Subject: Re: [PATCH v4 1/5] remoteproc: Use u64 len for da_to_va

From: Mathieu Poirier <[email-masked]>
Date: Tue, 11 Feb 2020 15:37:15 -0700

On Tue, Feb 11, 2020 at 05:39:21PM +0100, Clément Leger wrote:
> Hi Arnaud,
> 
> ----- On 11 Feb, 2020, at 16:53, Arnaud Pouliquen [email-masked] 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 <[email-masked]>
> >> ---
> >>  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.

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. 

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. 

> 
> > 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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