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[209.85.220.65]) by mx.google.com with SMTPS id h68sor10271630pfj.73.2019.04.01.08.38.52 for (Google Transport Security); Mon, 01 Apr 2019 08:38:52 -0700 (PDT) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=rz+eKGWd; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HpLKq1u6zgG4u47m+oJy6q6/PWHFj2n1/o90qI1J+5Q=; b=rz+eKGWdIEAATVPKtPNa1Orgm+SbBpSOUItB/oKEP9YFvpyeRSiNTjebBofH85vmuv Ruo6xVKWsDadspv/HufxX8zlWaE2YfFITksk0W67DGyhwRPZzC7+gzZB1ALf/n+tyHvS D0yOd7NPpE0szXEAh4t1t4OxUCepvNGSbAokE8BiKS8d9NdDUhY7hSE5Ylh0xSoAv/R5 /JqgbBqVDIITLjgEaRXeiJ5w48h29NLd5psds/vI1hvwGhFuRBI5pib3dyhgzrQc6NTv h+gs0qckSWse4iFFCLh5ue5/qaD/TT8WdpCkVjuCA/Dr/MnpB2rUzW08V20dFWPmm68Z sg0w== X-Google-Smtp-Source: APXvYqwkizGwSG7ZyEmRuIQOd2nXeyJg5S4D8809WfJkrKIsV5+aD0+BiMFtb4gqUAAsYahc3/6PhBK4XlY5d3rLnhw= X-Received: by 2002:a62:69c2:: with SMTP id e185mr21673086pfc.119.1554133132011; Mon, 01 Apr 2019 08:38:52 -0700 (PDT) MIME-Version: 1.0 References: <20190322154513.GQ13384@arrakis.emea.arm.com> In-Reply-To: <20190322154513.GQ13384@arrakis.emea.arm.com> From: Andrey Konovalov Date: Mon, 1 Apr 2019 17:38:40 +0200 Message-ID: Subject: Re: [PATCH v13 11/20] tracing, arm64: untag user pointers in seq_print_user_ip To: Catalin Marinas Cc: Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , "David (ChunMing) Zhou" , Yishai Hadas , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Linux ARM , Linux Memory Management List , linux-arch , netdev , bpf , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , LKML , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Mar 22, 2019 at 4:45 PM Catalin Marinas wrote: > > On Wed, Mar 20, 2019 at 03:51:25PM +0100, Andrey Konovalov wrote: > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > pass tagged user pointers (with the top byte set to something else other > > than 0x00) as syscall arguments. > > > > seq_print_user_ip() uses provided user pointers for vma lookups, which > > can only by done with untagged pointers. > > > > Untag user pointers in this function. > > > > Signed-off-by: Andrey Konovalov > > --- > > kernel/trace/trace_output.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > > index 54373d93e251..6376bee93c84 100644 > > --- a/kernel/trace/trace_output.c > > +++ b/kernel/trace/trace_output.c > > @@ -370,6 +370,7 @@ static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm, > > { > > struct file *file = NULL; > > unsigned long vmstart = 0; > > + unsigned long untagged_ip = untagged_addr(ip); > > int ret = 1; > > > > if (s->full) > > @@ -379,7 +380,7 @@ static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm, > > const struct vm_area_struct *vma; > > > > down_read(&mm->mmap_sem); > > - vma = find_vma(mm, ip); > > + vma = find_vma(mm, untagged_ip); > > if (vma) { > > file = vma->vm_file; > > vmstart = vma->vm_start; > > @@ -388,7 +389,7 @@ static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm, > > ret = trace_seq_path(s, &file->f_path); > > if (ret) > > trace_seq_printf(s, "[+0x%lx]", > > - ip - vmstart); > > + untagged_ip - vmstart); > > } > > up_read(&mm->mmap_sem); > > } > > How would we end up with a tagged address here? Does "ip" here imply > instruction pointer, which we wouldn't tag? Yes, it's the instruction pointer. I think I got confused and decided that it's OK to have instruction pointer tagged, but I guess it's not a part of this ABI relaxation. I'll drop the patches that untag instruction pointers.