| Message ID | 1586420572-28353-1-git-send-email-peng.fan@nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] remoteproc: drop memset when loading elf segments | expand |
On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: > 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. > > Since memset is not strictly required, let's drop it. > This would imply that we trust that the firmware doesn't expect remoteproc to zero out the memory, which we've always done. So I don't think we can say that it's not required. > Signed-off-by: Peng Fan <peng.fan@nxp.com> > --- > drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c b/drivers/remoteproc/remoteproc_elf_loader.c > index 16e2c496fd45..cc50fe70d50c 100644 > --- a/drivers/remoteproc/remoteproc_elf_loader.c > +++ b/drivers/remoteproc/remoteproc_elf_loader.c > @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw) > memcpy(ptr, elf_data + offset, filesz); > > /* > - * Zero out remaining memory for this segment. > + * No need zero out remaining memory for this segment. > * > * This isn't strictly required since dma_alloc_coherent already > - * did this for us. albeit harmless, we may consider removing > - * this. > + * did this for us. In the case of recovery this comment is wrong, we do not dma_alloc_coherent() the carveout during a recovery. And in your case you ioremapped existing TCM, so it's never true. > */ > - if (memsz > filesz) > - memset(ptr + filesz, 0, memsz - filesz); So I think you do want to zero out this region. Question is how we do it... Regards, Bjorn > } > > if (ret == 0) > -- > 2.16.4 >
Hi Bjorn, > Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > segments > > On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: > > > 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. > > > > Since memset is not strictly required, let's drop it. > > > > This would imply that we trust that the firmware doesn't expect remoteproc > to zero out the memory, which we've always done. So I don't think we can say > that it's not required. Saying an image runs on a remote core needs Linux to help zero out BSS section, this not make sense to me. My case is as following, I need to load section 7 data. I no need to let remoteproc to memset section 8/9/10/11/12, the firmware itself could handle that. Just because the memsz is larger than filesz, remoreproc must memset? Section Headers: [Nr] Name Type Addr Off Size ES Flg Lk Inf Al [ 0] NULL 00000000 000000 000000 00 0 0 0 [ 1] .interrupts PROGBITS 1ffe0000 010000 000240 00 A 0 0 4 [ 2] .resource_table PROGBITS 1ffe0240 010240 000058 00 A 0 0 1 [ 3] .text PROGBITS 1ffe02a0 0102a0 009ccc 00 AX 0 0 16 [ 4] .ARM ARM_EXIDX 1ffe9f6c 019f6c 000008 00 AL 3 0 4 [ 5] .init_array INIT_ARRAY 1ffe9f74 019f74 000004 04 WA 0 0 4 [ 6] .fini_array FINI_ARRAY 1ffe9f78 019f78 000004 04 WA 0 0 4 [ 7] .data PROGBITS 1fff9240 029240 000084 00 WA 0 0 4 [ 8] .ncache.init PROGBITS 1fff92c4 0292c4 000000 00 W 0 0 1 [ 9] .ncache NOBITS 1fff92c4 0292c4 000a80 00 WA 0 0 4 [10] .bss NOBITS 1fff9d44 0292c4 01f5c0 00 WA 0 0 4 [11] .heap NOBITS 20019304 0292c4 000404 00 WA 0 0 1 [12] .stack NOBITS 20019708 0292c4 000400 00 WA 0 0 1 > > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > --- > > drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c > > b/drivers/remoteproc/remoteproc_elf_loader.c > > index 16e2c496fd45..cc50fe70d50c 100644 > > --- a/drivers/remoteproc/remoteproc_elf_loader.c > > +++ b/drivers/remoteproc/remoteproc_elf_loader.c > > @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc *rproc, > const struct firmware *fw) > > memcpy(ptr, elf_data + offset, filesz); > > > > /* > > - * Zero out remaining memory for this segment. > > + * No need zero out remaining memory for this segment. > > * > > * This isn't strictly required since dma_alloc_coherent already > > - * did this for us. albeit harmless, we may consider removing > > - * this. > > + * did this for us. > > In the case of recovery this comment is wrong, we do not > dma_alloc_coherent() the carveout during a recovery. Isn't the it the firmware's job to memset the region? > > And in your case you ioremapped existing TCM, so it's never true. > > > */ > > - if (memsz > filesz) > > - memset(ptr + filesz, 0, memsz - filesz); > > So I think you do want to zero out this region. Question is how we do it... I have contacted our M4 owners, we no need clear it from Linux side. We also support booting m4 before booting Linux, at that case, Linux has noting to do with memset. It is just I try loading m4 image with Linux, and met the issue that memset trigger abort. Thanks, Peng. > > Regards, > Bjorn > > > } > > > > if (ret == 0) > > -- > > 2.16.4 > >
