From: "Björn Töpel" <bjorn@kernel.org>
To: Pu Lehui <pulehui@huaweicloud.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
Alexandre Ghiti <alex@ghiti.fr>,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
"Steven Rostedt (Google)" <rostedt@goodmis.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
Pu Lehui <pulehui@huawei.com>
Subject: Re: [PATCH] riscv: fgraph: Fix stack layout to match __arch_ftrace_regs argument of ftrace_return_to_handler
Date: Wed, 12 Mar 2025 20:35:14 +0100 [thread overview]
Message-ID: <87wmcucaa5.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <20250311132243.2178271-1-pulehui@huaweicloud.com>
Pu Lehui <pulehui@huaweicloud.com> writes:
> From: Pu Lehui <pulehui@huawei.com>
>
> Naresh Kamboju reported a "Bad frame pointer" kernel warning while
> running LTP trace ftrace_stress_test.sh in riscv. We can reproduce the
> same issue with the following command:
>
> ```
> $ cd /sys/kernel/debug/tracing
> $ echo 'f:myprobe do_nanosleep%return args1=$retval' > dynamic_events
> $ echo 1 > events/fprobes/enable
> $ echo 1 > tracing_on
> $ sleep 1
> ```
>
> And we can get the following kernel warning:
>
> [ 127.692888] ------------[ cut here ]------------
> [ 127.693755] Bad frame pointer: expected ff2000000065be50, received ba34c141e9594000
> [ 127.693755] from func do_nanosleep return to ffffffff800ccb16
> [ 127.698699] WARNING: CPU: 1 PID: 129 at kernel/trace/fgraph.c:755 ftrace_return_to_handler+0x1b2/0x1be
> [ 127.699894] Modules linked in:
> [ 127.700908] CPU: 1 UID: 0 PID: 129 Comm: sleep Not tainted 6.14.0-rc3-g0ab191c74642 #32
> [ 127.701453] Hardware name: riscv-virtio,qemu (DT)
> [ 127.701859] epc : ftrace_return_to_handler+0x1b2/0x1be
> [ 127.702032] ra : ftrace_return_to_handler+0x1b2/0x1be
> [ 127.702151] epc : ffffffff8013b5e0 ra : ffffffff8013b5e0 sp : ff2000000065bd10
> [ 127.702221] gp : ffffffff819c12f8 tp : ff60000080853100 t0 : 6e00000000000000
> [ 127.702284] t1 : 0000000000000020 t2 : 6e7566206d6f7266 s0 : ff2000000065bd80
> [ 127.702346] s1 : ff60000081262000 a0 : 000000000000007b a1 : ffffffff81894f20
> [ 127.702408] a2 : 0000000000000010 a3 : fffffffffffffffe a4 : 0000000000000000
> [ 127.702470] a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
> [ 127.702530] s2 : ba34c141e9594000 s3 : 0000000000000000 s4 : ff2000000065bdd0
> [ 127.702591] s5 : 00007fff8adcf400 s6 : 000055556dc1d8c0 s7 : 0000000000000068
> [ 127.702651] s8 : 00007fff8adf5d10 s9 : 000000000000006d s10: 0000000000000001
> [ 127.702710] s11: 00005555737377c8 t3 : ffffffff819d899e t4 : ffffffff819d899e
> [ 127.702769] t5 : ffffffff819d89a0 t6 : ff2000000065bb18
> [ 127.702826] status: 0000000200000120 badaddr: 0000000000000000 cause: 0000000000000003
> [ 127.703292] [<ffffffff8013b5e0>] ftrace_return_to_handler+0x1b2/0x1be
> [ 127.703760] [<ffffffff80017bce>] return_to_handler+0x16/0x26
> [ 127.704009] [<ffffffff80017bb8>] return_to_handler+0x0/0x26
> [ 127.704057] [<ffffffff800d3352>] common_nsleep+0x42/0x54
> [ 127.704117] [<ffffffff800d44a2>] __riscv_sys_clock_nanosleep+0xba/0x10a
> [ 127.704176] [<ffffffff80901c56>] do_trap_ecall_u+0x188/0x218
> [ 127.704295] [<ffffffff8090cc3e>] handle_exception+0x14a/0x156
> [ 127.705436] ---[ end trace 0000000000000000 ]---
>
> The reason is that the stack layout for constructing argument for the
> ftrace_return_to_handler in the return_to_handler does not match the
> __arch_ftrace_regs structure of riscv, leading to unexpected results.
>
> Fixes: a3ed4157b7d8 ("fgraph: Replace fgraph_ret_regs with ftrace_regs")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Closes: https://lore.kernel.org/all/CA+G9fYvp_oAxeDFj88Tk2rfEZ7jtYKAKSwfYS66=57Db9TBdyA@mail.gmail.com
> Signed-off-by: Pu Lehui <pulehui@huawei.com>
With this patch, I get (from ftrace startup tests):
Testing tracer function_graph: PASSED
instead of the splat above! Thanks!
Tested-by: Björn Töpel <bjorn@rivosinc.com>
next prev parent reply other threads:[~2025-03-12 19:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-11 13:22 [PATCH] riscv: fgraph: Fix stack layout to match __arch_ftrace_regs argument of ftrace_return_to_handler Pu Lehui
2025-03-11 14:14 ` Alexandre Ghiti
2025-03-12 19:35 ` Björn Töpel [this message]
2025-03-16 1:16 ` kernel test robot
2025-03-17 3:06 ` Pu Lehui
2025-03-27 3:24 ` patchwork-bot+linux-riscv
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