Re: [PATCH V3 11/14] coresight: sink: Add TRBE driver

Anshuman Khandual
2021-02-15T09:47:43Z

On 2/13/21 1:56 AM, Mathieu Poirier wrote:
> On Wed, Jan 27, 2021 at 02:25:35PM +0530, Anshuman Khandual wrote:
>> Trace Buffer Extension (TRBE) implements a trace buffer per CPU which is
>> accessible via the system registers. The TRBE supports different addressing
>> modes including CPU virtual address and buffer modes including the circular
>> buffer mode. The TRBE buffer is addressed by a base pointer (TRBBASER_EL1),
>> an write pointer (TRBPTR_EL1) and a limit pointer (TRBLIMITR_EL1). But the
>> access to the trace buffer could be prohibited by a higher exception level
>> (EL3 or EL2), indicated by TRBIDR_EL1.P. The TRBE can also generate a CPU
>> private interrupt (PPI) on address translation errors and when the buffer
>> is full. Overall implementation here is inspired from the Arm SPE driver.
>>
>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>> Cc: Mike Leach <mike.leach@linaro.org>
>> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> Changes in V3:
>>
>> - Added new DT bindings document TRBE.yaml
>> - Changed TRBLIMITR_TRIG_MODE_SHIFT from 2 to 3
>> - Dropped isb() from trbe_reset_local()
>> - Dropped gap between (void *) and buf->trbe_base
>> - Changed 'int' to 'unsigned int' in is_trbe_available()
>> - Dropped unused function set_trbe_running(), set_trbe_virtual_mode(),
>> set_trbe_enabled() and set_trbe_limit_pointer()
>> - Changed get_trbe_flag_update(), is_trbe_programmable() and
>> get_trbe_address_align() to accept TRBIDR value
>> - Changed is_trbe_running(), is_trbe_abort(), is_trbe_wrap(), is_trbe_trg(),
>> is_trbe_irq(), get_trbe_bsc() and get_trbe_ec() to accept TRBSR value
>> - Dropped snapshot mode condition in arm_trbe_alloc_buffer()
>> - Exit arm_trbe_init() when arm64_kernel_unmapped_at_el0() is enabled
>> - Compute trbe_limit before trbe_write to get the updated handle
>> - Added trbe_stop_and_truncate_event()
>> - Dropped trbe_handle_fatal()
>>
>> Documentation/trace/coresight/coresight-trbe.rst | 39 +
>> arch/arm64/include/asm/sysreg.h | 1 +
>> drivers/hwtracing/coresight/Kconfig | 11 +
>> drivers/hwtracing/coresight/Makefile | 1 +
>> drivers/hwtracing/coresight/coresight-trbe.c | 1023 ++++++++++++++++++++++
>> drivers/hwtracing/coresight/coresight-trbe.h | 160 ++++
>> 6 files changed, 1235 insertions(+)
>> create mode 100644 Documentation/trace/coresight/coresight-trbe.rst
>> create mode 100644 drivers/hwtracing/coresight/coresight-trbe.c
>> create mode 100644 drivers/hwtracing/coresight/coresight-trbe.h
>>
>> diff --git a/Documentation/trace/coresight/coresight-trbe.rst b/Documentation/trace/coresight/coresight-trbe.rst
>> new file mode 100644
>> index 0000000..1cbb819
>> --- /dev/null
>> +++ b/Documentation/trace/coresight/coresight-trbe.rst
>> @@ -0,0 +1,39 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +==============================
>> +Trace Buffer Extension (TRBE).
>> +==============================
>> +
>> + :Author: Anshuman Khandual <anshuman.khandual@arm.com>
>> + :Date: November 2020
>> +
>> +Hardware Description
>> +--------------------
>> +
>> +Trace Buffer Extension (TRBE) is a percpu hardware which captures in system
>> +memory, CPU traces generated from a corresponding percpu tracing unit. This
>> +gets plugged in as a coresight sink device because the corresponding trace
>> +genarators (ETE), are plugged in as source device.
>> +
>> +The TRBE is not compliant to CoreSight architecture specifications, but is
>> +driven via the CoreSight driver framework to support the ETE (which is
>> +CoreSight compliant) integration.
>> +
>> +Sysfs files and directories
>> +---------------------------
>> +
>> +The TRBE devices appear on the existing coresight bus alongside the other
>> +coresight devices::
>> +
>> + >$ ls /sys/bus/coresight/devices
>> + trbe0 trbe1 trbe2 trbe3
>> +
>> +The ``trbe<N>`` named TRBEs are associated with a CPU.::
