On 02/28/17 at 02:06pm, Dave Young wrote:
> On 02/24/17 at 06:38pm, Baoquan He wrote:
> > Otherwise it will print false positve message as below. So add
> > a check when do the search.
> >
> > "Cannot get kernel page_offset_base symbol address"
> >
> > Signed-off-by: Baoquan He <bhe at redhat.com>
> > ---
> > kexec/arch/i386/crashdump-x86.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> > index 88aeee3..b2c1be5 100644
> > --- a/kexec/arch/i386/crashdump-x86.c
> > +++ b/kexec/arch/i386/crashdump-x86.c
> > @@ -150,8 +150,6 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
> > off_t size;
> > uint32_t elf_flags = 0;
> > uint64_t stext_sym;
> > - const unsigned long long pud_mask = ~((1 << 30) - 1);
> > - unsigned long long vaddr, lowest_vaddr = 0;
> >
> > if (elf_info->machine != EM_X86_64)
> > return 0;
> > @@ -181,8 +179,11 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
> >
> > end_phdr = &ehdr.e_phdr[ehdr.e_phnum];
> >
> > +#ifdef CONFIG_RANDOMIZE_MEMORY
>
> It does not work in userspace code.
Could be it only works when make header and install. Otherwise it can't
be seen by user space. I built a rhel kernel package and test passed.
Anyway, since it doesn't work in all cases, I have made another way to
fix it, just take out the error message and put it where get_kernel_sym
is called.
>
> Maybe mute the error message or move it to kexec --debug is more
> reasonable..
>
> > /* Search for the real PAGE_OFFSET when KASLR memory randomization
> > * is enabled */
> > + const unsigned long long pud_mask = ~((1 << 30) - 1);
> > + unsigned long long vaddr, lowest_vaddr = 0;
> > if (get_kernel_sym("page_offset_base") != 0) {
> > for(phdr = ehdr.e_phdr; phdr != end_phdr; phdr++) {
> > if (phdr->p_type == PT_LOAD) {
> > @@ -194,6 +195,7 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
> > if (lowest_vaddr != 0)
> > elf_info->page_offset = lowest_vaddr;
> > }
> > +#endif
> >
> > /* Traverse through the Elf headers and find the region where
> > * _stext symbol is located in. That's where kernel is mapped */
> > --
> > 2.5.5
> >
> >
> > _______________________________________________
> > kexec mailing list
> > kexec at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
>
> Thanks
> Dave
>
> _______________________________________________
> kexec mailing list
> kexec at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
