diff mbox series

[bpf-next,v2,2/5] bpf/verifier: improve XOR and OR range computation

Message ID 20240417122341.331524-3-cupertino.miranda@oracle.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf/verifier: range computation improvements | expand

Checks

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bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Posting correctly formatted
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netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 955 this patch: 955
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 10 maintainers not CCed: john.fastabend@gmail.com jolsa@kernel.org sdf@google.com kpsingh@kernel.org daniel@iogearbox.net martin.lau@linux.dev haoluo@google.com andrii@kernel.org eddyz87@gmail.com song@kernel.org
netdev/build_clang success Errors and warnings before: 955 this patch: 955
netdev/verify_signedoff success Signed-off-by tag matches author and committer
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netdev/checkpatch fail ERROR: Unrecognized email address: 'Cupertino Miranda <cupertino.miranda@oracle.com' ERROR: Unrecognized email address: 'Jose Marchesi <jose.marchesi@oracle.com'
netdev/build_clang_rust success No Rust files in patch. Skipping build
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Commit Message

Cupertino Miranda April 17, 2024, 12:23 p.m. UTC 
Range for XOR and OR operators would not be attempted unless src_reg
would resolve to a single value, i.e. a known constant value.
This condition is unnecessary, and the following XOR/OR operator
handling could compute a possible better range.

Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Faust <david.faust@oracle.com>
Cc: Jose Marchesi <jose.marchesi@oracle.com
Cc: Elena Zannoni <elena.zannoni@oracle.com>
---
 kernel/bpf/verifier.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Eduard Zingerman April 18, 2024, 11:57 p.m. UTC | #1 
On Wed, 2024-04-17 at 13:23 +0100, Cupertino Miranda wrote:
> Range for XOR and OR operators would not be attempted unless src_reg
> would resolve to a single value, i.e. a known constant value.
> This condition is unnecessary, and the following XOR/OR operator
> handling could compute a possible better range.
> 
> Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com
> Cc: Yonghong Song <yonghong.song@linux.dev>
> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Cc: David Faust <david.faust@oracle.com>
> Cc: Jose Marchesi <jose.marchesi@oracle.com
> Cc: Elena Zannoni <elena.zannoni@oracle.com>
> ---

I agree with this reasoning regarding OR/XOR processing.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
diff mbox series

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0aa6580af7a2..f410eb027e25 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13453,12 +13453,12 @@  static int is_safe_to_compute_dst_reg_range(struct bpf_insn *insn,
 	case BPF_ADD:
 	case BPF_SUB:
 	case BPF_AND:
+	case BPF_XOR:
+	case BPF_OR:
 		return COMPUTABLE_RANGE;
 
 	/* Compute range for the following only if the src_reg is known.
 	 */
-	case BPF_XOR:
-	case BPF_OR:
 	case BPF_MUL:
 		return src_known ? COMPUTABLE_RANGE : UNCOMPUTABLE_RANGE;