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coresight: Interpret ETMv3 config with ATTR_CFG_GET_FLD()

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Currently we're programming attr->config directly into ETMCR after some
validation. This obscures which fields are being used, and also makes it
impossible to move fields around or use other configN fields in the
future.

Improve it by only reading the fields that are valid and then setting
the appropriate ETMCR bits based on each one.

The ETMCR_CTXID_SIZE part can be removed as it was never a valid option
because it's not in ETM3X_SUPPORTED_OPTIONS.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Tested-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20251128-james-cs-syncfreq-v8-6-4d319764cc58@linaro.org
This commit is contained in:
James Clark 2025-11-28 11:55:18 +00:00 committed by Suzuki K Poulose
parent 458db62571
commit a1d19cd2b1
1 changed files with 13 additions and 11 deletions
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24
drivers/hwtracing/coresight/coresight-etm3x-core.c
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@ -28,6 +28,7 @@
#include <linux/uaccess.h>
#include <linux/clk.h>
#include <linux/perf_event.h>
#include <linux/perf/arm_pmu.h>
#include <asm/sections.h>
#include "coresight-etm.h"
@ -339,21 +340,22 @@ static int etm_parse_event_config(struct etm_drvdata *drvdata,
if (attr->config & ~ETM3X_SUPPORTED_OPTIONS)
return -EINVAL;
config->ctrl = attr->config;
config->ctrl = 0;
/* Don't trace contextID when runs in non-root PID namespace */
if (!task_is_in_init_pid_ns(current))
config->ctrl &= ~ETMCR_CTXID_SIZE;
if (ATTR_CFG_GET_FLD(attr, cycacc))
config->ctrl |= ETMCR_CYC_ACC;
if (ATTR_CFG_GET_FLD(attr, timestamp))
config->ctrl |= ETMCR_TIMESTAMP_EN;
/*
* Possible to have cores with PTM (supports ret stack) and ETM
* (never has ret stack) on the same SoC. So if we have a request
* for return stack that can't be honoured on this core then
* clear the bit - trace will still continue normally
* Possible to have cores with PTM (supports ret stack) and ETM (never
* has ret stack) on the same SoC. So only enable when it can be honored
* - trace will still continue normally otherwise.
*/
if ((config->ctrl & ETMCR_RETURN_STACK) &&
!(drvdata->etmccer & ETMCCER_RETSTACK))
config->ctrl &= ~ETMCR_RETURN_STACK;
if (ATTR_CFG_GET_FLD(attr, retstack) &&
(drvdata->etmccer & ETMCCER_RETSTACK))
config->ctrl |= ETMCR_RETURN_STACK;
return 0;
}