a verbose build output? I'd think pahole scream first.. > > > > It does. For me, pahole segfaults at scripts/link-vmlinux.sh:131. This is > pretty easy for me to reproduce. I have logs, what other information would > be helpful? How about a pahole backtrace? that'd be great.. I'll try to reproduce, but with the latest clang it will take me some time jirka > > -Tom > > > jirka > > > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 10:46 ` Jiri Olsa @ 2021-01-12 13:10 ` Jiri Olsa 2021-01-12 16:14 ` Sedat Dilek 0 siblings, 1 reply; 19+ messages in thread From: Jiri Olsa @ 2021-01-12 13:10 UTC (permalink / raw) To: Tom Stellard Cc: Sedat Dilek, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On Tue, Jan 12, 2021 at 11:46:22AM +0100, Jiri Olsa wrote: > On Mon, Jan 11, 2021 at 02:34:04PM -0800, Tom Stellard wrote: > > On 1/11/21 2:31 PM, Jiri Olsa wrote: > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > > > SNIP > > > > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > > > - Sedat - > > > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > > > + info BTFIDS vmlinux > > > > + [ != silent_ ] > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > BTFIDS vmlinux > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > hm, is there a .BTF section in vmlinux? > > > > > > is this working over vmlinux: > > > $ bpftool btf dump file ./vmlinux > > > > > > do you have a verbose build output? I'd think pahole scream first.. > > > > > > > It does. For me, pahole segfaults at scripts/link-vmlinux.sh:131. This is > > pretty easy for me to reproduce. I have logs, what other information would > > be helpful? How about a pahole backtrace? > > that'd be great.. I'll try to reproduce, but with the latest clang > it will take me some time reproduced, attached pahole patch fixes it for me, looks like gcc never left function without name, which does not seem to be the case for clang I'll send full patch later today jirka --- diff --git a/btf_encoder.c b/btf_encoder.c index c40f059580da..781fb35a2646 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -70,6 +70,8 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym) return 0; if (!elf_sym__value(sym)) return 0; + if (!elf_sym__name(sym, btfe->symtab)) + return 0; if (functions_cnt == functions_alloc) { functions_alloc = max(1000, functions_alloc * 3 / 2); @@ -620,9 +622,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, if (!has_arg_names(cu, &fn->proto)) continue; if (functions_cnt) { - struct elf_function *func; + const char *name = function__name(fn, cu); + struct elf_function *func = NULL; - func = find_function(btfe, function__name(fn, cu)); + if (name) + func = find_function(btfe, name); if (!func || func->generated) continue; func->generated = true; ^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 13:10 ` Jiri Olsa @ 2021-01-12 16:14 ` Sedat Dilek 2021-01-12 16:21 ` Jiri Olsa 0 siblings, 1 reply; 19+ messages in thread From: Sedat Dilek @ 2021-01-12 16:14 UTC (permalink / raw) To: Jiri Olsa Cc: Tom Stellard, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On Tue, Jan 12, 2021 at 2:10 PM Jiri Olsa <jolsa@redhat.com> wrote: > > On Tue, Jan 12, 2021 at 11:46:22AM +0100, Jiri Olsa wrote: > > On Mon, Jan 11, 2021 at 02:34:04PM -0800, Tom Stellard wrote: > > > On 1/11/21 2:31 PM, Jiri Olsa wrote: > > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > > > > > SNIP > > > > > > > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > > > > > - Sedat - > > > > > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > > > > > + info BTFIDS vmlinux > > > > > + [ != silent_ ] > > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > > BTFIDS vmlinux > > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > > > hm, is there a .BTF section in vmlinux? > > > > > > > > is this working over vmlinux: > > > > $ bpftool btf dump file ./vmlinux > > > > > > > > do you have a verbose build output? I'd think pahole scream first.. > > > > > > > > > > It does. For me, pahole segfaults at scripts/link-vmlinux.sh:131. This is > > > pretty easy for me to reproduce. I have logs, what other information would > > > be helpful? How about a pahole backtrace? > > > > that'd be great.. I'll try to reproduce, but with the latest clang > > it will take me some time > > reproduced, attached pahole patch fixes it for me, > > looks like gcc never left function without name, > which does not seem to be the case for clang > > I'll send full patch later today > Thanks for the diff. Unfortunately, it does not apply on latest pahole git. $ git describe v1.19-7-gb688e3597060 - Sedat - > jirka > > > --- > diff --git a/btf_encoder.c b/btf_encoder.c > index c40f059580da..781fb35a2646 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -70,6 +70,8 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym) > return 0; > if (!elf_sym__value(sym)) > return 0; > + if (!elf_sym__name(sym, btfe->symtab)) > + return 0; > > if (functions_cnt == functions_alloc) { > functions_alloc = max(1000, functions_alloc * 3 / 2); > @@ -620,9 +622,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > if (!has_arg_names(cu, &fn->proto)) > continue; > if (functions_cnt) { > - struct elf_function *func; > + const char *name = function__name(fn, cu); > + struct elf_function *func = NULL; > > - func = find_function(btfe, function__name(fn, cu)); > + if (name) > + func = find_function(btfe, name); > if (!func || func->generated) > continue; > func->generated = true; > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 16:14 ` Sedat Dilek @ 2021-01-12 16:21 ` Jiri Olsa 2021-01-12 17:18 ` Sedat Dilek 2021-01-12 20:47 ` Sedat Dilek 0 siblings, 2 replies; 19+ messages in thread From: Jiri Olsa @ 2021-01-12 16:21 UTC (permalink / raw) To: Sedat Dilek Cc: Tom Stellard, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On Tue, Jan 12, 2021 at 05:14:42PM +0100, Sedat Dilek wrote: > On Tue, Jan 12, 2021 at 2:10 PM Jiri Olsa <jolsa@redhat.com> wrote: > > > > On Tue, Jan 12, 2021 at 11:46:22AM +0100, Jiri Olsa wrote: > > > On Mon, Jan 11, 2021 at 02:34:04PM -0800, Tom Stellard wrote: > > > > On 1/11/21 2:31 PM, Jiri Olsa wrote: > > > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > > > > > > > SNIP > > > > > > > > > > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > > > > > > > - Sedat - > > > > > > > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > > > > > > > + info BTFIDS vmlinux > > > > > > + [ != silent_ ] > > > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > > > BTFIDS vmlinux > > > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > > > > > hm, is