Date:   Wed, 12 Feb 2020 11:37:00 +0100 (CET)
From:   Clément Leger <cleger@...ray.eu>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Arnaud Pouliquen <arnaud.pouliquen@...com>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-remoteproc <linux-remoteproc@...r.kernel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Andy Gross <agross@...nel.org>,
        Patrice Chotard <patrice.chotard@...com>,
        linux-doc <linux-doc@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Loic PALLARDY <loic.pallardy@...com>, s-anna <s-anna@...com>
Subject: Re: [PATCH v4 1/5] remoteproc: Use u64 len for da_to_va

Hi Mathieu,

----- On 11 Feb, 2020, at 23:37, Mathieu Poirier mathieu.poirier@...aro.org wrote:

> On Tue, Feb 11, 2020 at 05:39:21PM +0100, Clément Leger wrote:
>> Hi Arnaud,
>> 
>> ----- On 11 Feb, 2020, at 16:53, Arnaud Pouliquen arnaud.pouliquen@...com wrote:
>> 
>> > On 2/10/20 5:22 PM, Clement Leger wrote:
>> >> With upcoming changes in elf loader for elf64 support, section size will
>> >> be a u64. When used with da_to_va, this will potentially lead to
>> >> overflow if using the current "int" type for len argument. Change
>> >> da_to_va prototype to use a u64 for len and fix all users of this
>> >> function.
>> >> 
>> >> Signed-off-by: Clement Leger <cleger@...ray.eu>
>> >> ---
>> >>  drivers/remoteproc/imx_rproc.c           | 11 ++++++-----
>> >>  drivers/remoteproc/keystone_remoteproc.c |  4 ++--
>> >>  drivers/remoteproc/qcom_q6v5_adsp.c      |  2 +-
>> >>  drivers/remoteproc/qcom_q6v5_mss.c       |  2 +-
>> >>  drivers/remoteproc/qcom_q6v5_pas.c       |  2 +-
>> >>  drivers/remoteproc/qcom_q6v5_wcss.c      |  2 +-
>> >>  drivers/remoteproc/qcom_wcnss.c          |  2 +-
>> >>  drivers/remoteproc/remoteproc_core.c     |  2 +-
>> >>  drivers/remoteproc/remoteproc_internal.h |  2 +-
>> >>  drivers/remoteproc/st_slim_rproc.c       |  4 ++--
>> >>  drivers/remoteproc/wkup_m3_rproc.c       |  4 ++--
>> >>  include/linux/remoteproc.h               |  2 +-
>> >>  12 files changed, 20 insertions(+), 19 deletions(-)
>> >> 
>> >> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
>> >> index 3e72b6f38d4b..f497f5b49b18 100644
>> >> --- a/drivers/remoteproc/imx_rproc.c
>> >> +++ b/drivers/remoteproc/imx_rproc.c
>> >> @@ -186,7 +186,7 @@ static int imx_rproc_stop(struct rproc *rproc)
>> >>  }
>> >>  
>> >>  static int imx_rproc_da_to_sys(struct imx_rproc *priv, u64 da,
>> >> -			       int len, u64 *sys)
>> >> +			       u64 len, u64 *sys)
>> >>  {
>> >>  	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
>> >>  	int i;
>> >> @@ -203,19 +203,19 @@ static int imx_rproc_da_to_sys(struct imx_rproc *priv, u64
>> >> da,
>> >>  		}
>> >>  	}
>> >>  
>> >> -	dev_warn(priv->dev, "Translation failed: da = 0x%llx len = 0x%x\n",
>> >> +	dev_warn(priv->dev, "Translation failed: da = 0x%llx len = 0x%llx\n",
>> >>  		 da, len);
>> >>  	return -ENOENT;
>> >>  }
>> >>  
>> >> -static void *imx_rproc_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *imx_rproc_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct imx_rproc *priv = rproc->priv;
>> >>  	void *va = NULL;
>> >>  	u64 sys;
