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.
> 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....@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.
The rest looks fine.
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)
>
