On 10/21/24 6:34 PM, Alexei Starovoitov wrote:
On Sun, Oct 20, 2024 at 12:16 PM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:
To identify whether a st_ops program requests private stack or not,
the st_ops stub function is checked. If the stub function has the
following name
<st_ops_name>__<member_name>__priv_stack
then the corresponding st_ops member func requests to use private
stack. The information that the private stack is requested or not
is encoded in struct bpf_struct_ops_func_info which will later be
used by verifier.
Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
include/linux/bpf.h | 2 ++
kernel/bpf/bpf_struct_ops.c | 35 +++++++++++++++++++++++++----------
kernel/bpf/verifier.c | 8 +++++++-
3 files changed, 34 insertions(+), 11 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f3884ce2603d..376e43fc72b9 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1491,6 +1491,7 @@ struct bpf_prog_aux {
bool exception_boundary;
bool is_extended; /* true if extended by freplace program */
bool priv_stack_eligible;
+ bool priv_stack_always;
u64 prog_array_member_cnt; /* counts how many times as member of prog_array */
struct mutex ext_mutex; /* mutex for is_extended and prog_array_member_cnt */
struct bpf_arena *arena;
@@ -1776,6 +1777,7 @@ struct bpf_struct_ops {
struct bpf_struct_ops_func_info {
struct bpf_ctx_arg_aux *info;
u32 cnt;
+ bool priv_stack_always;
};
struct bpf_struct_ops_desc {
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 8279b5a57798..2cd4bd086c7a 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -145,33 +145,44 @@ void bpf_struct_ops_image_free(void *image)
}
#define MAYBE_NULL_SUFFIX "__nullable"
-#define MAX_STUB_NAME 128
+#define MAX_STUB_NAME 140
/* Return the type info of a stub function, if it exists.
*
- * The name of a stub function is made up of the name of the struct_ops and
- * the name of the function pointer member, separated by "__". For example,
- * if the struct_ops type is named "foo_ops" and the function pointer
- * member is named "bar", the stub function name would be "foo_ops__bar".
+ * The name of a stub function is made up of the name of the struct_ops,
+ * the name of the function pointer member and optionally "priv_stack"
+ * suffix, separated by "__". For example, if the struct_ops type is named
+ * "foo_ops" and the function pointer member is named "bar", the stub
+ * function name would be "foo_ops__bar". If a suffix "priv_stack" exists,
+ * the stub function name would be "foo_ops__bar__priv_stack".
*/
static const struct btf_type *
find_stub_func_proto(const struct btf *btf, const char *st_op_name,
- const char *member_name)
+ const char *member_name, bool *priv_stack_always)
{
char stub_func_name[MAX_STUB_NAME];
const struct btf_type *func_type;
s32 btf_id;
int cp;
- cp = snprintf(stub_func_name, MAX_STUB_NAME, "%s__%s",
+ cp = snprintf(stub_func_name, MAX_STUB_NAME, "%s__%s__priv_stack",
st_op_name, member_name);
I don't think this approach fits.
pw-bot: cr
Okay, I will use check_member() callback function then. It should avoid
this hack.
Also looking at original
commit 1611603537a4 ("bpf: Create argument information for nullable arguments.")
that added this %s__%s notation I'm not sure why we went
with that approach.
Just to avoid adding __nullable suffix in the actual callback
and using cfi stub callback names with such suffixes as
a "proxy" for the real callback?
Did we ever use this functionality for anything other than
bpf_testmod_ops__test_maybe_null selftest ?
Martin ?