there a .BTF section in vmlinux? > > > > > > > > > > is this working over vmlinux: > > > > > $ bpftool btf dump file ./vmlinux > > > > > > > > > > do you have a verbose build output? I'd think pahole scream first.. > > > > > > > > > > > > > It does. For me, pahole segfaults at scripts/link-vmlinux.sh:131. This is > > > > pretty easy for me to reproduce. I have logs, what other information would > > > > be helpful? How about a pahole backtrace? > > > > > > that'd be great.. I'll try to reproduce, but with the latest clang > > > it will take me some time > > > > reproduced, attached pahole patch fixes it for me, > > > > looks like gcc never left function without name, > > which does not seem to be the case for clang > > > > I'll send full patch later today > > > > Thanks for the diff. > > Unfortunately, it does not apply on latest pahole git. > > $ git describe > v1.19-7-gb688e3597060 sry wrong master.. how about this one jirka --- diff --git a/btf_encoder.c b/btf_encoder.c index 333973054b61..17f7a14f2ef0 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -72,6 +72,8 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym) if (elf_sym__type(sym) != STT_FUNC) return 0; + if (!elf_sym__name(sym, btfe->symtab)) + return 0; if (functions_cnt == functions_alloc) { functions_alloc = max(1000, functions_alloc * 3 / 2); @@ -730,9 +732,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, if (!has_arg_names(cu, &fn->proto)) continue; if (functions_cnt) { - struct elf_function *func; + const char *name = function__name(fn, cu); + struct elf_function *func = NULL; - func = find_function(btfe, function__name(fn, cu)); + if (name) + func = find_function(btfe, name); if (!func || func->generated) continue; func->generated = true; -- 2.26.2 ^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 16:21 ` Jiri Olsa @ 2021-01-12 17:18 ` Sedat Dilek 2021-01-12 20:47 ` Sedat Dilek 1 sibling, 0 replies; 19+ messages in thread From: Sedat Dilek @ 2021-01-12 17:18 UTC (permalink / raw) To: Jiri Olsa Cc: Tom Stellard, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On Tue, Jan 12, 2021 at 5:22 PM Jiri Olsa <jolsa@redhat.com> wrote: > > On Tue, Jan 12, 2021 at 05:14:42PM +0100, Sedat Dilek wrote: > > On Tue, Jan 12, 2021 at 2:10 PM Jiri Olsa <jolsa@redhat.com> wrote: > > > > > > On Tue, Jan 12, 2021 at 11:46:22AM +0100, Jiri Olsa wrote: > > > > On Mon, Jan 11, 2021 at 02:34:04PM -0800, Tom Stellard wrote: > > > > > On 1/11/21 2:31 PM, Jiri Olsa wrote: > > > > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > > > > > > > > > SNIP > > > > > > > > > > > > > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > > > > > > > > > - Sedat - > > > > > > > > > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > > > > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > > > > > > > > > + info BTFIDS vmlinux > > > > > > > + [ != silent_ ] > > > > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > > > > BTFIDS vmlinux > > > > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > > > > > > > hm, is there a .BTF section in vmlinux? > > > > > > > > > > > > is this working over vmlinux: > > > > > > $ bpftool btf dump file ./vmlinux > > > > > > > > > > > > do you have a verbose build output? I'd think pahole scream first.. > > > > > > > > > > > > > > > > It does. For me, pahole segfaults at scripts/link-vmlinux.sh:131. This is > > > > > pretty easy for me to reproduce. I have logs, what other information would > > > > > be helpful? How about a pahole backtrace? > > > > > > > > that'd be great.. I'll try to reproduce, but with the latest clang > > > > it will take me some time > > > > > > reproduced, attached pahole patch fixes it for me, > > > > > > looks like gcc never left function without name, > > > which does not seem to be the case for clang > > > > > > I'll send full patch later today > > > > > > > Thanks for the diff. > > > > Unfortunately, it does not apply on latest pahole git. > > > > $ git describe > > v1.19-7-gb688e3597060 > > sry wrong master.. how about this one > I have applied the previous diff on top of tagsv1.19. Thanks for the follow-up. Please CC me on the patch you wanted to send later. - Sedat - > jirka > > > --- > diff --git a/btf_encoder.c b/btf_encoder.c > index 333973054b61..17f7a14f2ef0 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -72,6 +72,8 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym) > > if (elf_sym__type(sym) != STT_FUNC) > return 0; > + if (!elf_sym__name(sym, btfe->symtab)) > + return 0; > > if (functions_cnt == functions_alloc) { > functions_alloc = max(1000, functions_alloc * 3 / 2); > @@ -730,9 +732,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > if (!has_arg_names(cu, &fn->proto)) > continue; > if (functions_cnt) { > - struct elf_function *func; > + const char *name = function__name(fn, cu); > + struct elf_function *func = NULL; > > - func = find_function(btfe, function__name(fn, cu)); > + if (name) > + func = find_function(btfe, name); > if (!func || func->generated) > continue; > func->generated = true; > -- > 2.26.2 > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 16:21 ` Jiri Olsa 2021-01-12 17:18 ` Sedat Dilek @ 2021-01-12 20:47 ` Sedat Dilek 2021-01-12 21:36 ` Sedat Dilek 1 sibling, 1 reply; 19+ messages in thread From: Sedat Dilek @ 2021-01-12 20:47 UTC (permalink / raw) To: Jiri Olsa Cc: Tom Stellard, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list Is it possible that someone tests with Nick Desaulniers's DWARF v5 patchset? With b4 tool installed: link="https://lore.kernel.org/r/CAKwvOdkZEiHK01OD420USb0j=F0LcrnRbauv9Yw26tu-GRbYkg@mail.gmail.com" b4 -d am $link ...should give you a file which you can directly apply with git tool. File: v3_20201203_ndesaulniers_kbuild_make_dwarf_version_a_choice.mbx As my selfmade LLVM toolchain seems to be no good choice I jumped to gcc-10. I see gazillions of DW_AT_ and DW_TAG_INVALID (0x48) warnings: die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x1c2a25e> not handled! This might be due to DWARF version 5 patchset. I did not check DWARF v2 (default) or DWARF v4 choices. Beyond this, I noticed: $ git grep LLVM_OBJCOPY scripts/ tools/ scripts/Makefile.modfinal: LLVM_OBJCOPY=$(OBJCOPY) $(PAHOLE) -J --btf_base vmlinux $@; \ scripts/link-vmlinux.sh: LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} tools/testing/selftests/bpf/Makefile:LLVM_OBJCOPY ?