From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leo Yan Subject: Re: [PATCH bpf-next 4/5] samples/bpf: Refine printing symbol for sampleip Date: Thu, 19 Apr 2018 13:33:35 +0800 Message-ID: <20180419053335.GB27295@leoy-ThinkPad-X240s> References: <1524101646-6544-1-git-send-email-leo.yan@linaro.org> <1524101646-6544-5-git-send-email-leo.yan@linaro.org> <20180419044743.srjhqegvir5exub5@ast-mbp> <20180419051249.GA27295@leoy-ThinkPad-X240s> <20180419052124.xzaz66vehd6pofnh@ast-mbp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Alexei Starovoitov Return-path: Content-Disposition: inline In-Reply-To: <20180419052124.xzaz66vehd6pofnh@ast-mbp> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Apr 18, 2018 at 10:21:25PM -0700, Alexei Starovoitov wrote: > On Thu, Apr 19, 2018 at 01:12:49PM +0800, Leo Yan wrote: > > On Wed, Apr 18, 2018 at 09:47:45PM -0700, Alexei Starovoitov wrote: > > > On Thu, Apr 19, 2018 at 09:34:05AM +0800, Leo Yan wrote: > > > > The code defines macro 'PAGE_OFFSET' and uses it to decide if the > > > > address is in kernel space or not. But different architecture has > > > > different 'PAGE_OFFSET' so this program cannot be used for all > > > > platforms. > > > > > > > > This commit changes to check returned pointer from ksym_search() to > > > > judge if the address falls into kernel space or not, and removes > > > > macro 'PAGE_OFFSET' as it isn't used anymore. As result, this program > > > > has no architecture dependency. > > > > > > > > Signed-off-by: Leo Yan > > > > --- > > > > samples/bpf/sampleip_user.c | 8 +++----- > > > > 1 file changed, 3 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c > > > > index 4ed690b..0eea1b3 100644 > > > > --- a/samples/bpf/sampleip_user.c > > > > +++ b/samples/bpf/sampleip_user.c > > > > @@ -26,7 +26,6 @@ > > > > #define DEFAULT_FREQ 99 > > > > #define DEFAULT_SECS 5 > > > > #define MAX_IPS 8192 > > > > -#define PAGE_OFFSET 0xffff880000000000 > > > > > > > > static int nr_cpus; > > > > > > > > @@ -107,14 +106,13 @@ static void print_ip_map(int fd) > > > > /* sort and print */ > > > > qsort(counts, max, sizeof(struct ipcount), count_cmp); > > > > for (i = 0; i < max; i++) { > > > > - if (counts[i].ip > PAGE_OFFSET) { > > > > - sym = ksym_search(counts[i].ip); > > > > > > yes. it is x64 specific, since it's a sample code, > > > but simply removing it is not a fix. > > > It makes this sampleip code behaving incorrectly. > > > To do such 'cleanup of ksym' please refactor it in the true generic way, > > > so these ksym* helpers can work on all archs and put this new > > > functionality into selftests. > > > > Just want to check, are you suggesting to create a standalone > > testing for kallsyms (like a folder tools/testing/selftests/ksym) or > > do you mean to place the generic code into folder > > tools/testing/selftests/bpf/? > > I think the minimal first step is to cleanup ksym bits into something > that bpf selftests can use and keep it as new .c in > tools/testing/selftests/bpf/ > Later if it becomes useful for other tests in selftests it can be moved. Thanks for explanation, now it's clear for me :) > Thanks! >