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| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-09-24 18:57:05 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-09-24 18:04:45 +0000 |
| commit | 765e7328d64dec47a33fd7ac8c070b411297c275 (patch) | |
| tree | e63d25c4bf061ac2fac32cb92e0eee72463024f7 /include/linux | |
| parent | 9eda94d7e89894024e5178d91e140b6fb0835d8e (diff) | |
| download | linux-765e7328d64dec47a33fd7ac8c070b411297c275.tar.gz linux-765e7328d64dec47a33fd7ac8c070b411297c275.zip | |
bpf: Track backtracking stack slots with bitmaps
Precision backtracking keeps the stack slots that still need a precise
mark in one u64 per frame, which ties it to frames of at most 64 slots.
Turn the per-frame masks into bitmaps sized by MAX_BPF_STACK_SLOTS and
use the bitmap helpers for setting, clearing, testing and iterating
them. The formatting helper takes a bitmap and the leftover-slot bug
reports print the formatted slot list instead of a hex mask.
mark_reg_stack_read() collected zero spills in a u64 of its own before
handing it to the backtracker; it now counts them and revisits the
range to mark each slot, which drops the only remaining mask-typed
entry point.
No functional change.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260924165740.2146806-5-memxor@gmail.com
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/bpf_verifier.h | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 7d5da5b38e0e..781dc5ca1fe2 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -900,7 +900,7 @@ struct backtrack_state { struct bpf_verifier_env *env; u32 frame; u32 reg_masks[MAX_CALL_FRAMES]; - u64 stack_masks[MAX_CALL_FRAMES]; + unsigned long stack_masks[MAX_CALL_FRAMES][BITS_TO_LONGS(MAX_BPF_STACK_SLOTS)]; u8 stack_arg_masks[MAX_CALL_FRAMES]; }; @@ -1367,12 +1367,7 @@ static inline void bpf_bt_set_frame_reg(struct backtrack_state *bt, u32 frame, u static inline void bpf_bt_set_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot) { - bt->stack_masks[frame] |= 1ull << slot; -} - -static inline void bpf_bt_set_frame_slot_mask(struct backtrack_state *bt, u32 frame, u64 mask) -{ - bt->stack_masks[frame] |= mask; + __set_bit(slot, bt->stack_masks[frame]); } static inline void bt_set_frame_stack_arg_slot(struct backtrack_state *bt, u32 frame, u32 slot) @@ -1387,7 +1382,7 @@ static inline bool bt_is_frame_reg_set(struct backtrack_state *bt, u32 frame, u3 static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot) { - return bt->stack_masks[frame] & (1ull << slot); + return test_bit(slot, bt->stack_masks[frame]); } bool bpf_map_is_rdonly(const struct bpf_map *map); @@ -1588,7 +1583,7 @@ struct bpf_subprog_info *bpf_find_containing_subprog(struct bpf_verifier_env *en const char *bpf_subprog_name(const struct bpf_verifier_env *env, int subprog); int bpf_jmp_offset(struct bpf_insn *insn); struct bpf_iarray *bpf_insn_successors(struct bpf_verifier_env *env, u32 idx); -void bpf_fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask); +void bpf_fmt_stack_mask(char *buf, ssize_t buf_sz, const unsigned long *stack_mask); bool bpf_subprog_is_global(const struct bpf_verifier_env *env, int subprog); /* Kinds of member a by-value struct or union may be composed of. */ |