= llvm-objcopy When only passing gcc-10 as compiler and ld.bfd as linker - LLVM_OBJCOPY=objcopy is passed. Means objcopy from GNU/binutils is used. As far as I understand the code you want here llvm-objcopy (scripts/Makefile.modfinal)? I did a next tryout with gcc-10 and LLVM=1 means use all equivalent LLVM tools to GNU/binutils. Means use llvm-objcopy, llvm-nm, llvm-ar, llvm-objdump, etc. Please see the link below under [1]. En plus, I tried pahole with Jirka "Convulted" Olsa (JCO) fix by passing... PAHOLE=/opt/pahole/bin/pahole ...to my make line. Again I see that DW_TAG_INVALID (0x48) warnings. Can someone enlighten me what that means? Finally, with all that warnings observed I could "successfully" generate Linux-kernel Debian packages. I do NOT install software I do NOT trust - not booted - NoNoNo... Thanks. In the dark, - Sedat - [1] https://www.kernel.org/doc/html/latest/kbuild/llvm.html#llvm-utilities ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 20:47 ` Sedat Dilek @ 2021-01-12 21:36 ` Sedat Dilek 0 siblings, 0 replies; 19+ messages in thread From: Sedat Dilek @ 2021-01-12 21:36 UTC (permalink / raw) To: Jiri Olsa Cc: Tom Stellard, Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list On Tue, Jan 12, 2021 at 9:47 PM Sedat Dilek <sedat.dilek@gmail.com> wrote: > En plus, I tried pahole with Jirka "Convulted" Olsa (JCO) fix by passing... > PAHOLE=/opt/pahole/bin/pahole > ...to my make line. > Grrr, my selfmade pahole misses that patch. How can I re-invoke make ... with new really fixed pahole version? Fallen into a (pa)hole, - Sedat - P.S.: Download Jiri's patch link="https://lore.kernel.org/bpf/20210112194724.GB1291051@krava/T/#t" b4 -d am $link - EOT - ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-11 22:31 ` Jiri Olsa 2021-01-11 22:34 ` Tom Stellard @ 2021-01-14 14:13 ` Sedat Dilek 2021-01-14 14:24 ` Jiri Olsa 1 sibling, 1 reply; 19+ messages in thread From: Sedat Dilek @ 2021-01-14 14:13 UTC (permalink / raw) To: Jiri Olsa Cc: Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On Mon, Jan 11, 2021 at 11:31 PM Jiri Olsa <jolsa@redhat.com> wrote: > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > SNIP > > > > > > > > > Building a new Linux-kernel... > > > > > > > > - Sedat - > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > would solve this problem, so let's try to repro this. > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > + info BTFIDS vmlinux > > + [ != silent_ ] > > + printf %-7s %s\n BTFIDS vmlinux > > BTFIDS vmlinux > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > FAILED: load BTF from vmlinux: Invalid argument > > hm, is there a .BTF section in vmlinux? > > is this working over vmlinux: > $ bpftool btf dump file ./vmlinux > I switched to LLVM v12 from <apt.llvm.org> and saw the same FAILED line. The generated vmlinux file is cleaned on failure. + info BTFIDS vmlinux + [ != silent_ ] + printf %-7s %s\n BTFIDS vmlinux BTFIDS vmlinux + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux FAILED: load BTF from vmlinux: Invalid argument + on_exit + [ 255 -ne 0 ] + cleanup + rm -f .btf.vmlinux.bin.o + rm -f .tmp_System.map + rm -f .tmp_initcalls.lds + rm -f .tmp_symversions.lds + rm -f .tmp_vmlinux.btf .tmp_vmlinux.kallsyms1 .tmp_vmlinux.kallsyms1.S .tmp_vmlinux.kallsyms1.o .tmp_vmlinux.kallsyms2 .tmp_vmlinux.kallsyms2.S .tmp_vmlinux.kallsyms 2.o + rm -f System.map + rm -f vmlinux + rm -f vmlinux.o Dunno, how to suppress this. - Sedat - > do you have a verbose build output? I'd think pahole scream first.. > > jirka > ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-14 14:13 ` Sedat Dilek @ 2021-01-14 14:24 ` Jiri Olsa 2021-01-14 14:29 ` Sedat Dilek 0 siblings, 1 reply; 19+ messages in thread From: Jiri Olsa @ 2021-01-14 14:24 UTC (permalink / raw) To: Sedat Dilek Cc: Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On Thu, Jan 14, 2021 at 03:13:18PM +0100, Sedat Dilek wrote: > On Mon, Jan 11, 2021 at 11:31 PM Jiri Olsa <jolsa@redhat.com> wrote: > > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > SNIP > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > - Sedat - > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > + info BTFIDS vmlinux > > > + [ != silent_ ] > > > + printf %-7s %s\n BTFIDS vmlinux > > > BTFIDS vmlinux > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > FAILED: load BTF from vmlinux: Invalid argument > > > > hm, is there a .BTF section in vmlinux? > > > > is this working over vmlinux: > > $ bpftool btf dump file ./vmlinux > > > > I switched to LLVM v12 from <apt.llvm.org> and saw the same FAILED line. > > The generated vmlinux file is cleaned on failure. > > + info BTFIDS vmlinux > + [ != silent_ ] > + printf %-7s %s\n BTFIDS vmlinux > BTFIDS vmlinux > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > FAILED: load BTF from vmlinux: Invalid argument did pahole generated the .BTF section? earlier in the log jirka ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-14 14:24 ` Jiri Olsa @ 2021-01-14 14:29 ` Sedat Dilek [not found] ` <CA+icZUXp5gkxCr+mybQ8uO3xx+rVmmRSnN7Dfx0Xmr+VQWyZAA@mail.gmail.com> 0 siblings, 1 reply; 19+ messages in thread From: Sedat Dilek @ 2021-01-14 14:29 UTC (permalink / raw) To: Jiri Olsa Cc: Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On Thu, Jan 14, 2021 at 3:24 PM Jiri Olsa <jolsa@redhat.com> wrote: > > On Thu, Jan 14, 2021 at 03:13:18PM +0100, Sedat Dilek wrote: > > On Mon, Jan 11, 2021 at 11:31 PM Jiri Olsa <jolsa@redhat.com> wrote: > > > > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > > > SNIP > > > > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > > > - Sedat - > > > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > > > + info BTFIDS vmlinux > > > > + [ != silent_ ] > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > BTFIDS vmlinux > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > hm, is there a .BTF section in vmlinux? > > > > > > is this working over vmlinux: > > > $ bpftool btf dump file ./vmlinux > > > > > > > I switched to LLVM v12 from <apt.llvm.org> and saw the same FAILED line. > > > > The generated vmlinux file is cleaned on failure. > > > > + info BTFIDS vmlinux > > + [ != silent_ ] > > + printf %-7s %s\n BTFIDS vmlinux > > BTFIDS vmlinux > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > FAILED: load BTF from vmlinux: Invalid argument > > did pahole generated the .BTF section? earlier in the log > > jirka > Cannot say. I did: $ git diff diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 2d0b28758aa5..c6e679d08bbe 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -401,12 +401,6 @@ fi vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} -# fill in BTF IDs -if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then - info BTFIDS vmlinux - ${RESOLVE_BTFIDS} vmlinux -fi - if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then info SORTTAB vmlinux if ! sorttable vmlinux; then - Sedat - ^ permalink raw reply related [flat|nested] 19+ messages in thread
