Currently the sysfs interface maps the BERT error region as "memory"
(through acpi_os_map_memory()) in order to copy the error records into
memory buffers through memory operations (eg memory_read_from_buffer()).
The OS system cannot detect whether the BERT error region is part of
system RAM or it is "device memory" (eg BMC memory) and therefore it
cannot detect which memory attributes the bus to memory support (and
corresponding kernel mapping, unless firmware provides the required
information).
The acpi_os_map_memory() arch backend implementation determines the
mapping attributes. On arm64, if the BERT error region is not present in
the EFI memory map, the error region is mapped as device-nGnRnE; this
triggers alignment faults since memcpy unaligned accesses are not
allowed in device-nGnRnE regions.
The ACPI sysfs code cannot therefore map by default the BERT error
region with memory semantics but should use a safer default.
Change the sysfs code to map the BERT error region as MMIO (through
acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the
error region into the kernel buffer.
Link: https://lore.kernel.org/linux-arm-kernel/[email protected]
Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com
Signed-off-by: Lorenzo Pieralisi <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Hanjun Guo <[email protected]>
Cc: Sudeep Holla <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
---
drivers/acpi/sysfs.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index a4b638bea6f1..cc2fe0618178 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
loff_t offset, size_t count)
{
struct acpi_data_attr *data_attr;
- void *base;
- ssize_t rc;
+ void __iomem *base;
+ ssize_t size;
data_attr = container_of(bin_attr, struct acpi_data_attr, attr);
+ size = data_attr->attr.size;
+
+ if (offset < 0)
+ return -EINVAL;
+
+ if (offset >= size)
+ return 0;
- base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
+ if (count > size - offset)
+ count = size - offset;
+
+ base = acpi_os_map_iomem(data_attr->addr, size);
if (!base)
return -ENOMEM;
- rc = memory_read_from_buffer(buf, count, &offset, base,
- data_attr->attr.size);
- acpi_os_unmap_memory(base, data_attr->attr.size);
- return rc;
+ memcpy_fromio(buf, base + offset, count);
+
+ acpi_os_unmap_iomem(base, size);
+
+ return count;
}
static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
--
2.31.0
On Thu, Apr 07, 2022 at 11:51:20AM +0100, Lorenzo Pieralisi wrote:
> Currently the sysfs interface maps the BERT error region as "memory"
> (through acpi_os_map_memory()) in order to copy the error records into
> memory buffers through memory operations (eg memory_read_from_buffer()).
>
> The OS system cannot detect whether the BERT error region is part of
> system RAM or it is "device memory" (eg BMC memory) and therefore it
> cannot detect which memory attributes the bus to memory support (and
> corresponding kernel mapping, unless firmware provides the required
> information).
>
> The acpi_os_map_memory() arch backend implementation determines the
> mapping attributes. On arm64, if the BERT error region is not present in
> the EFI memory map, the error region is mapped as device-nGnRnE; this
> triggers alignment faults since memcpy unaligned accesses are not
> allowed in device-nGnRnE regions.
>
> The ACPI sysfs code cannot therefore map by default the BERT error
> region with memory semantics but should use a safer default.
>
> Change the sysfs code to map the BERT error region as MMIO (through
> acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the
> error region into the kernel buffer.
>
> Link: https://lore.kernel.org/linux-arm-kernel/[email protected]
> Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com
> Signed-off-by: Lorenzo Pieralisi <[email protected]>
> Cc: Ard Biesheuvel <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Hanjun Guo <[email protected]>
> Cc: Sudeep Holla <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> ---
> drivers/acpi/sysfs.c | 25 ++++++++++++++++++-------
> 1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> index a4b638bea6f1..cc2fe0618178 100644
> --- a/drivers/acpi/sysfs.c
> +++ b/drivers/acpi/sysfs.c
> @@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
> loff_t offset, size_t count)
> {
> struct acpi_data_attr *data_attr;
> - void *base;
> - ssize_t rc;
> + void __iomem *base;
> + ssize_t size;
>
> data_attr = container_of(bin_attr, struct acpi_data_attr, attr);
> + size = data_attr->attr.size;
> +
> + if (offset < 0)
> + return -EINVAL;
> +
> + if (offset >= size)
> + return 0;
>
> - base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
> + if (count > size - offset)
> + count = size - offset;
> +
> + base = acpi_os_map_iomem(data_attr->addr, size);
> if (!base)
> return -ENOMEM;
> - rc = memory_read_from_buffer(buf, count, &offset, base,
> - data_attr->attr.size);
> - acpi_os_unmap_memory(base, data_attr->attr.size);
>
> - return rc;
> + memcpy_fromio(buf, base + offset, count);
> +
> + acpi_os_unmap_iomem(base, size);
> +
> + return count;
> }
>
> static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
I've tested this patch with the reproducer and I was unable to reproduce
the issue.