>> +
>> + >$ ls /sys/bus/coresight/devices/trbe0/
>> + align dbm
>> +
>> +*Key file items are:-*
>> + * ``align``: TRBE write pointer alignment
>> + * ``dbm``: TRBE updates memory with access and dirty flags
>> +
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index 85ae4db..9e2e9b7 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -97,6 +97,7 @@
>> #define SET_PSTATE_UAO(x) __emit_inst(0xd500401f | PSTATE_UAO | ((!!x) << PSTATE_Imm_shift))
>> #define SET_PSTATE_SSBS(x) __emit_inst(0xd500401f | PSTATE_SSBS | ((!!x) << PSTATE_Imm_shift))
>> #define SET_PSTATE_TCO(x) __emit_inst(0xd500401f | PSTATE_TCO | ((!!x) << PSTATE_Imm_shift))
>> +#define TSB_CSYNC __emit_inst(0xd503225f)
>>
>> #define set_pstate_pan(x) asm volatile(SET_PSTATE_PAN(x))
>> #define set_pstate_uao(x) asm volatile(SET_PSTATE_UAO(x))
>> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
>> index f154ae7..aa657ab 100644
>> --- a/drivers/hwtracing/coresight/Kconfig
>> +++ b/drivers/hwtracing/coresight/Kconfig
>> @@ -164,6 +164,17 @@ config CORESIGHT_CTI
>> To compile this driver as a module, choose M here: the
>> module will be called coresight-cti.
>>
>> +config CORESIGHT_TRBE
>> + bool "Trace Buffer Extension (TRBE) driver"
>> + depends on ARM64
>> + help
>> + This driver provides support for percpu Trace Buffer Extension (TRBE).
>> + TRBE always needs to be used along with it's corresponding percpu ETE
>> + component. ETE generates trace data which is then captured with TRBE.
>> + Unlike traditional sink devices, TRBE is a CPU feature accessible via
>> + system registers. But it's explicit dependency with trace unit (ETE)
>> + requires it to be plugged in as a coresight sink device.
>> +
>> config CORESIGHT_CTI_INTEGRATION_REGS
>> bool "Access CTI CoreSight Integration Registers"
>> depends on CORESIGHT_CTI
>> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
>> index f20e357..d608165 100644
>> --- a/drivers/hwtracing/coresight/Makefile
>> +++ b/drivers/hwtracing/coresight/Makefile
>> @@ -21,5 +21,6 @@ obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
>> obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
>> obj-$(CONFIG_CORESIGHT_CATU) += coresight-catu.o
>> obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o
>> +obj-$(CONFIG_CORESIGHT_TRBE) += coresight-trbe.o
>> coresight-cti-y := coresight-cti-core.o coresight-cti-platform.o \
>> coresight-cti-sysfs.o
>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
>> new file mode 100644
>> index 0000000..1464d8b
>> --- /dev/null
>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>> @@ -0,0 +1,1023 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * This driver enables Trace Buffer Extension (TRBE) as a per-cpu coresight
>> + * sink device could then pair with an appropriate per-cpu coresight source
>> + * device (ETE) thus generating required trace data. Trace can be enabled
>> + * via the perf framework.
>> + *
>> + * Copyright (C) 2020 ARM Ltd.
>> + *
>> + * Author: Anshuman Khandual <anshuman.khandual@arm.com>
>> + */
>> +#define DRVNAME "arm_trbe"
>> +
>> +#define pr_fmt(fmt) DRVNAME ": " fmt
>> +
>> +#include "coresight-trbe.h"
>> +
>> +#define PERF_IDX2OFF(idx, buf) ((idx) % ((buf)->nr_pages << PAGE_SHIFT))
>> +
>> +/*
>> + * A padding packet that will help the user space tools
>> + * in skipping relevant sections in the captured trace
>> + * data which could not be decoded. TRBE doesn't support
>> + * formatting the trace data, unlike the legacy CoreSight
>> + * sinks and thus we use ETE trace packets to pad the
>> + * sections of the buffer.
>> + */
>> +#define ETE_IGNORE_PACKET 0x70
>> +
>> +/*
>> + * Minimum amount of meaningful trace will contain:
>> + * A-Sync, Trace Info, Trace On, Address, Atom.
>> + * This is about 44bytes of ETE trace. To be on
>> + * the safer side, we assume 64bytes is the minimum
>> + * space required for a meaningful session, before
>> + * we hit a "WRAP" event.
>> + */
