libbpf: Fix ptr_is_aligned() usages

Currently ptr_is_aligned() takes size, and not alignment, as a
parameter, which may be overly pessimistic e.g. for __i128 on s390,
which must be only 8-byte aligned. Fix by using btf__align_of().

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211021104658.624944-2-iii@linux.ibm.com

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index e98c201f29b51bea3b18f3bb559438b7e9b17ba2..e9e5801ece4ca1e3c07d953892df4043bc185c8e 100644 (file)
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -1657,9 +1657,15 @@ static int btf_dump_base_type_check_zero(struct btf_dump *d,
        return 0;
 }
 
-static bool ptr_is_aligned(const void *data, int data_sz)
+static bool ptr_is_aligned(const struct btf *btf, __u32 type_id,
+                          const void *data)
 {
-       return ((uintptr_t)data) % data_sz == 0;
+       int alignment = btf__align_of(btf, type_id);
+
+       if (alignment == 0)
+               return false;
+
+       return ((uintptr_t)data) % alignment == 0;
 }
 
 static int btf_dump_int_data(struct btf_dump *d,
@@ -1681,7 +1687,7 @@ static int btf_dump_int_data(struct btf_dump *d,
        /* handle packed int data - accesses of integers not aligned on
         * int boundaries can cause problems on some platforms.
         */
-       if (!ptr_is_aligned(data, sz)) {
+       if (!ptr_is_aligned(d->btf, type_id, data)) {
                memcpy(buf, data, sz);
                data = buf;
        }
@@ -1770,7 +1776,7 @@ static int btf_dump_float_data(struct btf_dump *d,
        int sz = t->size;
 
        /* handle unaligned data; copy to local union */
-       if (!ptr_is_aligned(data, sz)) {
+       if (!ptr_is_aligned(d->btf, type_id, data)) {
                memcpy(&fl, data, sz);
                flp = &fl;
        }
@@ -1933,7 +1939,7 @@ static int btf_dump_ptr_data(struct btf_dump *d,
                              __u32 id,
                              const void *data)
 {
-       if (ptr_is_aligned(data, d->ptr_sz) && d->ptr_sz == sizeof(void *)) {
+       if (ptr_is_aligned(d->btf, id, data) && d->ptr_sz == sizeof(void *)) {
                btf_dump_type_values(d, "%p", *(void **)data);
        } else {
                union ptr_data pt;
@@ -1953,10 +1959,8 @@ static int btf_dump_get_enum_value(struct btf_dump *d,
                                   __u32 id,
                                   __s64 *value)
 {
-       int sz = t->size;
-
        /* handle unaligned enum value */
-       if (!ptr_is_aligned(data, sz)) {
+       if (!ptr_is_aligned(d->btf, id, data)) {
                __u64 val;
                int err;