On Wed, Jul 2, 2014 at 4:04 PM, Alexei Starovoitov <ast@xxxxxxxxxxxx> wrote: >>> + reg = regs + BPF_REG_1; /* 1st arg to a function */ >>> + reg->ptr = PTR_TO_CTX; >> Wait, doesn't this depend on doing "BPF_MOV64_REG(BPF_REG_CTX, >> BPF_REG_ARG1)" (the bpf-to-ebpf prologue), which is only enforced on >> filters converted from bpf? In fact, shouldn't this set >> regs[BPF_REG_CTX] instead of regs[BPF_REG_1] ? > > nope. it's REG_1. > as you said r6=r1 is only emitted by converted classic filters. > Verifier will see this 'r6=r1' assignment and will copy the r1 type into r6. You're right. I read BPF_MOV64_REG() AT&T-syntax-style. BTW, check_stack_write() in kernel/bpf/verifier.c has a couple of assignments of a slot->ptr to 0 (instead of INVALID_PTR). I assume this is unintended. -Chema -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
