On Tue, Jul 27, 2021 at 09:02:33AM +0530, Aneesh Kumar K.V wrote:
> David Gibson <da...@gibson.dropbear.id.au> writes:
>
> > On Thu, Jul 22, 2021 at 12:37:46PM +0530, Aneesh Kumar K.V wrote:
> >> David Gibson <da...@gibson.dropbear.id.au> writes:
> >>
> >> > On Mon, Jun 28, 2021 at 08:41:15PM +0530, Aneesh Kumar K.V wrote:
>
> ....
>
> >
> >> >
> >> >> + nid = of_read_number(&aa.arrays[index], 1);
> >> >> +
> >> >> + if (nid == 0xffff || nid >= nr_node_ids)
> >> >> + nid = default_nid;
> >> >> + if (nid > 0 && affinity_form == FORM1_AFFINITY) {
> >> >> + int i;
> >> >> + const __be32 *associativity;
> >> >> +
> >> >> + index = lmb->aa_index * aa.array_sz;
> >> >> + associativity = &aa.arrays[index];
> >> >> + /*
> >> >> + * lookup array associativity entries have
> >> >> different format
> >> >> + * There is no length of the array as the first
> >> >> element.
> >> >
> >> > The difference it very small, and this is not a hot path. Couldn't
> >> > you reduce a chunk of code by prepending aa.array_sz, then re-using
> >> > __initialize_form1_numa_distance. Or even making
> >> > __initialize_form1_numa_distance() take the length as a parameter.
> >>
> >> The changes are small but confusing w.r.t how we look at the
> >> associativity-lookup-arrays. The way we interpret associativity array
> >> and associativity lookup array using primary_domain_index is different.
> >> Hence the '-1' in the node lookup here.
> >
> > They're really not, though. It's exactly the same interpretation of
> > the associativity array itself - it's just that one of them has the
> > array prepended with a (redundant) length. So you can make
> > __initialize_form1_numa_distance() work on the "bare" associativity
> > array, with a given length. Here you call it with aa.array_sz as the
> > length, and in the other place you call it with prop[0] as the length.
> >
> >>
> >> index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
> >> nid = of_read_number(&aa.arrays[index], 1);
> >>
> >>
> >> >
> >> >> + */
> >> >> + for (i = 0; i < max_associativity_domain_index;
> >> >> i++) {
> >> >> + const __be32 *entry;
> >> >> +
> >> >> + entry =
> >> >> &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
> >> >
> >> > Does anywhere verify that distance_ref_points[i] <= aa.array_size for
> >> > every i?
> >>
> >> We do check for
> >>
> >> if (primary_domain_index <= aa.array_sz &&
> >
> > Right, but that doesn't check the other distance_ref_points entries.
> > Not that there's any reason to have extra entries with Form2, but we
> > still don't want stray array accesses.
>
> This is how the change looks. I am not convinced this makes it simpler.
It's not, but that's because the lookup_array_assoc flag is not needed...
> I will add that as the last patch and we can drop that if we find that
> not helpful?
>
> modified arch/powerpc/mm/numa.c
> @@ -171,20 +171,31 @@ static void unmap_cpu_from_node(unsigned long cpu)
> }
> #endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */
>
> -/*
> - * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
> - * info is found.
> - */
> -static int associativity_to_nid(const __be32 *associativity)
> +static int __associativity_to_nid(const __be32 *associativity,
> + bool lookup_array_assoc,
> + int max_array_index)
> {
> int nid = NUMA_NO_NODE;
> + int index;
>
> if (!numa_enabled)
> goto out;
> + /*
> + * ibm,associativity-lookup-array doesn't have element
> + * count at the start of the associativity. Hence
> + * decrement the primary_domain_index when used with
> + * lookup-array associativity.
> + */
> + if (lookup_array_assoc)
> + index = primary_domain_index - 1;
> + else {
> + index = primary_domain_index;
> + max_array_index = of_read_number(associativity, 1);
> + }
> + if (index > max_array_index)
> + goto out;
So, the associativity-array-with-length is exactly a length, followed
by an associativity-array-without-length. What I was suggesting is
you make this function only take an
associativity-array-without-length, with the length passed separately.
Where you want to use it on an associativity-array-with-length, stored
in __be32 *awl, you just invoke it as:
associativity_to_nid(awl + 1, of_read_number(awl, 1));
> - if (of_read_number(associativity, 1) >= primary_domain_index)
> - nid = of_read_number(&associativity[primary_domain_index], 1);
> -
> + nid = of_read_number(&associativity[index], 1);
> /* POWER4 LPAR uses 0xffff as invalid node */
> if (nid == 0xffff || nid >= nr_node_ids)
> nid = NUMA_NO_NODE;
> @@ -192,6 +203,15 @@ static int associativity_to_nid(const __be32
> *associativity)
> return nid;
> }
>
> +/*
> + * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
> + * info is found.
