bpf: encapsulate precision backtracking bookkeeping

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[ Upstream commit 407958a0e9 ]

Add struct backtrack_state and straightforward API around it to keep
track of register and stack masks used and maintained during precision
backtracking process. Having this logic separately allow to keep
high-level backtracking algorithm cleaner, but also it sets us up to
cleanly keep track of register and stack masks per frame, allowing (with
some further logic adjustments) to perform precision backpropagation
across multiple frames (i.e., subprog calls).

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: f655badf2a ("bpf: fix propagate_precision() logic for inner frames")
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Andrii Nakryiko 2023-05-04 21:33:10 -07:00 • committed by Greg Kroah-Hartman

parent 7e76a302ed

commit fc2778c42f

2 changed files with 196 additions and 67 deletions

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14

include/linux/bpf_verifier.h

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249

kernel/bpf/verifier.c

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