Re: [PATCH v2 11/11] coresight: etm4x: docs: Adds detailed document for programming etm4x.

Mike Leach
2019-09-03T22:47:31Z

Hi Mathieu,

On Tue, 3 Sep 2019 at 20:38, Mathieu Poirier <mathieu.poirier@linaro.org> wrote:
>
> Hi Mike,
>
> On Thu, Aug 29, 2019 at 10:33:21PM +0100, Mike Leach wrote:
> > Add in detailed programmers reference for users wanting to program the
> > CoreSight ETM 4.x driver using sysfs.
> >
> > Signed-off-by: Mike Leach <mike.leach@linaro.org>
> > ---
> > .../coresight/coresight-etm4x-reference.txt | 458 ++++++++++++++++++
> > 1 file changed, 458 insertions(+)
> > create mode 100644 Documentation/trace/coresight/coresight-etm4x-reference.txt
> >
> > diff --git a/Documentation/trace/coresight/coresight-etm4x-reference.txt b/Documentation/trace/coresight/coresight-etm4x-reference.txt
> > new file mode 100644
> > index 000000000000..f0c370870992
> > --- /dev/null
> > +++ b/Documentation/trace/coresight/coresight-etm4x-reference.txt
> > @@ -0,0 +1,458 @@
> > +ETMv4 sysfs linux driver programming reference - v2.
> > +====================================================
> > +
> > +Supplement to existing ETMv4 driver documentation.
> > +
> > +Sysfs files and directories
> > +---------------------------
> > +
> > +Root: /sys/bus/coresight/devices/etm<N>
> > +
> > +
> > +The following paragraphs explain the association between sysfs files and the
> > +ETMv4 registers that they effect. Note the register names are given without
> > +the ‘TRC’ prefix.
> > +
> > +File : mode (rw)
> > +Trace Registers : {CONFIGR + others}
> > +Notes : Bit select trace features. See ‘mode’ section below. Bits
> > + in this will cause equivalent programming of trace config and
> > + other registers to enable the features requested.
> > +Syntax & eg : 'echo bitfield > mode'
> > + bitfield up to 32 bits setting trace features.
> > +Example : $> echo 0x > mode
>
> I suspect things look different on your end than they do on mine. The biggest
> problem is related to multi-line fields. For instance the above looks like this
> on my side:
>
> File : mode (rw)
> Trace Registers : {CONFIGR + others}
> Notes : Bit select trace features. See ‘mode’ section below. Bits
> in this will cause equivalent programming of trace config and
> other registers to enable the features requested.
> Syntax & eg : 'echo bitfield > mode'
> bitfield up to 32 bits setting trace features.
> Example : $> echo 0x > mode
>
> It would be nicer to have multi-line fields aligned with the first line, such
> as:
>
> File : mode (rw)
> Trace Registers : {CONFIGR + others}
> Notes : Bit select trace features. See ‘mode’ section below. Bits
> in this will cause equivalent programming of trace config and
> other registers to enable the features requested.
> Syntax & eg : 'echo bitfield > mode'
> bitfield up to 32 bits setting trace features.
> Example : $> echo 0x > mode
>

Problem is I am not seeing any difference between what you say I am
writing and what you prefer. When i looked at the file in my text
editor the fields where aligned - I would not have submitted it
otherwise.
I am happy to revisit it but we need a way of seeing a common view.

> I'm also not sure about the prompt, i.e "$>". I suspect it should be "$" and
> an additional ">" got inserted.

prompt came from examples lifted from a DB410 session. Don't really
have any strong preference for what represents a prompt in the docs,
so happy to change it to anything appropriate.

