On Wed, Feb 26, 2025 at 12:53 PM <devel-requ...@lists.crash-utility.osci.io> wrote:
> Date: Wed, 26 Feb 2025 17:51:21 +1300 > From: Tao Liu <l...@redhat.com> > Subject: [Crash-utility] [PATCH] symbols: redetermine the end of > kernel range for in_ksymbol_range > To: devel@lists.crash-utility.osci.io > Cc: k-hagio...@nec.com, Tao Liu <l...@redhat.com> > Message-ID: <20250226045121.16717-1-l...@redhat.com> > Content-Type: text/plain; charset="US-ASCII"; x-default=true > > For in_ksymbol_range(), it determine the kernel range by > st->symtable[0].value > as the start and st->symtable[st->symcnt-1].value as the end, this > however, implies the last element is in the kernel range. In most > cases it was correct, but it is no longer valid with the kernel commit [1]. > > The xen_elfnote_phys32_entry_value introduced by [1], is beyound the kernel > range(doesn't belong to any kernel section), thus doesn't get relocated > by relocate(). So in order to have a correct in_ksymbol_range(), we need > to eliminate those symbols. > > Applied: https://github.com/crash-utility/crash/commit/25828e83d5f8990598dde5840929bf60f4e83810 Thanks Lianbo > Without the patch: > crash> sym schedule > ffffffff973ffb30 (T) schedule /root/linux-6.14-rc3/kernel/sched/core.c: > 6848 > crash> sym 0xffffffff973ffb30 > sym: invalid address: 0xffffffff973ffb30 > > With the patch: > crash> sym schedule > ffffffff973ffb30 (T) schedule /root/linux-6.14-rc3/kernel/sched/core.c: > 6848 > crash> sym 0xffffffff973ffb30 > ffffffff973ffb30 (T) schedule /root/linux-6.14-rc3/kernel/sched/core.c: > 6848 > > [1]: > https://github.com/torvalds/linux/commit/223abe96ac0d227b22d48ab447dd9384b7a6c9fa > > Signed-off-by: Tao Liu <l...@redhat.com> > --- > v2 -> v1: In fact the gnu_qsort() does sort the symbols with no > problem, unlike the root cause described in v1. It's because > xen_elfnote_phys32_entry_value doesn't belong to any kernel > section, so the > symval >= st->first_section_start && symval <= > st->last_section_end > check will not success in relocate(), so the symbol is not > relocated. > But I'm not sure if xen_elfnote_phys32_entry_value should be > relocated or not, it looks to be an absoluate symbol to me, > but the code comment is not very clear... > v1 patch: > https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01373.html > v1 discussion: > https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01378.html > --- > --- > symbols.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/symbols.c b/symbols.c > index 6385d02..edbafa4 100644 > --- a/symbols.c > +++ b/symbols.c > @@ -5443,8 +5443,14 @@ old_module: > int > in_ksymbol_range(ulong value) > { > + int i; > + for (i = st->symcnt-1; i >= 0; i--) { > + if (!strstr(st->symtable[i].name, "xen_elfnote")) > + break; > + } > + > if ((value >= st->symtable[0].value) && > - (value <= st->symtable[st->symcnt-1].value)) { > + (value <= st->symtable[i].value)) { > if ((st->flags & PERCPU_SYMS) && (value < > st->first_ksymbol)) > return FALSE; > else > -- > 2.47.0 >
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