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From: David Miller <davem@davemloft.net>
To: jannh@google.com
Cc: alexei.starovoitov@gmail.com, torvalds@linux-foundation.org,
	mhiramat@kernel.org, rostedt@goodmis.org, luto@amacapital.net,
	linux-kernel@vger.kernel.org, mingo@kernel.org,
	akpm@linux-foundation.org, stable@vger.kernel.org,
	changbin.du@gmail.com, keescook@chromium.org, luto@kernel.org,
	daniel@iogearbox.net, netdev@vger.kernel.org,
	bpf@vger.kernel.org
Subject: Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault
Date: Fri, 22 Feb 2019 15:16:06 -0800 (PST)	[thread overview]
Message-ID: <20190222.151606.344940961752699587.davem@davemloft.net> (raw)
In-Reply-To: <CAG48ez0nMEMP5-eSFWmLKs30zApgZ57zqU1Od9cROBYQvoJxsg@mail.gmail.com>

From: Jann Horn <jannh@google.com>
Date: Sat, 23 Feb 2019 00:11:58 +0100

> I think what Linus is saying is: There are some scenarios (like a
> system with the old 4G/4G X86 patch) where *the same* address can
> refer to two different pieces of memory, depending on whether you
> interpret it as a kernel pointer or a user pointer.

Exactly.

On sparc64 the kernel is mapped exactly at the same virtual addresses
as userspace processes usually are mapped, even 32-bit ones.  The
difference is the MMU context only.

  reply	other threads:[~2019-02-22 23:16 UTC|newest]

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-15 17:47 [PATCH 0/2 v2] [GIT PULL (take two)] tracing: Two more fixes Steven Rostedt
2019-02-15 17:47 ` [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault Steven Rostedt
2019-02-15 17:55   ` Linus Torvalds
2019-02-15 22:15     ` Steven Rostedt
2019-02-15 23:49       ` Andy Lutomirski
2019-02-16  0:19         ` Steven Rostedt
2019-02-16  1:32           ` Andy Lutomirski
2019-02-16  2:08             ` Steven Rostedt
2019-02-16  2:14               ` Andy Lutomirski
2019-02-16  2:21                 ` Steven Rostedt
2019-02-18 17:58           ` Linus Torvalds
2019-02-18 18:23             ` Linus Torvalds
2019-02-19 16:18               ` Steven Rostedt
2019-02-19 18:43                 ` Linus Torvalds
2019-02-19 19:03                   ` Steven Rostedt
2019-02-20  8:10                     ` Masami Hiramatsu
2019-02-20 13:57                       ` Jann Horn
2019-02-20 14:47                         ` Steven Rostedt
2019-02-20 15:08                         ` Masami Hiramatsu
2019-02-20 14:49                       ` Steven Rostedt
2019-02-20 16:04                         ` Masami Hiramatsu
2019-02-20 16:42                           ` Steven Rostedt
2019-02-21  7:37                             ` Masami Hiramatsu
2019-02-22  8:27                         ` Masami Hiramatsu
2019-02-22  8:35                           ` Masami Hiramatsu
2019-02-22 17:43                             ` Linus Torvalds
2019-02-22 17:48                               ` Andy Lutomirski
2019-02-22 18:28                                 ` Linus Torvalds
2019-02-22 19:52                                   ` Andy Lutomirski
2019-02-22 19:27                               ` Alexei Starovoitov
2019-02-22 19:30                                 ` Steven Rostedt
2019-02-22 19:34                                   ` Alexei Starovoitov
2019-02-22 19:39                                     ` Steven Rostedt
2019-02-22 19:55                                     ` Andy Lutomirski
2019-02-22 21:43                                       ` Jann Horn
2019-02-22 22:08                                         ` Nadav Amit
2019-02-22 22:17                                           ` Jann Horn
2019-02-22 22:21                                             ` Nadav Amit
2019-02-22 22:39                                               ` Nadav Amit
2019-02-22 23:02                                                 ` Jann Horn
2019-02-22 23:22                                                   ` Nadav Amit
2019-02-22 23:59                                                   ` Andy Lutomirski
2019-02-23  0:03                                                     ` Alexei Starovoitov
2019-02-23  0:15                                                     ` Nadav Amit
2019-02-24 19:35                                                       ` Andy Lutomirski
2019-02-25 13:36                                                     ` Masami Hiramatsu
2019-02-22 21:20                                 ` Linus Torvalds
2019-02-22 21:38                                   ` David Miller
2019-02-22 21:59                                     ` Linus Torvalds
2019-02-22 22:51                                       ` Alexei Starovoitov
2019-02-22 23:11                                         ` Jann Horn
2019-02-22 23:16                                           ` David Miller [this message]
2019-02-22 23:16                                         ` Linus Torvalds
2019-02-22 23:56                                           ` Alexei Starovoitov
2019-02-23  0:08                                             ` Linus Torvalds
2019-02-23  2:28                                               ` Alexei Starovoitov
2019-02-23  2:32                                                 ` Linus Torvalds
2019-02-23  3:02                                                 ` Steven Rostedt
2019-02-23  4:51                                             ` Masami Hiramatsu
2019-02-26  3:57                                       ` Christoph Hellwig
2019-02-26 15:24                                 ` Joel Fernandes
2019-02-28 12:29                                   ` Masami Hiramatsu
2019-02-28 15:18                                     ` Joel Fernandes
2019-02-23  3:47                               ` Masami Hiramatsu
2019-02-24  0:44                                 ` Steven Rostedt
2019-02-24  4:38                                   ` Andy Lutomirski
2019-02-24 15:17                                     ` Masami Hiramatsu
2019-02-24 17:26                                       ` Linus Torvalds
2019-02-25  2:40                                         ` Masami Hiramatsu
2019-02-25  4:49                                           ` Andy Lutomirski
2019-02-25  8:09                                             ` Masami Hiramatsu
2019-02-25 16:40                                               ` Steven Rostedt
2019-02-26  1:35                                                 ` Masami Hiramatsu
2019-02-25  8:33                                         ` Peter Zijlstra
2019-02-25 14:52                                           ` Peter Zijlstra
2019-02-25 16:48                                     ` Kees Cook
2019-02-25 16:58                                       ` Andy Lutomirski
2019-02-25 17:07                                         ` Kees Cook
2019-02-21  7:52   ` Masami Hiramatsu
2019-02-21 14:36     ` Steven Rostedt
2019-02-21 15:58       ` Masami Hiramatsu
2019-02-21 16:16         ` Masami Hiramatsu
2019-02-21 16:32           ` Steven Rostedt
2019-02-23 14:48     ` Masami Hiramatsu
2019-02-15 17:47 ` [PATCH 2/2 v2] tracing: Fix number of entries in trace header Steven Rostedt

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