On Mon, Apr 25, 2022 at 8:48 AM HAGIO KAZUHITO(萩尾 一仁)
<k-hagio-ab@xxxxxxx> wrote:
>
> Hi Pingfan,
>
> -----Original Message-----
> > On Wed, Apr 20, 2022 at 11:58:29PM +0000, HAGIO KAZUHITO(萩尾 一仁) wrote:
> > > Currently get_mem_section() validates if SYMBOL(mem_section) is the address
> > > of the mem_section array first. But there was a report that the first
> > > validation wrongly returned TRUE with -x vmlinux and SPARSEMEM_EXTREME
> > > (4.15+) on s390x. This leads to crash failing statup with the following
> > > seek error:
> > >
> > > crash: seek error: kernel virtual address: 67fffc2800 type: "memory section root table"
> > >
> > > Skip the first validation when satisfying the conditions.
> > >
> >
> > I still prefer to your V1, which is discussed internally. In which, the
> > logic was made straight forward. And I suggest some slight change to
> > your V1, which folds "-x vmlinux" logic into is_sparsemem_extreme().
> >
> > What about the following: (not tested yet, if it is good, I can test it)
>
> Thanks for your review and suggestion.
>
> The purpose of my patch is to distinguish between SPARSEMEM_EXTREME
> v1 and v2, i.e. whether it has 83e3c48729d9 or not.
>
Not sure about dwarf, but is it possible to utilize the array length
info in is_sparsemem_extreme()?
For SPARSEMEM_EXTREME,
#ifdef CONFIG_SPARSEMEM_EXTREME
extern struct mem_section *mem_section[NR_SECTION_ROOTS];
#else
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
#endif
And if DWARF_INFO_GET_SYMBOL_ARRAY_LENGTH works, then there is a big
gap between "NR_SECTION_ROOTS * 8-bytes" and "sizeof(struct
mem_section) * NR_SECTION_ROOTS * SECTIONS_PER_ROOT"
Thanks,
Pingfan
> is_sparsemem_extreme() has to return whether it's SPARSEMEM_EXTREME or
> SPARSEMEM, so unfortunately it's not suitable to use that logic in
> the function.
>
> Thanks,
> Kazu
>
> >
> >
> > diff --git a/makedumpfile.c b/makedumpfile.c
> > index a2f45c8..3ebe372 100644
> > --- a/makedumpfile.c
> > +++ b/makedumpfile.c
> > @@ -2240,11 +2240,18 @@ int
> > is_sparsemem_extreme(void)
> > {
> > if ((ARRAY_LENGTH(mem_section)
> > - == divideup(NR_MEM_SECTIONS(), _SECTIONS_PER_ROOT_EXTREME()))
> > - || (ARRAY_LENGTH(mem_section) == NOT_FOUND_STRUCTURE))
> > - return TRUE;
> > - else
> > + == divideup(NR_MEM_SECTIONS(), _SECTIONS_PER_ROOT_EXTREME())) {
> > + return TRUE;
> > + } else if (info->name_vmlinux) {
> > + unsigned long flag = 0;
> > +
> > + if (get_symbol_type_name("mem_section", DWARF_INFO_GET_SYMBOL_TYPE,
> > + NULL, &flag)
> > + && !(flag & TYPE_ARRAY))
> > + return TRUE;
> > + } else {
> > return FALSE;
> > + }
> > }
> >
> > int
> > @@ -3704,28 +3711,24 @@ get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,
> > {
> > int ret = FALSE;
> > unsigned long *mem_sec = NULL;
> > + unsigned long mem_section_ptr = SYMBOL(mem_section);
> >
> > if ((mem_sec = malloc(mem_section_size)) == NULL) {
> > ERRMSG("Can't allocate memory for the mem_section. %s\n",
> > strerror(errno));
> > return FALSE;
> > }
> > - ret = validate_mem_section(mem_sec, SYMBOL(mem_section),
> > - mem_section_size, mem_maps, num_section);
> > -
> > - if (!ret && is_sparsemem_extreme()) {
> > - unsigned long mem_section_ptr;
> >
> > + if (is_sparsemem_extreme()) {
> > if (!readmem(VADDR, SYMBOL(mem_section), &mem_section_ptr,
> > sizeof(mem_section_ptr)))
> > goto out;
> > + }
> >
> > - ret = validate_mem_section(mem_sec, mem_section_ptr,
> > - mem_section_size, mem_maps, num_section);
> > -
> > - if (!ret)
> > + ret = validate_mem_section(mem_sec, mem_section_ptr,
> > + mem_section_size, mem_maps, num_section);
> > + if (!ret)
> > ERRMSG("Could not validate mem_section.\n");
> > - }
> > out:
> > if (mem_sec != NULL)
> > free(mem_sec);
> > --
> >
> > Thanks,
> >
> > Pingfan
> >
> > > Reported-by: Dave Wysochanski <dwysocha@xxxxxxxxxx>
> > > Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
> > > ---
> > > makedumpfile.c | 31 +++++++++++++++++++++++++++++++
> > > 1 file changed, 31 insertions(+)
> > >
> > > diff --git a/makedumpfile.c b/makedumpfile.c
> > > index a2f45c84cee3..65d1c7c2f02c 100644
> > > --- a/makedumpfile.c
> > > +++ b/makedumpfile.c
> > > @@ -3698,6 +3698,22 @@ validate_mem_section(unsigned long *mem_sec,
> > > return ret;
> > > }
> > >
> > > +/*
> > > + * SYMBOL(mem_section) varies with the combination of memory model and
> > > + * its source:
> > > + *
> > > + * SPARSEMEM
> > > + * vmcoreinfo: address of mem_section root array
> > > + * -x vmlinux: address of mem_section root array
> > > + *
> > > + * SPARSEMEM_EXTREME v1
> > > + * vmcoreinfo: address of mem_section root array
> > > + * -x vmlinux: address of mem_section root array
> > > + *
> > > + * SPARSEMEM_EXTREME v2 (with 83e3c48729d9 and a0b1280368d1) 4.15+
> > > + * vmcoreinfo: address of mem_section root array
> > > + * -x vmlinux: address of pointer to mem_section root array
> > > + */
> > > static int
> > > get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,
> > > unsigned int num_section)
> > > @@ -3710,12 +3726,27 @@ get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,
> > > strerror(errno));
> > > return FALSE;
> > > }
> > > +
> > > + /*
> > > + * There was a report that the first validation wrongly returned TRUE
> > > + * with -x vmlinux and SPARSEMEM_EXTREME v2 on s390x, so skip it.
> > > + * Howerver, leave the fallback validation as it is for the -i option.
> > > + */
> > > + if (is_sparsemem_extreme() && info->name_vmlinux) {
> > > + unsigned long flag = 0;
> > > + if (get_symbol_type_name("mem_section", DWARF_INFO_GET_SYMBOL_TYPE,
> > > + NULL, &flag)
> > > + && !(flag & TYPE_ARRAY))
> > > + goto skip_1st_validation;
> > > + }
> > > +
> > > ret = validate_mem_section(mem_sec, SYMBOL(mem_section),
> > > mem_section_size, mem_maps, num_section);
> > >
> > > if (!ret && is_sparsemem_extreme()) {
> > > unsigned long mem_section_ptr;
> > >
> > > +skip_1st_validation:
> > > if (!readmem(VADDR, SYMBOL(mem_section), &mem_section_ptr,
> > > sizeof(mem_section_ptr)))
> > > goto out;
> > > --
> > > 2.27.0
> > >
_______________________________________________
kexec mailing list
kexec@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/kexec
