From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Dave Marchevsky <davemarchevsky@fb.com>,
Delyan Kratunov <delyank@fb.com>
Subject: [PATCH bpf-next v1 02/25] bpf: Allow specifying volatile type modifier for kptrs
Date: Tue, 11 Oct 2022 06:52:17 +0530 [thread overview]
Message-ID: <20221011012240.3149-3-memxor@gmail.com> (raw)
In-Reply-To: <20221011012240.3149-1-memxor@gmail.com>
This is useful in particular to mark the pointer as volatile, so that
compiler treats each load and store to the field as a volatile access.
The alternative is having to define and use READ_ONCE and WRITE_ONCE in
the BPF program.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
include/linux/btf.h | 5 +++++
kernel/bpf/btf.c | 3 +++
2 files changed, 8 insertions(+)
diff --git a/include/linux/btf.h b/include/linux/btf.h
index f9aababc5d78..86aad9b2ce02 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -288,6 +288,11 @@ static inline bool btf_type_is_typedef(const struct btf_type *t)
return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
}
+static inline bool btf_type_is_volatile(const struct btf_type *t)
+{
+ return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE;
+}
+
static inline bool btf_type_is_func(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index eba603cec2c5..ad301e78f7ee 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3225,6 +3225,9 @@ static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
enum bpf_kptr_type type;
u32 res_id;
+ /* Permit modifiers on the pointer itself */
+ if (btf_type_is_volatile(t))
+ t = btf_type_by_id(btf, t->type);
/* For PTR, sz is always == 8 */
if (!btf_type_is_ptr(t))
return BTF_FIELD_IGNORE;
--
2.34.1
next prev parent reply other threads:[~2022-10-11 1:23 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-11 1:22 [PATCH bpf-next v1 00/25] Local kptrs, BPF linked lists Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 01/25] bpf: Document UAPI details for special BPF types Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` Kumar Kartikeya Dwivedi [this message]
2022-10-11 1:22 ` [PATCH bpf-next v1 03/25] bpf: Clobber stack slot when writing over spilled PTR_TO_BTF_ID Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 04/25] bpf: Fix slot type check in check_stack_write_var_off Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 05/25] bpf: Drop reg_type_may_be_refcounted_or_null Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 06/25] bpf: Refactor kptr_off_tab into fields_tab Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 07/25] bpf: Consolidate spin_lock, timer management " Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 08/25] bpf: Refactor map->off_arr handling Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 09/25] bpf: Support bpf_list_head in map values Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 10/25] bpf: Introduce local kptrs Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 11/25] bpf: Recognize bpf_{spin_lock,list_head,list_node} in " Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 12/25] bpf: Verify ownership relationships for owning types Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 13/25] bpf: Support locking bpf_spin_lock in local kptr Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 14/25] bpf: Allow locking bpf_spin_lock global variables Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 15/25] bpf: Rewrite kfunc argument handling Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 16/25] bpf: Drop kfunc bits from btf_check_func_arg_match Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 17/25] bpf: Support constant scalar arguments for kfuncs Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 18/25] bpf: Teach verifier about non-size constant arguments Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 19/25] bpf: Introduce bpf_kptr_new Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 20/25] bpf: Introduce bpf_kptr_drop Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 21/25] bpf: Permit NULL checking pointer with non-zero fixed offset Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 22/25] bpf: Introduce single ownership BPF linked list API Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 23/25] libbpf: Add support for private BSS map section Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 24/25] selftests/bpf: Add __contains macro to bpf_experimental.h Kumar Kartikeya Dwivedi
2022-10-11 1:22 ` [PATCH bpf-next v1 25/25] selftests/bpf: Add BPF linked list API tests Kumar Kartikeya Dwivedi
2022-10-11 1:51 ` [PATCH bpf-next v1 00/25] Local kptrs, BPF linked lists Kumar Kartikeya Dwivedi
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