Re: [Qemu-devel] [PATCH v3 3/3] tpm_tis: convert tpm_tis_show_buffer() to use trace event

[Liam Merwick]

On 12/02/2019 21:01, Stefan Berger wrote:
> On 2/12/19 3:48 PM, 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 <address@hidden>
> > ---
> >
> > Sample trace output
> >
> > % 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 trace-30665
> > tpm_tis_show_buffer 0.000 pid=30665 string=tpm_tis: To TPM len=0xc 
> > line=80 01 00 00 00 0C 00 00 01 44 00 00
> > tpm_tis_show_buffer 256.581 pid=30665 string=tpm_tis: From TPM len=0xa 
> > line=80 01 00 00 00 0A 00 00 01 01
>
>
> should now be 'length=10' and then a new line with just the bytes?

The example I gave was using --enable-trace-backends=simple (which 
AFAICT doesn't use the format string, just the name/type of the parameters)

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

Below is the output with --enable-trace-backends=log which does include 
the newline

address@hidden:tpm_tis_show_buffer direction: To TPM len: 12
buf: 80 01 00 00 00 0C 00 00 01 44 00 00
address@hidden:tpm_tis_show_buffer direction: From TPM len: 10
buf: 80 01 00 00 00 0A 00 00 01 01

(those include a few tweaks for v4 I made based on investigating this 
question: dropped "tpm_tis: " since the function name is now printed by 
the tracing framework, renamed some of the parameters to 
trace_tpm_tis_show_buffer() and adjusted the format string)


diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
index 18e19d5f900d..d7b9bee85741 100644
--- a/hw/tpm/tpm_tis.c
+++ b/hw/tpm/tpm_tis.c
@@ -155,8 +155,7 @@ static void tpm_tis_sts_set(TPMLocality *l, uint32_t 
flags)
 static void tpm_tis_tpm_send(TPMState *s, uint8_t locty)
 {
     if (trace_event_get_state_backends(TRACE_TPM_TIS_SHOW_BUFFER)) {
-        tpm_tis_show_buffer(s->buffer, s->be_buffer_size,
-                            "tpm_tis: To TPM");
+        tpm_tis_show_buffer(s->buffer, s->be_buffer_size, "To TPM");
     }

     /*
@@ -325,8 +324,7 @@ static void tpm_tis_request_completed(TPMIf *ti, int 
ret)
     s->rw_offset = 0;

     if (trace_event_get_state_backends(TRACE_TPM_TIS_SHOW_BUFFER)) {
-        tpm_tis_show_buffer(s->buffer, s->be_buffer_size,
-                            "tpm_tis: From TPM");
+        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 c0267d075027..f45dcd220993 100644
--- a/hw/tpm/trace-events
+++ b/hw/tpm/trace-events
@@ -36,7 +36,7 @@ tpm_emulator_pre_save(void) ""
 tpm_emulator_inst_init(void) ""

 # hw/tpm/tpm_tis.c
-tpm_tis_show_buffer(const char *string, size_t len, const char *line) 
"tpm_tis: %s length = %zu\n%s"
+tpm_tis_show_buffer(const char *direction, size_t len, const char *buf) 
"direction: %s len: %zu\nbuf: %s


> >   hw/tpm/tpm_tis.c    | 25 +++++++++++++++++--------
> >   hw/tpm/trace-events |  1 +
> >   2 files changed, 18 insertions(+), 8 deletions(-)
> >
> > diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
> > index 772431f20874..18e19d5f900d 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.
>
>
> This is missing the terminating null byte.


will fix in v4

Regards,
Liam


> > +     */
> > +    line_buffer = g_malloc(len * 3 + (len / 16));
> > +
> > +    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);
> >   }
> >   /*
> > @@ -145,7 +154,7 @@ 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) {
> > +    if (trace_event_get_state_backends(TRACE_TPM_TIS_SHOW_BUFFER)) {
> >           tpm_tis_show_buffer(s->buffer, s->be_buffer_size,
> >                               "tpm_tis: To TPM");
> >       }
> > @@ -315,7 +324,7 @@ 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) {
> > +    if (trace_event_get_state_backends(TRACE_TPM_TIS_SHOW_BUFFER)) {
> >           tpm_tis_show_buffer(s->buffer, s->be_buffer_size,
> >                               "tpm_tis: From TPM");
> >       }
> > diff --git a/hw/tpm/trace-events b/hw/tpm/trace-events
> > index 920d32ad5514..c0267d075027 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 *string, size_t len, const char *line) 
> > "tpm_tis: %s length = %zu\n%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"