| Message ID | 20211012023218.399568-4-iii@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | btf_dump fixes for s390 | expand |
On Tue, Oct 12, 2021 at 4:32 AM Ilya Leoshkevich <iii@linux.ibm.com> wrote: > > On s390 __int128 can be 8-byte aligned, therefore in libbpf will > occasionally consider variables of this type non-aligned and try to > dump them as a bitfield, which is supported for at most 64-bit > integers. > > Fix by using the same trick as btf_dump_float_data(): copy non-aligned > values to the local buffer. > > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> > --- > tools/lib/bpf/btf_dump.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c > index ab45771d0cb4..d8264c1762e8 100644 > --- a/tools/lib/bpf/btf_dump.c > +++ b/tools/lib/bpf/btf_dump.c > @@ -1672,9 +1672,10 @@ static int btf_dump_int_data(struct btf_dump *d, > { > __u8 encoding = btf_int_encoding(t); > bool sign = encoding & BTF_INT_SIGNED; > + char buf[16] __aligned(16); > int sz = t->size; > > - if (sz == 0) { > + if (sz == 0 || sz > sizeof(buf)) { > pr_warn("unexpected size %d for id [%u]\n", sz, type_id); > return -EINVAL; > } > @@ -1682,8 +1683,10 @@ 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)) > - return btf_dump_bitfield_data(d, t, data, 0, 0); > + if (!ptr_is_aligned(data, sz)) { I think ptr_is_aligned() logic is wrong. We should probably not assume that __int128 has 16-byte alignment. Can you try fixing it by using btf__align_of() API to get the natural alignment? > + memcpy(buf, data, sz); > + data = buf; > + } > > switch (sz) { > case 16: { > -- > 2.31.1 >
On Tue, 2021-10-12 at 05:52 +0200, Andrii Nakryiko wrote: > On Tue, Oct 12, 2021 at 4:32 AM Ilya Leoshkevich <iii@linux.ibm.com> > wrote: > > > > On s390 __int128 can be 8-byte aligned, therefore in libbpf will > > occasionally consider variables of this type non-aligned and try to > > dump them as a bitfield, which is supported for at most 64-bit > > integers. > > > > Fix by using the same trick as btf_dump_float_data(): copy non- > > aligned > > values to the local buffer. > > > > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> > > --- > > tools/lib/bpf/btf_dump.c | 9 ++++++--- > > 1 file changed, 6 insertions(+), 3 deletions(-) > > > > diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c > > index ab45771d0cb4..d8264c1762e8 100644 > > --- a/tools/lib/bpf/btf_dump.c > > +++ b/tools/lib/bpf/btf_dump.c > > @@ -1672,9 +1672,10 @@ static int btf_dump_int_data(struct btf_dump > > *d, > > { > > __u8 encoding = btf_int_encoding(t); > > bool sign = encoding & BTF_INT_SIGNED; > > + char buf[16] __aligned(16); > > int sz = t->size; > > > > - if (sz == 0) { > > + if (sz == 0 || sz > sizeof(buf)) { > > pr_warn("unexpected size %d for id [%u]\n", sz, > > type_id); > > return -EINVAL; > > } > > @@ -1682,8 +1683,10 @@ 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)) > > - return btf_dump_bitfield_data(d, t, data, 0, 0); > > + if (!ptr_is_aligned(data, sz)) { > > I think ptr_is_aligned() logic is wrong. We should probably not > assume > that __int128 has 16-byte alignment. Can you try fixing it by using > btf__align_of() API to get the natural alignment? Ok, but this patch makes sense anyway, doesn't it? I can fix ptr_is_aligned() separately. > > > + memcpy(buf, data, sz); > > + data = buf; > > + } > > > > switch (sz) { > > case 16: { > > -- > > 2.31.1 > >
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index ab45771d0cb4..d8264c1762e8 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -1672,9 +1672,10 @@ static int btf_dump_int_data(struct btf_dump *d, { __u8 encoding = btf_int_encoding(t); bool sign = encoding & BTF_INT_SIGNED; + char buf[16] __aligned(16); int sz = t->size; - if (sz == 0) { + if (sz == 0 || sz > sizeof(buf)) { pr_warn("unexpected size %d for id [%u]\n", sz, type_id); return -EINVAL; } @@ -1682,8 +1683,10 @@ 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)) - return btf_dump_bitfield_data(d, t, data, 0, 0); + if (!ptr_is_aligned(data, sz)) { + memcpy(buf, data, sz); + data = buf; + } switch (sz) { case 16: {
On s390 __int128 can be 8-byte aligned, therefore in libbpf will occasionally consider variables of this type non-aligned and try to dump them as a bitfield, which is supported for at most 64-bit integers. Fix by using the same trick as btf_dump_float_data(): copy non-aligned values to the local buffer. Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> --- tools/lib/bpf/btf_dump.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)