Regards

Mike

>
> I wanted to read on but is it too difficult to know what is intentional and what
> isn't. Please address and resend.
>
> Thanks,
> Mathieu
>
> > +
> > +File : reset (wo)
> > +Trace Registers : All
> > +Notes : Reset all programming to trace nothing / no logic programmed.
> > +Syntax : 'echo 1 > reset'
> > +
> > +File : enable_source (wo)
> > +Trace Registers : PRGCTLR, All hardware regs.
> > +Notes : >0: Programs up the hardware with the current values held in
> > + the driver and enables trace.
> > + 0: disable trace hardware.
> > +Syntax : 'echo 1 > enable_source'
> > +
> > +File : cpu (ro)
> > +Trace Registers : None.
> > +Notes : CPU ID that this ETM is attached to.
> > +Example :$> cat cpu
> > + $> 0
> > +
> > +File : addr_idx (rw)
> > +Trace Registers : None.
> > +Notes : Virtual register to index address comparator and range
> > + features. Set index for first of the pair in a range.
> > +Syntax : 'echo idx > addr_idx'
> > + Where idx < nr_addr_cmp x 2
> > +
> > +File : addr_range (rw)
> > +Trace Registers : ACVR[idx, idx+1], VIIECTLR
> > +Notes : Pair of addresses for a range selected by addr_idx. Include
> > + / exclude according to the optional parameter, or if omitted
> > + uses the current ‘mode’ setting. Select comparator range in
> > + control register. Error if index is odd value.
> > +Depends : mode, addr_idx
> > +Syntax : 'echo addr1 addr2 [exclude] > addr_range'
> > + Where addr1 and addr2 define the range and addr1 < addr2.
> > + Optional exclude value - 0 for include, 1 for exclude.
> > +Example : $> echo 0x0000 0x2000 0 > addr_range
> > +
> > +File : addr_single (rw)
> > +Trace Registers : ACVR[idx]
> > +Notes : Set a single address comparator according to addr_idx. This
> > + is used if the address comparator is used as part of event
> > + generation logic etc.
> > +Depends : addr_idx
> > +Syntax : 'echo addr1 > addr_single'
> > +
> > +File : addr_start (rw)
> > +Trace Registers : ACVR[idx], VISSCTLR
> > +Notes : Set a trace start address comparator according to addr_idx.
> > + Select comparator in control register.
> > +Depends : addr_idx
> > +Syntax : 'echo addr1 > addr_start'
> > +
> > +File : addr_stop (rw)
> > +Trace Registers : ACVR[idx], VISSCTLR
> > +Notes : Set a trace stop address comparator according to addr_idx.
> > + Select comparator in control register.
> > +Depends : addr_idx
> > +Syntax : 'echo addr1 > addr_stop'
> > +
> > +File : addr_context (rw)
> > +Trace Registers : ACATR[idx,{6:4}]
> > +Notes : Link context ID comparator to address comparator addr_idx
> > +Depends : addr_idx.
> > +Syntax : 'echo ctxt_idx > addr_context'
> > + Where ctxt_idx is the index of the linked context id / vmid
> > + comparator.
> > +
> > +File : addr_ctxtype (rw)
> > +Trace Registers : ACATR[idx,{3:2}]
> > +Notes : Input value string. Set type for linked context ID comparator
> > +Depends : addr_idx
> > +Syntax : 'echo type > addr_ctxtype'
> > + Type one of {all, vmid, ctxid, none}
> > +Example : $> echo ctxid > addr_ctxtype
> > +
> > +File : addr_exlevel_s_ns (rw)
> > +Trace Registers : ACATR[idx,{14:8}]
> > +Notes : Set the ELx secure and non-secure matching bits for the
> > + selected address comparator
> > +Depends : addr_idx
> > +Syntax : 'echo val > addr_exlevel_s_ns'
> > + val is a 7 bit value for exception levels to exclude. Input
> > + value shifted to correct bits in register.
> > +Example : $> echo 0x4F > addr_exlevel_s_ns
> > +
> > +File : addr_instdatatype (rw)
> > +Trace Registers : ACATR[idx,{1:0}]
> > +Notes : Set the comparator address type for matching. Driver only
> > + supports setting instruction address type.
> > +Depends : addr_idx
> > +
> > +File : addr_cmp_view (ro)
> > +Trace Registers : ACVR[idx, idx+1], ACATR[idx], VIIECTLR
> > +Notes : Read the currently selected address comparator. If part of
> > + address range then display both addresses.
> > +Depends : addr_idx
> > +Syntax : 'cat addr_cmp_view'
> > +Example : $> cat addr_cmp_view
> > + addr_cmp[0] range 0x0 0xffffffffffffffff include ctrl(0x4b00)
> > +
> > +File : nr_addr_cmp (ro)
> > +Trace Registers : From IDR4
> > +Notes : Number of address comparator pairs
