On 10/12/22 5:58 AM, Chengming Zhou wrote:
When tracing a kernel function with arg type is u32*, btf_ctx_access()
would report error: arg2 type INT is not a struct.
The commit bb6728d75611 ("bpf: Allow access to int pointer arguments
in tracing programs") added support for int pointer, but don't skip
modifiers before checking it's type. This patch fixes it.
A selftest is needed. You can refer to the selftest added in the patch set [0]
of the commit bb6728d75611.
This belongs to bpf-next. Please tag it as bpf-next and also v2 in the next
revision:
Documentation/bpf/bpf_devel_QA.rst (Q: How do I indicate which tree....)
[0]: https://lore.kernel.org/bpf/20211208193245.172141-2-jolsa@xxxxxxxxxx/
Fixes: bb6728d75611 ("bpf: Allow access to int pointer arguments in tracing programs")
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
---
kernel/bpf/btf.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index eba603cec2c5..2b343c42ed10 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -5316,8 +5316,8 @@ static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
/* t comes in already as a pointer */
t = btf_type_by_id(btf, t->type);
- /* allow const */
- if (BTF_INFO_KIND(t->info) == BTF_KIND_CONST)
+ /* skip modifiers */
+ while (btf_type_is_modifier(t))
There is btf_type_skip_modifiers() that should be useful here.
t = btf_type_by_id(btf, t->type);
return btf_type_is_int(t);