Tested-by: Aristeu Rozanski <[email protected]>
--
Aristeu
On Thu, Apr 7, 2022 at 12:51 PM Lorenzo Pieralisi
<[email protected]> wrote:
>
> Currently the sysfs interface maps the BERT error region as "memory"
> (through acpi_os_map_memory()) in order to copy the error records into
> memory buffers through memory operations (eg memory_read_from_buffer()).
>
> The OS system cannot detect whether the BERT error region is part of
> system RAM or it is "device memory" (eg BMC memory) and therefore it
> cannot detect which memory attributes the bus to memory support (and
> corresponding kernel mapping, unless firmware provides the required
> information).
>
> The acpi_os_map_memory() arch backend implementation determines the
> mapping attributes. On arm64, if the BERT error region is not present in
> the EFI memory map, the error region is mapped as device-nGnRnE; this
> triggers alignment faults since memcpy unaligned accesses are not
> allowed in device-nGnRnE regions.
>
> The ACPI sysfs code cannot therefore map by default the BERT error
> region with memory semantics but should use a safer default.
>
> Change the sysfs code to map the BERT error region as MMIO (through
> acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the
> error region into the kernel buffer.
>
Hi,
I tested this patch on top of the arm tree for-kernelci branch (a2c0b0fbe014).
I wasn't able to trigger the original problem on the same HW, and the patch
didn't introduce any new issues on these runs, nor on other randomly
chosen aarch64 machines.
Tested-by: Veronika Kabatova <[email protected]>
> Link: https://lore.kernel.org/linux-arm-kernel/[email protected]
> Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com
> Signed-off-by: Lorenzo Pieralisi <[email protected]>
> Cc: Ard Biesheuvel <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Hanjun Guo <[email protected]>
> Cc: Sudeep Holla <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> ---
> drivers/acpi/sysfs.c | 25 ++++++++++++++++++-------
> 1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> index a4b638bea6f1..cc2fe0618178 100644
> --- a/drivers/acpi/sysfs.c
> +++ b/drivers/acpi/sysfs.c
> @@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
> loff_t offset, size_t count)
> {
> struct acpi_data_attr *data_attr;
> - void *base;
> - ssize_t rc;
> + void __iomem *base;
> + ssize_t size;
>
> data_attr = container_of(bin_attr, struct acpi_data_attr, attr);
> + size = data_attr->attr.size;
> +
> + if (offset < 0)
> + return -EINVAL;
> +
> + if (offset >= size)
> + return 0;
>
> - base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
> + if (count > size - offset)
> + count = size - offset;
> +
> + base = acpi_os_map_iomem(data_attr->addr, size);
> if (!base)
> return -ENOMEM;
> - rc = memory_read_from_buffer(buf, count, &offset, base,
> - data_attr->attr.size);
> - acpi_os_unmap_memory(base, data_attr->attr.size);
>
> - return rc;
> + memcpy_fromio(buf, base + offset, count);
> +
> + acpi_os_unmap_iomem(base, size);
> +
> + return count;
> }
>
> static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
> --
> 2.31.0
>
On Thu, 7 Apr 2022 at 12:51, Lorenzo Pieralisi
<[email protected]> wrote:
>
> Currently the sysfs interface maps the BERT error region as "memory"
> (through acpi_os_map_memory()) in order to copy the error records into
> memory buffers through memory operations (eg memory_read_from_buffer()).
>
> The OS system cannot detect whether the BERT error region is part of
> system RAM or it is "device memory" (eg BMC memory) and therefore it
> cannot detect which memory attributes the bus to memory support (and
> corresponding kernel mapping, unless firmware provides the required
> information).
>
> The acpi_os_map_memory() arch backend implementation determines the
> mapping attributes. On arm64, if the BERT error region is not present in
> the EFI memory map, the error region is mapped as device-nGnRnE; this
> triggers alignment faults since memcpy unaligned accesses are not
> allowed in device-nGnRnE regions.
>
> The ACPI sysfs code cannot therefore map by default the BERT error
> region with memory semantics but should use a safer default.
>
> Change the sysfs code to map the BERT error region as MMIO (through
> acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the
> error region into the kernel buffer.
