coresight: trbe: Decouple buffer base from the hardware base

We always set the TRBBASER_EL1 to the base of the virtual ring
buffer. We are about to change this for working around an erratum.
So, in preparation to that, allow the driver to choose a different
base for the TRBBASER_EL1 (which is within the buffer range).

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20211019163153.3692640-8-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index e3767f2..ae0bde9 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -57,6 +57,8 @@ struct trbe_buf {
         * trbe_limit sibling pointers.
         */
        unsigned long trbe_base;
+       /* The base programmed into the TRBE */
+       unsigned long trbe_hw_base;
        unsigned long trbe_limit;
        unsigned long trbe_write;
        int nr_pages;
@@ -470,12 +472,13 @@ static void set_trbe_limit_pointer_enabled(unsigned long addr)
 
 static void trbe_enable_hw(struct trbe_buf *buf)
 {
-       WARN_ON(buf->trbe_write < buf->trbe_base);
+       WARN_ON(buf->trbe_hw_base < buf->trbe_base);
+       WARN_ON(buf->trbe_write < buf->trbe_hw_base);
        WARN_ON(buf->trbe_write >= buf->trbe_limit);
        set_trbe_disabled();
        isb();
        clr_trbe_status();
-       set_trbe_base_pointer(buf->trbe_base);
+       set_trbe_base_pointer(buf->trbe_hw_base);
        set_trbe_write_pointer(buf->trbe_write);
 
        /*
@@ -520,7 +523,12 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle,
        else
                write = get_trbe_write_pointer();
 
-       end_off = write - get_trbe_base_pointer();
+       /*
+        * TRBE may use a different base address than the base
+        * of the ring buffer. Thus use the beginning of the ring
+        * buffer to compute the offsets.
+        */
+       end_off = write - buf->trbe_base;
        start_off = PERF_IDX2OFF(handle->head, buf);
 
        if (WARN_ON_ONCE(end_off < start_off))
@@ -678,6 +686,8 @@ static int __arm_trbe_enable(struct trbe_buf *buf,
                trbe_stop_and_truncate_event(handle);
                return -ENOSPC;
        }
+       /* Set the base of the TRBE to the buffer base */
+       buf->trbe_hw_base = buf->trbe_base;
        *this_cpu_ptr(buf->cpudata->drvdata->handle) = handle;
        trbe_enable_hw(buf);
        return 0;
@@ -771,7 +781,7 @@ static bool is_perf_trbe(struct perf_output_handle *handle)
        struct trbe_drvdata *drvdata = cpudata->drvdata;
        int cpu = smp_processor_id();
 
-       WARN_ON(buf->trbe_base != get_trbe_base_pointer());
+       WARN_ON(buf->trbe_hw_base != get_trbe_base_pointer());
        WARN_ON(buf->trbe_limit != get_trbe_limit_pointer());
 
        if (cpudata->mode != CS_MODE_PERF)