On Thu 09 Apr 18:29 PDT 2020, Peng Fan wrote: > Hi Bjorn, > > > Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > > segments > > > > On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: > > > > > 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. > > > > > > Since memset is not strictly required, let's drop it. > > > > > > > This would imply that we trust that the firmware doesn't expect remoteproc > > to zero out the memory, which we've always done. So I don't think we can say > > that it's not required. > > Saying an image runs on a remote core needs Linux to help zero out BSS section, > this not make sense to me. Maybe not, but it has always done it, so if there's firmware out there that depends on it such change would break them.. > My case is as following, I need to load section 7 data. > I no need to let remoteproc to memset section 8/9/10/11/12, the firmware itself > could handle that. Just because the memsz is larger than filesz, remoreproc must > memset? By having a PT_LOAD segment covering these I think it's reasonable to assume that the ELF loader should be able to touch the associated memory. > Section Headers: > [Nr] Name Type Addr Off Size ES Flg Lk Inf Al > [ 0] NULL 00000000 000000 000000 00 0 0 0 > [ 1] .interrupts PROGBITS 1ffe0000 010000 000240 00 A 0 0 4 > [ 2] .resource_table PROGBITS 1ffe0240 010240 000058 00 A 0 0 1 > [ 3] .text PROGBITS 1ffe02a0 0102a0 009ccc 00 AX 0 0 16 > [ 4] .ARM ARM_EXIDX 1ffe9f6c 019f6c 000008 00 AL 3 0 4 > [ 5] .init_array INIT_ARRAY 1ffe9f74 019f74 000004 04 WA 0 0 4 > [ 6] .fini_array FINI_ARRAY 1ffe9f78 019f78 000004 04 WA 0 0 4 > [ 7] .data PROGBITS 1fff9240 029240 000084 00 WA 0 0 4 > [ 8] .ncache.init PROGBITS 1fff92c4 0292c4 000000 00 W 0 0 1 > [ 9] .ncache NOBITS 1fff92c4 0292c4 000a80 00 WA 0 0 4 > [10] .bss NOBITS 1fff9d44 0292c4 01f5c0 00 WA 0 0 4 > [11] .heap NOBITS 20019304 0292c4 000404 00 WA 0 0 1 > [12] .stack NOBITS 20019708 0292c4 000400 00 WA 0 0 1 > > > > > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > > --- > > > drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- > > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c > > > b/drivers/remoteproc/remoteproc_elf_loader.c > > > index 16e2c496fd45..cc50fe70d50c 100644 > > > --- a/drivers/remoteproc/remoteproc_elf_loader.c > > > +++ b/drivers/remoteproc/remoteproc_elf_loader.c > > > @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc *rproc, > > const struct firmware *fw) > > > memcpy(ptr, elf_data + offset, filesz); > > > > > > /* > > > - * Zero out remaining memory for this segment. > > > + * No need zero out remaining memory for this segment. > > > * > > > * This isn't strictly required since dma_alloc_coherent already > > > - * did this for us. albeit harmless, we may consider removing > > > - * this. > > > + * did this for us. > > > > In the case of recovery this comment is wrong, we do not > > dma_alloc_coherent() the carveout during a recovery. > > Isn't the it the firmware's job to memset the region? > I'm not aware of this being a documented requirement, we've always done it here for them, so removing this call would be a change in behavior. > > > > And in your case you ioremapped existing TCM, so it's never true. > > > > > */ > > > - if (memsz > filesz) > > > - memset(ptr + filesz, 0, memsz - filesz); > > > > So I think you do want to zero out this region. Question is how we do it... > > I have contacted our M4 owners, we no need clear it from Linux side. And I think _most_ firmware out there, like yours, does clear BSS etc during initialization. > We also support booting m4 before booting Linux, at that case, Linux has > noting to do with memset. It is just I try loading m4 image with Linux, > and met the issue that memset trigger abort. > Please see the proposal for attaching to already running remoteproc's from Mathieu. I don't expect that you want to load your PROGBITS either in this case? Regards, Bjorn
> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > segments > > On Thu 09 Apr 18:29 PDT 2020, Peng Fan wrote: > > > Hi Bjorn, > > > > > Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > > > segments > > > > > > On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: > > > > > > > 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. > > > > > > > > Since memset is not strictly required, let's drop it. > > > > > > > > > > This would imply that we trust that the firmware doesn't expect > > > remoteproc to zero out the memory, which we've always done. So I > > > don't think we can say that it's not required. > > > > Saying an image runs on a remote core needs Linux to help zero out BSS > > section, this not make sense to me. > > Maybe not, but it has always done it, so if there's firmware out there that > depends on it such change would break them.. Got it. > > > My case is as following, I need to load section 7 data. > > I no need to let remoteproc to memset section 8/9/10/11/12, the > > firmware itself could handle that. Just because the memsz is larger > > than filesz, remoreproc must memset? > > By having a PT_LOAD segment covering these I think it's reasonable to > assume that the ELF loader should be able to touch the associated memory. > > > Section Headers: > > [Nr] Name Type Addr Off Size > ES Flg Lk Inf Al > > [ 0] NULL 00000000 000000 > 000000 00 0 0 0 > > [ 1] .interrupts PROGBITS 1ffe0000 010000 000240 00 > A 0 0 4 > > [ 2] .resource_table PROGBITS 1ffe0240 010240 000058 00 > A 0 0 1 > > [ 3] .text PROGBITS 1ffe02a0 0102a0 009ccc 00 > AX 0 0 16 > > [ 4] .ARM ARM_EXIDX 1ffe9f6c 019f6c 000008 > 00 AL 3 0 4 > > [ 5] .init_array INIT_ARRAY 1ffe9f74 019f74 000004 04 > WA 0 0 4 > > [ 6] .fini_array FINI_ARRAY 1ffe9f78 019f78 000004 04 > WA 0 0 4 > > [ 7] .data PROGBITS 1fff9240 029240 000084 > 00 WA 0 0 4 > > [ 8] .ncache.init PROGBITS 1fff92c4 0292c4 000000 00 > W 0 0 1 > > [ 9] .ncache NOBITS 1fff92c4 0292c4 000a80 > 00 WA 0 0 4 > > [10] .bss NOBITS 1fff9d44 0292c4 01f5c0 > 00 WA 0 0 4 > > [11] .heap NOBITS 20019304 0292c4 000404 > 00 WA 0 0 1 > > [12] .stack NOBITS 20019708 0292c4 000400 > 00 WA 0 0 1 > > > > > > > > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > > > --- > > > > drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- > > > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c > > > > b/drivers/remoteproc/remoteproc_elf_loader.c > > > > index 16e2c496fd45..cc50fe70d50c 100644 > > > > --- a/drivers/remoteproc/remoteproc_elf_loader.c > > > > +++ b/drivers/remoteproc/remoteproc_elf_loader.c > > > > @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc > > > > *rproc, > > > const struct firmware *fw) > > > > memcpy(ptr, elf_data + offset, filesz); > > > > > > > > /* > > > > - * Zero out remaining memory for this segment. > > > > + * No need zero out remaining memory for this segment. > > > > * > > > > * This isn't strictly required since dma_alloc_coherent already > > > > - * did this for us. albeit harmless, we may consider removing > > > > - * this. > > > > + * did this for us. > > > > > > In the case of recovery this comment is wrong, we do not > > > dma_alloc_coherent() the carveout during a recovery. > > > > Isn't the it the firmware's job to memset the region? > > > > I'm not aware of this being a documented requirement, we've always done it > here for them, so removing this call would be a change in behavior. > > > > > > > And in your case you ioremapped existing TCM, so it's never true. > > > > > > > */ > > > > - if (memsz > filesz) > > > > - memset(ptr + filesz, 0, memsz - filesz); > > > > > > So I think you do want to zero out this region. Question is how we do