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.
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
> >
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