>
> Link: https://lore.kernel.org/linux-arm-kernel/[email protected]
> Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com
> Signed-off-by: Lorenzo Pieralisi <[email protected]>
> Cc: Ard Biesheuvel <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Hanjun Guo <[email protected]>
> Cc: Sudeep Holla <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
> ---
> drivers/acpi/sysfs.c | 25 ++++++++++++++++++-------
> 1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> index a4b638bea6f1..cc2fe0618178 100644
> --- a/drivers/acpi/sysfs.c
> +++ b/drivers/acpi/sysfs.c
> @@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
> loff_t offset, size_t count)
> {
> struct acpi_data_attr *data_attr;
> - void *base;
> - ssize_t rc;
> + void __iomem *base;
> + ssize_t size;
>
> data_attr = container_of(bin_attr, struct acpi_data_attr, attr);
> + size = data_attr->attr.size;
> +
> + if (offset < 0)
> + return -EINVAL;
> +
> + if (offset >= size)
> + return 0;
>
> - base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
> + if (count > size - offset)
> + count = size - offset;
> +
> + base = acpi_os_map_iomem(data_attr->addr, size);
> if (!base)
> return -ENOMEM;
> - rc = memory_read_from_buffer(buf, count, &offset, base,
> - data_attr->attr.size);
> - acpi_os_unmap_memory(base, data_attr->attr.size);
>
> - return rc;
> + memcpy_fromio(buf, base + offset, count);
> +
> + acpi_os_unmap_iomem(base, size);
> +
> + return count;
> }
>
> static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
> --
> 2.31.0
>
On Wed, Apr 13, 2022 at 7:41 PM Ard Biesheuvel <[email protected]> wrote:
>
> On Thu, 7 Apr 2022 at 12:51, Lorenzo Pieralisi
> <[email protected]> wrote:
> >
> > Currently the sysfs interface maps the BERT error region as "memory"
> > (through acpi_os_map_memory()) in order to copy the error records into
> > memory buffers through memory operations (eg memory_read_from_buffer()).
> >
> > The OS system cannot detect whether the BERT error region is part of
> > system RAM or it is "device memory" (eg BMC memory) and therefore it
> > cannot detect which memory attributes the bus to memory support (and
> > corresponding kernel mapping, unless firmware provides the required
> > information).
> >
> > The acpi_os_map_memory() arch backend implementation determines the
> > mapping attributes. On arm64, if the BERT error region is not present in
> > the EFI memory map, the error region is mapped as device-nGnRnE; this
> > triggers alignment faults since memcpy unaligned accesses are not
> > allowed in device-nGnRnE regions.
> >
> > The ACPI sysfs code cannot therefore map by default the BERT error
> > region with memory semantics but should use a safer default.
> >
> > Change the sysfs code to map the BERT error region as MMIO (through
> > acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the
> > error region into the kernel buffer.
> >
> > Link: https://lore.kernel.org/linux-arm-kernel/[email protected]
> > Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com
> > Signed-off-by: Lorenzo Pieralisi <[email protected]>
> > Cc: Ard Biesheuvel <[email protected]>
> > Cc: Will Deacon <[email protected]>
> > Cc: Hanjun Guo <[email protected]>
> > Cc: Sudeep Holla <[email protected]>
> > Cc: Catalin Marinas <[email protected]>
> > Cc: "Rafael J. Wysocki" <[email protected]>
>
> Acked-by: Ard Biesheuvel <[email protected]>
Applied as 5.19 material, thanks!
> > ---
> > drivers/acpi/sysfs.c | 25 ++++++++++++++++++-------
> > 1 file changed, 18 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> > index a4b638bea6f1..cc2fe0618178 100644
> > --- a/drivers/acpi/sysfs.c
> > +++ b/drivers/acpi/sysfs.c
> > @@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
> > loff_t offset, size_t count)
> > {
> > struct acpi_data_attr *data_attr;
> > - void *base;
> > - ssize_t rc;
> > + void __iomem *base;
> > + ssize_t size;
> >
> > data_attr = container_of(bin_attr, struct acpi_data_attr, attr);
> > + size = data_attr->attr.size;
> > +
> > + if (offset < 0)
> > + return -EINVAL;
> > +
> > + if (offset >= size)
> > + return 0;
> >
> > - base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
> > + if (count > size - offset)
> > + count = size - offset;
> > +
> > + base = acpi_os_map_iomem(data_attr->addr, size);
> > if (!base)
> > return -ENOMEM;
> > - rc = memory_read_from_buffer(buf, count, &offset, base,
> > - data_attr->attr.size);
> > - acpi_os_unmap_memory(base, data_attr->attr.size);
> >
> > - return rc;
> > + memcpy_fromio(buf, base + offset, count);
> > +
> > + acpi_os_unmap_iomem(base, size);
> > +
> > + return count;
> > }
> >
> > static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr)
> > --
> > 2.31.0
> >