linux-rng/kernel/bpf/backtrack.c, branch master

bpf: Drop duplicate blank lines in kernel/bpf/

2026-08-13T17:27:40Z

There are many adjacent blank lines in kernel/bpf/ that have accumulated over time. Drop them for cleanup. No functional changes intended. Signed-off-by: Leon Hwang Signed-off-by: Andrii Nakryiko Reviewed-by: Emil Tsalapatis Link: https://lore.kernel.org/bpf/20260813152324.97937-2-leon.hwang@linux.dev

bpf: Do not print a newline after disassembly in bpf_verbose_insn()

2026-08-08T09:05:49Z

At the moment there are more callsites that want bpf_verbose_insn() to not print a newline after the instruction, than callsites that want a newline. Drop '\n' from disasm.c. Non-functional change. The changes in bpftool are verified by writing a bpf program using a variety of instructions and comparing `prog dump xlated` output in the following modes: plain, opcodes, visual, visual opcodes. The output before and after the changes is identical. Signed-off-by: Eduard Zingerman Signed-off-by: Daniel Borkmann Reviewed-by: Quentin Monnet Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20260807-static-zext-v4-1-b6c270013c77@gmail.com

bpf: Rename ARG_CONST_SIZE{,_OR_ZERO} to ARG_MEM_SIZE{,_OR_ZERO}

2026-08-02T22:29:14Z

ARG_CONST_SIZE does not require a constant: check_mem_size_reg() accepts any bounded scalar and verifies the memory access against its maximum (reg_umax). Rename ARG_CONST_SIZE and ARG_CONST_SIZE_OR_ZERO to ARG_MEM_SIZE and ARG_MEM_SIZE_OR_ZERO to reflect that. ARG_CONST_ALLOC_ SIZE_OR_ZERO, which does require a constant, is left unchanged. Pure rename, no functional change. Signed-off-by: Amery Hung Link: https://lore.kernel.org/bpf/20260801074633.1595644-10-ameryhung@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi

bpf: Add precision marking and backtracking for stack argument slots

2026-05-13T16:27:30Z

Extend the precision marking and backtracking infrastructure to support stack argument slots (r11-based accesses). Without this, precision demands for scalar values passed through stack arguments are silently dropped, which could allow the verifier to incorrectly prune states with different constant values in stack arg slots. Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20260513045025.2387526-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov

bpf: Refactor jmp history to use dedicated spi/frame fields

2026-05-13T16:27:30Z

Move stack slot index (spi) and frame number out of the flags field in bpf_jmp_history_entry into dedicated bitfields. This simplifies the encoding and makes room for new flags. Previously, spi and frame were packed into the lower 9 bits of the 12-bit flags field (3 bits frame + 6 bits spi), with INSN_F_STACK_ACCESS at BIT(9) and INSN_F_DST/SRC_REG_STACK at BIT(10)/BIT(11). But this has no room for an INSN_F_* flag for stack arguments. To resolve this issue, bpf_jmp_history_entry field idx is narrowed to 20 bits (sufficient for insn indices up to 1M), and the freed bits hold spi (6 bits) and frame (3 bits) as dedicated struct fields. The flags enum is simplified accordingly: INSN_F_STACK_ACCESS -> BIT(0) INSN_F_DST_REG_STACK -> BIT(1) INSN_F_SRC_REG_STACK -> BIT(2) which allows more room for additional INSN_F_* flags. bpf_push_jmp_history() now takes explicit spi and frame parameters instead of encoding them into flags. The insn_stack_access_flags(), insn_stack_access_spi(), and insn_stack_access_frameno() helpers are removed. No functional change. Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20260513045020.2385962-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov

bpf: Move backtracking logic to backtrack.c

2026-04-12T19:36:58Z

Move precision propagation and backtracking logic to backtrack.c to reduce verifier.c size. No functional changes. Acked-by: Kumar Kartikeya Dwivedi Acked-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260412152936.54262-6-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov