[PATCH bpf-next v3 3/7] bpf: Move is_valid_bpf_tramp_flags() to the public trampoline code

Xu Kuohai
2022-04-24T15:36:32Z

is_valid_bpf_tramp_flags() is not relevant to architecture, so move it
to the public trampoline code.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
arch/x86/net/bpf_jit_comp.c | 20 --------------------
include/linux/bpf.h | 5 +++++
kernel/bpf/bpf_struct_ops.c | 4 ++--
kernel/bpf/trampoline.c | 34 +++++++++++++++++++++++++++++++---
4 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 8fe35ed11fd6..774f05f92737 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1900,23 +1900,6 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
return 0;
}

-static bool is_valid_bpf_tramp_flags(unsigned int flags)
-{
- if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
- (flags & BPF_TRAMP_F_SKIP_FRAME))
- return false;
-
- /*
- * BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
- * and it must be used alone.
- */
- if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) &&
- (flags & ~BPF_TRAMP_F_RET_FENTRY_RET))
- return false;
-
- return true;
-}
-
/* Example:
* __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
* its 'struct btf_func_model' will be nr_args=2
@@ -1995,9 +1978,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
if (nr_args > 6)
return -ENOTSUPP;

- if (!is_valid_bpf_tramp_flags(flags))
- return -EINVAL;
-
/* Generated trampoline stack layout:
*
* RBP + 8 [ return address ]
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 7bf441563ffc..90f878de2842 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -706,6 +706,11 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *i
const struct btf_func_model *m, u32 flags,
struct bpf_tramp_progs *tprogs,
void *orig_call);
+int bpf_prepare_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end,
+ const struct btf_func_model *m, u32 flags,
+ struct bpf_tramp_progs *tprogs,
+ void *orig_call);
+
/* these two functions are called from generated trampoline */
u64 notrace __bpf_prog_enter(struct bpf_prog *prog);
void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start);
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index de01d37c2d3b..3248dd86783a 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -325,8 +325,8 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_progs *tprogs,
tprogs[BPF_TRAMP_FENTRY].progs[0] = prog;
tprogs[BPF_TRAMP_FENTRY].nr_progs = 1;
flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0;
- return arch_prepare_bpf_trampoline(NULL, image, image_end,
- model, flags, tprogs, NULL);
+ return bpf_prepare_trampoline(NULL, image, image_end, model, flags,
+ tprogs, NULL);
}

static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index ada97751ae1b..00e6ad80fed2 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -360,9 +360,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr)
if (ip_arg)
flags |= BPF_TRAMP_F_IP_ARG;

- err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE,
- &tr->func.model, flags, tprogs,
- tr->func.addr);
+ err = bpf_prepare_trampoline(im, im->image, im->image + PAGE_SIZE,
+ &tr->func.model, flags, tprogs,
+ tr->func.addr);
if (err < 0)
goto out;

@@ -641,6 +641,34 @@ arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image
return -ENOTSUPP;
}

+static bool is_valid_bpf_tramp_flags(unsigned int flags)
+{
+ if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
+ (flags & BPF_TRAMP_F_SKIP_FRAME))
+ return false;
+
+ /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
+ * and it must be used alone.
+ */
+ if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) &&
+ (flags & ~BPF_TRAMP_F_RET_FENTRY_RET))
+ return false;
+
+ return true;
+}
+
+int bpf_prepare_trampoline(struct bpf_tramp_image *tr, void *image,
+ void *image_end, const struct btf_func_model *m,
+ u32 flags, struct bpf_tramp_progs *tprogs,
+ void *orig_call)
+{
+ if (!is_valid_bpf_tramp_flags(flags))
+ return -EINVAL;
+
+ return arch_prepare_bpf_trampoline(tr, image, image_end, m, flags,
+ tprogs, orig_call);
+}
+
static int __init init_trampolines(void)
{
int i;
--
2.30.2