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    SubjectRe: [PATCH v2 bpf-next 05/13] bpf: Rename BPF_XADD and prepare to encode other atomics in .imm
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    On 11/27/20 9:57 AM, Brendan Jackman wrote:
    > A subsequent patch will add additional atomic operations. These new
    > operations will use the same opcode field as the existing XADD, with
    > the immediate discriminating different operations.
    >
    > In preparation, rename the instruction mode BPF_ATOMIC and start
    > calling the zero immediate BPF_ADD.
    >
    > This is possible (doesn't break existing valid BPF progs) because the
    > immediate field is currently reserved MBZ and BPF_ADD is zero.
    >
    > All uses are removed from the tree but the BPF_XADD definition is
    > kept around to avoid breaking builds for people including kernel
    > headers.
    >
    > Signed-off-by: Brendan Jackman <jackmanb@google.com>
    > ---
    > Documentation/networking/filter.rst | 30 +++++++-----
    > arch/arm/net/bpf_jit_32.c | 7 ++-
    > arch/arm64/net/bpf_jit_comp.c | 16 +++++--
    > arch/mips/net/ebpf_jit.c | 11 +++--
    > arch/powerpc/net/bpf_jit_comp64.c | 25 ++++++++--
    > arch/riscv/net/bpf_jit_comp32.c | 20 ++++++--
    > arch/riscv/net/bpf_jit_comp64.c | 16 +++++--
    > arch/s390/net/bpf_jit_comp.c | 27 ++++++-----
    > arch/sparc/net/bpf_jit_comp_64.c | 17 +++++--
    > arch/x86/net/bpf_jit_comp.c | 46 ++++++++++++++-----
    > arch/x86/net/bpf_jit_comp32.c | 6 +--
    > drivers/net/ethernet/netronome/nfp/bpf/jit.c | 14 ++++--
    > drivers/net/ethernet/netronome/nfp/bpf/main.h | 4 +-
    > .../net/ethernet/netronome/nfp/bpf/verifier.c | 15 ++++--
    > include/linux/filter.h | 8 ++--
    > include/uapi/linux/bpf.h | 3 +-
    > kernel/bpf/core.c | 31 +++++++++----
    > kernel/bpf/disasm.c | 6 ++-
    > kernel/bpf/verifier.c | 24 ++++++----
    > lib/test_bpf.c | 2 +-
    > samples/bpf/bpf_insn.h | 4 +-
    > samples/bpf/sock_example.c | 2 +-
    > samples/bpf/test_cgrp2_attach.c | 4 +-
    > tools/include/linux/filter.h | 7 +--
    > tools/include/uapi/linux/bpf.h | 3 +-
    > .../bpf/prog_tests/cgroup_attach_multi.c | 4 +-
    > tools/testing/selftests/bpf/verifier/ctx.c | 7 ++-
    > .../testing/selftests/bpf/verifier/leak_ptr.c | 4 +-
    > tools/testing/selftests/bpf/verifier/unpriv.c | 3 +-
    > tools/testing/selftests/bpf/verifier/xadd.c | 2 +-
    > 30 files changed, 248 insertions(+), 120 deletions(-)
    >
    > diff --git a/Documentation/networking/filter.rst b/Documentation/networking/filter.rst
    [...]
    > diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
    > index 0a721f6e8676..1c9efc74edfc 100644
    > --- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
    > +++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
    > @@ -3109,13 +3109,19 @@ mem_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta, bool is64)
    > return 0;
    > }
    >
    > -static int mem_xadd4(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
    > +static int mem_atomic4(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
    > {
    > + if (meta->insn.off != BPF_ADD)
    > + return -EOPNOTSUPP;

    You probably missed this change. it should be meta->insn.imm != BPF_ADD.

    > +
    > return mem_xadd(nfp_prog, meta, false);
    > }
    >
    > -static int mem_xadd8(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
    > +static int mem_atomic8(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
    > {
    > + if (meta->insn.off != BPF_ADD)

    same as above.

    > + return -EOPNOTSUPP;
    > +
    > return mem_xadd(nfp_prog, meta, true);
    > }
    >
    > @@ -3475,8 +3481,8 @@ static const instr_cb_t instr_cb[256] = {
    > [BPF_STX | BPF_MEM | BPF_H] = mem_stx2,
    > [BPF_STX | BPF_MEM | BPF_W] = mem_stx4,
    > [BPF_STX | BPF_MEM | BPF_DW] = mem_stx8,
    > - [BPF_STX | BPF_XADD | BPF_W] = mem_xadd4,
    > - [BPF_STX | BPF_XADD | BPF_DW] = mem_xadd8,
    > + [BPF_STX | BPF_ATOMIC | BPF_W] = mem_atomic4,
    > + [BPF_STX | BPF_ATOMIC | BPF_DW] = mem_atomic8,
    > [BPF_ST | BPF_MEM | BPF_B] = mem_st1,
    > [BPF_ST | BPF_MEM | BPF_H] = mem_st2,
    > [BPF_ST | BPF_MEM | BPF_W] = mem_st4,
    [...]

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