From: Linus Torvalds <torvalds@linux-foundation.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Steven Rostedt <rostedt@kernel.org>,
linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org,
x86@kernel.org, Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrii Nakryiko <andrii@kernel.org>,
Indu Bhagat <indu.bhagat@oracle.com>,
"Jose E. Marchesi" <jemarch@gnu.org>,
Beau Belgrave <beaub@linux.microsoft.com>,
Jens Remus <jremus@linux.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>,
Florian Weimer <fweimer@redhat.com>, Sam James <sam@gentoo.org>
Subject: Re: [PATCH v8 10/12] unwind_user/sframe: Enable debugging in uaccess regions
Date: Tue, 8 Jul 2025 08:52:17 -0700 [thread overview]
Message-ID: <CAHk-=wjOnFbRJ9V81VEeSK+=HuD8ODSq+S3STTh1JwYQLWXXXg@mail.gmail.com> (raw)
In-Reply-To: <orpxec72lzxzkwhcu3gateqbcw6cdlojxvxmvopa2jxr67d4az@rvgfflvrbzk5>
On Tue, 8 Jul 2025 at 07:34, Josh Poimboeuf <jpoimboe@kernel.org> wrote:
>
> I had found those debug printks really useful for debugging
> corrupt/missing .sframe data, but yeah, this patch is ridiculously bad.
> Sorry for putting that out into the world ;-)
I suspect that code that is still needs that level of debugging should
just not use the 'unsafe' user access helpers.
They really are meant for "this sequence turns into three CPU
instructions" kind of uses, and the "unsafe" part of the naming was
very much intended to be a "please don't use this unless you are being
very careful and limited" marker.
Now, I do think that the "goto label for exceptions" part of the
unsafe accessors can be very convenient, so maybe we should make
_that_ part of the interface more widely available. IOW, without the
whole user_read_access_begin/user_read_access_end dance?
That model is already used by "__{get,put}_kernel_nofault()", but I
think it's limited to just some unusual code in mm/maccess.c.
Linus
next prev parent reply other threads:[~2025-07-08 15:52 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-08 2:11 [PATCH v8 00/12] unwind_deferred: Implement sframe handling Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 01/12] unwind_user/sframe: Add support for reading .sframe headers Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 02/12] unwind_user/sframe: Store sframe section data in per-mm maple tree Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 03/12] x86/uaccess: Add unsafe_copy_from_user() implementation Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 04/12] unwind_user/sframe: Add support for reading .sframe contents Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 05/12] unwind_user/sframe: Detect .sframe sections in executables Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 06/12] unwind_user/sframe: Wire up unwind_user to sframe Steven Rostedt
2025-07-08 19:58 ` Mathieu Desnoyers
2025-07-08 20:11 ` Steven Rostedt
2025-07-09 7:58 ` Jens Remus
2025-07-09 13:46 ` Mathieu Desnoyers
2025-07-09 13:51 ` Mathieu Desnoyers
2025-07-09 14:06 ` Steven Rostedt
2025-07-09 14:10 ` Mathieu Desnoyers
2025-07-09 14:29 ` Steven Rostedt
2025-07-09 15:14 ` Mathieu Desnoyers
2025-07-10 8:03 ` Jens Remus
2025-07-10 9:26 ` Jens Remus
2025-07-10 15:30 ` Steven Rostedt
2025-07-10 20:51 ` Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 07/12] unwind_user/sframe/x86: Enable sframe unwinding on x86 Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 08/12] unwind_user/sframe: Remove .sframe section on detected corruption Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 09/12] unwind_user/sframe: Show file name in debug output Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 10/12] unwind_user/sframe: Enable debugging in uaccess regions Steven Rostedt
2025-07-08 3:38 ` Linus Torvalds
2025-07-08 13:23 ` Steven Rostedt
2025-07-08 14:34 ` Josh Poimboeuf
2025-07-08 14:41 ` Steven Rostedt
2025-07-08 15:53 ` Linus Torvalds
2025-07-08 16:31 ` Steven Rostedt
2025-07-08 18:57 ` Josh Poimboeuf
2025-07-08 15:52 ` Linus Torvalds [this message]
2025-07-08 2:11 ` [PATCH v8 11/12] unwind_user/sframe: Add .sframe validation option Steven Rostedt
2025-07-08 2:11 ` [PATCH v8 12/12] unwind_user/sframe: Add prctl() interface for registering .sframe sections Steven Rostedt
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