>> >>  	int i;
>> >>  
>> >> -	if (len <= 0)
>> >> +	if (len == 0)
>> >>  		return NULL;
>> >>  
>> >>  	/*
>> >> @@ -235,7 +235,8 @@ static void *imx_rproc_da_to_va(struct rproc *rproc, u64 da,
>> >> int len)
>> >>  		}
>> >>  	}
>> >>  
>> >> -	dev_dbg(&rproc->dev, "da = 0x%llx len = 0x%x va = 0x%p\n", da, len, va);
>> >> +	dev_dbg(&rproc->dev, "da = 0x%llx len = 0x%llx va = 0x%p\n",
>> >> +		da, len, va);
>> >>  
>> >>  	return va;
>> >>  }
>> >> diff --git a/drivers/remoteproc/keystone_remoteproc.c
>> >> b/drivers/remoteproc/keystone_remoteproc.c
>> >> index 5c4658f00b3d..466093f48814 100644
>> >> --- a/drivers/remoteproc/keystone_remoteproc.c
>> >> +++ b/drivers/remoteproc/keystone_remoteproc.c
>> >> @@ -246,7 +246,7 @@ static void keystone_rproc_kick(struct rproc *rproc, int
>> >> vqid)
>> >>   * can be used either by the remoteproc core for loading (when using kernel
>> >>   * remoteproc loader), or by any rpmsg bus drivers.
>> >>   */
>> >> -static void *keystone_rproc_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *keystone_rproc_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct keystone_rproc *ksproc = rproc->priv;
>> >>  	void __iomem *va = NULL;
>> >> @@ -255,7 +255,7 @@ static void *keystone_rproc_da_to_va(struct rproc *rproc,
>> >> u64 da, int len)
>> >>  	size_t size;
>> >>  	int i;
>> >>  
>> >> -	if (len <= 0)
>> >> +	if (len == 0)
>> >>  		return NULL;
>> >>  
>> >>  	for (i = 0; i < ksproc->num_mems; i++) {
>> >> diff --git a/drivers/remoteproc/qcom_q6v5_adsp.c
>> >> b/drivers/remoteproc/qcom_q6v5_adsp.c
>> >> index e953886b2eb7..7518e67a49e5 100644
>> >> --- a/drivers/remoteproc/qcom_q6v5_adsp.c
>> >> +++ b/drivers/remoteproc/qcom_q6v5_adsp.c
>> >> @@ -270,7 +270,7 @@ static int adsp_stop(struct rproc *rproc)
>> >>  	return ret;
>> >>  }
>> >>  
>> >> -static void *adsp_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *adsp_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct qcom_adsp *adsp = (struct qcom_adsp *)rproc->priv;
>> >>  	int offset;
>> >> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c
>> >> b/drivers/remoteproc/qcom_q6v5_mss.c
>> >> index 471128a2e723..248febde6fc1 100644
>> >> --- a/drivers/remoteproc/qcom_q6v5_mss.c
>> >> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
>> >> @@ -1148,7 +1148,7 @@ static int q6v5_stop(struct rproc *rproc)
>> >>  	return 0;
>> >>  }
>> >>  
>> >> -static void *q6v5_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *q6v5_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct q6v5 *qproc = rproc->priv;
>> >>  	int offset;
>> >> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c
>> >> b/drivers/remoteproc/qcom_q6v5_pas.c
>> >> index db4b3c4bacd7..cf2cd609c90d 100644
>> >> --- a/drivers/remoteproc/qcom_q6v5_pas.c
>> >> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
>> >> @@ -159,7 +159,7 @@ static int adsp_stop(struct rproc *rproc)
>> >>  	return ret;
>> >>  }
>> >>  
>> >> -static void *adsp_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *adsp_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct qcom_adsp *adsp = (struct qcom_adsp *)rproc->priv;
>> >>  	int offset;
