linux-kernel - Re: [PATCH v1] perf arm-spe: Unaligned pointer work around

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Message-ID: <CAP-5=fUc8zFup-87JjDfX38GoRpPdPwTdtfsxPqKmqJr1aHWGw@mail.gmail.com>
Date: Tue, 14 May 2024 08:39:20 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Leo Yan <leo.yan@...ux.dev>, 
	James Clark <james.clark@....com>
Subject: Re: [PATCH v1] perf arm-spe: Unaligned pointer work around

On Mon, May 13, 2024 at 10:24 PM Ian Rogers <irogers@...gle.com> wrote:
>
> Use get_unaligned_leXX instead of leXX_to_cpu to handle unaligned
> pointers. Such pointers occur with libFuzzer testing.
>
> A similar change for intel-pt was done in:
> https://lore.kernel.org/r/20231005190451.175568-6-adrian.hunter@intel.com
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>

+Leo Yan +James Clark surprisingly missed by get_maintainer.pl.

Thanks,
Ian

> ---
>  .../arm-spe-decoder/arm-spe-pkt-decoder.c     | 23 ++++---------------
>  1 file changed, 5 insertions(+), 18 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 a454c6737563..7bf607d0f6d8 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
> @@ -10,24 +10,11 @@
>  #include <byteswap.h>
>  #include <linux/bitops.h>
>  #include <stdarg.h>
> +#include <linux/kernel.h>
> +#include <asm-generic/unaligned.h>
>
>  #include "arm-spe-pkt-decoder.h"
>
> -#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> -#define le16_to_cpu bswap_16
> -#define le32_to_cpu bswap_32
> -#define le64_to_cpu bswap_64
> -#define memcpy_le64(d, s, n) do { \
> -       memcpy((d), (s), (n));    \
> -       *(d) = le64_to_cpu(*(d)); \
> -} while (0)
> -#else
> -#define le16_to_cpu
> -#define le32_to_cpu
> -#define le64_to_cpu
> -#define memcpy_le64 memcpy
> -#endif
> -
>  static const char * const arm_spe_packet_name[] = {
>         [ARM_SPE_PAD]           = "PAD",
>         [ARM_SPE_END]           = "END",
> @@ -70,9 +57,9 @@ static int arm_spe_get_payload(const unsigned char *buf, size_t len,
>
>         switch (payload_len) {
>         case 1: packet->payload = *(uint8_t *)buf; break;
> -       case 2: packet->payload = le16_to_cpu(*(uint16_t *)buf); break;
> -       case 4: packet->payload = le32_to_cpu(*(uint32_t *)buf); break;
> -       case 8: packet->payload = le64_to_cpu(*(uint64_t *)buf); break;
> +       case 2: packet->payload = get_unaligned_le16(buf); break;
> +       case 4: packet->payload = get_unaligned_le32(buf); break;
> +       case 8: packet->payload = get_unaligned_le64(buf); break;
>         default: return ARM_SPE_BAD_PACKET;
>         }
>
> --
> 2.45.0.rc1.225.g2a3ae87e7f-goog
>