From: Andreas Schwab <schwab@linux-m68k.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: me@carlosedp.com, Palmer Dabbelt <palmer@sifive.com>,
linux-kernel@vger.kernel.org, joel@sing.id.au,
Paul Walmsley <paul.walmsley@sifive.com>,
linux-riscv@lists.infradead.org, marco@decred.org
Subject: Re: [PATCH] RISC-V: Break load reservations during switch_to
Date: Thu, 06 Jun 2019 21:32:01 +0200 [thread overview]
Message-ID: <87ftom4ij2.fsf@igel.home> (raw)
In-Reply-To: <20190606090518.GB1369@infradead.org> (Christoph Hellwig's message of "Thu, 6 Jun 2019 02:05:18 -0700")
On Jun 06 2019, Christoph Hellwig <hch@infradead.org> wrote:
> On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote:
>> REG_S ra, TASK_THREAD_RA_RA(a3)
>> + /*
>> + * The Linux ABI allows programs to depend on load reservations being
>> + * broken on context switches, but the ISA doesn't require that the
>> + * hardware ever breaks a load reservation. The only way to break a
>> + * load reservation is with a store conditional, so we emit one here.
>> + * Since nothing ever takes a load reservation on TASK_THREAD_RA_RA we
>> + * know this will always fail, but just to be on the safe side this
>> + * writes the same value that was unconditionally written by the
>> + * previous instruction.
>> + */
>> +#if (TASK_THREAD_RA_RA != 0)
>
> I don't think this check works as intended. TASK_THREAD_RA_RA is a
> parameterized macro,
Is it? Just because it is used before an open paren doesn't mean that
the macro takes a parameter.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
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WARNING: multiple messages have this Message-ID (diff)
From: Andreas Schwab <schwab@linux-m68k.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Palmer Dabbelt <palmer@sifive.com>,
linux-riscv@lists.infradead.org,
Paul Walmsley <paul.walmsley@sifive.com>,
marco@decred.org, me@carlosedp.com, joel@sing.id.au,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] RISC-V: Break load reservations during switch_to
Date: Thu, 06 Jun 2019 21:32:01 +0200 [thread overview]
Message-ID: <87ftom4ij2.fsf@igel.home> (raw)
In-Reply-To: <20190606090518.GB1369@infradead.org> (Christoph Hellwig's message of "Thu, 6 Jun 2019 02:05:18 -0700")
On Jun 06 2019, Christoph Hellwig <hch@infradead.org> wrote:
> On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote:
>> REG_S ra, TASK_THREAD_RA_RA(a3)
>> + /*
>> + * The Linux ABI allows programs to depend on load reservations being
>> + * broken on context switches, but the ISA doesn't require that the
>> + * hardware ever breaks a load reservation. The only way to break a
>> + * load reservation is with a store conditional, so we emit one here.
>> + * Since nothing ever takes a load reservation on TASK_THREAD_RA_RA we
>> + * know this will always fail, but just to be on the safe side this
>> + * writes the same value that was unconditionally written by the
>> + * previous instruction.
>> + */
>> +#if (TASK_THREAD_RA_RA != 0)
>
> I don't think this check works as intended. TASK_THREAD_RA_RA is a
> parameterized macro,
Is it? Just because it is used before an open paren doesn't mean that
the macro takes a parameter.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
next prev parent reply other threads:[~2019-06-06 19:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 23:17 [PATCH] RISC-V: Break load reservations during switch_to Palmer Dabbelt
2019-06-05 23:17 ` Palmer Dabbelt
2019-06-06 8:37 ` Marco Peereboom
2019-06-06 8:37 ` Marco Peereboom
2019-06-06 9:05 ` Christoph Hellwig
2019-06-06 9:05 ` Christoph Hellwig
2019-06-06 19:10 ` Palmer Dabbelt
2019-06-06 19:10 ` Palmer Dabbelt
2019-06-06 19:32 ` Andreas Schwab [this message]
2019-06-06 19:32 ` Andreas Schwab
2019-06-07 22:12 ` Palmer Dabbelt
2019-06-07 22:12 ` Palmer Dabbelt
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