>> >> diff --git a/drivers/remoteproc/qcom_q6v5_wcss.c
>> >> b/drivers/remoteproc/qcom_q6v5_wcss.c
>> >> index f93e1e4a1cc0..3a6b82a16961 100644
>> >> --- a/drivers/remoteproc/qcom_q6v5_wcss.c
>> >> +++ b/drivers/remoteproc/qcom_q6v5_wcss.c
>> >> @@ -406,7 +406,7 @@ static int q6v5_wcss_stop(struct rproc *rproc)
>> >>  	return 0;
>> >>  }
>> >>  
>> >> -static void *q6v5_wcss_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *q6v5_wcss_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct q6v5_wcss *wcss = rproc->priv;
>> >>  	int offset;
>> >> diff --git a/drivers/remoteproc/qcom_wcnss.c b/drivers/remoteproc/qcom_wcnss.c
>> >> index dc135754bb9c..f893219e45a8 100644
>> >> --- a/drivers/remoteproc/qcom_wcnss.c
>> >> +++ b/drivers/remoteproc/qcom_wcnss.c
>> >> @@ -287,7 +287,7 @@ static int wcnss_stop(struct rproc *rproc)
>> >>  	return ret;
>> >>  }
>> >>  
>> >> -static void *wcnss_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *wcnss_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct qcom_wcnss *wcnss = (struct qcom_wcnss *)rproc->priv;
>> >>  	int offset;
>> >> diff --git a/drivers/remoteproc/remoteproc_core.c
>> >> b/drivers/remoteproc/remoteproc_core.c
>> >> index 307df98347ba..9e6d3c6a60ee 100644
>> >> --- a/drivers/remoteproc/remoteproc_core.c
>> >> +++ b/drivers/remoteproc/remoteproc_core.c
>> >> @@ -185,7 +185,7 @@ EXPORT_SYMBOL(rproc_va_to_pa);
>> >>   * here the output of the DMA API for the carveouts, which should be more
>> >>   * correct.
>> >>   */
>> >> -void *rproc_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +void *rproc_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> > 
>> > This function is exported, don't see any update in consequence...
>> > references:
>> > https://elixir.bootlin.com/linux/v5.6-rc1/ident/rproc_da_to_va
>> > For instance the function rproc_trace_read use it. it quite strange that my gcc
>> > does not warns for the cast but i suppose that some could.
>> 
>> Agreed, even if len should never have been a signed type since it can't be
>> negative. I will try to fix all callers.
>> 
>> > An indirect consequence is that the len field in rproc_mem_entry struct should
>> > probably been updated to u64 to be aligned.
>> 
>> Ok, I will do that once we settle on the type of len.
>> 
>> > 
>> > I'm still wondering about the use of size_t instead,which seems more rational
>> > from my window.
>> > So i you or Mathieu remember it was decided to use u64, please could remind me
>> > the arguments?
>> 
>> I tried to find the notes of a meeting we had for OpenAMP but I did not found
>> them. Anyway, the argument was coming from Tomas or someone else, (I can't
>> remember) talking about a 32 bits CPU executing code on a 64 bits accelerator.
>> In that case, the size_t type could fail due to being only 32bits on the host
>> CPU but larger than 4G.
>> 
>> However, I can't say if it's a real usecase or not... All I can say is
>> that keeping it open is probably better if one day somebody comes with such
>> architecture.
> 
> In order to support a 32bit AP with a 64bit MCU we'd also have to deal with all
> the dma_attr_t in the structure we use.

