[PATCH bpf-next v6 1/4] bpf: Remove is_valid_bpf_tramp_flags()
From: Xu Kuohai <hidden>
Date: 2022-06-25 16:02:57
Also in:
bpf, lkml, netdev
Subsystem:
bpf jit for x86 64-bit, bpf [core], bpf [general] (safe dynamic programs and tools), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Before generating bpf trampoline, x86 calls is_valid_bpf_tramp_flags() to check the input flags. This check is architecture independent. So, to be consistent with x86, arm64 should also do this check before generating bpf trampoline. However, the BPF_TRAMP_F_XXX flags are not used by user code and the flags argument is almost constant at copmile time, so this run time check is a bit redundant. Remove is_valid_bpf_tramp_flags() and add some comments to the usage of BPF_TRAMP_F_XXX flags, as suggested by Alexei. Signed-off-by: Xu Kuohai <redacted> Acked-by: Song Liu <redacted> --- 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 2c51ca9f7cec..4f8938db03b1 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c@@ -1927,23 +1927,6 @@ 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
@@ -2022,9 +2005,6 @@ 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 7e0068c3399c..84b2d9dba79a 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
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