RE: [PATCH V3 1/7] remoteproc: elf: support platform specific memory hook

From: Peng Fan
Date: Wed Dec 09 2020 - 10:01:02 EST

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> Subject: RE: [PATCH V3 1/7] remoteproc: elf: support platform specific
> memory hook
>
> Hi Bjorn,
>
> > Subject: Re: [PATCH V3 1/7] remoteproc: elf: support platform specific
> > memory hook
> >
> > On Fri 04 Dec 01:40 CST 2020, Peng Fan (OSS) wrote:
> >
> > > From: Peng Fan <peng.fan@xxxxxxx>
> > >
> > > To arm64, "dc zva, dst" is used in memset.
> > > Per ARM DDI 0487A.j, chapter C5.3.8 DC ZVA, Data Cache Zero by VA,
> > >
> > > "If the memory region being zeroed is any type of Device memory,
> > > this instruction can give an alignment fault which is prioritized in
> > > the same way as other alignment faults that are determined by the
> > > memory type."
> > >
> > > On i.MX platforms, when elf is loaded to onchip TCM area, the region
> > > is ioremapped, so "dc zva, dst" will trigger abort. And ioremap_wc()
> > > on i.MX not able to write correct data to TCM area.
> > >
> > > So we need to use io helpers, and extend the elf loader to support
> > > platform specific memory functions.
> > >
> > > Acked-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > > Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > > ---
> > > drivers/remoteproc/remoteproc_elf_loader.c | 20
> > ++++++++++++++++++--
> > > include/linux/remoteproc.h | 4 ++++
> > > 2 files changed, 22 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c
> > > b/drivers/remoteproc/remoteproc_elf_loader.c
> > > index df68d87752e4..6cb71fe47261 100644
> > > --- a/drivers/remoteproc/remoteproc_elf_loader.c
> > > +++ b/drivers/remoteproc/remoteproc_elf_loader.c
> > > @@ -129,6 +129,22 @@ u64 rproc_elf_get_boot_addr(struct rproc
> > > *rproc, const struct firmware *fw) }
> > EXPORT_SYMBOL(rproc_elf_get_boot_addr);
> > >
> > > +static void rproc_elf_memcpy(struct rproc *rproc, void *dest, const
> > > +void *src, size_t count) {
> > > + if (!rproc->ops->elf_memcpy)
> > > + memcpy(dest, src, count);
> > > +
> > > + rproc->ops->elf_memcpy(rproc, dest, src, count);
> >
> > Looking at the current set of remoteproc drivers I get a feeling that
> > we'll end up with a while bunch of functions that all just wraps
> > memcpy_toio(). And the reason for this is that we are we're "abusing"
> > the carveout to carry the __iomem pointer without keeping track of it.
> >
> > And this is not the only time we're supposed to use an io-accessor,
> > another example is rproc_copy_segment() in rproc_coredump.c
> >
> > It also means that if a platform driver for some reason where to
> > support both ioremap and normal carveouts the elf_memcpy op would be
> quite quirky.
> >
> >
> > So I would prefer if we track the knowledge about void *va being a
> > __iomem or not in the struct rproc_mem_entry and make rproc_da_to_va()
> > return this information as well.
> >
> > Then instead of extending the ops we can make this simply call memcpy
> > or
> > memcpy_toio() depending on this.
>
> A draft proposal as below, are you ok with the approach?

Mathieu, do you have any comments?

Thanks,
Peng.