it... > > > > I have contacted our M4 owners, we no need clear it from Linux side. > > And I think _most_ firmware out there, like yours, does clear BSS etc during > initialization. > > > We also support booting m4 before booting Linux, at that case, Linux > > has noting to do with memset. It is just I try loading m4 image with > > Linux, and met the issue that memset trigger abort. > > > > Please see the proposal for attaching to already running remoteproc's from > Mathieu. I don't expect that you want to load your PROGBITS either in this > case? No need to load for early boot case. It is just userspace load trigger kernel panic, because memset arm64 could not work for ioremapped memory. How about adding ops hooks for memset and memcpy to let driver have their own implementation? Thanks, Peng. > > Regards, > Bjorn
On 4/13/20 4:05 AM, Peng Fan wrote: > >> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf >> segments >> >> On Thu 09 Apr 18:29 PDT 2020, Peng Fan wrote: >> >>> Hi Bjorn, >>> >>>> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf >>>> segments >>>> >>>> On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: >>>> >>>>> 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. >>>>> >>>>> Since memset is not strictly required, let's drop it. >>>>> >>>> >>>> This would imply that we trust that the firmware doesn't expect >>>> remoteproc to zero out the memory, which we've always done. So I >>>> don't think we can say that it's not required. >>> >>> Saying an image runs on a remote core needs Linux to help zero out BSS >>> section, this not make sense to me. >> >> Maybe not, but it has always done it, so if there's firmware out there that >> depends on it such change would break them.. > > Got it. > >> >>> My case is as following, I need to load section 7 data. >>> I no need to let remoteproc to memset section 8/9/10/11/12, the >>> firmware itself could handle that. Just because the memsz is larger >>> than filesz, remoreproc must memset? >> >> By having a PT_LOAD segment covering these I think it's reasonable to >> assume that the ELF loader should be able to touch the associated memory. >> >>> Section Headers: >>> [Nr] Name Type Addr Off Size >> ES Flg Lk Inf Al >>> [ 0] NULL 00000000 000000 >> 000000 00 0 0 0 >>> [ 1] .interrupts PROGBITS 1ffe0000 010000 000240 00 >> A 0 0 4 >>> [ 2] .resource_table PROGBITS 1ffe0240 010240 000058 00 >> A 0 0 1 >>> [ 3] .text PROGBITS 1ffe02a0 0102a0 009ccc 00 >> AX 0 0 16 >>> [ 4] .ARM ARM_EXIDX 1ffe9f6c 019f6c 000008 >> 00 AL 3 0 4 >>> [ 5] .init_array INIT_ARRAY 1ffe9f74 019f74 000004 04 >> WA 0 0 4 >>> [ 6] .fini_array FINI_ARRAY 1ffe9f78 019f78 000004 04 >> WA 0 0 4 >>> [ 7] .data PROGBITS 1fff9240 029240 000084 >> 00 WA 0 0 4 >>> [ 8] .ncache.init PROGBITS 1fff92c4 0292c4 000000 00 >> W 0 0 1 >>> [ 9] .ncache NOBITS 1fff92c4 0292c4 000a80 >> 00 WA 0 0 4 >>> [10] .bss NOBITS 1fff9d44 0292c4 01f5c0 >> 00 WA 0 0 4 >>> [11] .heap NOBITS 20019304 0292c4 000404 >> 00 WA 0 0 1 >>> [12] .stack NOBITS 20019708 0292c4 000400 >> 00 WA 0 0 1 >>> >>>> >>>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>>>> --- >>>>> drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- >>>>> 1 file changed, 2 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/drivers/remoteproc/remoteproc_elf_loader.c >>>>> b/drivers/remoteproc/remoteproc_elf_loader.c >>>>> index 16e2c496fd45..cc50fe70d50c 100644 >>>>> --- a/drivers/remoteproc/remoteproc_elf_loader.c >>>>> +++ b/drivers/remoteproc/remoteproc_elf_loader.c >>>>> @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc >>>>> *rproc, >>>> const struct firmware *fw) >>>>> memcpy(ptr, elf_data + offset, filesz); >>>>> >>>>> /* >>>>> - * Zero out remaining memory for this segment. >>>>> + * No need zero out remaining memory for this segment. >>>>> * >>>>> * This isn't strictly required since dma_alloc_coherent already >>>>> - * did this for us. albeit harmless, we may consider removing >>>>> - * this. >>>>> + * did this for us. >>>> >>>> In the case of recovery this comment is wrong, we do not >>>> dma_alloc_coherent() the carveout during