[parent not found: <CA+icZUXp5gkxCr+mybQ8uO3xx+rVmmRSnN7Dfx0Xmr+VQWyZAA@mail.gmail.com>]
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build [not found] ` <CA+icZUXp5gkxCr+mybQ8uO3xx+rVmmRSnN7Dfx0Xmr+VQWyZAA@mail.gmail.com> @ 2021-01-14 15:13 ` Sedat Dilek 0 siblings, 0 replies; 19+ messages in thread From: Sedat Dilek @ 2021-01-14 15:13 UTC (permalink / raw) To: Jiri Olsa Cc: Andrii Nakryiko, Jiri Olsa, Yonghong Song, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard [-- Attachment #1: Type: text/plain, Size: 3509 bytes --] On Thu, Jan 14, 2021 at 3:50 PM Sedat Dilek <sedat.dilek@gmail.com> wrote: > > On Thu, Jan 14, 2021 at 3:29 PM Sedat Dilek <sedat.dilek@gmail.com> wrote: > > > > On Thu, Jan 14, 2021 at 3:24 PM Jiri Olsa <jolsa@redhat.com> wrote: > > > > > > On Thu, Jan 14, 2021 at 03:13:18PM +0100, Sedat Dilek wrote: > > > > On Mon, Jan 11, 2021 at 11:31 PM Jiri Olsa <jolsa@redhat.com> wrote: > > > > > > > > > > On Mon, Jan 11, 2021 at 10:30:22PM +0100, Sedat Dilek wrote: > > > > > > > > > > SNIP > > > > > > > > > > > > > > > > > > > > > Building a new Linux-kernel... > > > > > > > > > > > > > > > > - Sedat - > > > > > > > > > > > > > > > > [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > > > > > > > > [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > > > > > > > > [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > > > > > > > > > > > There are no significant bug fixes between pahole 1.19 and master that > > > > > > > would solve this problem, so let's try to repro this. > > > > > > > > > > > > > > > > > > > You are right pahole fom latest Git does not solve the issue. > > > > > > > > > > > > + info BTFIDS vmlinux > > > > > > + [ != silent_ ] > > > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > > > BTFIDS vmlinux > > > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > > > > > hm, is there a .BTF section in vmlinux? > > > > > > > > > > is this working over vmlinux: > > > > > $ bpftool btf dump file ./vmlinux > > > > > > > > > > > > > I switched to LLVM v12 from <apt.llvm.org> and saw the same FAILED line. > > > > > > > > The generated vmlinux file is cleaned on failure. > > > > > > > > + info BTFIDS vmlinux > > > > + [ != silent_ ] > > > > + printf %-7s %s\n BTFIDS vmlinux > > > > BTFIDS vmlinux > > > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > > > FAILED: load BTF from vmlinux: Invalid argument > > > > > > did pahole generated the .BTF section? earlier in the log > > > > > > jirka > > > > > > > Cannot say. > > > > I did: > > > > $ git diff > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index 2d0b28758aa5..c6e679d08bbe 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -401,12 +401,6 @@ fi > > > > vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} > > > > -# fill in BTF IDs > > -if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then > > - info BTFIDS vmlinux > > - ${RESOLVE_BTFIDS} vmlinux > > -fi > > - > > if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then > > info SORTTAB vmlinux > > if ! sorttable vmlinux; then > > > > Before... > > Encountered error while encoding BTF. > + llvm-objcopy --only-section=.BTF --set-section-flags > .BTF=alloc,readonly --strip-all .tmp_vmlinux.btf .btf.vmlinux.bin.o > > ...I see lots of errors. > > I have cut the relevant stuff and placed it in the attachment. > > With freshly installed bpftool: > > $ /usr/sbin/bpftool btf dump file ./vmlinux > Error: failed to load BTF from ./vmlinux: Invalid argument > This is with CONFIG_DEBUG_INFO_DWARF4=y. ( See attached patch with cover-letter - applied here on top of Linux v5.11-rc3+). Concerning this I am looking into [1]: die__process_unit: DW_TAG_label (0xa) @ <0xa7> not handled! die__process_unit: tag not supported 0xa (label)! - Sedat - [1] http://www.dwarfstd.org/doc/DWARF4.pdf > 3.5 LABEL ENTRIES [-- Attachment #2: v4_20210112_ndesaulniers_kbuild_dwarf_v5_support.cover --] [-- Type: application/octet-stream, Size: 3093 bytes --] Sender: "ndesaulniers via sendgmr" <ndesaulniers@ndesaulniers1.mtv.corp.google.com> Date: Tue, 12 Jan 2021 16:32:32 -0800 Message-Id: <20210113003235.716547-1-ndesaulniers@google.com> Subject: [PATCH v4 0/3] Kbuild: DWARF v5 support From: Nick Desaulniers <ndesaulniers@google.com> To: Masahiro Yamada <masahiroy@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Sedat Dilek <sedat.dilek@gmail.com>, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, Jakub Jelinek <jakub@redhat.com>, Fangrui Song <maskray@google.com>, Caroline Tice <cmtice@google.com>, Nick Clifton <nickc@redhat.com>, Nick Desaulniers <ndesaulniers@google.com> List-ID: <linux-arch.vger.kernel.org> X-Mailing-List: linux-arch@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit DWARF v5 is the latest standard of the DWARF debug info format. DWARF5 wins significantly in terms of size when mixed with compression (CONFIG_DEBUG_INFO_COMPRESSED). Link: http://www.dwarfstd.org/doc/DWARF5.pdf Patch 1 is a cleanup from Masahiro and isn't DWARF v5 specific. Patch 2 is a cleanup that lays the ground work and isn't DWARF v5 specific. Patch 3 implements Kconfig and Kbuild support for DWARFv5. Changes from v3: Changes as per Arvind: * only add -Wa,-gdwarf-5 for (LLVM=1|CC=clang)+LLVM_IAS=0 builds. * add -gdwarf-5 to Kconfig shell script. * only run Kconfig shell script for Clang. Apologies to Sedat and Nathan; I appreciate previous testing/review, but I did no carry forward your Tested-by and Reviewed-by tags, as the patches have changed too much IMO. Changes from v2: * Drop two of the earlier patches that have been accepted already. * Add measurements with GCC 10.2 to commit message. * Update help text as per Arvind with help from Caroline. * Improve case/wording between DWARF Versions as per Masahiro. Changes from the RFC: * split patch in 3 patch series, include Fangrui's patch, too. * prefer `DWARF vX` format, as per Fangrui. * use spaces between assignment in Makefile as per Masahiro. * simplify setting dwarf-version-y as per Masahiro. * indent `prompt` in Kconfig change as per Masahiro. * remove explicit default in Kconfig as per Masahiro. * add comments to test_dwarf5_support.sh. * change echo in test_dwarf5_support.sh as per Masahiro. * remove -u from test_dwarf5_support.sh as per