Re: [PATCH 4/4] perf cs-etm: Add exception level consistency check

[James Clark <james.clark@arm.com>]

On 25/05/2023 12:39, Mike Leach wrote:
> Hi James,
> 
> My concern here is that for etmv3 trace, OpenCSD will only provide
> memory spaces as either secure or non-secure, The ETMv3 does not
> trace, and hence OpenCSD cannot provide the different ELs.
> The memory callback will be either OCSD_MEM_SPACE_S or OCSD_MEM_SPACE_N.
> 

As long as none of the bits are set for EL1-EL3 then no validation will
be done so it should be fine. But I will try to test ETMv3.

> Can this patch - and the set handle this. (assuming perf supports our
> ETMv3 coresight kernel driver)

For the whole set, the tracked EL will stay as ocsd_EL_unknown and
cs_etm__get_machine() will return host so the behavior will be unchanged
from before. This is assuming OpenCSD will set the EL to unknown in
elem->context.exception_level in this case.

> 
> Regards
> 
> Mike
> 
> On Wed, 24 May 2023 at 14:20, James Clark <james.clark@arm.com> wrote:
>>
>> Assert that our own tracking of the exception level matches what
>> OpenCSD provides. OpenCSD doesn't distinguish between EL0 and EL1 in the
>> memory access callback so the extra tracking was required. But a rough
>> assert can still be done.
>>
>> Signed-off-by: James Clark <james.clark@arm.com>
>> ---
>>  .../perf/util/cs-etm-decoder/cs-etm-decoder.c |  6 +--
>>  .../perf/util/cs-etm-decoder/cs-etm-decoder.h |  4 +-
>>  tools/perf/util/cs-etm.c                      | 37 +++++++++++++------
>>  3 files changed, 32 insertions(+), 15 deletions(-)
>>
>> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
>> index ac227cd03eb0..50b3c248d1e5 100644
>> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
>> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
>> @@ -52,15 +52,15 @@ struct cs_etm_decoder {
>>  static u32
>>  cs_etm_decoder__mem_access(const void *context,
>>                            const ocsd_vaddr_t address,
>> -                          const ocsd_mem_space_acc_t mem_space __maybe_unused,
>> +                          const ocsd_mem_space_acc_t mem_space,
>>                            const u8 trace_chan_id,
>>                            const u32 req_size,
>>                            u8 *buffer)
>>  {
>>         struct cs_etm_decoder *decoder = (struct cs_etm_decoder *) context;
>>
>> -       return decoder->mem_access(decoder->data, trace_chan_id,
>> -                                  address, req_size, buffer);
>> +       return decoder->mem_access(decoder->data, trace_chan_id, address,
>> +                                  req_size, buffer, mem_space);
>>  }
>>
>>  int cs_etm_decoder__add_mem_access_cb(struct cs_etm_decoder *decoder,
>> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
>> index 21d403f55d96..272c2efe78ee 100644
>> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
>> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
>> @@ -11,6 +11,7 @@
>>  #define INCLUDE__CS_ETM_DECODER_H__
>>
>>  #include <linux/types.h>
>> +#include <opencsd/ocsd_if_types.h>
>>  #include <stdio.h>
>>
>>  struct cs_etm_decoder;
>> @@ -19,7 +20,8 @@ struct cs_etm_packet_queue;
>>
>>  struct cs_etm_queue;
>>
>> -typedef u32 (*cs_etm_mem_cb_type)(struct cs_etm_queue *, u8, u64, size_t, u8 *);
>> +typedef u32 (*cs_etm_mem_cb_type)(struct cs_etm_queue *, u8, u64, size_t, u8 *,
>> +                                 const ocsd_mem_space_acc_t);
>>
>>  struct cs_etmv3_trace_params {
>>         u32 reg_ctrl;
>> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
>> index b9ba19327f26..ccf34ed8ddf2 100644
>> --- a/tools/perf/util/cs-etm.c
>> +++ b/tools/perf/util/cs-etm.c
>> @@ -931,7 +931,8 @@ static u8 cs_etm__cpu_mode(struct cs_etm_queue *etmq, u64 address,
>>  }
>>
>>  static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u8 trace_chan_id,
>> -                             u64 address, size_t size, u8 *buffer)
>> +                             u64 address, size_t size, u8 *buffer,
>> +                             const ocsd_mem_space_acc_t mem_space)
