From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH bpf-next] bpf: Allow bpf_jit_enable = 2 with BPF_JIT_ALWAYS_ON config Date: Wed, 25 Apr 2018 11:12:21 +0200 Message-ID: References: <1524644322-9263-1-git-send-email-leo.yan@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: Leo Yan , "David S. Miller" , Alexei Starovoitov , Kirill Tkhai , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1524644322-9263-1-git-send-email-leo.yan@linaro.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 04/25/2018 10:18 AM, Leo Yan wrote: > After enabled BPF_JIT_ALWAYS_ON config, bpf_jit_enable always equals to > 1; it is impossible to set 'bpf_jit_enable = 2' and the kernel has no > chance to call bpf_jit_dump(). > > This patch relaxes bpf_jit_enable range to [1..2] when kernel config > BPF_JIT_ALWAYS_ON is enabled so can invoke jit dump. > > Signed-off-by: Leo Yan Is there a specific reason why you need this here instead of retrieving the dump from the newer interface available from bpftool (tools/bpf/bpftool/)? The bpf_jit_enable = 2 is not recommended these days since it dumps into the kernel log which is often readable from unpriv as well. bpftool makes use of the BPF_OBJ_GET_INFO_BY_FD interface via bpf syscall to get the JIT dump instead when bpf_jit_enable is set. > --- > net/core/sysctl_net_core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c > index b1a2c5e..6a39b22 100644 > --- a/net/core/sysctl_net_core.c > +++ b/net/core/sysctl_net_core.c > @@ -371,7 +371,7 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write, > .proc_handler = proc_dointvec_minmax_bpf_enable, > # ifdef CONFIG_BPF_JIT_ALWAYS_ON > .extra1 = &one, > - .extra2 = &one, > + .extra2 = &two, > # else > .extra1 = &zero, > .extra2 = &two, >