>> +#define TRBE_TRACE_MIN_BUF_SIZE 64
>> +
>> +enum trbe_fault_action {
>> + TRBE_FAULT_ACT_WRAP,
>> + TRBE_FAULT_ACT_SPURIOUS,
>> + TRBE_FAULT_ACT_FATAL,
>> +};
>> +
>> +struct trbe_buf {
>> + unsigned long trbe_base;
>> + unsigned long trbe_limit;
>> + unsigned long trbe_write;
>> + int nr_pages;
>> + void **pages;
>> + bool snapshot;
>> + struct trbe_cpudata *cpudata;
>> +};
>> +
>> +struct trbe_cpudata {
>> + bool trbe_dbm;
>> + u64 trbe_align;
>> + int cpu;
>> + enum cs_mode mode;
>> + struct trbe_buf *buf;
>> + struct trbe_drvdata *drvdata;
>> +};
>> +
>> +struct trbe_drvdata {
>> + struct trbe_cpudata __percpu *cpudata;
>> + struct perf_output_handle __percpu **handle;
>> + struct hlist_node hotplug_node;
>> + int irq;
>> + cpumask_t supported_cpus;
>> + enum cpuhp_state trbe_online;
>> + struct platform_device *pdev;
>> +};
>> +
>> +static int trbe_alloc_node(struct perf_event *event)
>> +{
>> + if (event->cpu == -1)
>> + return NUMA_NO_NODE;
>> + return cpu_to_node(event->cpu);
>> +}
>> +
>> +static void trbe_drain_buffer(void)
>> +{
>> + asm(TSB_CSYNC);
>> + dsb(nsh);
>> +}
>> +
>> +static void trbe_drain_and_disable_local(void)
>> +{
>> + trbe_drain_buffer();
>> + write_sysreg_s(0, SYS_TRBLIMITR_EL1);
>> + isb();
>> +}
>> +
>> +static void trbe_reset_local(void)
>> +{
>> + trbe_drain_and_disable_local();
>> + write_sysreg_s(0, SYS_TRBPTR_EL1);
>> + write_sysreg_s(0, SYS_TRBBASER_EL1);
>> + write_sysreg_s(0, SYS_TRBSR_EL1);
>> +}
>> +
>> +static void trbe_stop_and_truncate_event(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> +
>> + /*
>> + * We cannot proceed with the buffer collection and we
>> + * do not have any data for the current session. The
>> + * etm_perf driver expects to close out the aux_buffer
>> + * at event_stop(). So disable the TRBE here and leave
>> + * the update_buffer() to return a 0 size.
>> + */
>> + trbe_drain_and_disable_local();
>> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
>> + *this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL;
>> +}
>> +
>> +/*
>> + * TRBE Buffer Management
>> + *
>> + * The TRBE buffer spans from the base pointer till the limit pointer. When enabled,
>> + * it starts writing trace data from the write pointer onward till the limit pointer.
>> + * When the write pointer reaches the address just before the limit pointer, it gets
>> + * wrapped around again to the base pointer. This is called a TRBE wrap event, which
>> + * generates a maintenance interrupt when operated in WRAP or FILL mode. This driver
>> + * uses FILL mode, where the TRBE stops the trace collection at wrap event. The IRQ
>> + * handler updates the AUX buffer and re-enables the TRBE with updated WRITE and
>> + * LIMIT pointers.
>> + *
>> + * Wrap around with an IRQ
>> + * ------ < ------ < ------- < ----- < -----
>> + * | |
>> + * ------ > ------ > ------- > ----- > -----
>> + *
>> + * +---------------+-----------------------+
>> + * | | |
>> + * +---------------+-----------------------+
>> + * Base Pointer Write Pointer Limit Pointer
>> + *
>> + * The base and limit pointers always needs to be PAGE_SIZE aligned. But the write
>> + * pointer can be aligned to the implementation defined TRBE trace buffer alignment
>> + * as captured in trbe_cpudata->trbe_align.
>> + *
>> + *
>> + * head tail wakeup
>> + * +---------------------------------------+----- ~ ~ ------
>> + * |$$$$$$$|################|$$$$$$$$$$$$$$| |
>> + * +---------------------------------------+----- ~ ~ ------
>> + * Base Pointer Write Pointer Limit Pointer
>> + *
>> + * The perf_output_handle indices (head, tail, wakeup) are monotonically increasing
>> + * values which tracks all the driver writes and user reads from the perf auxiliary
>> + * buffer. Generally [head..tail] is the area where the driver can write into unless
>> + * the wakeup is behind the tail. Enabled TRBE buffer span needs to be adjusted and
>> + * configured depending on the perf_output_handle indices, so that the driver does
