Messages in this thread | | | Date | Tue, 22 Aug 2017 17:25:54 +0200 | From | Daniel Borkmann <> | Subject | Re: [PATCH v4 net-next] arm: eBPF JIT compiler |
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On 08/22/2017 05:08 PM, Daniel Borkmann wrote: > On 08/22/2017 08:36 AM, Shubham Bansal wrote: > [...] >> + >> +static int out_offset = -1; /* initialized on the first pass of build_body() */ > > Hm, why is this a global var actually? There can be > multiple parallel calls to bpf_int_jit_compile(), we > don't take a global lock on this. Unless I'm missing > something this should really reside in jit_ctx, no?
Hm, okay, it's for generating the out jmp offsets in tail call emission which are supposed to always be the same relative offsets; should be fine then.
> Given this is on emit_bpf_tail_call(), did you get > tail calls working the way I suggested to test? > >> +static int emit_bpf_tail_call(struct jit_ctx *ctx) >> { > [...] >> + const int idx0 = ctx->idx; >> +#define cur_offset (ctx->idx - idx0) >> +#define jmp_offset (out_offset - (cur_offset)) > [...] >> + >> + /* out: */ >> + if (out_offset == -1) >> + out_offset = cur_offset; >> + if (cur_offset != out_offset) { >> + pr_err_once("tail_call out_offset = %d, expected %d!\n", >> + cur_offset, out_offset); >> + return -1; >> + } >> + return 0; >> +#undef cur_offset >> +#undef jmp_offset >> }
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