>>  {
>>         u8  cpumode;
>>         u64 offset;
>> @@ -947,6 +948,20 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u8 trace_chan_id,
>>         if (!tidq)
>>                 return 0;
>>
>> +       /*
>> +        * We've already tracked EL along side the PID in cs_etm__set_thread()
>> +        * so double check that it matches what OpenCSD thinks as well. It
>> +        * doesn't distinguish between EL0 and EL1 for this mem access callback
>> +        * so we had to do the extra tracking.
>> +        */
>> +       if (mem_space & OCSD_MEM_SPACE_EL1N) {
>> +               /* Includes both non secure EL1 and EL0 */
>> +               assert(tidq->el == ocsd_EL1 || tidq->el == ocsd_EL0);
>> +       } else if (mem_space & OCSD_MEM_SPACE_EL2)
>> +               assert(tidq->el == ocsd_EL2);
>> +       else if (mem_space & OCSD_MEM_SPACE_EL3)
>> +               assert(tidq->el == ocsd_EL3);
>> +
>>         cpumode = cs_etm__cpu_mode(etmq, address, tidq->el);
>>
>>         if (!thread__find_map(tidq->thread, cpumode, address, &al))
>> @@ -1195,8 +1210,8 @@ static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
>>  {
>>         u8 instrBytes[2];
>>
>> -       cs_etm__mem_access(etmq, trace_chan_id, addr,
>> -                          ARRAY_SIZE(instrBytes), instrBytes);
>> +       cs_etm__mem_access(etmq, trace_chan_id, addr, ARRAY_SIZE(instrBytes),
>> +                          instrBytes, 0);
>>         /*
>>          * T32 instruction size is indicated by bits[15:11] of the first
>>          * 16-bit word of the instruction: 0b11101, 0b11110 and 0b11111
>> @@ -1387,8 +1402,8 @@ static void cs_etm__copy_insn(struct cs_etm_queue *etmq,
>>         else
>>                 sample->insn_len = 4;
>>
>> -       cs_etm__mem_access(etmq, trace_chan_id, sample->ip,
>> -                          sample->insn_len, (void *)sample->insn);
>> +       cs_etm__mem_access(etmq, trace_chan_id, sample->ip, sample->insn_len,
>> +                          (void *)sample->insn, 0);
>>  }
>>
>>  u64 cs_etm__convert_sample_time(struct cs_etm_queue *etmq, u64 cs_timestamp)
>> @@ -1940,8 +1955,8 @@ static bool cs_etm__is_svc_instr(struct cs_etm_queue *etmq, u8 trace_chan_id,
>>                  * so below only read 2 bytes as instruction size for T32.
>>                  */
>>                 addr = end_addr - 2;
>> -               cs_etm__mem_access(etmq, trace_chan_id, addr,
>> -                                  sizeof(instr16), (u8 *)&instr16);
>> +               cs_etm__mem_access(etmq, trace_chan_id, addr, sizeof(instr16),
>> +                                  (u8 *)&instr16, 0);
>>                 if ((instr16 & 0xFF00) == 0xDF00)
>>                         return true;
>>
>> @@ -1956,8 +1971,8 @@ static bool cs_etm__is_svc_instr(struct cs_etm_queue *etmq, u8 trace_chan_id,
>>                  * +---------+---------+-------------------------+
>>                  */
>>                 addr = end_addr - 4;
>> -               cs_etm__mem_access(etmq, trace_chan_id, addr,
>> -                                  sizeof(instr32), (u8 *)&instr32);
>> +               cs_etm__mem_access(etmq, trace_chan_id, addr, sizeof(instr32),
>> +                                  (u8 *)&instr32, 0);
>>                 if ((instr32 & 0x0F000000) == 0x0F000000 &&
>>                     (instr32 & 0xF0000000) != 0xF0000000)
>>                         return true;
>> @@ -1973,8 +1988,8 @@ static bool cs_etm__is_svc_instr(struct cs_etm_queue *etmq, u8 trace_chan_id,
>>                  * +-----------------------+---------+-----------+
>>                  */
>>                 addr = end_addr - 4;
>> -               cs_etm__mem_access(etmq, trace_chan_id, addr,
>> -                                  sizeof(instr32), (u8 *)&instr32);
>> +               cs_etm__mem_access(etmq, trace_chan_id, addr, sizeof(instr32),
>> +                                  (u8 *)&instr32, 0);
>>                 if ((instr32 & 0xFFE0001F) == 0xd4000001)
>>                         return true;
>>
>> --
>> 2.34.1
>>
> 
>