a recovery. >>> >>> Isn't the it the firmware's job to memset the region? >>> >> >> I'm not aware of this being a documented requirement, we've always done it >> here for them, so removing this call would be a change in behavior. >> >>>> >>>> And in your case you ioremapped existing TCM, so it's never true. >>>> >>>>> */ >>>>> - if (memsz > filesz) >>>>> - memset(ptr + filesz, 0, memsz - filesz); >>>> >>>> So I think you do want to zero out this region. Question is how we do it... >>> >>> I have contacted our M4 owners, we no need clear it from Linux side. >> >> And I think _most_ firmware out there, like yours, does clear BSS etc during >> initialization. >> >>> We also support booting m4 before booting Linux, at that case, Linux >>> has noting to do with memset. It is just I try loading m4 image with >>> Linux, and met the issue that memset trigger abort. >>> >> >> Please see the proposal for attaching to already running remoteproc's from >> Mathieu. I don't expect that you want to load your PROGBITS either in this >> case? > > No need to load for early boot case. It is just userspace load trigger > kernel panic, because memset arm64 could not work for ioremapped memory. > > How about adding ops hooks for memset and memcpy to let driver > have their own implementation? Hi Peng, The trick is to use the ioremap_wc() variant instead of ioremap() in your platform driver while mapping the TCMs. I know multiple folks have run into this issue. This is what most of the remoteproc drivers use, and mmio-sram driver also uses the same. regards Suman
> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > segments > > On 4/13/20 4:05 AM, Peng Fan wrote: > > > >> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > >> segments > >> > >> On Thu 09 Apr 18:29 PDT 2020, Peng Fan wrote: > >> > >>> Hi Bjorn, > >>> > >>>> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf > >>>> segments > >>>> > >>>> On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: > >>>> > >>>>> 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. > >>>>> > >>>>> Since memset is not strictly required, let's drop it. > >>>>> > >>>> > >>>> This would imply that we trust that the firmware doesn't expect > >>>> remoteproc to zero out the memory, which we've always done. So I > >>>> don't think we can say that it's not required. > >>> > >>> Saying an image runs on a remote core needs Linux to help zero out > >>> BSS section, this not make sense to me. > >> > >> Maybe not, but it has always done it, so if there's firmware out > >> there that depends on it such change would break them.. > > > > Got it. > > > >> > >>> My case is as following, I need to load section 7 data. > >>> I no need to let remoteproc to memset section 8/9/10/11/12, the > >>> firmware itself could handle that. Just because the memsz is larger > >>> than filesz, remoreproc must memset? > >> > >> By having a PT_LOAD segment covering these I think it's reasonable to > >> assume that the ELF loader should be able to touch the associated > memory. > >> > >>> Section Headers: > >>> [Nr] Name Type Addr Off > Size > >> ES Flg Lk Inf Al > >>> [ 0] NULL 00000000 000000 > >> 000000 00 0 0 0 > >>> [ 1] .interrupts PROGBITS 1ffe0000 010000 000240 > 00 > >> A 0 0 4 > >>> [ 2] .resource_table PROGBITS 1ffe0240 010240 000058 > 00 > >> A 0 0 1 > >>> [ 3] .text PROGBITS 1ffe02a0 0102a0 > 009ccc 00 > >> AX 0 0 16 > >>> [ 4] .ARM ARM_EXIDX 1ffe9f6c 019f6c > 000008 > >> 00 AL 3 0 4 > >>> [ 5] .init_array INIT_ARRAY 1ffe9f74 019f74 000004 > 04 > >> WA 0 0 4 > >>> [ 6] .fini_array FINI_ARRAY 1ffe9f78 019f78 000004 > 04 > >> WA 0 0 4 > >>> [ 7] .data PROGBITS 1fff9240 029240 > 000084 > >> 00 WA 0 0 4 > >>> [ 8] .ncache.init PROGBITS 1fff92c4 0292c4 000000 > 00 > >> W 0 0 1 > >>> [ 9] .ncache NOBITS 1fff92c4 0292c4 > 000a80 > >> 00 WA 0 0 4 > >>> [10] .bss NOBITS 1fff9d44 0292c4 > 01f5c0 > >> 00 WA 0 0 4 > >>> [11] .heap NOBITS 20019304 0292c4 > 000404 > >> 00 WA 0 0 1 > >>> [12] .stack NOBITS 20019708 0292c4 > 000400 > >> 00 WA 0 0 1 > >>> > >>>> > >>>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> > >>>>> --- > >>>>> drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- > >>>>> 