From: Yonghong Song <yhs@fb.com>
To: <ast@fb.com>, <daniel@iogearbox.net>, <netdev@vger.kernel.org>,
<ecree@solarflare.com>
Cc: <kernel-team@fb.com>
Subject: [PATCH bpf-next v6 04/10] bpf: remove never-hit branches in verifier adjust_scalar_min_max_vals
Date: Mon, 23 Apr 2018 14:27:46 -0700 [thread overview]
Message-ID: <20180423212752.986580-5-yhs@fb.com> (raw)
In-Reply-To: <20180423212752.986580-1-yhs@fb.com>
In verifier function adjust_scalar_min_max_vals,
when src_known is false and the opcode is BPF_LSH/BPF_RSH,
early return will happen in the function. So remove
the branch in handling BPF_LSH/BPF_RSH when src_known is false.
Signed-off-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/verifier.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d531119..217d92a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2934,10 +2934,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
dst_reg->umin_value <<= umin_val;
dst_reg->umax_value <<= umax_val;
}
- if (src_known)
- dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
- else
- dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val);
+ dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
/* We may learn something more from the var_off */
__update_reg_bounds(dst_reg);
break;
@@ -2965,11 +2962,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
*/
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
- if (src_known)
- dst_reg->var_off = tnum_rshift(dst_reg->var_off,
- umin_val);
- else
- dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val);
+ dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
dst_reg->umin_value >>= umax_val;
dst_reg->umax_value >>= umin_val;
/* We may learn something more from the var_off */
--
2.9.5
next prev parent reply other threads:[~2018-04-23 21:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-23 21:27 [PATCH bpf-next v6 00/10] bpf: add bpf_get_stack helper Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 01/10] bpf: change prototype for stack_map_get_build_id_offset Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 02/10] bpf: add bpf_get_stack helper Yonghong Song
2018-04-25 9:00 ` Daniel Borkmann
2018-04-25 16:44 ` Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 03/10] bpf/verifier: refine retval R0 state for " Yonghong Song
2018-04-23 21:27 ` Yonghong Song [this message]
2018-04-23 21:27 ` [PATCH bpf-next v6 05/10] bpf/verifier: improve register value range tracking with ARSH Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 06/10] tools/bpf: add bpf_get_stack helper to tools headers Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 07/10] samples/bpf: move common-purpose trace functions to selftests Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 08/10] tools/bpf: add a verifier test case for bpf_get_stack helper and ARSH Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 09/10] tools/bpf: add a test for bpf_get_stack with raw tracepoint prog Yonghong Song
2018-04-23 21:27 ` [PATCH bpf-next v6 10/10] tools/bpf: add a test for bpf_get_stack with " Yonghong Song
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