From: Conor Dooley <conor.dooley@microchip.com>
To: Song Shuai <suagrfillet@gmail.com>
Cc: <guoren@kernel.org>, <rostedt@goodmis.org>, <mhiramat@kernel.org>,
<mark.rutland@arm.com>, <paul.walmsley@sifive.com>,
<palmer@dabbelt.com>, <aou@eecs.berkeley.edu>,
<linux-riscv@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] riscv/ftrace: fix ftrace_modify_call bug
Date: Tue, 22 Nov 2022 08:57:30 +0000 [thread overview]
Message-ID: <Y3yO+ii+NEVPTYFo@wendy> (raw)
In-Reply-To: <20221122075440.1165172-1-suagrfillet@gmail.com>
On Tue, Nov 22, 2022 at 03:54:40PM +0800, Song Shuai wrote:
> With this commit (riscv: ftrace: Reduce the detour code size to half)
AFAICT the above patch has not been applied & this patch here should be
folded into the offending patch?
I've marked this one as "Not Applicable" in patchwork as a result, but
let me know if that is an incorrect assumption.
Thanks,
Conor.
> patched, ftrace bug occurred When hosting kprobe and function tracer
> at the same function.
>
> Obviously, the variable caller in ftrace_modify_call was assigned by
> rec->ip with 4 offset failing the code replacing at function entry.
> And the caller should be assigned by rec->ip directly to indicate
> the function entry.
>
> The following is the ftrace bug log.
>
> ```
> [ 419.632855] 00000000f8776803: expected (ffe00297 1a4282e7) but got (1a8282e7 f0227179)
> [ 419.633390] ------------[ ftrace bug ]------------
> [ 419.633553] ftrace failed to modify
> [ 419.633569] [<ffffffff802091cc>] kernel_read+0x0/0x52
> [ 419.633863] actual: 97:02:e0:ff:e7:82:82:1a
> [ 419.634087] Updating ftrace call site to call a different ftrace function
> [ 419.634279] ftrace record flags: e0000002
> [ 419.634487] (2) R
> [ 419.634487] expected tramp: ffffffff800093cc
> [ 419.634935] ------------[ cut here ]------------
> ```
>
> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> ---
> arch/riscv/kernel/ftrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
> index 8c77f236fc71..61b24d767e2e 100644
> --- a/arch/riscv/kernel/ftrace.c
> +++ b/arch/riscv/kernel/ftrace.c
> @@ -132,7 +132,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
> unsigned long addr)
> {
> unsigned int call[2];
> - unsigned long caller = rec->ip + 4;
> + unsigned long caller = rec->ip;
> int ret;
>
> make_call_t0(caller, old_addr, call);
> --
> 2.20.1
>
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next prev parent reply other threads:[~2022-11-22 8:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 7:54 [PATCH] riscv/ftrace: fix ftrace_modify_call bug Song Shuai
2022-11-22 8:57 ` Guo Ren
2022-11-22 9:11 ` Song Shuai
[not found] ` <CAJF2gTT=r4VeWqpe+Tw2JDdTDU+r2mJiPmHq_i8eV5YRmrrLRA@mail.gmail.com>
2022-11-22 9:51 ` Song Shuai
2022-11-22 8:57 ` Conor Dooley [this message]
2022-11-22 9:46 ` Song Shuai
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