On Wed, Feb 17, 2021 at 1:44 PM Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx> wrote: > > Em Sat, Feb 13, 2021 at 05:46:48PM +0100, Jiri Olsa escreveu: > > Currently when processing DWARF function, we check its entrypoint > > against ftrace addresses, assuming that the ftrace address matches > > with function's entrypoint. > > > > This is not the case on some architectures as reported by Nathan > > when building kernel on arm [1]. > > > > Fixing the check to take into account the whole function not > > just the entrypoint. > > > > Most of the is_ftrace_func code was contributed by Andrii. > > Applied locally, will go out after tests, > Hi Arnaldo, Is it possible to have a pahole version 1.21 with this patch and the one from Yonghong Son? >From my local pahole Git: $ git log --oneline --no-merges v1.20.. 2f83aefdbddf (for-1.20/btf_encoder-ftrace_elf-clang-jolsa-v2) btf_encoder: Match ftrace addresses within elf functions f21eafdfc877 (for-1.20/btf_encoder-sanitized_int-clang-yhs-v2) btf_encoder: sanitize non-regular int base type Both patches fixes all issues seen so far with LLVM/Clang >= 12.0.0-rc1 and DWARF-v5 and BTF (debug-info) and pahole on Linux/x86_64 and according to Nathan on Linux/arm64. Yesterday, I tried with LLVM/Clang 13-git from <apt.llvm.org>. BTW, Nick's DWARF-v5 patches are pending in <kbuild.git#kbuild> (see [1]). Personally, I can wait until [1] is in Linus Git. Please, let me/us know what you are planning. ( I know it is Linux v5.12 merge-window. ) Thanks. Regards, - Sedat - [1] https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git/log/?h=kbuild > - Arnaldo > > > [1] https://lore.kernel.org/bpf/20210209034416.GA1669105@ubuntu-m3-large-x86/ > > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > > --- > > v2 changes: > > - update functions addr directly [Andrii] > > > > btf_encoder.c | 40 ++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 38 insertions(+), 2 deletions(-) > > > > diff --git a/btf_encoder.c b/btf_encoder.c > > index b124ec20a689..80e896961d4e 100644 > > --- a/btf_encoder.c > > +++ b/btf_encoder.c > > @@ -36,6 +36,7 @@ struct funcs_layout { > > struct elf_function { > > const char *name; > > unsigned long addr; > > + unsigned long size; > > unsigned long sh_addr; > > bool generated; > > }; > > @@ -98,6 +99,7 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym, > > > > functions[functions_cnt].name = name; > > functions[functions_cnt].addr = elf_sym__value(sym); > > + functions[functions_cnt].size = elf_sym__size(sym); > > functions[functions_cnt].sh_addr = sh.sh_addr; > > functions[functions_cnt].generated = false; > > functions_cnt++; > > @@ -236,6 +238,39 @@ get_kmod_addrs(struct btf_elf *btfe, __u64 **paddrs, __u64 *pcount) > > return 0; > > } > > > > +static int is_ftrace_func(struct elf_function *func, __u64 *addrs, __u64 count) > > +{ > > + __u64 start = func->addr; > > + __u64 addr, end = func->addr + func->size; > > + > > + /* > > + * The invariant here is addr[r] that is the smallest address > > + * that is >= than function start addr. Except the corner case > > + * where there is no such r, but for that we have a final check > > + * in the return. > > + */ > > + size_t l = 0, r = count - 1, m; > > + > > + /* make sure we don't use invalid r */ > > + if (count == 0) > > + return false; > > + > > + while (l < r) { > > + m = l + (r - l) / 2; > > + addr = addrs[m]; > > + > > + if (addr >= start) { > > + /* we satisfy invariant, so tighten r */ > > + r = m; > > + } else { > > + /* m is not good enough as l, maybe m + 1 will be */ > > + l = m + 1; > > + } > > + } > > + > > + return start <= addrs[r] && addrs[r] < end; > > +} > > + > > static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > { > > __u64 *addrs, count, i; > > @@ -283,10 +318,11 @@ static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > * functions[x]::addr is relative address within section > > * and needs to be relocated by adding sh_addr. > > */ > > - __u64 addr = kmod ? func->addr + func->sh_addr : func->addr; > > + if (kmod) > > + func->addr += func->sh_addr; > > > > /* Make sure function is within ftrace addresses. */ > > - if (bsearch(&addr, addrs, count, sizeof(addrs[0]), addrs_cmp)) { > > + if (is_ftrace_func(func, addrs, count)) { > > /* > > * We iterate over sorted array, so we can easily skip > > * not valid item and move following valid field into > > -- > > 2.29.2 > > > > -- > > - Arnaldo