Masahiro. * add a -gdwarf-5 cc-option check to Kconfig as per Jakub. Masahiro Yamada (1): Remove $(cc-option,-gdwarf-4) dependency from CONFIG_DEBUG_INFO_DWARF4 Nick Desaulniers (2): Kbuild: make DWARF version a choice Kbuild: implement support for DWARF v5 Makefile | 15 +++++++---- include/asm-generic/vmlinux.lds.h | 6 ++++- lib/Kconfig.debug | 41 +++++++++++++++++++++++++------ scripts/test_dwarf5_support.sh | 9 +++++++ 4 files changed, 58 insertions(+), 13 deletions(-) create mode 100755 scripts/test_dwarf5_support.sh -- 2.30.0.284.gd98b1dd5eaa7-goog [-- Attachment #3: v4_20210112_ndesaulniers_kbuild_dwarf_v5_support.mbx --] [-- Type: application/octet-stream, Size: 12905 bytes --] From MAILER-DAEMON Wed Jan 13 01:13:04 2021 Sender: "ndesaulniers via sendgmr" <ndesaulniers@ndesaulniers1.mtv.corp.google.com> Date: Tue, 12 Jan 2021 16:32:33 -0800 In-Reply-To: <20210113003235.716547-1-ndesaulniers@google.com> Message-Id: <20210113003235.716547-2-ndesaulniers@google.com> References: <20210113003235.716547-1-ndesaulniers@google.com> Subject: [PATCH v4 1/3] Remove $(cc-option,-gdwarf-4) dependency from CONFIG_DEBUG_INFO_DWARF4 From: Nick Desaulniers <ndesaulniers@google.com> To: Masahiro Yamada <masahiroy@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Sedat Dilek <sedat.dilek@gmail.com>, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, Jakub Jelinek <jakub@redhat.com>, Fangrui Song <maskray@google.com>, Caroline Tice <cmtice@google.com>, Nick Clifton <nickc@redhat.com>, Nick Desaulniers <ndesaulniers@google.com> List-ID: <linux-arch.vger.kernel.org> X-Mailing-List: linux-arch@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit From: Masahiro Yamada <masahiroy@kernel.org> The -gdwarf-4 flag is supported by GCC 4.5+, and also by Clang. You can see it at https://godbolt.org/z/6ed1oW For gcc 4.5.3 pane, line 37: .value 0x4 For clang 10.0.1 pane, line 117: .short 4 Given Documentation/process/changes.rst stating GCC 4.9 is the minimal version, this cc-option is unneeded. Note ---- CONFIG_DEBUG_INFO_DWARF4 controls the DWARF version only for C files. As you can see in the top Makefile, -gdwarf-4 is only passed to CFLAGS. ifdef CONFIG_DEBUG_INFO_DWARF4 DEBUG_CFLAGS += -gdwarf-4 endif This flag is used when compiling *.c files. On the other hand, the assembler is always given -gdwarf-2. KBUILD_AFLAGS += -Wa,-gdwarf-2 Hence, the debug info that comes from *.S files is always DWARF v2. This is simply because GAS supported only -gdwarf-2 for a long time. Recently, GAS gained the support for --dwarf-[3|4|5] options. [1] And, also we have Clang integrated assembler. So, the debug info for *.S files might be improved if we want. In my understanding, the current code is intentional, not a bug. [1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=31bf18645d98b4d3d7357353be840e320649a67d Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> --- lib/Kconfig.debug | 1 - 1 file changed, 1 deletion(-) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 78361f0abe3a..dd7d8d35b2a5 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -258,7 +258,6 @@ config DEBUG_INFO_SPLIT config DEBUG_INFO_DWARF4 bool "Generate dwarf4 debuginfo" - depends on $(cc-option,-gdwarf-4) help Generate dwarf4 debug info. This requires recent versions of gcc and gdb. It makes the debug information larger. -- 2.30.0.284.gd98b1dd5eaa7-goog From MAILER-DAEMON Wed Jan 13 01:13:04 2021 Sender: "ndesaulniers via sendgmr" <ndesaulniers@ndesaulniers1.mtv.corp.google.com> Date: Tue, 12 Jan 2021 16:32:34 -0800 In-Reply-To: <20210113003235.716547-1-ndesaulniers@google.com> Message-Id: <20210113003235.716547-3-ndesaulniers@google.com> References: <20210113003235.716547-1-ndesaulniers@google.com> Subject: [PATCH v4 2/3] Kbuild: make DWARF version a choice From: Nick Desaulniers <ndesaulniers@google.com> To: Masahiro Yamada <masahiroy@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Sedat Dilek <sedat.dilek@gmail.com>, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, Jakub Jelinek <jakub@redhat.com>, Fangrui Song <maskray@google.com>, Caroline Tice <cmtice@google.com>, Nick Clifton <nickc@redhat.com>, Nick Desaulniers <ndesaulniers@google.com> List-ID: <linux-arch.vger.kernel.org> X-Mailing-List: linux-arch@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Modifies CONFIG_DEBUG_INFO_DWARF4 to be a member of a choice. Adds an explicit CONFIG_DEBUG_INFO_DWARF2, which is the default. Does so in a way that's forward compatible with existing configs, and makes adding future versions more straightforward. Suggested-by: Fangrui Song <maskray@google.com> Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- Makefile | 14 +++++++++----- lib/Kconfig.debug | 21 ++++++++++++++++----- 2 files changed, 25 insertions(+), 10 deletions(-) diff --git a/Makefile b/Makefile index d49c3f39ceb4..656fff17b331 100644 --- a/Makefile +++ b/Makefile @@ -826,12 +826,16 @@ else DEBUG_CFLAGS += -g endif -ifneq ($(LLVM_IAS),1) -KBUILD_AFLAGS += -Wa,-gdwarf-2 +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF2) := 2 +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4 +DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y) +ifneq ($(dwarf-version-y)$(LLVM_IAS),21) +# Binutils 2.35+ required for -gdwarf-4+ support. +dwarf-aflag := $(call as-option,-Wa$(comma)-gdwarf-$(dwarf-version-y)) +ifdef CONFIG_CC_IS_CLANG +DEBUG_CFLAGS += $(dwarf-aflag) endif - -ifdef CONFIG_DEBUG_INFO_DWARF4 -DEBUG_CFLAGS += -gdwarf-4 +KBUILD_AFLAGS += $(dwarf-aflag) endif ifdef CONFIG_DEBUG_INFO_REDUCED diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index dd7d8d35b2a5..e80770fac4f0 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -256,13 +256,24 @@ config DEBUG_INFO_SPLIT to know about the .dwo files and include them. Incompatible with older versions of ccache. +choice + prompt "DWARF version" + help + Which version of DWARF debug info to emit. + +config DEBUG_INFO_DWARF2 + bool "Generate DWARF Version 2 debuginfo" + help + Generate DWARF v2 debug info. + config DEBUG_INFO_DWARF4 - bool "Generate dwarf4 debuginfo" + bool "Generate DWARF Version 4 debuginfo" help - Generate dwarf4 debug info. This requires recent versions - of gcc and gdb. It makes the debug information larger. - But it significantly improves the success of resolving - variables in gdb on optimized code. + Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. + It makes the debug information larger, but it significantly + improves the success of resolving variables in gdb on optimized code. + +endchoice # "DWARF version" config