>> + * not override into areas in the perf auxiliary buffer which is being or yet to be
>> + * consumed from the user space. The enabled TRBE buffer area is a moving subset of
>> + * the allocated perf auxiliary buffer.
>> + */
>> +static void trbe_pad_buf(struct perf_output_handle *handle, int len)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> + u64 head = PERF_IDX2OFF(handle->head, buf);
>> +
>> + memset((void *)buf->trbe_base + head, ETE_IGNORE_PACKET, len);
>> + if (!buf->snapshot)
>> + perf_aux_output_skip(handle, len);
>> +}
>> +
>> +static unsigned long trbe_snapshot_offset(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> +
>> + /*
>> + * The ETE trace has alignment synchronization packets allowing
>> + * the decoder to reset in case of an overflow or corruption.
>> + * So we can use the entire buffer for the snapshot mode.
>> + */
>> + return buf->nr_pages * PAGE_SIZE;
>> +}
>> +
>> +/*
>> + * TRBE Limit Calculation
>> + *
>> + * The following markers are used to illustrate various TRBE buffer situations.
>> + *
>> + * $$$$ - Data area, unconsumed captured trace data, not to be overridden
>> + * #### - Free area, enabled, trace will be written
>> + * %%%% - Free area, disabled, trace will not be written
>> + * ==== - Free area, padded with ETE_IGNORE_PACKET, trace will be skipped
>> + */
>> +static unsigned long __trbe_normal_offset(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> + struct trbe_cpudata *cpudata = buf->cpudata;
>> + const u64 bufsize = buf->nr_pages * PAGE_SIZE;
>> + u64 limit = bufsize;
>> + u64 head, tail, wakeup;
>> +
>> + head = PERF_IDX2OFF(handle->head, buf);
>> +
>> + /*
>> + * head
>> + * ------->|
>> + * |
>> + * head TRBE align tail
>> + * +----|-------|---------------|-------+
>> + * |$$$$|=======|###############|$$$$$$$|
>> + * +----|-------|---------------|-------+
>> + * trbe_base trbe_base + nr_pages
>> + *
>> + * Perf aux buffer output head position can be misaligned depending on
>> + * various factors including user space reads. In case misaligned, head
>> + * needs to be aligned before TRBE can be configured. Pad the alignment
>> + * gap with ETE_IGNORE_PACKET bytes that will be ignored by user tools
>> + * and skip this section thus advancing the head.
>> + */
>> + if (!IS_ALIGNED(head, cpudata->trbe_align)) {
>> + unsigned long delta = roundup(head, cpudata->trbe_align) - head;
>> +
>> + delta = min(delta, handle->size);
>> + trbe_pad_buf(handle, delta);
>> + head = PERF_IDX2OFF(handle->head, buf);
>> + }
>> +
>> + /*
>> + * head = tail (size = 0)
>> + * +----|-------------------------------+
>> + * |$$$$|$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ |
>> + * +----|-------------------------------+
>> + * trbe_base trbe_base + nr_pages
>> + *
>> + * Perf aux buffer does not have any space for the driver to write into.
>> + * Just communicate trace truncation event to the user space by marking
>> + * it with PERF_AUX_FLAG_TRUNCATED.
>> + */
>> + if (!handle->size) {
>> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
>> + return 0;
>> + }
>> +
>> + /* Compute the tail and wakeup indices now that we've aligned head */
>> + tail = PERF_IDX2OFF(handle->head + handle->size, buf);
>> + wakeup = PERF_IDX2OFF(handle->wakeup, buf);
>> +
>> + /*
>> + * Lets calculate the buffer area which TRBE could write into. There
>> + * are three possible scenarios here. Limit needs to be aligned with
>> + * PAGE_SIZE per the TRBE requirement. Always avoid clobbering the
>> + * unconsumed data.
>> + *
>> + * 1) head < tail
>> + *
>> + * head tail
>> + * +----|-----------------------|-------+
>> + * |$$$$|#######################|$$$$$$$|
>> + * +----|-----------------------|-------+
>> + * trbe_base limit trbe_base + nr_pages
>> + *
>> + * TRBE could write into [head..tail] area. Unless the tail is right at
>> + * the end of the buffer, neither an wrap around nor an IRQ is expected