>
> diff --git a/drivers/remoteproc/remoteproc_core.c
> b/drivers/remoteproc/remoteproc_core.c
> index 46c2937ebea9..bbb6e0613c1b 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -189,13 +189,13 @@ 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, size_t len)
> +void *rproc_da_to_va(struct rproc *rproc, u64 da, size_t len, bool
> +*iomem)
> {
> struct rproc_mem_entry *carveout;
> void *ptr = NULL;
>
> if (rproc->ops->da_to_va) {
> - ptr = rproc->ops->da_to_va(rproc, da, len);
> + ptr = rproc->ops->da_to_va(rproc, da, len, iomem);
> if (ptr)
> goto out;
> }
> @@ -217,6 +217,9 @@ void *rproc_da_to_va(struct rproc *rproc, u64 da,
> size_t len)
>
> ptr = carveout->va + offset;
>
> + if (iomem)
> + iomem = carveout->iomem;
> +
> break;
> }
>
> diff --git a/drivers/remoteproc/remoteproc_coredump.c
> b/drivers/remoteproc/remoteproc_coredump.c
> index 34530dc20cb4..5ff9389e6319 100644
> --- a/drivers/remoteproc/remoteproc_coredump.c
> +++ b/drivers/remoteproc/remoteproc_coredump.c
> @@ -153,18 +153,22 @@ static void rproc_copy_segment(struct rproc *rproc,
> void *dest,
> size_t offset, size_t size) {
> void *ptr;
> + bool iomem;
>
> if (segment->dump) {
> segment->dump(rproc, segment, dest, offset, size);
> } else {
> - ptr = rproc_da_to_va(rproc, segment->da + offset, size);
> + ptr = rproc_da_to_va(rproc, segment->da + offset, size,
> + &iomem);
> if (!ptr) {
> dev_err(&rproc->dev,
> "invalid copy request for
> segment %pad with offset %zu and size %zu)\n",
> &segment->da, offset, size);
> memset(dest, 0xff, size);
> } else {
> - memcpy(dest, ptr, size);
> + if (iomem)
> + memcpy_fromio(dest, ptr, size);
> + else
> + memcpy(dest, ptr, size);
> }
> }
> }
> diff --git a/drivers/remoteproc/remoteproc_elf_loader.c
> b/drivers/remoteproc/remoteproc_elf_loader.c
> index df68d87752e4..20538143249e 100644
> --- a/drivers/remoteproc/remoteproc_elf_loader.c
> +++ b/drivers/remoteproc/remoteproc_elf_loader.c
> @@ -175,6 +175,7 @@ int rproc_elf_load_segments(struct rproc *rproc,
> const struct firmware *fw)
> u64 offset = elf_phdr_get_p_offset(class, phdr);
> u32 type = elf_phdr_get_p_type(class, phdr);
> void *ptr;
> + bool iomem;
>
> if (type != PT_LOAD)
> continue;
> @@ -204,7 +205,7 @@ int rproc_elf_load_segments(struct rproc *rproc,
> const struct firmware *fw)
> }
>
> /* grab the kernel address for this device address */
> - ptr = rproc_da_to_va(rproc, da, memsz);
> + ptr = rproc_da_to_va(rproc, da, memsz, &iomem);
> if (!ptr) {
> dev_err(dev, "bad phdr da 0x%llx mem
> 0x%llx\n", da,
> memsz);
> @@ -213,8 +214,12 @@ int rproc_elf_load_segments(struct rproc *rproc,
> const struct firmware *fw)
> }
>
> /* put the segment where the remote processor expects
> it */
> - if (filesz)
> - memcpy(ptr, elf_data + offset, filesz);
> + if (filesz) {
> + if (iomem)
> + memcpy_fromio(ptr, elf_data + offset,
> filesz);
> + else
> + memcpy(ptr, elf_data + offset, filesz);
> + }
>
> /*
> * Zero out remaining memory for this segment.
> @@ -223,8 +228,12 @@ int rproc_elf_load_segments(struct rproc *rproc,
> const struct firmware *fw)
> * did this for us. albeit harmless, we may consider
> removing
> * this.
> */
> - if (memsz > filesz)
> - memset(ptr + filesz, 0, memsz - filesz);
> + if (memsz > filesz) {
> + if (iomem)
> + memset_toio(ptr + filesz, 0, memsz -
> filesz);
> + else
> + memset(ptr + filesz, 0, memsz -
> filesz);
> + }
> }
>
> return ret;
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h index
> e8ac041c64d9..01bb9fa12784 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -329,6 +329,7 @@ struct rproc;
> */
> struct rproc_mem_entry {
> void *va;
> + bool iomem;
> dma_addr_t dma;
> size_t len;
> u32 da;
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index
> d6473a72a336..dfa0bd7812a5 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -194,7 +194,7 @@ copy_from_user(void *to, const void __user *from,
> unsigned long n) }
>
> static __always_inline unsigned long __must_check -copy_to_user(void
> __user *to, const void *from, unsigned long n)
> +copy_to_user(void __user *to, const void *_toiofrom, unsigned long n)
> {
> if (likely(check_copy_size(from, n, true)))
> n = _copy_to_user(to, from, n);
>
> Thanks,
> Peng.
>
> >
> > Regards,
> > Bjorn
> >
> > > +}
> > > +
> > > +static void rproc_elf_memset(struct rproc *rproc, void *s, int c,
> > > +size_t count) {
> > > + if (!rproc->ops->elf_memset)
> > > + memset(s, c, count);
> > > +
> > > + rproc->ops->elf_memset(rproc, s, c, count); }
> > > +
> > > /**
> > > * rproc_elf_load_segments() - load firmware segments to memory
> > > * @rproc: remote processor which will be booted using these fw
> > > segments @@ -214,7 +230,7 @@ int rproc_elf_load_segments(struct
> > > rproc *rproc, const struct firmware *fw)
> > >
> > > /* put the segment where the remote processor expects it */
> > > if (filesz)
> > > - memcpy(ptr, elf_data + offset, filesz);
> > > + rproc_elf_memcpy(rproc, ptr, elf_data + offset, filesz);
> > >
> > > /*
> > > * Zero out remaining memory for this segment.
> > > @@ -224,7 +240,7 @@ int rproc_elf_load_segments(struct rproc *rproc,
> > const struct firmware *fw)
> > > * this.
> > > */
> > > if (memsz > filesz)
> > > - memset(ptr + filesz, 0, memsz - filesz);
> > > + rproc_elf_memset(rproc, ptr + filesz, 0, memsz - filesz);
> > > }
> > >
> > > return ret;
> > > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > > index e8ac041c64d9..06c52f88a3fd 100644
> > > --- a/include/linux/remoteproc.h
> > > +++ b/include/linux/remoteproc.h
> > > @@ -373,6 +373,8 @@ enum rsc_handling_status {
> > > * expects to find it
> > > * @sanity_check: sanity check the fw image
> > > * @get_boot_addr: get boot address to entry point specified in
> > firmware
> > > + * @elf_memcpy: platform specific elf loader memcpy
> > > + * @elf_memset: platform specific elf loader memset
> > > * @panic: optional callback to react to system panic, core will delay
> > > * panic at least the returned number of milliseconds
> > > */
> > > @@ -392,6 +394,8 @@ struct rproc_ops {
> > > int (*load)(struct rproc *rproc, const struct firmware *fw);
> > > int (*sanity_check)(struct rproc *rproc, const struct firmware *fw);
> > > u64 (*get_boot_addr)(struct rproc *rproc, const struct firmware
> > > *fw);
> > > + void (*elf_memcpy)(struct rproc *rproc, void *dest, const void
> > > +*src,
> > size_t count);
> > > + void (*elf_memset)(struct rproc *rproc, void *s, int c, size_t
> > > +count);
> > > unsigned long (*panic)(struct rproc *rproc); };
> > >
> > > --
> > > 2.28.0
> > >

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