DEBUG_INFO_BTF bool "Generate BTF typeinfo" -- 2.30.0.284.gd98b1dd5eaa7-goog From MAILER-DAEMON Wed Jan 13 01:13:04 2021 Sender: "ndesaulniers via sendgmr" <ndesaulniers@ndesaulniers1.mtv.corp.google.com> Date: Tue, 12 Jan 2021 16:32:35 -0800 In-Reply-To: <20210113003235.716547-1-ndesaulniers@google.com> Message-Id: <20210113003235.716547-4-ndesaulniers@google.com> References: <20210113003235.716547-1-ndesaulniers@google.com> Subject: [PATCH v4 3/3] Kbuild: implement support for DWARF v5 From: Nick Desaulniers <ndesaulniers@google.com> To: Masahiro Yamada <masahiroy@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Sedat Dilek <sedat.dilek@gmail.com>, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, Jakub Jelinek <jakub@redhat.com>, Fangrui Song <maskray@google.com>, Caroline Tice <cmtice@google.com>, Nick Clifton <nickc@redhat.com>, Nick Desaulniers <ndesaulniers@google.com>, Arvind Sankar <nivedita@alum.mit.edu> List-ID: <linux-arch.vger.kernel.org> X-Mailing-List: linux-arch@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit DWARF v5 is the latest standard of the DWARF debug info format. Feature detection of DWARF5 is onerous, especially given that we've removed $(AS), so we must query $(CC) for DWARF5 assembler directive support. GNU `as` only recently gained support for specifying -gdwarf-5. The DWARF version of a binary can be validated with: $ llvm-dwarfdump vmlinux | head -n 4 | grep version or $ readelf --debug-dump=info vmlinux 2>/dev/null | grep Version DWARF5 wins significantly in terms of size when mixed with compression (CONFIG_DEBUG_INFO_COMPRESSED). 363M vmlinux.clang12.dwarf5.compressed 434M vmlinux.clang12.dwarf4.compressed 439M vmlinux.clang12.dwarf2.compressed 457M vmlinux.clang12.dwarf5 536M vmlinux.clang12.dwarf4 548M vmlinux.clang12.dwarf2 515M vmlinux.gcc10.2.dwarf5.compressed 599M vmlinux.gcc10.2.dwarf4.compressed 624M vmlinux.gcc10.2.dwarf2.compressed 630M vmlinux.gcc10.2.dwarf5 765M vmlinux.gcc10.2.dwarf4 809M vmlinux.gcc10.2.dwarf2 Though the quality of debug info is harder to quantify; size is not a proxy for quality. Jakub notes: All [GCC] 5.1 - 6.x did was start accepting -gdwarf-5 as experimental option that enabled some small DWARF subset (initially only a few DW_LANG_* codes newly added to DWARF5 drafts). Only GCC 7 (released after DWARF 5 has been finalized) started emitting DWARF5 section headers and got most of the DWARF5 changes in... Version check GCC so that we don't need to worry about the difference in command line args between GNU readelf and llvm-readelf/llvm-dwarfdump to validate the DWARF Version in the assembler feature detection script. Link: http://www.dwarfstd.org/doc/DWARF5.pdf Suggested-by: Arvind Sankar <nivedita@alum.mit.edu> Suggested-by: Jakub Jelinek <jakub@redhat.com> Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Suggested-by: Fangrui Song <maskray@google.com> Suggested-by: Caroline Tice <cmtice@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- Makefile | 1 + include/asm-generic/vmlinux.lds.h | 6 +++++- lib/Kconfig.debug | 17 +++++++++++++++++ scripts/test_dwarf5_support.sh | 9 +++++++++ 4 files changed, 32 insertions(+), 1 deletion(-) create mode 100755 scripts/test_dwarf5_support.sh diff --git a/Makefile b/Makefile index 656fff17b331..1067cfd98249 100644 --- a/Makefile +++ b/Makefile @@ -828,6 +828,7 @@ endif dwarf-version-$(CONFIG_DEBUG_INFO_DWARF2) := 2 dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4 +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5 DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y) ifneq ($(dwarf-version-y)$(LLVM_IAS),21) # Binutils 2.35+ required for -gdwarf-4+ support. diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 49944f00d2b3..37dc4110875e 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -843,7 +843,11 @@ .debug_types 0 : { *(.debug_types) } \ /* DWARF 5 */ \ .debug_macro 0 : { *(.debug_macro) } \ - .debug_addr 0 : { *(.debug_addr) } + .debug_addr 0 : { *(.debug_addr) } \ + .debug_line_str 0 : { *(.debug_line_str) } \ + .debug_loclists 0 : { *(.debug_loclists) } \ + .debug_rnglists 0 : { *(.debug_rnglists) } \ + .debug_str_offsets 0 : { *(.debug_str_offsets) } /* Stabs debugging sections. */ #define STABS_DEBUG \ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index e80770fac4f0..60a4f5e27ada 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -273,6 +273,23 @@ config DEBUG_INFO_DWARF4 It makes the debug information larger, but it significantly improves the success of resolving variables in gdb on optimized code. +config DEBUG_INFO_DWARF5 + bool "Generate DWARF Version 5 debuginfo" + depends on GCC_VERSION >= 50000 || CC_IS_CLANG + depends on CC_IS_GCC || $(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC) $(CLANG_FLAGS)) + help + Generate DWARF v5 debug info. Requires binutils 2.35, gcc 5.0+ (gcc + 5.0+ accepts the -gdwarf-5 flag but only had partial support for some + draft features until 7.0), and gdb 8.0+. + + Changes to the structure of debug info in Version 5 allow for around + 15-18% savings in resulting image and debug info section sizes as + compared to DWARF Version 4. DWARF Version 5 standardizes previous + extensions such as accelerators for symbol indexing and the format + for fission (.dwo/.dwp) files. Users may not want to select this + config if they rely on tooling that has not yet been updated to + support DWARF Version 5. + endchoice # "DWARF version" config DEBUG_INFO_BTF diff --git a/scripts/test_dwarf5_support.sh b/scripts/test_dwarf5_support.sh new file mode 100755 index 000000000000..142a1b5c7fa2 --- /dev/null +++ b/scripts/test_dwarf5_support.sh @@ -0,0 +1,9 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +# Test that assembler accepts -gdwarf-5 and .file 0 directives, which were bugs +# in binutils < 2.35. +# https://sourceware.org/bugzilla/show_bug.cgi?id=25612 +# https://sourceware.org/bugzilla/show_bug.cgi?id=25614 +set -e +echo '.file 0 "filename"' | $* -gdwarf-5 -Wa,-gdwarf-5 -c -x assembler -o /dev/null - -- 2.30.0.284.gd98b1dd5eaa7-goog ^ permalink raw reply related [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build [not found] ` <CA+icZUVrF_LCVhELbNLA7=FzEZK4=jk3QLD9XT2w5bQNo=nnOA@mail.gmail.com> 2021-01-11 22:31 ` Jiri Olsa @ 2021-01-12 0:57 ` Yonghong Song 2021-01-12 4:09 ` Sedat Dilek 1 sibling, 1 reply; 19+ messages in thread From: Yonghong Song @ 2021-01-12 0:57 UTC (permalink / raw) To: sedat.dilek, Andrii Nakryiko Cc: Jiri Olsa, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On 1/11/21 1:30 PM, Sedat Dilek wrote: > On