>> + * while being enabled.
>> + *
>> + * 2) head == tail
>> + *
>> + * head = tail (size > 0)
>> + * +----|-------------------------------+
>> + * |%%%%|###############################|
>> + * +----|-------------------------------+
>> + * trbe_base limit = trbe_base + nr_pages
>> + *
>> + * TRBE should just write into [head..base + nr_pages] area even though
>> + * the entire buffer is empty. Reason being, when the trace reaches the
>> + * end of the buffer, it will just wrap around with an IRQ giving an
>> + * opportunity to reconfigure the buffer.
>> + *
>> + * 3) tail < head
>> + *
>> + * tail head
>> + * +----|-----------------------|-------+
>> + * |%%%%|$$$$$$$$$$$$$$$$$$$$$$$|#######|
>> + * +----|-----------------------|-------+
>> + * trbe_base limit = trbe_base + nr_pages
>> + *
>> + * TRBE should just write into [head..base + nr_pages] area even though
>> + * the [trbe_base..tail] is also empty. Reason being, when the trace
>> + * reaches the end of the buffer, it will just wrap around with an IRQ
>> + * giving an opportunity to reconfigure the buffer.
>> + */
>> + if (head < tail)
>> + limit = round_down(tail, PAGE_SIZE);
>> +
>> + /*
>> + * Wakeup may be arbitrarily far into the future. If it's not in the
>> + * current generation, either we'll wrap before hitting it, or it's
>> + * in the past and has been handled already.
>> + *
>> + * If there's a wakeup before we wrap, arrange to be woken up by the
>> + * page boundary following it. Keep the tail boundary if that's lower.
>> + *
>> + * head wakeup tail
>> + * +----|---------------|-------|-------+
>> + * |$$$$|###############|%%%%%%%|$$$$$$$|
>> + * +----|---------------|-------|-------+
>> + * trbe_base limit trbe_base + nr_pages
>> + */
>> + if (handle->wakeup < (handle->head + handle->size) && head <= wakeup)
>> + limit = min(limit, round_up(wakeup, PAGE_SIZE));
>> +
>> + /*
>> + * There are two situation when this can happen i.e limit is before
>> + * the head and hence TRBE cannot be configured.
>> + *
>> + * 1) head < tail (aligned down with PAGE_SIZE) and also they are both
>> + * within the same PAGE size range.
>> + *
>> + * PAGE_SIZE
>> + * |----------------------|
>> + *
>> + * limit head tail
>> + * +------------|------|--------|-------+
>> + * |$$$$$$$$$$$$$$$$$$$|========|$$$$$$$|
>> + * +------------|------|--------|-------+
>> + * trbe_base trbe_base + nr_pages
>> + *
>> + * 2) head < wakeup (aligned up with PAGE_SIZE) < tail and also both
>> + * head and wakeup are within same PAGE size range.
>> + *
>> + * PAGE_SIZE
>> + * |----------------------|
>> + *
>> + * limit head wakeup tail
>> + * +----|------|-------|--------|-------+
>> + * |$$$$$$$$$$$|=======|========|$$$$$$$|
>> + * +----|------|-------|--------|-------+
>> + * trbe_base trbe_base + nr_pages
>> + */
>> + if (limit > head)
>> + return limit;
>> +
>> + trbe_pad_buf(handle, handle->size);
>> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
>> + return 0;
>> +}
>> +
>> +static unsigned long trbe_normal_offset(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = perf_get_aux(handle);
>> + u64 limit = __trbe_normal_offset(handle);
>> + u64 head = PERF_IDX2OFF(handle->head, buf);
>> +
>> + /*
>> + * If the head is too close to the limit and we don't
>> + * have space for a meaningful run, we rather pad it
>> + * and start fresh.
>> + */
>> + if (limit && (limit - head < TRBE_TRACE_MIN_BUF_SIZE)) {
>> + trbe_pad_buf(handle, limit - head);
>> + limit = __trbe_normal_offset(handle);
>> + }
>> + return limit;
>> +}
>> +
>> +static unsigned long compute_trbe_buffer_limit(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> + unsigned long offset;
>> +
>> + if (buf->snapshot)
>> + offset = trbe_snapshot_offset(handle);
>> + else
>> + offset = trbe_normal_offset(handle);
>> + return buf->trbe_base + offset;
>> +}
>
> I won't review the trace buffer management functions in this revision, I will
> leave that for the next version.