1 file changed, 2 insertions(+), 5 deletions(-) > >>>>> > >>>>> diff --git a/drivers/remoteproc/remoteproc_elf_loader.c > >>>>> b/drivers/remoteproc/remoteproc_elf_loader.c > >>>>> index 16e2c496fd45..cc50fe70d50c 100644 > >>>>> --- a/drivers/remoteproc/remoteproc_elf_loader.c > >>>>> +++ b/drivers/remoteproc/remoteproc_elf_loader.c > >>>>> @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc > >>>>> *rproc, > >>>> const struct firmware *fw) > >>>>> memcpy(ptr, elf_data + offset, filesz); > >>>>> > >>>>> /* > >>>>> - * Zero out remaining memory for this segment. > >>>>> + * No need zero out remaining memory for this segment. > >>>>> * > >>>>> * This isn't strictly required since dma_alloc_coherent > already > >>>>> - * did this for us. albeit harmless, we may consider removing > >>>>> - * this. > >>>>> + * did this for us. > >>>> > >>>> In the case of recovery this comment is wrong, we do not > >>>> dma_alloc_coherent() the carveout during a recovery. > >>> > >>> Isn't the it the firmware's job to memset the region? > >>> > >> > >> I'm not aware of this being a documented requirement, we've always > >> done it here for them, so removing this call would be a change in behavior. > >> > >>>> > >>>> And in your case you ioremapped existing TCM, so it's never true. > >>>> > >>>>> */ > >>>>> - if (memsz > filesz) > >>>>> - memset(ptr + filesz, 0, memsz - filesz); > >>>> > >>>> So I think you do want to zero out this region. Question is how we do it... > >>> > >>> I have contacted our M4 owners, we no need clear it from Linux side. > >> > >> And I think _most_ firmware out there, like yours, does clear BSS etc > >> during initialization. > >> > >>> We also support booting m4 before booting Linux, at that case, Linux > >>> has noting to do with memset. It is just I try loading m4 image with > >>> Linux, and met the issue that memset trigger abort. > >>> > >> > >> Please see the proposal for attaching to already running remoteproc's > >> from Mathieu. I don't expect that you want to load your PROGBITS > >> either in this case? > > > > No need to load for early boot case. It is just userspace load trigger > > kernel panic, because memset arm64 could not work for ioremapped > memory. > > > > How about adding ops hooks for memset and memcpy to let driver have > > their own implementation? > > Hi Peng, > > The trick is to use the ioremap_wc() variant instead of ioremap() in your > platform driver while mapping the TCMs. I know multiple folks have run into > this issue. This is what most of the remoteproc drivers use, and mmio-sram > driver also uses the same. TCM is different from OCRAM in i.MX chips. ioremap_wc not work for TCM memory, I just tried that. I am thinking we change memset/memcpy to use memset_io/memcpy_fromio/memcpy_toio for remoteproc common code, Thanks, Peng. > > regards > Suman
On 4/21/20 2:42 AM, Peng Fan wrote: >> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf >> segments >> >> On 4/13/20 4:05 AM, Peng Fan wrote: >>> >>>> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf >>>> segments >>>> >>>> On Thu 09 Apr 18:29 PDT 2020, Peng Fan wrote: >>>> >>>>> Hi Bjorn, >>>>> >>>>>> Subject: Re: [PATCH 1/2] remoteproc: drop memset when loading elf >>>>>> segments >>>>>> >>>>>> On Thu 09 Apr 01:22 PDT 2020, Peng Fan wrote: >>>>>> >>>>>>> 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. >>>>>>> >>>>>>> Since memset is not strictly required, let's drop it. >>>>>>> >>>>>> >>>>>> This would imply that we trust that the firmware doesn't expect >>>>>> remoteproc to zero out the memory, which we've always done. So I >>>>>> don't think we can say that it's not required. >>>>> >>>>> Saying an image runs on a remote core needs Linux to help zero out >>>>> BSS section, this not make sense to me. >>>> >>>> Maybe not, but it has always done it, so if there's firmware out >>>> there that depends on it such change would break them.. >>> >>> Got it. >>> >>>> >>>>> My case is as following, I need to load section 7 data. >>>>> I no need to let