Re: [Qemu-devel] [PATCH v5 3/3] tpm_tis: convert tpm_tis_show_buffer() to use trace event

[Stefan Berger <stefanb@linux.ibm.com>]

On 2/15/19 8:35 AM, Liam Merwick wrote:
> cppcheck reports:
>
> [hw/tpm/tpm_tis.c:113]: (warning) %d in format string (no. 2) requires 'int' but the argument type is 'unsigned int'
>
> Rather than just converting the format specifier to use '%u", the
> tpm_tis_show_buffer() function is converted to use trace points and
> the two debug callers use the trace event infrastructure so that it's
> available in production cases also and not just when DEBUG_TIS is enabled.
>
> Signed-off-by: Liam Merwick <liam.merwick@oracle.com>

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>


> ---
> v3 -> v4
> - Allow for null terminator in buffer length calc.
> - dropped "tpm_tis: " from direction string since function name is now printed
> - Minor tweak to trace event format string and function parameter names
>
> Sample trace output
>
> --enable-trace-backends=simple
>
> % echo tpm_tis_show_buffer > /tmp/events
> % export QTEST_QEMU_BINARY="/home/Development/qemu-upstream/x86_64-softmmu/qemu-system-x86_64 --trace events=/tmp/events"
> % tests/tpm-tis-test
> /D=/home/Development/qemu-upstream/hw/tpm/tpm-tis/test_check_localities: OK
> /D=/home/Development/qemu-upstream/hw/tpm/tpm-tis/test_check_access_reg: OK
> /D=/home/Development/qemu-upstream/hw/tpm/tpm-tis/test_check_access_reg_seize: OK
> /D=/home/Development/qemu-upstream/hw/tpm/tpm-tis/test_check_access_reg_release: OK
> /D=/home/Development/qemu-upstream/hw/tpm/tpm-tis/test_check_transmit: OK
> % ./scripts/simpletrace.py trace-events-all `ls -1rt trace-[0-9]* | tail -1`
> tpm_tis_show_buffer 0.000 pid=8416 direction=To TPM len=0xc line=80 01 00 00 00 0C 00 00 01 44 00 00
> tpm_tis_show_buffer 303.909 pid=8416 direction=From TPM len=0xa line=80 01 00 00 00 0A 00 00 01 01
>
> --enable-trace-backends=log
>
> 1255@1550051983.333949:tpm_tis_show_buffer direction: To TPM len: 12
> buf: 80 01 00 00 00 0C 00 00 01 44 00 00
> 1255@1550051983.334213:tpm_tis_show_buffer direction: From TPM len: 10
> buf: 80 01 00 00 00 0A 00 00 01 01
>
>   hw/tpm/tpm_tis.c    | 31 +++++++++++++++++++------------
>   hw/tpm/trace-events |  1 +
>   2 files changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
> index 772431f20874..d7b9bee85741 100644
> --- a/hw/tpm/tpm_tis.c
> +++ b/hw/tpm/tpm_tis.c
> @@ -108,17 +108,26 @@ static uint8_t tpm_tis_locality_from_addr(hwaddr addr)
>   static void tpm_tis_show_buffer(const unsigned char *buffer,
>                                   size_t buffer_size, const char *string)
>   {
> -    uint32_t len, i;
> +    size_t len, i;
> +    char *line_buffer, *p;
>   
>       len = MIN(tpm_cmd_get_size(buffer), buffer_size);
> -    printf("tpm_tis: %s length = %d\n", string, len);
> -    for (i = 0; i < len; i++) {
> +
> +    /*
> +     * allocate enough room for 3 chars per buffer entry plus a
> +     * newline after every 16 chars and a final null terminator.
> +     */
> +    line_buffer = g_malloc(len * 3 + (len / 16) + 1);
> +
> +    for (i = 0, p = line_buffer; i < len; i++) {
>           if (i && !(i % 16)) {
> -            printf("\n");
> +            p += sprintf(p, "\n");
>           }
> -        printf("%.2X ", buffer[i]);
> +        p += sprintf(p, "%.2X ", buffer[i]);
>       }
> -    printf("\n");
> +    trace_tpm_tis_show_buffer(string, len, line_buffer);
> +
> +    g_free(line_buffer);
>   }
>   
>   /*
> @@ -145,9 +154,8 @@ static void tpm_tis_sts_set(TPMLocality *l, uint32_t flags)
>    */
>   static void tpm_tis_tpm_send(TPMState *s, uint8_t locty)
>   {
> -    if (DEBUG_TIS) {
> -        tpm_tis_show_buffer(s->buffer, s->be_buffer_size,
> -                            "tpm_tis: To TPM");
> +    if (trace_event_get_state_backends(TRACE_TPM_TIS_SHOW_BUFFER)) {
> +        tpm_tis_show_buffer(s->buffer, s->be_buffer_size, "To TPM");
>       }
>   
>       /*
> @@ -315,9 +323,8 @@ static void tpm_tis_request_completed(TPMIf *ti, int ret)
>       s->loc[locty].state = TPM_TIS_STATE_COMPLETION;
>       s->rw_offset = 0;
>   
> -    if (DEBUG_TIS) {
> -        tpm_tis_show_buffer(s->buffer, s->be_buffer_size,
> -                            "tpm_tis: From TPM");
> +    if (trace_event_get_state_backends(TRACE_TPM_TIS_SHOW_BUFFER)) {
> +        tpm_tis_show_buffer(s->buffer, s->be_buffer_size, "From TPM");
>       }
>   
>       if (TPM_TIS_IS_VALID_LOCTY(s->next_locty)) {
> diff --git a/hw/tpm/trace-events b/hw/tpm/trace-events
> index 920d32ad5514..f45dcd220993 100644
> --- a/hw/tpm/trace-events
> +++ b/hw/tpm/trace-events
> @@ -36,6 +36,7 @@ tpm_emulator_pre_save(void) ""
>   tpm_emulator_inst_init(void) ""
>   
>   # hw/tpm/tpm_tis.c
> +tpm_tis_show_buffer(const char *direction, size_t len, const char *buf) "direction: %s len: %zu\nbuf: %s"
>   tpm_tis_raise_irq(uint32_t irqmask) "Raising IRQ for flag 0x%08x"
>   tpm_tis_new_active_locality(uint8_t locty) "Active locality is now %d"
>   tpm_tis_abort(uint8_t locty) "New active locality is %d"