Date:   Tue, 18 Feb 2020 10:01:43 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Clément Leger <cleger@...rayinc.com>
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

On Tue, 18 Feb 2020 at 03:10, Clément Leger <cleger@...rayinc.com> wrote:
>
> Hi Mathieu,
>
> ----- On 12 Feb, 2020, at 22:59, Mathieu Poirier mathieu.poirier@...aro.org wrote:
>
> > On Wed, 12 Feb 2020 at 03:37, Clément Leger <cleger@...ray.eu> wrote:
> >>
> >> 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.
> >
> > If @len becomes big enough that it doesn't fit in 31bit then it is
> > very likely that things will break even before we get to call
> > rproc_da_to_va().  Fixing it here is possible but will introduce a
> > fair amount of ripple effect that we probably don't want to deal with
> > right now.
>
> I did the modification using u64 and tried to follow various code path.
> Some end up in dma_alloc_coherent which uses a size_t member. Since
> these might be called by rproc with a u64 len, I would be more
> inclined to use a size_t. I can probably also add a check in elf loader
> which verifies that if sizeof(size_t) < sizeof(u64), then the len must
> fit in 32bits. This seems more clean IMHO.
>

I'm all good with that.

> Clément.
>
> >
> > Other people might feel more opinionated on this but as far as I'm
> > concerned, I would keep it as it is and fix it for real when the time
> > comes to add support for 64bit MCUs.
> >
> >>
> >> 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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