Totally ok with that... 

> 
> Also something that became very clear to me while thinking about this patchset
> is that supporting elf64 does __not__ mean we support 64bit MCU.  As long as
> the addresses conveyed by the elf64 image fit within 32 bits we are fine.
> Supporting 64bit MCUs is a completely different topic, one that will demand
> serious refactoring.

Exactly, an elf64 can potentially contain an executable fitting in 32 bits.

> 
> So moving from "int len" to "u64 len" doesn't give us much.  It doesn't hurt to
> do it but if @len ever becomes bigger than 31 bits we'll have other problems to
> deal with.

Agreed, so what would be your recommendation reagrding the type of len ?
I'm ok with Arnaud statement too and using a size_t is probably more
"type-safe" than a u64. At least it adds some information.

Thanks,

Clément

> 
>> 
>> > As an alternative a check should be added for 32 bits processors to ensure that
>> > the size is not higher than
>> > its address range capability...
>> 
>> Agreed.
>> I was even thinking about a mecanism for remoteproc drivers to declare the type
>> of supported elfs files (such as EM_*, ELFCLASS* and other needed thing).
>> Or should it be supported by overriding .sanity_check in drivers  to reject
>> elf64 for instance ?
>> 
>> Since elf is a "specific format" and that rproc can support other formats,
>> I did not want to add a specific elf_sanity_check field to rproc ops.
>> 
>> Regards,
>> 
>> Clément
>> 
>> > 
>> > Regards
>> > Arnaud
>> > 
>> >>  {
>> >>  	struct rproc_mem_entry *carveout;
>> >>  	void *ptr = NULL;
>> >> diff --git a/drivers/remoteproc/remoteproc_internal.h
>> >> b/drivers/remoteproc/remoteproc_internal.h
>> >> index 493ef9262411..004867061721 100644
>> >> --- a/drivers/remoteproc/remoteproc_internal.h
>> >> +++ b/drivers/remoteproc/remoteproc_internal.h
>> >> @@ -50,7 +50,7 @@ void rproc_exit_sysfs(void);
>> >>  void rproc_free_vring(struct rproc_vring *rvring);
>> >>  int rproc_alloc_vring(struct rproc_vdev *rvdev, int i);
>> >>  
>> >> -void *rproc_da_to_va(struct rproc *rproc, u64 da, int len);
>> >> +void *rproc_da_to_va(struct rproc *rproc, u64 da, u64 len);
>> >>  phys_addr_t rproc_va_to_pa(void *cpu_addr);
>> >>  int rproc_trigger_recovery(struct rproc *rproc);
>> >>  
>> >> diff --git a/drivers/remoteproc/st_slim_rproc.c
>> >> b/drivers/remoteproc/st_slim_rproc.c
>> >> index 04492fead3c8..fc01cd879b60 100644
>> >> --- a/drivers/remoteproc/st_slim_rproc.c
>> >> +++ b/drivers/remoteproc/st_slim_rproc.c
>> >> @@ -174,7 +174,7 @@ static int slim_rproc_stop(struct rproc *rproc)
>> >>  	return 0;
>> >>  }
>> >>  
>> >> -static void *slim_rproc_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *slim_rproc_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct st_slim_rproc *slim_rproc = rproc->priv;
>> >>  	void *va = NULL;
>> >> @@ -191,7 +191,7 @@ static void *slim_rproc_da_to_va(struct rproc *rproc, u64
>> >> da, int len)
>> >>  		}
>> >>  	}
>> >>  
>> >> -	dev_dbg(&rproc->dev, "da = 0x%llx len = 0x%x va = 0x%pK\n",
>> >> +	dev_dbg(&rproc->dev, "da = 0x%llx len = 0x%llx va = 0x%pK\n",
>> >>  		da, len, va);
>> >>  
>> >>  	return va;
>> >> diff --git a/drivers/remoteproc/wkup_m3_rproc.c
>> >> b/drivers/remoteproc/wkup_m3_rproc.c
>> >> index 3984e585c847..91485b467407 100644
>> >> --- a/drivers/remoteproc/wkup_m3_rproc.c
>> >> +++ b/drivers/remoteproc/wkup_m3_rproc.c
>> >> @@ -80,14 +80,14 @@ static int wkup_m3_rproc_stop(struct rproc *rproc)
>> >>  	return 0;
>> >>  }
>> >>  
>> >> -static void *wkup_m3_rproc_da_to_va(struct rproc *rproc, u64 da, int len)
>> >> +static void *wkup_m3_rproc_da_to_va(struct rproc *rproc, u64 da, u64 len)
>> >>  {
>> >>  	struct wkup_m3_rproc *wkupm3 = rproc->priv;
>> >>  	void *va = NULL;
>> >>  	int i;
>> >>  	u32 offset;
>> >>  
>> >> -	if (len <= 0)
>> >> +	if (len == 0)
>> >>  		return NULL;
>> >>  
>> >>  	for (i = 0; i < WKUPM3_MEM_MAX; i++) {
>> >> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>> >> index 16ad66683ad0..f84bd5fe0211 100644
>> >> --- a/include/linux/remoteproc.h
>> >> +++ b/include/linux/remoteproc.h
>> >> @@ -374,7 +374,7 @@ struct rproc_ops {
>> >>  	int (*start)(struct rproc *rproc);
>> >>  	int (*stop)(struct rproc *rproc);
>> >>  	void (*kick)(struct rproc *rproc, int vqid);
>> >> -	void * (*da_to_va)(struct rproc *rproc, u64 da, int len);
>> >> +	void * (*da_to_va)(struct rproc *rproc, u64 da, u64 len);
>> >>  	int (*parse_fw)(struct rproc *rproc, const struct firmware *fw);
>> >>  	int (*handle_rsc)(struct rproc *rproc, u32 rsc_type, void *rsc,
> > >>  			  int offset, int avail);

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