From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: yuanjunqing <yuanjunqing66@163.com>
Cc: paulburton@kernel.org, chenhc@lemote.com,
linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
liulichao@loongson.cn
Subject: Re: [PATCH] MIPS: Fix IRQ tracing when call handle_fpe()
Date: Tue, 26 May 2020 15:04:41 +0200 [thread overview]
Message-ID: <20200526130441.GB8487@alpha.franken.de> (raw)
In-Reply-To: <76f2c756-0ae4-83f5-becf-6f1b3319f6fd@163.com>
On Tue, May 26, 2020 at 03:07:16PM +0800, yuanjunqing wrote:
>
> 在 2020/5/25 下午4:42, Thomas Bogendoerfer 写道:
> > On Mon, May 25, 2020 at 11:31:23AM +0800, YuanJunQing wrote:
> >> Register "a1" is unsaved in this function,
> >> when CONFIG_TRACE_IRQFLAGS is enabled,
> >> the TRACE_IRQS_OFF macro will call trace_hardirqs_off(),
> >> and this may change register "a1".
> >> The variment of register "a1" may send SIGFPE signal
> >> to task when call do_fpe(),and this may kill the task.
> >>
> >> Signed-off-by: YuanJunQing <yuanjunqing66@163.com>
> >> ---
> >> arch/mips/kernel/genex.S | 6 ++++--
> >> 1 file changed, 4 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
> >> index 8236fb291e3f..956a76429773 100644
> >> --- a/arch/mips/kernel/genex.S
> >> +++ b/arch/mips/kernel/genex.S
> >> @@ -480,16 +480,18 @@ NESTED(nmi_handler, PT_SIZE, sp)
> >> /* gas fails to assemble cfc1 for some archs (octeon).*/ \
> >> .set mips1
> >> SET_HARDFLOAT
> >> - cfc1 a1, fcr31
> >> + cfc1 s0, fcr31
> >> .set pop
> >> CLI
> >> TRACE_IRQS_OFF
> >> + move a1,s0
> >> .endm
> > do we realy need to read fcr31 that early ? Wouldn't it work to
> > just move the cfc1 below TRACE_IRQS_OFF ?
> >
>
> yes, it can work when we just move the cfc1 below TRACE_IRQS_OFF,
> and the code is written as follows.
>
> CLI
> TRACE_IRQS_OFF
> .set mips1
> SET_HARDFLOAT
> cfc1 a1, fcr31
> .set pop
> .endm
good, could we do the same with _cfcmsa a1, MSA_CSR in the msa case ?
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
next prev parent reply other threads:[~2020-05-26 13:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 3:31 [PATCH] MIPS: Fix IRQ tracing when call handle_fpe() YuanJunQing
2020-05-25 8:34 ` Sergei Shtylyov
2020-05-25 8:42 ` Thomas Bogendoerfer
2020-05-26 7:07 ` yuanjunqing
2020-05-26 13:04 ` Thomas Bogendoerfer [this message]
2020-05-27 2:31 ` yuanjunqing
2020-05-26 13:05 ` Thomas Bogendoerfer
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