Okay.

>
>> +
>> +static void clr_trbe_status(void)
>> +{
>> + u64 trbsr = read_sysreg_s(SYS_TRBSR_EL1);
>> +
>> + WARN_ON(is_trbe_enabled());
>> + trbsr &= ~TRBSR_IRQ;
>> + trbsr &= ~TRBSR_TRG;
>> + trbsr &= ~TRBSR_WRAP;
>> + trbsr &= ~(TRBSR_EC_MASK << TRBSR_EC_SHIFT);
>> + trbsr &= ~(TRBSR_BSC_MASK << TRBSR_BSC_SHIFT);
>> + trbsr &= ~TRBSR_STOP;
>> + write_sysreg_s(trbsr, SYS_TRBSR_EL1);
>> +}
>
> I haven't read the TRBE progammer's manual but looking a the documentation the above
> looks good.
>
>> +
>> +static void set_trbe_limit_pointer_enabled(unsigned long addr)
>> +{
>> + u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1);
>> +
>> + WARN_ON(!IS_ALIGNED(addr, (1UL << TRBLIMITR_LIMIT_SHIFT)));
>> + WARN_ON(!IS_ALIGNED(addr, PAGE_SIZE));
>> +
>> + trblimitr &= ~TRBLIMITR_NVM;
>> + trblimitr &= ~(TRBLIMITR_FILL_MODE_MASK << TRBLIMITR_FILL_MODE_SHIFT);
>> + trblimitr &= ~(TRBLIMITR_TRIG_MODE_MASK << TRBLIMITR_TRIG_MODE_SHIFT);
>> + trblimitr &= ~(TRBLIMITR_LIMIT_MASK << TRBLIMITR_LIMIT_SHIFT);
>> +
>> + /*
>> + * Fill trace buffer mode is used here while configuring the
>> + * TRBE for trace capture. In this particular mode, the trace
>> + * collection is stopped and a maintenance interrupt is raised
>> + * when the current write pointer wraps. This pause in trace
>> + * collection gives the software an opportunity to capture the
>> + * trace data in the interrupt handler, before reconfiguring
>> + * the TRBE.
>> + */
>> + trblimitr |= (TRBE_FILL_MODE_FILL & TRBLIMITR_FILL_MODE_MASK) << TRBLIMITR_FILL_MODE_SHIFT;
>> +
>> + /*
>> + * Trigger mode is not used here while configuring the TRBE for
>> + * the trace capture. Hence just keep this in the ignore mode.
>> + */
>> + trblimitr |= (TRBE_TRIG_MODE_IGNORE & TRBLIMITR_TRIG_MODE_MASK) << TRBLIMITR_TRIG_MODE_SHIFT;
>> + trblimitr |= (addr & PAGE_MASK);
>> +
>> + trblimitr |= TRBLIMITR_ENABLE;
>> + write_sysreg_s(trblimitr, SYS_TRBLIMITR_EL1);
>> +}
>
> Same here
>
>> +
>> +static void trbe_enable_hw(struct trbe_buf *buf)
>> +{
>> + WARN_ON(buf->trbe_write < buf->trbe_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_write_pointer(buf->trbe_write);
>> +
>> + /*
>> + * Synchronize all the register updates
>> + * till now before enabling the TRBE.
>> + */
>> + isb();
>> + set_trbe_limit_pointer_enabled(buf->trbe_limit);
>> +
>> + /* Synchronize the TRBE enable event */
>> + isb();
>> +}
>
> Ok
>
>> +
>> +static void *arm_trbe_alloc_buffer(struct coresight_device *csdev,
>> + struct perf_event *event, void **pages,
>> + int nr_pages, bool snapshot)
>> +{
>> + struct trbe_buf *buf;
>> + struct page **pglist;
>> + int i;
>> +
>> + /*
>> + * TRBE LIMIT and TRBE WRITE pointers must be page aligned. But with
>> + * just a single page, there is not much room left while writing into
>> + * a partially filled TRBE buffer. Hence restrict the minimum buffer
>> + * size as two pages.
>> + */
>> + if (nr_pages < 2)
>> + return NULL;
>> +
>> + buf = kzalloc_node(sizeof(*buf), GFP_KERNEL, trbe_alloc_node(event));
>> + if (IS_ERR(buf))
>> + return ERR_PTR(-ENOMEM);
>
> You know what do to.

Right, will check for NULL instead and return ERR_PTR(-ENOMEM) as
the function return type is (void *).

>
>> +
>> + pglist = kcalloc(nr_pages, sizeof(*pglist), GFP_KERNEL);
>> + if (IS_ERR(pglist)) {
>> + kfree(buf);
>> + return ERR_PTR(-ENOMEM);
>> + }
>
> Here too.

Yes, changed.

>
>> +
>> + for (i = 0; i < nr_pages; i++)
>> + pglist[i] = virt_to_page(pages[i]);
>> +
>> + buf->trbe_base = (unsigned long) vmap(pglist, nr_pages, VM_MAP, PAGE_KERNEL);
>> + if (IS_ERR((void *)buf->trbe_base)) {
>> + kfree(pglist);
>> + kfree(buf);
>> + return ERR_PTR(buf->trbe_base);
>> + }
>
> Here too.

Yes, changed.

>
>> + buf->trbe_limit = buf->trbe_base + nr_pages * PAGE_SIZE;
>> + buf->trbe_write = buf->trbe_base;
>> + buf->snapshot = snapshot;
>> + buf->nr_pages = nr_pages;
>> + buf->pages = pages;
>> + kfree(pglist);
>> + return buf;
>> +}
>> +
>> +void arm_trbe_free_buffer(void *config)

Added the missing 'static' here.

>> +{
>> + struct trbe_buf *buf = config;
>> +
>> + vunmap((void *)buf->trbe_base);
>> + kfree(buf);
>> +}
>
> Ok
>
>> +
>> +static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev,
>> + struct perf_output_handle *handle,
>> + void *config)
>> +{
>> + struct trbe_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>> + struct trbe_cpudata *cpudata = dev_get_drvdata(&csdev->dev);
>> + struct trbe_buf *buf = config;
>> + unsigned long size, offset;
>> +
>> + WARN_ON(buf->cpudata != cpudata);
>> + WARN_ON(cpudata->cpu != smp_processor_id());
>> + WARN_ON(cpudata->drvdata != drvdata);
>> + if (cpudata->mode != CS_MODE_PERF)
>> + return -EINVAL;
>> +
>> + /*
>> + * If the TRBE was disabled due to lack of space in the AUX buffer or a
>> + * spurious fault, the driver leaves it disabled, truncating the buffer.
>> + * Since the etm_perf driver expects to close out the AUX buffer, the
>> + * driver skips it. Thus, just pass in 0 size here to indicate that the
>> + * buffer was truncated.
>> + */
>> + if (!is_trbe_enabled())
>> + return 0;
>> + /*
>> + * perf handle structure needs to be shared with the TRBE IRQ handler for
>> + * capturing trace data and restarting the handle. There is a probability
>> + * of an undefined reference based crash when etm event is being stopped
>> + * while a TRBE IRQ also getting processed. This happens due the release
>> + * of perf handle via perf_aux_output_end() in etm_event_stop(). Stopping
>> + * the TRBE here will ensure that no IRQ could be generated when the perf
>> + * handle gets freed in etm_event_stop().
>> + */
>> + trbe_drain_and_disable_local();
>> + offset = get_trbe_write_pointer() - get_trbe_base_pointer();
>> + size = offset - PERF_IDX2OFF(handle->head, buf);
>> + if (buf->snapshot)
>> + handle->head += size;
>> + return size;
>> +}
>
> Ok - I really appreciate the comments.
>
>> +
>> +static int arm_trbe_enable(struct coresight_device *csdev, u32 mode, void *data)
>> +{
>> + struct trbe_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>> + struct trbe_cpudata *cpudata = dev_get_drvdata(&csdev->dev);
>> + struct perf_output_handle *handle = data;
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> +
>> + WARN_ON(cpudata->cpu != smp_processor_id());
>> + WARN_ON(cpudata->drvdata != drvdata);
>> + if (mode != CS_MODE_PERF)
>> + return -EINVAL;
>> +
>> + *this_cpu_ptr(drvdata->handle) = handle;
>> + cpudata->buf = buf;
>> + cpudata->mode = mode;
>> + buf->cpudata = cpudata;
>> + buf->trbe_limit = compute_trbe_buffer_limit(handle);
>> + buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf);
>> + if (buf->trbe_limit == buf->trbe_base) {
>> + trbe_stop_and_truncate_event(handle);
>> + return 0;
>> + }
>> + trbe_enable_hw(buf);
>> + return 0;
>> +}
>
> Ok
>
>> +
>> +static int arm_trbe_disable(struct coresight_device *csdev)
>> +{
>> + struct trbe_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>> + struct trbe_cpudata *cpudata = dev_get_drvdata(&csdev->dev);
>> + struct trbe_buf *buf = cpudata->buf;
>> +
>> + WARN_ON(buf->cpudata != cpudata);
>> + WARN_ON(cpudata->cpu != smp_processor_id());
>> + WARN_ON(cpudata->drvdata != drvdata);
>> + if (cpudata->mode != CS_MODE_PERF)
>> + return -EINVAL;
>> +
>> + trbe_drain_and_disable_local();
>> + buf->cpudata = NULL;
>> + cpudata->buf = NULL;
>> + cpudata->mode = CS_MODE_DISABLED;
>> + return 0;
>> +}
>
> Ok
>
>> +
>> +static void trbe_handle_spurious(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> +
>> + buf->trbe_limit = compute_trbe_buffer_limit(handle);
>> + buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf);
>> + if (buf->trbe_limit == buf->trbe_base) {
>> + trbe_drain_and_disable_local();
>> + return;
>> + }
>> + trbe_enable_hw(buf);
>> +}
>> +
>> +static void trbe_handle_overflow(struct perf_output_handle *handle)
>> +{
>> + struct perf_event *event = handle->event;
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> + unsigned long offset, size;
>> + struct etm_event_data *event_data;
>> +
>> + offset = get_trbe_limit_pointer() - get_trbe_base_pointer();
>> + size = offset - PERF_IDX2OFF(handle->head, buf);
>> + if (buf->snapshot)
>> + handle->head = offset;
>> + perf_aux_output_end(handle, size);
>> +
>> + event_data = perf_aux_output_begin(handle, event);
>> + if (!event_data) {
>> + trbe_drain_and_disable_local();
>> + *this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL;
>> + return;
>> + }
>> + buf->trbe_limit = compute_trbe_buffer_limit(handle);
>> + buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf);
>> + if (buf->trbe_limit == buf->trbe_base) {
>> + trbe_stop_and_truncate_event(handle);
>> + return;
>> + }
>> + *this_cpu_ptr(buf->cpudata->drvdata->handle) = handle;
>> + trbe_enable_hw(buf);
>> +}
>> +
>> +static bool is_perf_trbe(struct perf_output_handle *handle)
>> +{
>> + struct trbe_buf *buf = etm_perf_sink_config(handle);
>> + struct trbe_cpudata *cpudata = buf->cpudata;
>> + struct trbe_drvdata *drvdata = cpudata->drvdata;
>> + int cpu = smp_processor_id();
>> +
>> + WARN_ON(buf->trbe_base != get_trbe_base_pointer());
>> + WARN_ON(buf->trbe_limit != get_trbe_limit_pointer());
>> +
>> + if (cpudata->mode != CS_MODE_PERF)
>> + return false;
>> +
>> + if (cpudata->cpu != cpu)
>> + return false;
>> +
>> + if (!cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>> + return false;
>> +
>> + return true;
>> +}
>> +
>> +static enum trbe_fault_action trbe_get_fault_act(struct perf_output_handle *handle)
>
> @handle isn't used for anything.