> + */
> +static inline int associativity_to_nid(const __be32 *associativity)
> +{
> + return __associativity_to_nid(associativity, false, 0);
> +}
> +
> static int __cpu_form2_relative_distance(__be32 *cpu1_assoc, __be32
> *cpu2_assoc)
> {
> int dist;
> @@ -295,19 +315,38 @@ int of_node_to_nid(struct device_node *device)
> }
> EXPORT_SYMBOL(of_node_to_nid);
>
> -static void __initialize_form1_numa_distance(const __be32 *associativity)
> +static void __initialize_form1_numa_distance(const __be32 *associativity,
> + bool lookup_array_assoc,
> + int max_array_index)
> {
> int i, nid;
> + int index_offset = 0;
>
> if (affinity_form != FORM1_AFFINITY)
> return;
> + /*
> + * ibm,associativity-lookup-array doesn't have element
> + * count at the start of the associativity. Hence
> + * decrement the distance_ref_points index when used with
> + * lookup-array associativity.
> + */
> + if (lookup_array_assoc)
> + index_offset = 1;
> + else
> + max_array_index = of_read_number(associativity, 1);
>
> - nid = associativity_to_nid(associativity);
> + nid = __associativity_to_nid(associativity, lookup_array_assoc,
> max_array_index);
> if (nid != NUMA_NO_NODE) {
> for (i = 0; i < distance_ref_points_depth; i++) {
> const __be32 *entry;
> + int index = be32_to_cpu(distance_ref_points[i]) -
> index_offset;
>
> - entry =
> &associativity[be32_to_cpu(distance_ref_points[i])];
> + /*
> + * broken hierarchy, return with broken distance table
> + */
> + if (index > max_array_index)
> + return;
> + entry = &associativity[index];
> distance_lookup_table[nid][i] = of_read_number(entry,
> 1);
> }
> }
> @@ -321,7 +360,7 @@ static void initialize_form1_numa_distance(struct
> device_node *node)
> if (!associativity)
> return;
>
> - __initialize_form1_numa_distance(associativity);
> + __initialize_form1_numa_distance(associativity, false, 0);
> }
>
> /*
> @@ -586,27 +625,14 @@ static int get_nid_and_numa_distance(struct drmem_lmb
> *lmb)
>
> if (primary_domain_index <= aa.array_sz &&
> !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index <
> aa.n_arrays) {
> - index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
> - nid = of_read_number(&aa.arrays[index], 1);
> + const __be32 *associativity;
>
> - if (nid == 0xffff || nid >= nr_node_ids)
> - nid = default_nid;
> + index = lmb->aa_index * aa.array_sz;
> + associativity = &aa.arrays[index];
> + nid = __associativity_to_nid(associativity, true, aa.array_sz -
> 1);
> if (nid > 0 && affinity_form == FORM1_AFFINITY) {
> - int i;
> - const __be32 *associativity;
> -
> - index = lmb->aa_index * aa.array_sz;
> - associativity = &aa.arrays[index];
> - /*
> - * lookup array associativity entries have different
> format
> - * There is no length of the array as the first element.
> - */
> - for (i = 0; i < distance_ref_points_depth; i++) {
> - const __be32 *entry;
> -
> - entry =
> &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
> - distance_lookup_table[nid][i] =
> of_read_number(entry, 1);
> - }
> + __initialize_form1_numa_distance(associativity,
> + true, aa.array_sz - 1);
> }
> }
> return nid;
> @@ -632,9 +658,11 @@ int of_drconf_to_nid_single(struct drmem_lmb *lmb)
>
> if (primary_domain_index <= aa.array_sz &&
> !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index <
> aa.n_arrays) {
> - index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
> - nid = of_read_number(&aa.arrays[index], 1);
> + const __be32 *associativity;
>
> + index = lmb->aa_index * aa.array_sz;
> + associativity = &aa.arrays[index];
> + nid = __associativity_to_nid(associativity, true, aa.array_sz -
> 1);
> if (nid == 0xffff || nid >= nr_node_ids)
> nid = default_nid;
> }
> @@ -939,7 +967,7 @@ static int __init parse_numa_properties(void)
>
> if (__vphn_get_associativity(i, vphn_assoc) == 0) {
> nid = associativity_to_nid(vphn_assoc);
> - __initialize_form1_numa_distance(vphn_assoc);
> + __initialize_form1_numa_distance(vphn_assoc, false, 0);
> } else {
>
> /*
> @@ -953,7 +981,7 @@ static int __init parse_numa_properties(void)
> associativity = of_get_associativity(cpu);
> if (associativity) {
> nid = associativity_to_nid(associativity);
> - __initialize_form1_numa_distance(associativity);
> + __initialize_form1_numa_distance(associativity,
> false, 0);
> }
> of_node_put(cpu);
> }
> @@ -993,7 +1021,7 @@ static int __init parse_numa_properties(void)
> associativity = of_get_associativity(memory);
> if (associativity) {
> nid = associativity_to_nid(associativity);
> - __initialize_form1_numa_distance(associativity);
> + __initialize_form1_numa_distance(associativity, false,
> 0);
> } else
> nid = default_nid;
>
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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