> > +
> > +File : sshot_idx (rw)
> > +Trace Registers : None
> > +Notes : Select single shot register set.
> > +
> > +File : sshot_ctrl (rw)
> > +Trace Registers : SSCCR[idx]
> > +Notes : Access a single shot comparator control register.
> > +Depends : sshot_idx
> > +Syntax : 'echo val > sshot_ctrl'
> > + Writes val into the selected control register.
> > +
> > +File : sshot_status (ro)
> > +Trace Registers : SSCSR[idx]
> > +Notes : Read a single shot comparator status register
> > +Depends : sshot_idx
> > +Syntax : 'cat sshot_status'
> > + Read status.
> > +Example : $> cat sshot_status
> > + 0x1
> > +
> > +File : sshot_pe_ctrl (rw)
> > +Trace Registers : SSPCICR[idx]
> > +Notes : Access a single shot PE comparator input control register.
> > +Depends : sshot_idx
> > +Syntax : echo val > sshot_pe_ctrl
> > + Writes val into the selected control register.
> > +
> > +File : ns_exlevel_vinst (rw)
> > +Trace Registers : VICTLR{23:20}
> > +Notes : Program non-secure exception level filters. Set / clear NS
> > + exception filter bits. Setting ‘1’ excludes trace from the
> > + exception level.
> > +Syntax : 'echo bitfield > ns_exlevel_viinst'
> > + Where bitfield contains bits to set clear for EL0 to EL2
> > +Example : %> echo 0x4 > ns_exlevel_viinst
> > + ; Exclude EL2 NS trace.
> > +
> > +File : vinst_pe_cmp_start_stop (rw)
> > +Trace Registers : VIPCSSCTLR
> > +Notes : Access PE start stop comparator input control registers
> > +
> > +File : bb_ctrl (rw)
> > +Trace Registers : BBCTLR
> > +Notes : Define ranges that Branch Broadcast will operate in.
> > + Default (0x0) is all addresses.
> > +Depends : BB enabled.
> > +
> > +File : cyc_threshold (rw)
> > +Trace Registers : CCCTLR
> > +Notes : Set the threshold for which cycle counts will be emitted.
> > + Error if attempt to set below minimum defined in IDR3, masked
> > + to width of valid bits.
> > +Depends : CC enabled.
> > +
> > +File : syncfreq (rw)
> > +Trace Registers : SYNCPR
> > +Notes : Set trace synchronisation period. Power of 2 value, 0 (off)
> > + or 8-20. Driver defaults to 12 (every 4096 bytes).
> > +
> > +File : cntr_idx (rw)
> > +Trace Registers : none
> > +Notes : Select the counter to access
> > +Syntax : 'echo idx > cntr_idx'
> > + Where idx < nr_cntr
> > +
> > +File : cntr_ctrl (rw)
> > +Trace Registers : CNTCTLR[idx]
> > +Notes : Set counter control value
> > +Depends : cntr_idx
> > +Syntax : 'echo val > cntr_ctrl'
> > + Where val is per ETMv4 spec.
> > +
> > +File : cntrldvr (rw)
> > +Trace Registers : CNTRLDVR[idx]
> > +Notes : Set counter reload value
> > +Depends : cntr_idx
> > +Syntax : 'echo val > cntrldvr'
> > + Where val is per ETMv4 spec.
> > +
> > +File : nr_cntr (ro)
> > +Trace Registers : From IDR5
> > +Notes : Number of counters implemented.
> > +
> > +File : ctxid_idx (rw)
> > +Trace Registers : None
> > +Notes : Select the context ID comparator to access
> > +Syntax : 'echo idx > ctxid_idx'
> > + Where idx < numcidc
> > +
> > +File : ctxid_pid (rw)
> > +Trace Registers : CIDCVR[idx]
> > +Notes : Set the context ID comparator value
> > +Depends : ctxid_idx
> > +
> > +File : ctxid_masks (rw)
> > +Trace Registers : CIDCCTLR0, CIDCCTLR1, CIDCVR<0-7>
> > +Notes : Pair of values to set the byte masks for 1-8 context ID
> > + comparators. Automatically clears masked bytes to 0 in CID
> > + value registers.
> > +Syntax : 'echo m3m2m1m0 [m7m6m5m4] > ctxid_masks'
> > + 32 bit values made up of mask bytes, where mN represents a
> > + byte mask value for Ctxt ID comparator N.
> > + Second value not required on systems that have fewer than 4
> > + context ID comparators
> > +
> > +File : numcidc (ro)
> > +Trace Registers : From IDR4
> > +Notes : Number of Context ID comparators
> > +
> > +File : vmid_idx (rw)
> > +Trace Registers : None
> > +Notes : Select the VM ID comparator to access.
> > +Syntax : 'echo idx > vmid_idx'
> > + Where idx < numvmidc
> > +
> > +File : vmid_val (rw)
> > +Trace Registers : VMIDCVR[idx]
> > +Notes : Set the VM ID comparator value
> > +Depends : vmid_idx
> > +
> > +File : vmid_masks (rw)
> > +Trace Registers : VMIDCCTLR0, VMIDCCTLR1, VMIDCVR<0-7>
