lkml.org 
[lkml]   [2022]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH bpf-next v5 3/6] bpf: Remove is_valid_bpf_tramp_flags()
Date
BPF_TRAM_F_XXX flags are not used by user code and are almost constant
at compile time, so run time validation is a bit overkill. Remove
is_valid_bpf_tramp_flags() and add some usage comments.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
arch/x86/net/bpf_jit_comp.c | 20 --------------------
kernel/bpf/bpf_struct_ops.c | 3 +++
kernel/bpf/trampoline.c | 3 +++
3 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index a2b6d197c226..7698ef3b4821 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1922,23 +1922,6 @@ 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
@@ -2017,9 +2000,6 @@ 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/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index d9a3c9207240..0572cc5aeb28 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -341,6 +341,9 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,

tlinks[BPF_TRAMP_FENTRY].links[0] = link;
tlinks[BPF_TRAMP_FENTRY].nr_links = 1;
+ /* BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
+ * and it must be used alone.
+ */
flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0;
return arch_prepare_bpf_trampoline(NULL, image, image_end,
model, flags, tlinks, NULL);
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 93c7675f0c9e..bd3f2e673874 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -358,6 +358,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr)

if (tlinks[BPF_TRAMP_FEXIT].nr_links ||
tlinks[BPF_TRAMP_MODIFY_RETURN].nr_links)
+ /* NOTE: BPF_TRAMP_F_RESTORE_REGS and BPF_TRAMP_F_SKIP_FRAME
+ * should not be set together.
+ */
flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME;

if (ip_arg)
--
2.30.2
\
 
 \ /
  Last update: 2022-05-18 15:54    [W:0.529 / U:0.348 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site