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

From: Peng Fan
Date: Sun Dec 06 2020 - 21:08:52 EST

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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?

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
> >

Next message: Qi Liu: "Re: [PATCH v5] coresight: etm4x: Modify core-commit of cpu to avoid the overflow of HiSilicon ETM"
Previous message: Kuan-Ying Lee: "Re: [PATCH] kasan: fix slab double free when cpu-hotplug"
In reply to: Bjorn Andersson: "Re: [PATCH V3 1/7] remoteproc: elf: support platform specific memory hook"
Next in thread: Peng Fan (OSS): "[PATCH V3 3/7] remoteproc: imx_rproc: correct err message"
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