> > +Notes : Pair of values to set the byte masks for 1-8 VM ID
> > + comparators. Automatically clears masked bytes to 0 in VMID
> > + value registers.
> > +Syntax : 'echo m3m2m1m0 [m7m6m5m4] > vmid_masks'
> > + Where mN represents a byte mask value for VMID comparator N.
> > + Second value not required on systems that have fewer than
> > + 4 VMID comparators.
> > +
> > +File : numvmidc (ro)
> > +Trace Registers : From IDR4
> > +Notes : Number of VMID comparators
> > +
> > +File : res_idx (rw)
> > +Trace Registers : None.
> > +Notes : Select the resource selector control to access. Must be 2 or
> > + higher as selectors 0 and 1 are hardwired.
> > +Syntax : 'echo idx > res_idx'
> > + Where 2 <= idx < nr_resource x 2
> > +
> > +File : res_ctrl (rw)
> > +Trace Registers : RSCTLR[idx]
> > +Notes : Set resource selector control value. Value per ETMv4 spec.
> > +Depends : res_idx
> > +Syntax : 'echo val > res_cntr'
> > + Where val is per ETMv4 spec.
> > +
> > +File : nr_resource (ro)
> > +Trace Registers : From IDR4
> > +Notes : Number of resource selector pairs
> > +
> > +File : event (rw)
> > +Trace Registers : EVENTCTRL0R
> > +Notes : Set up to 4 implemented event fields.
> > +Syntax : 'echo ev3ev2ev1ev0 > event'
> > + Where evN is an 8 bit event field. Up to 4 event fields make up
> > + the 32bit input value. Number of valid fields implementation
> > + dependent defined in IDR0.
> > +
> > +File : event_instren (rw)
> > +Trace Registers : EVENTCTRL1R
> > +Notes : Choose events which insert event packets into trace stream.
> > +Depends : EVENTCTRL0R
> > +Syntax : 'echo bitfield > event_instren'
> > + Where bitfield is up to 4 bits according to number of event
> > + fields.
> > +
> > +File : event_ts (rw)
> > +Trace Registers : TSCTLR
> > +Notes : Set the event that will generate timestamp requests.
> > +Depends : TS activated
> > +Syntax : 'echo evfield > event_ts'
> > + Where evfield is an 8 bit event selector.
> > +
> > +File : seq_idx (rw)
> > +Trace Registers : None
> > +Notes : Sequencer event register select - 0 to 2
> > +
> > +
> > +File : seq_state (rw)
> > +Trace Registers : SEQSTR
> > +Notes : Sequencer current state - 0 to 3.
> > +
> > +File : seq_event (rw)
> > +Trace Registers : SEQEVR[idx]
> > +Notes : State transition event registers
> > +Depends : seq_idx
> > +Syntax : 'echo evBevF > seq_event'
> > + Where evBevF is a 16 bit value made up of two event selectors,
> > + evB - back, evF - forwards.
> > +
> > +File : seq_reset_event (rw)
> > +Trace Registers : SEQRSTEVR
> > +Notes : Sequencer reset event
> > +Syntax : 'echo evfield > seq_reset_event'
> > + Where evfield is an 8 bit event selector.
> > +
> > +File : nrseqstate (ro)
> > +Trace Registers : From IDR5
> > +Notes : Number of sequencer states (0 or 4)
> > +
> > +File : nr_pe_cmp (ro)
> > +Trace Registers : From IDR4
> > +Notes : Number of PE comparator inputs
> > +
> > +File : nr_ext_inp (ro)
> > +Trace Registers : From IDR5
> > +Notes : Number of external inputs
> > +
> > +File : nr_ss_cmp (ro)
> > +Trace Registers : From IDR4
> > +Notes : Number of Single Shot control registers
> > +
> > +Note: When programming any address comparator the driver will tag the
> > +comparator with a type used - i.e. RANGE, SINGLE, START, STOP. Once this tag
> > +is set, then only the values can be changed using the same sysfs file / type
> > +used to program it.
> > +
> > +Thus:-
> > +% echo 0 > addr_idx ; select address comparator 0
> > +% echo 0x1000 0x5000 0 > addr_range ; set address range on comparators 0 and 1.
> > +% echo 0x2000 > addr_start ; this will error as comparator 0 is a
> > + ; range comparator
> > +% echo 2 > addr_idx ; select address comparator 2
> > +% echo 0x2000 > addr_start ; this is OK as comparator 2 is unused,
> > +% echo 0x3000 > addr_stop ; this will error as comparator 2 a start
> > + ; address comparator
> > +% echo 2 > addr_idx ; select address comparator 3
> > +% echo 0x3000 > addr_stop ; this is OK
> > +
> > +To remove programming on all the comparators (and all the other hardware) use
> > +the reset parameter:
> > +
> > +% echo 1 > reset
> > +
> > +The ‘mode’ sysfs parameter.