Okay, will drop.

>
>> +{
>> + u64 trbsr = read_sysreg_s(SYS_TRBSR_EL1);
>> + int ec = get_trbe_ec(trbsr);
>> + int bsc = get_trbe_bsc(trbsr);
>> +
>> + WARN_ON(is_trbe_running(trbsr));
>> + if (is_trbe_trg(trbsr) || is_trbe_abort(trbsr))
>> + return TRBE_FAULT_ACT_FATAL;
>> +
>> + if ((ec == TRBE_EC_STAGE1_ABORT) || (ec == TRBE_EC_STAGE2_ABORT))
>> + return TRBE_FAULT_ACT_FATAL;
>> +
>> + if (is_trbe_wrap(trbsr) && (ec == TRBE_EC_OTHERS) && (bsc == TRBE_BSC_FILLED)) {
>> + if (get_trbe_write_pointer() == get_trbe_base_pointer())
>> + return TRBE_FAULT_ACT_WRAP;
>> + }
>> + return TRBE_FAULT_ACT_SPURIOUS;
>> +}
>> +
>> +static irqreturn_t arm_trbe_irq_handler(int irq, void *dev)
>> +{
>> + struct perf_output_handle **handle_ptr = dev;
>> + struct perf_output_handle *handle = *handle_ptr;
>> + enum trbe_fault_action act;
>> +
>> + WARN_ON(!is_trbe_irq(read_sysreg_s(SYS_TRBSR_EL1)));
>> + clr_trbe_irq();
>> +
>> + /*
>> + * Ensure the trace is visible to the CPUs and
>> + * any external aborts have been resolved.
>> + */
>> + trbe_drain_buffer();
>> + isb();
>> +
>> + if (!perf_get_aux(handle))
>> + return IRQ_NONE;
>> +
>> + if (!is_perf_trbe(handle))
>> + return IRQ_NONE;
>> +
>> + irq_work_run();
>
> I trust Will that this is the right thing to do.
>
> I will stop here for this revision. I will dive more in the mechanic of the
> TRBE on the next revision.

Okay, will collate all the changes till now and respin sooner.

- Anshuman