diff mbox series

[bpf-next,v6,1/4] bpf: Remove is_valid_bpf_tramp_flags()

Message ID 20220625161255.547944-2-xukuohai@huawei.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf trampoline for arm64 | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 4 this patch: 4
netdev/cc_maintainers success CCed 19 of 19 maintainers
netdev/build_clang success Errors and warnings before: 6 this patch: 6
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 4 this patch: 4
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 50 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-1 success Logs for Kernel LATEST on ubuntu-latest with gcc
bpf/vmtest-bpf-next-VM_Test-2 success Logs for Kernel LATEST on ubuntu-latest with llvm-15
bpf/vmtest-bpf-next-VM_Test-3 success Logs for Kernel LATEST on z15 with gcc

Commit Message

Xu Kuohai June 25, 2022, 4:12 p.m. UTC 
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 <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 mbox series

Patch

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)