Commit 632f96d2 authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Andrii Nakryiko
Browse files

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: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211021104658.624944-2-iii@linux.ibm.com
parent 549beec0

tools/lib/bpf/btf_dump.c

+12 −8
Original line number Diff line number Diff line
@@ -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;