From: Sven Schnelle <svens@linux.ibm.com>
To: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Florent Revest <revest@chromium.org>,
linux-trace-kernel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Jiri Olsa <jolsa@kernel.org>,
Alan Maguire <alan.maguire@oracle.com>,
Mark Rutland <mark.rutland@arm.com>,
linux-arch@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Naveen N Rao <naveen@kernel.org>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Date: Wed, 16 Oct 2024 20:14:54 +0200 [thread overview]
Message-ID: <yt9d5xprgbj5.fsf@linux.ibm.com> (raw)
In-Reply-To: <20241016234628.b7eba1db0db39d2197a2ea4f@kernel.org> (Masami Hiramatsu's message of "Wed, 16 Oct 2024 23:46:28 +0900")
Masami Hiramatsu (Google) <mhiramat@kernel.org> writes:
> On Wed, 16 Oct 2024 14:07:31 +0200
> Sven Schnelle <svens@linux.ibm.com> wrote:
>> "Masami Hiramatsu (Google)" <mhiramat@kernel.org> writes:
>> I think that still has the issue that the size is encoded in the
>> leftmost fields of the pointer, which doesn't work on all
>> architectures. I reported this already in v15
>> (https://lore.kernel.org/all/yt9dmsjyx067.fsf@linux.ibm.com/)
>
> Oops, thanks for reporting. I should missed that.
>
>> I haven't yet fully understood why this logic is needed, but the
>> WARN_ON_ONCE triggers on s390. I'm assuming this fails because fp always
>> has the upper bits of the address set on x86 (and likely others). As an
>> example, in my test setup, fp is 0x8feec218 on s390, while it is
>> 0xffff888100add118 in x86-kvm.
>
> Ah, so s390 kernel/user memory layout is something like 4G/4G?
> Hmm, this encode expects the leftmost 4bit is filled. For the
> architecture which has 32bit address space, we may be possible to
> use "unsigned long long" for 'val' on shadow stack (and use the
> first 32bit for fp and another 32bit for size).
>
> Anyway, I need to redesign it depending on architecture.
Could you explain a bit more what redesign means? Thanks!
next prev parent reply other threads:[~2024-10-16 18:15 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-16 0:57 [PATCH v17 00/16] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
2024-10-16 0:57 ` [PATCH v17 01/16] function_graph: Pass ftrace_regs to entryfunc Masami Hiramatsu (Google)
2024-10-16 13:53 ` Steven Rostedt
2024-10-16 22:15 ` Masami Hiramatsu
2024-10-21 17:03 ` Will Deacon
2024-10-22 22:55 ` Masami Hiramatsu
2024-10-16 0:58 ` [PATCH v17 02/16] function_graph: Replace fgraph_ret_regs with ftrace_regs Masami Hiramatsu (Google)
2024-10-21 16:46 ` Will Deacon
2024-10-23 8:58 ` Masami Hiramatsu
2024-10-16 0:58 ` [PATCH v17 03/16] function_graph: Pass ftrace_regs to retfunc Masami Hiramatsu (Google)
2024-10-16 0:58 ` [PATCH v17 04/16] fprobe: Use ftrace_regs in fprobe entry handler Masami Hiramatsu (Google)
2024-10-16 0:58 ` [PATCH v17 05/16] fprobe: Use ftrace_regs in fprobe exit handler Masami Hiramatsu (Google)
2024-10-16 0:59 ` [PATCH v17 06/16] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs Masami Hiramatsu (Google)
2024-10-21 16:46 ` Will Deacon
2024-10-23 8:57 ` Masami Hiramatsu
2024-10-16 0:59 ` [PATCH v17 07/16] tracing: Add ftrace_fill_perf_regs() for perf event Masami Hiramatsu (Google)
2024-10-21 17:01 ` Will Deacon
2024-10-23 8:58 ` Masami Hiramatsu
2024-10-16 0:59 ` [PATCH v17 08/16] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS Masami Hiramatsu (Google)
2024-10-16 0:59 ` [PATCH v17 09/16] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled Masami Hiramatsu (Google)
2024-10-16 0:59 ` [PATCH v17 10/16] ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC Masami Hiramatsu (Google)
2024-10-16 1:00 ` [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer Masami Hiramatsu (Google)
2024-10-16 12:07 ` Sven Schnelle
2024-10-16 14:10 ` Steven Rostedt
2024-10-16 18:13 ` Sven Schnelle
2024-10-17 21:10 ` Steven Rostedt
2024-10-18 12:49 ` Heiko Carstens
2024-10-21 15:15 ` Masami Hiramatsu
2024-10-21 16:31 ` Heiko Carstens
2024-10-22 9:00 ` Masami Hiramatsu
2024-10-16 14:46 ` Masami Hiramatsu
2024-10-16 18:14 ` Sven Schnelle [this message]
2024-10-18 0:45 ` Masami Hiramatsu
2024-10-16 1:00 ` [PATCH v17 12/16] tracing/fprobe: Remove nr_maxactive from fprobe Masami Hiramatsu (Google)
2024-10-16 1:00 ` [PATCH v17 13/16] selftests: ftrace: Remove obsolate maxactive syntax check Masami Hiramatsu (Google)
2024-10-16 1:00 ` [PATCH v17 14/16] selftests/ftrace: Add a test case for repeating register/unregister fprobe Masami Hiramatsu (Google)
2024-10-16 1:00 ` [PATCH v17 15/16] Documentation: probes: Update fprobe on function-graph tracer Masami Hiramatsu (Google)
2024-10-16 1:01 ` [PATCH v17 16/16] bpf: Add get_entry_ip() for arm64 Masami Hiramatsu (Google)
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