From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: Leo Yan <leo.yan@linaro.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Mike Leach <mike.leach@linaro.org>,
Coresight ML <coresight@lists.linaro.org>
Subject: Re: [PATCH v2 1/5] perf cs-etm: Refactor instruction size handling
Date: Mon, 23 Sep 2019 17:51:04 +0100 [thread overview]
Message-ID: <2b675e24-8b06-fbd6-ab73-214a6afb2a07@arm.com> (raw)
In-Reply-To: <20190923160759.14866-2-leo.yan@linaro.org>
Hi Leo,
On 23/09/2019 17:07, Leo Yan wrote:
> In cs-etm.c there have several functions need to know instruction size
> based on address, e.g. cs_etm__instr_addr() and cs_etm__copy_insn()
> these two functions both calculate the instruction size separately.
> Furthermore, if we consider to add new features later which also might
> require to calculate instruction size.
>
> For this reason, this patch refactors the code to introduce a new
> function cs_etm__instr_size(), it will be a central place to calculate
> the instruction size based on ISA type and instruction address.
>
> For a neat implementation, cs_etm__instr_addr() will always execute the
> loop without checking ISA type, this allows cs_etm__instr_size() and
> cs_etm__instr_addr() have no any duplicate code with each other and both
> functions can be changed independently later without breaking anything.
> As a side effect, cs_etm__instr_addr() will do a few more iterations for
> A32/A64 instructions, this would be fine if consider perf tool runs in
> the user space.
>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
Your changes look fine to me. However, please see my comment below.
> ---
> tools/perf/util/cs-etm.c | 48 +++++++++++++++++++++++-----------------
> 1 file changed, 28 insertions(+), 20 deletions(-)
>
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index f87b9c1c9f9a..1de3f9361193 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -917,6 +917,26 @@ static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
> return ((instrBytes[1] & 0xF8) >= 0xE8) ? 4 : 2;
> }
>
> +static inline int cs_etm__instr_size(struct cs_etm_queue *etmq,
> + u8 trace_chan_id,
> + enum cs_etm_isa isa,
> + u64 addr)
> +{
> + int insn_len;
> +
> + /*
> + * T32 instruction size might be 32-bit or 16-bit, decide by calling
> + * cs_etm__t32_instr_size().
> + */
> + if (isa == CS_ETM_ISA_T32)
> + insn_len = cs_etm__t32_instr_size(etmq, trace_chan_id, addr);
> + /* Otherwise, A64 and A32 instruction size are always 32-bit. */
> + else
> + insn_len = 4;
> +
> + return insn_len;
> +}
> +
> static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
> {
> /* Returns 0 for the CS_ETM_DISCONTINUITY packet */
> @@ -941,19 +961,15 @@ static inline u64 cs_etm__instr_addr(struct cs_etm_queue *etmq,
> const struct cs_etm_packet *packet,
> u64 offset)
> {
> - if (packet->isa == CS_ETM_ISA_T32) {
> - u64 addr = packet->start_addr;
> + u64 addr = packet->start_addr;
>
> - while (offset > 0) {
> - addr += cs_etm__t32_instr_size(etmq,
> - trace_chan_id, addr);
> - offset--;
> - }
> - return addr;
> + while (offset > 0) {
Given that offset is u64, the check above is not appropriate. You could either
change it to :
while (offset) // if you are sure (s64)offset always is a postive
integer and we always reduce it by 1.
Otherwise you may switch the offset to a signed type. I understand that this
is not introduced by your changes. But you may fix that up in a separate patch.
Kind regards
Suzuki
next prev parent reply other threads:[~2019-09-23 16:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-23 16:07 [PATCH v2 0/5] perf cs-etm: Support thread stack and callchain Leo Yan
2019-09-23 16:07 ` [PATCH v2 1/5] perf cs-etm: Refactor instruction size handling Leo Yan
2019-09-23 16:51 ` Suzuki K Poulose [this message]
2019-09-23 17:13 ` Leo Yan
2019-09-23 16:07 ` [PATCH v2 2/5] perf cs-etm: Support thread stack Leo Yan
2019-09-23 16:07 ` [PATCH v2 3/5] perf cs-etm: Support branch filter Leo Yan
2019-09-23 16:07 ` [PATCH v2 4/5] perf cs-etm: Support callchain for instruction sample Leo Yan
2019-09-23 16:07 ` [PATCH v2 5/5] perf cs-etm: Correct " Leo Yan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2b675e24-8b06-fbd6-ab73-214a6afb2a07@arm.com \
--to=suzuki.poulose@arm.com \
--cc=acme@kernel.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=coresight@lists.linaro.org \
--cc=jolsa@redhat.com \
--cc=leo.yan@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mathieu.poirier@linaro.org \
--cc=mike.leach@linaro.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).