Messages in this thread | | | Date | Mon, 12 Oct 2020 08:21:02 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v2 03/14] perf arm-spe: Refactor payload length calculation |
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Hi Andre,
On Thu, Oct 08, 2020 at 02:44:59PM +0100, André Przywara wrote: > On 29/09/2020 14:39, Leo Yan wrote: > > Hi Leo, > > > Defines macro for payload length calculation instead of static function. > > What is the reason for that? I thought the kernel's direction is more > the other way: replacing macros with static functions ("Don't write CPP, > write C")? Ideally the compiler would generate the same code.
Okay, I didn't note this before. Will change back to use static function.
> > Currently the event packet's 'index' is assigned as payload length, but > > the flow is not directive: it firstly gets the packet length (includes > > header length and payload length) and then reduces header length from > > packet length, so finally get the payload length; to simplify the code, > > this patch directly assigns payload length to event packet's index. > > > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > > --- > > .../arm-spe-decoder/arm-spe-pkt-decoder.c | 26 ++++++++----------- > > .../arm-spe-decoder/arm-spe-pkt-decoder.h | 4 +++ > > 2 files changed, 15 insertions(+), 15 deletions(-) > > > > diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c > > index 7c7b5eb09fba..5a8696031e16 100644 > > --- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c > > +++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c > > @@ -69,22 +69,20 @@ const char *arm_spe_pkt_name(enum arm_spe_pkt_type type) > > return arm_spe_packet_name[type]; > > } > > > > -/* return ARM SPE payload size from its encoding, > > - * which is in bits 5:4 of the byte. > > - * 00 : byte > > - * 01 : halfword (2) > > - * 10 : word (4) > > - * 11 : doubleword (8) > > +/* > > + * Return ARM SPE payload size from header bits 5:4 > > + * 00 : byte > > + * 01 : halfword (2) > > + * 10 : word (4) > > + * 11 : doubleword (8) > > */ > > -static int payloadlen(unsigned char byte) > > -{ > > - return 1 << ((byte & 0x30) >> 4); > > -} > > +#define PAYLOAD_LEN(val) \ > > + (1 << (((val) & SPE_HEADER_SZ_MASK) >> SPE_HEADER_SZ_SHIFT)) > > This change of the expression is good (although it should be 1U), but > please keep it a function. The return type should be unsigned, I guess.
Will do.
> The rest looks fine.
Thanks a lot for reviewing!
Leo
> Cheers, > Andre > > > > > static int arm_spe_get_payload(const unsigned char *buf, size_t len, > > struct arm_spe_pkt *packet) > > { > > - size_t payload_len = payloadlen(buf[0]); > > + size_t payload_len = PAYLOAD_LEN(buf[0]); > > > > if (len < 1 + payload_len) > > return ARM_SPE_NEED_MORE_BYTES; > > @@ -136,8 +134,6 @@ static int arm_spe_get_timestamp(const unsigned char *buf, size_t len, > > static int arm_spe_get_events(const unsigned char *buf, size_t len, > > struct arm_spe_pkt *packet) > > { > > - int ret = arm_spe_get_payload(buf, len, packet); > > - > > packet->type = ARM_SPE_EVENTS; > > > > /* we use index to identify Events with a less number of > > @@ -145,9 +141,9 @@ static int arm_spe_get_events(const unsigned char *buf, size_t len, > > * LLC-REFILL, and REMOTE-ACCESS events are identified if > > * index > 1. > > */ > > - packet->index = ret - 1; > > + packet->index = PAYLOAD_LEN(buf[0]); > > > > - return ret; > > + return arm_spe_get_payload(buf, len, packet); > > } > > > > static int arm_spe_get_data_source(const unsigned char *buf, size_t len, > > diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h > > index 4c870521b8eb..f2d0af39a58c 100644 > > --- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h > > +++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h > > @@ -9,6 +9,7 @@ > > > > #include <stddef.h> > > #include <stdint.h> > > +#include <linux/bits.h> > > > > #define ARM_SPE_PKT_DESC_MAX 256 > > > > @@ -36,6 +37,9 @@ struct arm_spe_pkt { > > uint64_t payload; > > }; > > > > +#define SPE_HEADER_SZ_SHIFT (4) > > +#define SPE_HEADER_SZ_MASK GENMASK_ULL(5, 4) > > + > > #define SPE_ADDR_PKT_HDR_INDEX_INS (0x0) > > #define SPE_ADDR_PKT_HDR_INDEX_BRANCH (0x1) > > #define SPE_ADDR_PKT_HDR_INDEX_DATA_VIRT (0x2) > > >
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