remoteproc to memset section 8/9/10/11/12, the >>>>> firmware itself could handle that. Just because the memsz is larger >>>>> than filesz, remoreproc must memset? >>>> >>>> By having a PT_LOAD segment covering these I think it's reasonable to >>>> assume that the ELF loader should be able to touch the associated >> memory. >>>> >>>>> Section Headers: >>>>> [Nr] Name Type Addr Off >> Size >>>> ES Flg Lk Inf Al >>>>> [ 0] NULL 00000000 000000 >>>> 000000 00 0 0 0 >>>>> [ 1] .interrupts PROGBITS 1ffe0000 010000 000240 >> 00 >>>> A 0 0 4 >>>>> [ 2] .resource_table PROGBITS 1ffe0240 010240 000058 >> 00 >>>> A 0 0 1 >>>>> [ 3] .text PROGBITS 1ffe02a0 0102a0 >> 009ccc 00 >>>> AX 0 0 16 >>>>> [ 4] .ARM ARM_EXIDX 1ffe9f6c 019f6c >> 000008 >>>> 00 AL 3 0 4 >>>>> [ 5] .init_array INIT_ARRAY 1ffe9f74 019f74 000004 >> 04 >>>> WA 0 0 4 >>>>> [ 6] .fini_array FINI_ARRAY 1ffe9f78 019f78 000004 >> 04 >>>> WA 0 0 4 >>>>> [ 7] .data PROGBITS 1fff9240 029240 >> 000084 >>>> 00 WA 0 0 4 >>>>> [ 8] .ncache.init PROGBITS 1fff92c4 0292c4 000000 >> 00 >>>> W 0 0 1 >>>>> [ 9] .ncache NOBITS 1fff92c4 0292c4 >> 000a80 >>>> 00 WA 0 0 4 >>>>> [10] .bss NOBITS 1fff9d44 0292c4 >> 01f5c0 >>>> 00 WA 0 0 4 >>>>> [11] .heap NOBITS 20019304 0292c4 >> 000404 >>>> 00 WA 0 0 1 >>>>> [12] .stack NOBITS 20019708 0292c4 >> 000400 >>>> 00 WA 0 0 1 >>>>> >>>>>> >>>>>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>>>>>> --- >>>>>>> drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- >>>>>>> 1 file changed, 2 insertions(+), 5 deletions(-) >>>>>>> >>>>>>> diff --git a/drivers/remoteproc/remoteproc_elf_loader.c >>>>>>> b/drivers/remoteproc/remoteproc_elf_loader.c >>>>>>> index 16e2c496fd45..cc50fe70d50c 100644 >>>>>>> --- a/drivers/remoteproc/remoteproc_elf_loader.c >>>>>>> +++ b/drivers/remoteproc/remoteproc_elf_loader.c >>>>>>> @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc >>>>>>> *rproc, >>>>>> const struct firmware *fw) >>>>>>> memcpy(ptr, elf_data + offset, filesz); >>>>>>> >>>>>>> /* >>>>>>> - * Zero out remaining memory for this segment. >>>>>>> + * No need zero out remaining memory for this segment. >>>>>>> * >>>>>>> * This isn't strictly required since dma_alloc_coherent >> already >>>>>>> - * did this for us. albeit harmless, we may consider removing >>>>>>> - * this. >>>>>>> + * did this for us. >>>>>> >>>>>> In the case of recovery this comment is wrong, we do not >>>>>> dma_alloc_coherent() the carveout during a recovery. >>>>> >>>>> Isn't the it the firmware's job to memset the region? >>>>> >>>> >>>> I'm not aware of this being a documented requirement, we've always >>>> done it here for them, so removing this call would be a change in behavior. >>>> >>>>>> >>>>>> And in your case you ioremapped existing TCM, so it's never true. >>>>>> >>>>>>> */ >>>>>>> - if (memsz > filesz) >>>>>>> - memset(ptr + filesz, 0, memsz - filesz); >>>>>> >>>>>> So I think you do want to zero out this region. Question is how we do it... >>>>> >>>>> I have contacted our M4 owners, we no need clear it from Linux side. >>>> >>>> And I think _most_ firmware out there, like yours, does clear BSS etc >>>> during initialization. >>>> >>>>> We also support booting m4 before booting Linux, at that case, Linux >>>>> has noting to do with memset. It is just I try loading m4 image with >>>>> Linux, and met the issue that memset trigger abort. >>>>> >>>> >>>> Please see the proposal for attaching to already running remoteproc's >>>> from Mathieu. I don't expect that you want to load your PROGBITS >>>> either in this case? >>> >>> No need to load for early boot case. It is just userspace load trigger >>> kernel panic, because memset arm64 could not work for ioremapped >> memory. >>> >>> How about adding ops hooks for memset and memcpy to let driver have >>> their own implementation? >> >> Hi Peng, >> >> The trick is to use the ioremap_wc() variant instead of ioremap() in your >> platform driver while mapping the TCMs. I know multiple folks have run into >> this issue. This is what most of the remoteproc drivers use, and mmio-sram >> driver also uses the same. > > TCM is