From: Atish Patra <Atish.Patra@wdc.com>
To: "hch@lst.de" <hch@lst.de>
Cc: "linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"palmer@sifive.com" <palmer@sifive.com>,
"paul.walmsley@sifive.com" <paul.walmsley@sifive.com>
Subject: Re: [PATCH 5/6] riscv: don't use the rdtime(h) pseudo-instructions
Date: Tue, 27 Aug 2019 18:50:58 +0000 [thread overview]
Message-ID: <86633111d71e99e3cedca378d39e0349b424280d.camel@wdc.com> (raw)
In-Reply-To: <20190826113034.GC15002@lst.de>
On Mon, 2019-08-26 at 13:30 +0200, hch@lst.de wrote:
> On Sat, Aug 24, 2019 at 12:37:02AM +0000, Atish Patra wrote:
> > > -static inline cycles_t get_cycles_inline(void)
> > > +static inline cycles_t get_cycles(void)
> > > {
> > > - cycles_t n;
> > > -
> > > - __asm__ __volatile__ (
> > > - "rdtime %0"
> > > - : "=r" (n));
> > > - return n;
> > > + return csr_read(CSR_TIME);
> >
> > Does this work correctly in QEMU ? I was looking at the qemu code
> > and
> > it looks like it returns cpu_get_host_ticks which seems wrong to
> > me.
>
> It better should. rdtime is just a pseudo-instruction that the
> assembler translates to a CSR read. (in other words something
> totally
> pointless, no idea why it even is in the spec).
Yes. I did not see the usermode macro carefully in qemu code.
Reviewed-by: Atish Patra <atish.patra@wdc.com>
--
Regards,
Atish
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next prev parent reply other threads:[~2019-08-27 18:51 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 14:58 misc riscv cleanups Christoph Hellwig
2019-08-21 14:58 ` [PATCH 1/6] riscv: refactor the IPI code Christoph Hellwig
2019-08-24 1:03 ` Atish Patra
2019-09-05 8:44 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 2/6] riscv: cleanup send_ipi_mask Christoph Hellwig
2019-08-24 0:11 ` Atish Patra
2019-08-26 11:28 ` hch
2019-08-27 18:45 ` Atish Patra
2019-09-05 8:46 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 3/6] riscv: optimize send_ipi_single Christoph Hellwig
2019-08-24 0:26 ` Atish Patra
2019-08-26 11:29 ` hch
2019-08-27 18:48 ` Atish Patra
2019-09-05 8:48 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 4/6] riscv: cleanup riscv_cpuid_to_hartid_mask Christoph Hellwig
2019-08-24 0:03 ` Atish Patra
2019-09-05 8:50 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 5/6] riscv: don't use the rdtime(h) pseudo-instructions Christoph Hellwig
2019-08-24 0:37 ` Atish Patra
2019-08-24 0:43 ` Atish Patra
2019-08-26 11:30 ` hch
2019-08-27 18:50 ` Atish Patra [this message]
2019-09-05 8:55 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 6/6] riscv: move the TLB flush logic out of line Christoph Hellwig
2019-08-24 0:03 ` Atish Patra
2019-09-05 8:58 ` Paul Walmsley
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