> > +---------------------------
> > +
> > +This is a bitfield selection parameter that sets the overall trace mode for the
> > +ETM. The table below describes the bits, using the defines from the driver
> > +source file, along with a description of the feature these represent. Many
> > +features are optional and therefore dependent on implementation in the
> > +hardware.
> > +
> > +Bit assignements shown below:-
> > +
> > +bit (0) : #define ETM_MODE_EXCLUDE
> > +description : This is the default value for the include / exclude function when
> > + setting address ranges. Set 1 for exclude range. When the mode
> > + parameter is set this value is applied to the currently indexed
> > + address range.
> > +
> > +bit (4) : #define ETM_MODE_BB
> > +description : Set to enable branch broadcast if supported in hardware [IDR0].
> > +
> > +bit (5) : #define ETMv4_MODE_CYCACC
> > +description : Set to enable cycle accurate trace if supported [IDR0].
> > +
> > +bit (6) : ETMv4_MODE_CTXID
> > +description : Set to enable context ID tracing if supported in hardware [IDR2].
> > +
> > +bit (7) : ETM_MODE_VMID
> > +description : Set to enable virtual machine ID tracing if supported [IDR2].
> > +
> > +bit (11) : ETMv4_MODE_TIMESTAMP
> > +description : Set to enable timestamp generation if supported [IDR0].
> > +
> > +bit (12) : ETM_MODE_RETURNSTACK
> > +description : Set to enable trace return stack use if supported [IDR0].
> > +
> > +bit (13-14) : ETM_MODE_QELEM(val)
> > +description : ‘val’ determines level of Q element support enabled if
> > + implemented by the ETM [IDR0]
> > +
> > +bit (19) : ETM_MODE_ATB_TRIGGER
> > +description : Set to enable the ATBTRIGGER bit in the event control register
> > + [EVENTCTLR1] if supported [IDR5].
> > +
> > +bit (20) : ETM_MODE_LPOVERRIDE
> > +description : Set to enable the LPOVERRIDE bit in the event control register
> > + [EVENTCTLR1], if supported [IDR5].
> > +
> > +bit (21) : ETM_MODE_ISTALL_EN
> > +description : Set to enable the ISTALL bit in the stall control register
> > + [STALLCTLR]
> > +
> > +bit (23) : ETM_MODE_INSTPRIO
> > +description : Set to enable the INSTPRIORITY bit in the stall control register
> > + [STALLCTLR] , if supported [IDR0].
> > +
> > +bit (24) : ETM_MODE_NOOVERFLOW
> > +description : Set to enable the NOOVERFLOW bit in the stall control register
> > + [STALLCTLR], if supported [IDR3].
> > +
> > +bit (25) : ETM_MODE_TRACE_RESET
> > +description : Set to enable the TRCRESET bit in the viewinst control register
> > + [VICTLR] , if supported [IDR3].
> > +
> > +bit (26) : ETM_MODE_TRACE_ERR
> > +description : Set to enable the TRCCTRL bit in the viewinst control register
> > + [VICTLR].
> > +
> > +bit (27) : ETM_MODE_VIEWINST_STARTSTOP
> > +description : Set the initial state value of the ViewInst start / stop logic
> > + in the viewinst control register [VICTLR]
> > +
> > +bit (30) : ETM_MODE_EXCL_KERN
> > +description : Set default trace setup to exclude kernel mode trace (see note a)
> > +
> > +bit (31) : ETM_MODE_EXCL_USER
> > +description : Set default trace setup to exclude user space trace (see note a)
> > +
> > +Note a) On startup the ETM is programmed to trace the complete address space
> > +using address range comparator 0. ‘mode’ bits 30 / 31 modify this setting to
> > +set EL exclude bits for NS state in either user space (EL0) or kernel space
> > +(EL1) in the address range comparator. (the default setting excludes all
> > +secure EL, and NS EL2)
> > +
> > +Once the reset parameter has been used, and/or custom programming has been
> > +implemented - using these bits will result in the EL bits for address
> > +comparator 0 being set in the same way.
> > +
> > +Note b) Bits 2-3, 8-10, 15-16, 18, 22, control features that only work with
> > +data trace. As A profile data trace is architecturally prohibited in ETMv4,
> > +these have been omitted here. Possible uses could be where a kernel has
> > +support for control of R or M profile infrastructure as part of a heterogeneous
> > +system.
> > +
> > +Bits 17, 28-29 are unused.
> > --
> > 2.17.1
> >

--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK