On Wed, 2023-07-12 at 23:07 -0700, Yonghong Song wrote:
> > The existing 'be' and 'le' insns will do conditional bswap
> > depends on host endianness. This patch implements
> > unconditional bswap insns.
> >
> > Signed-off-by: Yonghong Song <yhs@xxxxxx>
Note sure if this is important, but here is an observation:
function is_reg64() has the following code:
...
if (class == BPF_ALU64 || class == BPF_JMP ||
/* BPF_END always use BPF_ALU class. */
(class == BPF_ALU && op == BPF_END && insn->imm == 64))
return true;
...
It probably has to be updated but I'm not sure how:
- either check insn->imm == 64 for ALU64 as well;
- or just update the comment, given that instruction always sets all 64-bits.
> > ---
> > arch/x86/net/bpf_jit_comp.c | 1 +
> > kernel/bpf/core.c | 14 ++++++++++++++
> > kernel/bpf/verifier.c | 2 +-
> > 3 files changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> > index a740a1a6e71d..adda5e7626b4 100644
> > --- a/arch/x86/net/bpf_jit_comp.c
> > +++ b/arch/x86/net/bpf_jit_comp.c
> > @@ -1322,6 +1322,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
> > break;
> >
> > case BPF_ALU | BPF_END | BPF_FROM_BE:
> > + case BPF_ALU64 | BPF_END | BPF_FROM_LE:
> > switch (imm32) {
> > case 16:
> > /* Emit 'ror %ax, 8' to swap lower 2 bytes */
> > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> > index fe648a158c9e..86bb412fee39 100644
> > --- a/kernel/bpf/core.c
> > +++ b/kernel/bpf/core.c
> > @@ -1524,6 +1524,7 @@ EXPORT_SYMBOL_GPL(__bpf_call_base);
> > INSN_3(ALU64, DIV, X), \
> > INSN_3(ALU64, MOD, X), \
> > INSN_2(ALU64, NEG), \
> > + INSN_3(ALU64, END, TO_LE), \
> > /* Immediate based. */ \
> > INSN_3(ALU64, ADD, K), \
> > INSN_3(ALU64, SUB, K), \
> > @@ -1845,6 +1846,19 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
> > break;
> > }
> > CONT;
> > + ALU64_END_TO_LE:
> > + switch (IMM) {
> > + case 16:
> > + DST = (__force u16) __swab16(DST);
> > + break;
> > + case 32:
> > + DST = (__force u32) __swab32(DST);
> > + break;
> > + case 64:
> > + DST = (__force u64) __swab64(DST);
> > + break;
> > + }
> > + CONT;
> >
> > /* CALL */
> > JMP_CALL:
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index 5fee9f24cb5e..22ba0744547b 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -13036,7 +13036,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
> > } else {
> > if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
> > (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
> > - BPF_CLASS(insn->code) == BPF_ALU64) {
> > + (BPF_CLASS(insn->code) == BPF_ALU64 && BPF_SRC(insn->code) != BPF_K)) {
> > verbose(env, "BPF_END uses reserved fields\n");
> > return -EINVAL;
> > }
