Re: [Crash-utility] [PATCH] Fix get_linux_banner_from_vmlinux() for vmlinux without ".rodata" symbol

On Mon, Jul 24, 2023 at 4:48 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com&gt; wrote: > From: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; > > As written in the previous patch, some recent kernels do not have the > ".rodata" symbol. As a result, the get_linux_banner_from_vmlinux() > returns FALSE and the slower fallback routine is used. > > Use "__start_rodata" symbol if the ".rodata" symbol is not available. > > Reported-by: Lianbo Jiang <lijiang(a)redhat.com&gt; > Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; > --- > Note that I chose to use ".rodata" first to not change the current > stable behavior for old vmcores, in this case. > > kernel.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/kernel.c b/kernel.c > index 9801812387bd..2114700eecc8 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -11891,8 +11891,13 @@ int get_linux_banner_from_vmlinux(char *buf, > size_t size) > { > struct bfd_section *sect; > long offset; > + ulong start_rodata; > > - if (!kernel_symbol_exists(".rodata")) > + if (kernel_symbol_exists(".rodata")) > + start_rodata = symbol_value(".rodata"); > + else if (kernel_symbol_exists("__start_rodata")) > + start_rodata = symbol_value("__start_rodata"); > + else > return FALSE; > > sect = bfd_get_section_by_name(st->bfd, ".rodata"); > @@ -11905,7 +11910,7 @@ int get_linux_banner_from_vmlinux(char *buf, > size_t size) > * value in vmlinux file, but relative offset to linux_banner > * object in .rodata section is idential. > */ > - offset = symbol_value("linux_banner") - symbol_value(".rodata"); > + offset = symbol_value("linux_banner") - start_rodata; > > if (!bfd_get_section_contents(st->bfd, > sect, > Looks good to me. So: Ack.