Re: [PATCH v3 1/5] RAS: Report all ARM processor CPER information to userspace

From: Borislav Petkov
Date: Wed Sep 11 2024 - 08:48:34 EST

On Wed, Sep 04, 2024 at 08:07:14AM +0200, Mauro Carvalho Chehab wrote:
> From: Jason Tian <jason@xxxxxxxxxxxxxxxxxxxxxx>
>
> The ARM processor CPER record was added at UEFI 2.6, and hasn't
> any changes up to UEFI 2.10 on its struct.

Did some fixups to the commit message, please use it in your next
submission.

There was also this typo:

Co-developed-by: Signed-off-by: Shengwei Luo <luoshengwei@xxxxxxxxxx>

From: Jason Tian <jason@xxxxxxxxxxxxxxxxxxxxxx>

RAS: Report all ARM processor CPER information to userspace

The ARM processor CPER record was added in UEFI v2.6 and remained
unchanged up to v2.10.

Yet, the original arm_event trace code added by

e9279e83ad1f ("trace, ras: add ARM processor error trace event")

is incomplete, as it only traces some fields of UAPI 2.6 table N.16, not
exporting any information from tables N.17 to N.29 of the record.

This is not enough for the user to be able to figure out what has
exactly happened or to take appropriate action.

According to the UEFI v2.9 specification chapter N2.4.4, the ARM
processor error section includes:

- several (ERR_INFO_NUM) ARM processor error information structures
(Tables N.17 to N.20);
- several (CONTEXT_INFO_NUM) ARM processor context information
structures (Tables N.21 to N.29);
- several vendor specific error information structures. The
size is given by Section Length minus the size of the other
fields.

In addition, it also exports two fields that are parsed by the GHES
driver when firmware reports it, e.g.:

- error severity
- CPU logical index

Report all of these information to userspace via a the ARM tracepoint so
that userspace can properly record the error and take decisions related
to CPU core isolation according to error severity and other info.

The updated ARM trace event now contains the following fields:

====================================== =============================
UEFI field on table N.16 ARM Processor trace fields
====================================== =============================
Validation handled when filling data for
affinity MPIDR and running
state.
ERR_INFO_NUM pei_len
CONTEXT_INFO_NUM ctx_len
Section Length indirectly reported by
pei_len, ctx_len and oem_len
Error affinity level affinity
MPIDR_EL1 mpidr
MIDR_EL1 midr
Running State running_state
PSCI State psci_state
Processor Error Information Structure pei_err - count at pei_len
Processor Context ctx_err- count at ctx_len
Vendor Specific Error Info oem - count at oem_len
====================================== =============================

It should be noted that decoding of tables N.17 to N.29, if needed, will
be handled in userspace. That gives more flexibility, as there won't be
any need to flood the kernel with micro-architecture specific error
decoding.

Also, decoding the other fields require a complex logic, and should be
done for each of the several values inside the record field. So, let
userspace daemons like rasdaemon decode them, parsing such tables and
having vendor-specific micro-architecture-specific decoders.

[mchehab: modified description, solved merge conflicts and fixed coding style]

Fixes: e9279e83ad1f ("trace, ras: add ARM processor error trace event")
Co-developed-by: Jason Tian <jason@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason Tian <jason@xxxxxxxxxxxxxxxxxxxxxx>
Co-developed-by: Shengwei Luo <luoshengwei@xxxxxxxxxx>
Signed-off-by: Shengwei Luo <luoshengwei@xxxxxxxxxx>
Co-developed-by: Daniel Ferguson <danielf@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Ferguson <danielf@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Tested-by: Shiju Jose <shiju.jose@xxxxxxxxxx>
Link: https://uefi.org/specs/UEFI/2.10/Apx_N_Common_Platform_Error_Record.html#arm-processor-error-section

> drivers/acpi/apei/ghes.c | 11 ++++-----
> drivers/ras/ras.c | 41 ++++++++++++++++++++++++++++++++--
> include/linux/ras.h | 16 +++++++++++---
> include/ras/ras_event.h | 48 +++++++++++++++++++++++++++++++++++-----
> 4 files changed, 99 insertions(+), 17 deletions(-)

Also, some cleanups ontop:

diff --git a/drivers/ras/ras.c b/drivers/ras/ras.c
index 6a0480c76e19..179b1744df71 100644
--- a/drivers/ras/ras.c
+++ b/drivers/ras/ras.c
@@ -70,14 +70,14 @@ void log_arm_hw_error(struct cper_sec_proc_arm *err, const u8 sev)
err_info = (struct cper_arm_err_info *)(err + 1);
ctx_info = (struct cper_arm_ctx_info *)(err_info + err->err_info_num);
ctx_err = (u8 *)ctx_info;
+
for (n = 0; n < err->context_info_num; n++) {
sz = sizeof(struct cper_arm_ctx_info) + ctx_info->size;
ctx_info = (struct cper_arm_ctx_info *)((long)ctx_info + sz);
ctx_len += sz;
}

- vsei_len = err->section_length - (sizeof(struct cper_sec_proc_arm) +
- pei_len + ctx_len);
+ vsei_len = err->section_length - (sizeof(struct cper_sec_proc_arm) + pei_len + ctx_len);
if (vsei_len < 0) {
pr_warn(FW_BUG "section length: %d\n", err->section_length);
pr_warn(FW_BUG "section length is too small\n");
diff --git a/include/linux/ras.h b/include/linux/ras.h
index df444492b434..468941bfe855 100644
--- a/include/linux/ras.h
+++ b/include/linux/ras.h
@@ -55,8 +55,8 @@ amd_convert_umc_mca_addr_to_sys_addr(struct atl_err *err) { return -EINVAL; }
#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
#include <asm/smp_plat.h>
/*
- * Include ARM specific SMP header which provides a function mapping mpidr to
- * cpu logical index.
+ * Include ARM-specific SMP header which provides a function mapping mpidr to
+ * CPU logical index.
*/
#define GET_LOGICAL_INDEX(mpidr) get_logical_index(mpidr & MPIDR_HWID_BITMASK)
#else


Thx.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette