diff mbox series

[v2,bpf-next,08/13] selftests/bpf: adjust OP_EQ/OP_NE handling to use subranges for branch taken

Message ID 20231112010609.848406-9-andrii@kernel.org (mailing list archive)
State Accepted
Commit 774f94c5e74d86d554c4fd1e97c517a1a7ee7fe0
Delegated to: BPF
Headers show
Series BPF register bounds range vs range support | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
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: 8 this patch: 8
netdev/cc_maintainers warning 12 maintainers not CCed: shuah@kernel.org jolsa@kernel.org john.fastabend@gmail.com linux-kselftest@vger.kernel.org yonghong.song@linux.dev martin.lau@linux.dev sdf@google.com mykolal@fb.com song@kernel.org haoluo@google.com eddyz87@gmail.com kpsingh@kernel.org
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
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: 8 this patch: 8
netdev/checkpatch warning WARNING: line length of 82 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-1 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-0 success Logs for Lint
bpf/vmtest-bpf-next-VM_Test-2 success Logs for Validate matrix.py
bpf/vmtest-bpf-next-VM_Test-3 success Logs for aarch64-gcc / build / build for aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-8 success Logs for aarch64-gcc / veristat
bpf/vmtest-bpf-next-VM_Test-4 success Logs for aarch64-gcc / test (test_maps, false, 360) / test_maps on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-7 success Logs for aarch64-gcc / test (test_verifier, false, 360) / test_verifier on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-6 success Logs for aarch64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-5 success Logs for aarch64-gcc / test (test_progs, false, 360) / test_progs on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-9 success Logs for s390x-gcc / build / build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-14 success Logs for s390x-gcc / veristat
bpf/vmtest-bpf-next-VM_Test-15 success Logs for set-matrix
bpf/vmtest-bpf-next-VM_Test-16 success Logs for x86_64-gcc / build / build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-17 success Logs for x86_64-gcc / test (test_maps, false, 360) / test_maps on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-18 success Logs for x86_64-gcc / test (test_progs, false, 360) / test_progs on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-19 success Logs for x86_64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-20 success Logs for x86_64-gcc / test (test_progs_no_alu32_parallel, true, 30) / test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-21 success Logs for x86_64-gcc / test (test_progs_parallel, true, 30) / test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-22 success Logs for x86_64-gcc / test (test_verifier, false, 360) / test_verifier on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-23 success Logs for x86_64-gcc / veristat / veristat on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-24 success Logs for x86_64-llvm-16 / build / build for x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-25 success Logs for x86_64-llvm-16 / test (test_maps, false, 360) / test_maps on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-26 success Logs for x86_64-llvm-16 / test (test_progs, false, 360) / test_progs on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-27 success Logs for x86_64-llvm-16 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-28 success Logs for x86_64-llvm-16 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-29 success Logs for x86_64-llvm-16 / veristat
bpf/vmtest-bpf-next-VM_Test-13 success Logs for s390x-gcc / test (test_verifier, false, 360) / test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-12 success Logs for s390x-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-11 success Logs for s390x-gcc / test (test_progs, false, 360) / test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-10 success Logs for s390x-gcc / test (test_maps, false, 360) / test_maps on s390x with gcc
bpf/vmtest-bpf-next-PR fail merge-conflict

Commit Message

Andrii Nakryiko Nov. 12, 2023, 1:06 a.m. UTC 
Similar to kernel-side BPF verifier logic enhancements, use 32-bit
subrange knowledge for is_branch_taken() logic in reg_bounds selftests.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 .../selftests/bpf/prog_tests/reg_bounds.c     | 30 ++++++++++++++++---
 1 file changed, 26 insertions(+), 4 deletions(-)

Comments

Eduard Zingerman Nov. 13, 2023, 11:46 p.m. UTC | #1 
On Sat, 2023-11-11 at 17:06 -0800, Andrii Nakryiko wrote:
> Similar to kernel-side BPF verifier logic enhancements, use 32-bit
> subrange knowledge for is_branch_taken() logic in reg_bounds selftests.
> 
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

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

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
index 7a524b381ed3..10f3b6898274 100644
--- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
+++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
@@ -748,16 +748,38 @@  static int reg_state_branch_taken_op(enum num_t t, struct reg_state *x, struct r
 		/* OP_EQ and OP_NE are sign-agnostic */
 		enum num_t tu = t_unsigned(t);
 		enum num_t ts = t_signed(t);
-		int br_u, br_s;
+		int br_u, br_s, br;
 
 		br_u = range_branch_taken_op(tu, x->r[tu], y->r[tu], op);
 		br_s = range_branch_taken_op(ts, x->r[ts], y->r[ts], op);
 
 		if (br_u >= 0 && br_s >= 0 && br_u != br_s)
 			ASSERT_FALSE(true, "branch taken inconsistency!\n");
-		if (br_u >= 0)
-			return br_u;
-		return br_s;
+
+		/* if 64-bit ranges are indecisive, use 32-bit subranges to
+		 * eliminate always/never taken branches, if possible
+		 */
+		if (br_u == -1 && (t == U64 || t == S64)) {
+			br = range_branch_taken_op(U32, x->r[U32], y->r[U32], op);
+			/* we can only reject for OP_EQ, never take branch
+			 * based on lower 32 bits
+			 */
+			if (op == OP_EQ && br == 0)
+				return 0;
+			/* for OP_NEQ we can be conclusive only if lower 32 bits
+			 * differ and thus inequality branch is always taken
+			 */
+			if (op == OP_NE && br == 1)
+				return 1;
+
+			br = range_branch_taken_op(S32, x->r[S32], y->r[S32], op);
+			if (op == OP_EQ && br == 0)
+				return 0;
+			if (op == OP_NE && br == 1)
+				return 1;
+		}
+
+		return br_u >= 0 ? br_u : br_s;
 	}
 	return range_branch_taken_op(t, x->r[t], y->r[t], op);
 }