different from OCRAM in i.MX chips. > ioremap_wc not work for TCM memory, I just tried that. What ARM core is this? Is it a standard ARM TCM memory? The TCM interfaces from standard ARM cores in general are treated as normal memory, so write combine should be ok on them. When you say it doesn't work, whats not working - the memcpy/memset or the remoteproc doesn't boot? > I am thinking we change memset/memcpy to use > memset_io/memcpy_fromio/memcpy_toio for remoteproc common code, This has other implications. Not everything is IO memory to make this change in the common core. If this is a custom memory interface requiring specific handling, then one option is to provide and use your own ops->load function within the driver. This is what I do for one of our remoteprocs that requires a specific memcpy handling semantics. regards Suman
----- On 21 Apr, 2020, at 20:25, s-anna s-anna@ti.com wrote: >>> >>> Hi Peng, >>> >>> The trick is to use the ioremap_wc() variant instead of ioremap() in your >>> platform driver while mapping the TCMs. I know multiple folks have run into >>> this issue. This is what most of the remoteproc drivers use, and mmio-sram >>> driver also uses the same. >> >> TCM is different from OCRAM in i.MX chips. >> ioremap_wc not work for TCM memory, I just tried that. > > What ARM core is this? Is it a standard ARM TCM memory? The TCM > interfaces from standard ARM cores in general are treated as normal > memory, so write combine should be ok on them. When you say it doesn't > work, whats not working - the memcpy/memset or the remoteproc doesn't boot? > >> I am thinking we change memset/memcpy to use >> memset_io/memcpy_fromio/memcpy_toio for remoteproc common code, > > This has other implications. Not everything is IO memory to make this > change in the common core. Hi Suman, AFAIK, most (if not all) the drivers are using ioremap to expose the remoteproc memories. Since these are IO memories, then care should be taken when writing/reading from them and memset_io/memcpy_fromio /memcpy_toio should be used (or ioread/write). Currently, this is not the case in the remoteproc driver and it works because everything is aligned and there is no misaligned access. IMHO, as suggested by Peng, remoteproc core should use such accessors. We (at Kalray) have some modifications to do that since there were some misalignment after modifying the resource table (64 bits fields). The only drawback that I can see using io memcpy is potentially a loss of performance for processors not requiring any alignement check. But other than that, it seems safer for everyon and performance in init does not seems really critical. > > If this is a custom memory interface requiring specific handling, then > one option is to provide and use your own ops->load function within the > driver. This is what I do for one of our remoteprocs that requires a > specific memcpy handling semantics. This does not only apply to firmware loading. This applies to all the resource table accesses which are currently done using direct accesses to members. They should also used io memcpy. Regards, Clément > > regards > Suman
diff --git a/drivers/remoteproc/remoteproc_elf_loader.c b/drivers/remoteproc/remoteproc_elf_loader.c index 16e2c496fd45..cc50fe70d50c 100644 --- a/drivers/remoteproc/remoteproc_elf_loader.c +++ b/drivers/remoteproc/remoteproc_elf_loader.c @@ -238,14 +238,11 @@ int rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw) memcpy(ptr, elf_data + offset, filesz); /* - * Zero out remaining memory for this segment. + * No need zero out remaining memory for this segment. * * This isn't strictly required since dma_alloc_coherent already - * did this for us. albeit harmless, we may consider removing - * this. + * did this for us. */ - if (memsz > filesz) - memset(ptr + filesz, 0, memsz - filesz); } if (ret == 0)
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. Since memset is not strictly required, let's drop it. Signed-off-by: Peng Fan <peng.fan@nxp.com> --- drivers/remoteproc/remoteproc_elf_loader.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)