bpf: Introduce bpf register BPF_REG_PARAMS

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Introduce BPF_REG_PARAMS as a dedicated BPF register for stack
argument accesses. It occupies the BPF register number 11 (R11),
which is used as the base pointer for the stack argument area,
keeping it separate from the R10-based (BPF_REG_FP) program stack.

The kernel-internal hidden register BPF_REG_AX previously occupied
slot 11 (MAX_BPF_REG). With BPF_REG_PARAMS taking that slot,
BPF_REG_AX moves to slot 12 and MAX_BPF_EXT_REG increases
accordingly.

Acked-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033506.2542005-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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This commit is contained in:

Yonghong Song 2026-04-22 20:35:06 -07:00 • committed by Alexei Starovoitov

parent 9b9f0b4270

commit 246ad6e5ee

6 changed files with 62 additions and 61 deletions

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5

include/linux/filter.h

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4

kernel/bpf/core.c

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14

tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c

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24

tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c

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12

tools/testing/selftests/bpf/progs/verifier_may_goto_1.c

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64

tools/testing/selftests/bpf/progs/verifier_sdiv.c

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