Mon, Jan 11, 2021 at 10:03 PM Andrii Nakryiko > <andrii.nakryiko@gmail.com> wrote: >> >> On Mon, Jan 11, 2021 at 9:56 AM Sedat Dilek <sedat.dilek@gmail.com> wrote: >>> >>> On Mon, Jan 11, 2021 at 5:05 PM Yonghong Song <yhs@fb.com> wrote: >>>> >>>> >>>> >>>> On 1/11/21 4:48 AM, Sedat Dilek wrote: >>>>> Hi BPF maintainers and Mashiro, >>>>> >>>>> Debian started to use CONFIG_DEBUG_INFO_BTF=y. >>>>> >>>>> My kernel-build fails like this: >>>>> >>>>> + info BTFIDS vmlinux >>>>> + [ != silent_ ] >>>>> + printf %-7s %s\n BTFIDS vmlinux >>>>> BTFIDS vmlinux >>>>> + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux >>>>> FAILED: load BTF from vmlinux: Invalid argument >>>>> >>>>> The root cause is my selfmade LLVM toolchain has no BPF support. >>>> >>>> linux build should depend on LLVM toolchain unless you use LLVM to build >>>> kernel. >>>> >>>>> >>>>> $ which llc >>>>> /home/dileks/src/llvm-toolchain/install/bin/llc >>>>> >>>>> $ llc --version >>>>> LLVM (http://llvm.org/ ): >>>>> LLVM version 11.0.1 >>>>> Optimized build. >>>>> Default target: x86_64-unknown-linux-gnu >>>>> Host CPU: sandybridge >>>>> >>>>> Registered Targets: >>>>> x86 - 32-bit X86: Pentium-Pro and above >>>>> x86-64 - 64-bit X86: EM64T and AMD64 >>>>> >>>>> Debian's llc-11 shows me BPF support is built-in. >>>>> >>>>> I see the breakag approx. 3 hours after the start of my kernel-build - >>>>> in the stage "vmlinux". >>>>> After 2 faulures in my build (2x 3 hours of build-time) I have still >>>>> no finished Linux v5.11-rc3 kernel. >>>>> This is a bit frustrating. >>>> >>>> You mean "BTFIDS vmlinux" takes more than 3 hours here? >>>> Maybe a bug in resolve_btfids due to somehow different ELF format >>>> resolve_btfids need to handle? >>>> >>> >>> [ CC Tom ] >>> >>> OMG no. >>> >>> 3 hours up to running scripts/link-vmlinux.sh. >>> >>> In the meantime I have built a LLVM toolchain with BPF support. >>> >>> $ llc --version >>> LLVM (http://llvm.org/ ): >>> LLVM version 11.0.1 >>> Optimized build. >>> Default target: x86_64-unknown-linux-gnu >>> Host CPU: sandybridge >>> >>> Registered Targets: >>> bpf - BPF (host endian) >>> bpfeb - BPF (big endian) >>> bpfel - BPF (little endian) >> >> As Yonghong mentioned, you don't need BPF target support in Clang to >> build the kernel, so the issue is elsewhere. It's somewhere between >> generated DWARF (we've seen multiple bugs in DWARF over time), >> pahole's BTF output and resolve_btfids's handling of that BTF. I've >> CC'ed Jiri, who can help with resolve_btfids. >> >> Meanwhile, if you can provide SHA from which you built Clang, kernel >> config you used, and probably exact invocation of the build you used, >> it would help reproduce the issue. >> > > OK, I see I have here DWARF v5 support patchset applied and enabled. > > Furthermore: I applied latest clang-cfi. > > This is with LLVM v11.0.1 final aka 43ff75f2c3feef64f9d73328230d34dac8832a91. Did you use llvm to compile kernel? If this is the case, latest pahole will segfault. I am using latest trunk llvm. It is possible that generated dwarf with llvm is different from generated dwarf with gcc and pahole did not process it correctly. I did not get time to debug this though. > > My kernel-config is attached. > > [1] https://patchwork.kernel.org/project/linux-kbuild/patch/20201204011129.2493105-1-ndesaulniers@google.com/ > [2] https://patchwork.kernel.org/project/linux-kbuild/patch/20201204011129.2493105-2-ndesaulniers@google.com/ > [3] https://github.com/samitolvanen/linux/commits/clang-cfi > >>> x86 - 32-bit X86: Pentium-43ff75f2c3feef64f9d73328230d34dac8832a91 > Pro and above >>> x86-64 - 64-bit X86: EM64T and AMD64 >>> >>> Tom reported BTF issues with pahole v1.19 (see [2] and [3]): >>> "I ran into this same bug trying to build the Fedora kBROKEN_5-11-rc3-CONFIG_DEBUG_INFO_BTF-y-FAILED-load-BTF-from-vmlinux.txt > ernel. The >>> problem is that pahole segfaults at: scripts/link-vmlinux.sh:131. This >>> looks to me like a bug in pahole." >>> >>> pahole ToT (post v1.19) offers some BTF fixes - I have manually build >>> and use it. >>> >>> Building a new Linux-kernel... >>> >>> - Sedat - >>> >>> [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ >>> [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 >>> [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 >> >> There are no significant bug fixes between pahole 1.19 and master that >> would solve this problem, so let's try to repro this. >> > > You are right pahole fom latest Git does not solve the issue. > > + info BTFIDS vmlinux > + [ != silent_ ] > + printf %-7s %s\n BTFIDS vmlinux > BTFIDS vmlinux > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > FAILED: load BTF from vmlinux: Invalid argument > > - Sedat - > >>> >>> >>> >>>>> >>>>> What about doing pre-checks - means before doing a single line of >>>>> compilation - to check for: >>>>> 1. Required binaries >>>>> 2. Required support of whatever feature in compiler, linker, toolchain etc. >>>>> >>>>> Recently, I fell over depmod binary not found in my PATH - in one of >>>>> the last steps (modfinal) of the kernel build. >>>>> >>>>> Any ideas to improve the situation? >>>>> ( ...and please no RTFM, see links below. ) >>>>> >>>>> Thanks. >>>>> >>>>> Regards, >>>>> - Sedat - >>>>> >>>>> >>>>> [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 >>>>> [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f >>>>> [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm >>>>> [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation >>>>> ^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build 2021-01-12 0:57 ` Yonghong Song @ 2021-01-12 4:09 ` Sedat Dilek 0 siblings, 0 replies; 19+ messages in thread From: Sedat Dilek @ 2021-01-12 4:09 UTC (permalink / raw) To: Yonghong Song Cc: Andrii Nakryiko, Jiri Olsa, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau, Song Liu, John Fastabend, KP Singh, Masahiro Yamada, bpf, Linux Kbuild mailing list, Tom Stellard On Tue, Jan 12, 2021 at 1:57 AM Yonghong Song <yhs@fb.com> wrote: > > > > On 1/11/21 1:30 PM, Sedat Dilek wrote: > > On Mon, Jan 11, 2021 at 10:03 PM Andrii Nakryiko > > <andrii.nakryiko@gmail.com> wrote: > >> > >> On Mon, Jan 11, 2021 at 9:56 AM Sedat Dilek <sedat.dilek@gmail.com> wrote: > >>> > >>> On Mon, Jan 11, 2021 at 5:05 PM Yonghong Song <yhs@fb.com> wrote: > >>>> > >>>> > >>>> > >>>> On 1/11/21 4:48 AM, Sedat Dilek wrote: > >>>>> Hi BPF maintainers and Mashiro, > >>>>> > >>>>> Debian started to use CONFIG_DEBUG_INFO_BTF=y. > >>>>> > >>>>> My kernel-build fails like this: > >>>>> > >>>>> + info BTFIDS vmlinux > >>>>> + [ != silent_ ] > >>>>> + printf %-7s %s\n BTFIDS vmlinux > >>>>> BTFIDS vmlinux > >>>>> + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > >>>>> FAILED: load BTF from vmlinux: Invalid argument > >>>>> > >>>>> The root cause is my selfmade LLVM toolchain has no BPF support. > >>>> > >>>> linux build should depend on LLVM toolchain unless you use LLVM to build > >>>> kernel. > >>>> > >>>>> > >>>>> $ which llc > >>>>> /home/dileks/src/llvm-toolchain/install/bin/llc > >>>>> > >>>>> $ llc --version > >>>>> LLVM (http://llvm.org/ ): > >>>>> LLVM version 11.0.1 > >>>>> Optimized build. > >>>>> Default target: x86_64-unknown-linux-gnu > >>>>> Host CPU: sandybridge > >>>>> > >>>>> Registered Targets: > >>>>> x86 - 32-bit X86: Pentium-Pro and above > >>>>> x86-64 - 64-bit X86: EM64T and AMD64 > >>>>> > >>>>> Debian's llc-11 shows me BPF support is built-in. > >>>>> > >>>>> I see the breakag approx. 3 hours after the start of my kernel-build - > >>>>> in the stage "vmlinux". > >>>>> After 2 faulures in my build (2x 3 hours of build-time) I have still > >>>>> no finished Linux v5.11-rc3 kernel. > >>>>> This is a bit frustrating. > >>>> > >>>> You mean "BTFIDS vmlinux" takes more than 3 hours here? > >>>> Maybe a bug in resolve_btfids due to somehow different ELF format > >>>> resolve_btfids need to handle? > >>>> > >>> > >>> [ CC Tom ] > >>> > >>> OMG no. > >>> > >>> 3 hours up to running scripts/link-vmlinux.sh. > >>> > >>> In the meantime I have built a LLVM toolchain with BPF support. > >>> > >>> $ llc --version > >>> LLVM (http://llvm.org/ ): > >>> LLVM version 11.0.1 > >>> Optimized build. > >>> Default target: x86_64-unknown-linux-gnu > >>> Host CPU: sandybridge > >>> > >>> Registered Targets: > >>> bpf - BPF (host endian) > >>> bpfeb - BPF (big endian) > >>> bpfel - BPF (little endian) > >> > >> As Yonghong mentioned, you don't need BPF target support in Clang to > >> build the kernel, so the issue is elsewhere. It's somewhere between > >> generated DWARF (we've seen multiple bugs in DWARF over time), > >> pahole's BTF output and resolve_btfids's handling of that BTF. I've > >> CC'ed Jiri, who can help with resolve_btfids. > >> > >> Meanwhile, if you can provide SHA from which you built Clang, kernel > >> config you used, and probably exact invocation of the build you used, > >> it would help reproduce the issue. > >> > > > > OK, I see I have here DWARF v5 support patchset applied and enabled. > > > > Furthermore: I applied latest clang-cfi. > > > > This is with LLVM v11.0.1 final aka 43ff75f2c3feef64f9d73328230d34dac8832a91. > > Did you use llvm to compile kernel? If this is the case, latest pahole > will segfault. I am using latest trunk llvm. It is possible that > generated dwarf with llvm is different from generated dwarf with gcc > and pahole did not process it correctly. I did not get time to > debug this though. > Yes, I used LLVM/Clang to compile the kernel. - Sedat - > > > > My kernel-config is attached. > > > > [1] https://patchwork.kernel.org/project/linux-kbuild/patch/20201204011129.2493105-1-ndesaulniers@google.com/ > > [2] https://patchwork.kernel.org/project/linux-kbuild/patch/20201204011129.2493105-2-ndesaulniers@google.com/ > > [3] https://github.com/samitolvanen/linux/commits/clang-cfi > > > >>> x86 - 32-bit X86: Pentium-43ff75f2c3feef64f9d73328230d34dac8832a91 > > Pro and above > >>> x86-64 - 64-bit X86: EM64T and AMD64 > >>> > >>> Tom reported BTF issues with pahole v1.19 (see [2] and [3]): > >>> "I ran into this same bug trying to build the Fedora kBROKEN_5-11-rc3-CONFIG_DEBUG_INFO_BTF-y-FAILED-load-BTF-from-vmlinux.txt > > ernel. The > >>> problem is that pahole segfaults at: scripts/link-vmlinux.sh:131. This > >>> looks to me like a bug in pahole." > >>> > >>> pahole ToT (post v1.19) offers some BTF fixes - I have manually build > >>> and use it. > >>> > >>> Building a new Linux-kernel... > >>> > >>> - Sedat - > >>> > >>> [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ > >>> [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 > >>> [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > >> > >> There are no significant bug fixes between pahole 1.19 and master that > >> would solve this problem, so let's try to repro this. > >> > > > > You are right pahole fom latest Git does not solve the issue. > > > > + info BTFIDS vmlinux > > + [ != silent_ ] > > + printf %-7s %s\n BTFIDS vmlinux > > BTFIDS vmlinux > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > FAILED: load BTF from vmlinux: Invalid argument > > > > - Sedat - > > > >>> > >>> > >>> > >>>>> > >>>>> What about doing pre-checks - means before doing a single line of > >>>>> compilation - to check for: > >>>>> 1. Required binaries > >>>>> 2. Required support of whatever feature in compiler, linker, toolchain etc. > >>>>> > >>>>> Recently, I fell over depmod binary not found in my PATH - in one of > >>>>> the last steps (modfinal) of the kernel build. > >>>>> > >>>>> Any ideas to improve the situation? > >>>>> ( ...and please no RTFM, see links below. ) > >>>>> > >>>>> Thanks. > >>>>> > >>>>> Regards, > >>>>> - Sedat - > >>>>> > >>>>> > >>>>> [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 > >>>>> [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f > >>>>> [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm > >>>>> [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation > >>>>> ^ permalink raw reply [flat|nested] 19+ messages in thread
end of thread, other threads:[~2021-01-14 15:14 UTC | newest]
Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
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2021-01-11 12:48 Check pahole availibity and BPF support of toolchain before starting a Linux kernel build Sedat Dilek
2021-01-11 16:05 ` Yonghong Song
2021-01-11 17:56 ` Sedat Dilek
2021-01-11 21:03 ` Andrii Nakryiko
[not found] ` <CA+icZUVrF_LCVhELbNLA7=FzEZK4=jk3QLD9XT2w5bQNo=nnOA@mail.gmail.com>
2021-01-11 22:31 ` Jiri Olsa
2021-01-11 22:34 ` Tom Stellard
2021-01-12 10:46 ` Jiri Olsa
2021-01-12 13:10 ` Jiri Olsa
2021-01-12 16:14 ` Sedat Dilek
2021-01-12 16:21 ` Jiri Olsa
2021-01-12 17:18 ` Sedat Dilek
2021-01-12 20:47 ` Sedat Dilek
2021-01-12 21:36 ` Sedat Dilek
2021-01-14 14:13 ` Sedat Dilek
2021-01-14 14:24 ` Jiri Olsa
2021-01-14 14:29 ` Sedat Dilek
[not found] ` <CA+icZUXp5gkxCr+mybQ8uO3xx+rVmmRSnN7Dfx0Xmr+VQWyZAA@mail.gmail.com>
2021-01-14 15:13 ` Sedat Dilek
2021-01-12 0:57 ` Yonghong Song
2021-01-12 4:09 ` Sedat Dilek
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