* [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP)
@ 2020-05-24 10:38 Philippe Mathieu-Daudé
2020-05-24 12:41 ` Alexander Bulekov
2020-05-26 7:23 ` Thomas Huth
0 siblings, 2 replies; 4+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-05-24 10:38 UTC (permalink / raw)
To: qemu-devel
Cc: qemu-trivial, Alexander Bulekov, qemu-arm,
Philippe Mathieu-Daudé, Peter Maydell
Replace fprintf() call by qemu_log_mask(LOG_UNIMP), which is
disabled by default. This avoid flooding the terminal when
fuzzing the device.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
hw/display/omap_dss.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/display/omap_dss.c b/hw/display/omap_dss.c
index 32dc0d6aa7..21fde58a26 100644
--- a/hw/display/omap_dss.c
+++ b/hw/display/omap_dss.c
@@ -619,7 +619,7 @@ static void omap_rfbi_transfer_start(struct omap_dss_s *s)
if (s->rfbi.control & (1 << 1)) { /* BYPASS */
/* TODO: in non-Bypass mode we probably need to just assert the
* DRQ and wait for DMA to write the pixels. */
- fprintf(stderr, "%s: Bypass mode unimplemented\n", __func__);
+ qemu_log_mask(LOG_UNIMP, "%s: Bypass mode unimplemented\n", __func__);
return;
}
--
2.21.3
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP)
2020-05-24 10:38 [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP) Philippe Mathieu-Daudé
@ 2020-05-24 12:41 ` Alexander Bulekov
2020-05-24 13:53 ` Philippe Mathieu-Daudé
2020-05-26 7:23 ` Thomas Huth
1 sibling, 1 reply; 4+ messages in thread
From: Alexander Bulekov @ 2020-05-24 12:41 UTC (permalink / raw)
To: Philippe Mathieu-Daudé
Cc: qemu-trivial, Peter Maydell, qemu-arm, qemu-devel
On 200524 1238, Philippe Mathieu-Daudé wrote:
> Replace fprintf() call by qemu_log_mask(LOG_UNIMP), which is
> disabled by default. This avoid flooding the terminal when
> fuzzing the device.
>
Hi Philippe,
libfuzzer also lets you pass -close_fd_mask=[1,2,3] to close stdout,
stderr or both. As a side-effect, In this mode, libfuzzer will write the
crashing stacktraces to individual files ./.$PID, instead of to the
terminal's output. As far as I know, closing the FDs doesn't bypass all
of printf's allocation/formatting code, so getting rid of calls can
still be a good idea for performance, sometimes.
-Alex
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> hw/display/omap_dss.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/display/omap_dss.c b/hw/display/omap_dss.c
> index 32dc0d6aa7..21fde58a26 100644
> --- a/hw/display/omap_dss.c
> +++ b/hw/display/omap_dss.c
> @@ -619,7 +619,7 @@ static void omap_rfbi_transfer_start(struct omap_dss_s *s)
> if (s->rfbi.control & (1 << 1)) { /* BYPASS */
> /* TODO: in non-Bypass mode we probably need to just assert the
> * DRQ and wait for DMA to write the pixels. */
> - fprintf(stderr, "%s: Bypass mode unimplemented\n", __func__);
> + qemu_log_mask(LOG_UNIMP, "%s: Bypass mode unimplemented\n", __func__);
> return;
> }
>
> --
> 2.21.3
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP)
2020-05-24 12:41 ` Alexander Bulekov
@ 2020-05-24 13:53 ` Philippe Mathieu-Daudé
0 siblings, 0 replies; 4+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-05-24 13:53 UTC (permalink / raw)
To: Alexander Bulekov; +Cc: qemu-trivial, Peter Maydell, qemu-arm, qemu-devel
On 5/24/20 2:41 PM, Alexander Bulekov wrote:
> On 200524 1238, Philippe Mathieu-Daudé wrote:
>> Replace fprintf() call by qemu_log_mask(LOG_UNIMP), which is
>> disabled by default. This avoid flooding the terminal when
>> fuzzing the device.
>>
> Hi Philippe,
> libfuzzer also lets you pass -close_fd_mask=[1,2,3] to close stdout,
> stderr or both. As a side-effect, In this mode, libfuzzer will write the
> crashing stacktraces to individual files ./.$PID, instead of to the
> terminal's output.
Thanks, good to know.
This information is worth adding in docs/devel/fuzzing.txt :P
> As far as I know, closing the FDs doesn't bypass all
> of printf's allocation/formatting code, so getting rid of calls can
> still be a good idea for performance, sometimes.
Certainly.
> -Alex
>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>> hw/display/omap_dss.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/display/omap_dss.c b/hw/display/omap_dss.c
>> index 32dc0d6aa7..21fde58a26 100644
>> --- a/hw/display/omap_dss.c
>> +++ b/hw/display/omap_dss.c
>> @@ -619,7 +619,7 @@ static void omap_rfbi_transfer_start(struct omap_dss_s *s)
>> if (s->rfbi.control & (1 << 1)) { /* BYPASS */
>> /* TODO: in non-Bypass mode we probably need to just assert the
>> * DRQ and wait for DMA to write the pixels. */
>> - fprintf(stderr, "%s: Bypass mode unimplemented\n", __func__);
>> + qemu_log_mask(LOG_UNIMP, "%s: Bypass mode unimplemented\n", __func__);
>> return;
>> }
>>
>> --
>> 2.21.3
>>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP)
2020-05-24 10:38 [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP) Philippe Mathieu-Daudé
2020-05-24 12:41 ` Alexander Bulekov
@ 2020-05-26 7:23 ` Thomas Huth
1 sibling, 0 replies; 4+ messages in thread
From: Thomas Huth @ 2020-05-26 7:23 UTC (permalink / raw)
To: Philippe Mathieu-Daudé, qemu-devel
Cc: qemu-trivial, Alexander Bulekov, qemu-arm, Peter Maydell
On 24/05/2020 12.38, Philippe Mathieu-Daudé wrote:
> Replace fprintf() call by qemu_log_mask(LOG_UNIMP), which is
> disabled by default. This avoid flooding the terminal when
> fuzzing the device.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> hw/display/omap_dss.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/display/omap_dss.c b/hw/display/omap_dss.c
> index 32dc0d6aa7..21fde58a26 100644
> --- a/hw/display/omap_dss.c
> +++ b/hw/display/omap_dss.c
> @@ -619,7 +619,7 @@ static void omap_rfbi_transfer_start(struct omap_dss_s *s)
> if (s->rfbi.control & (1 << 1)) { /* BYPASS */
> /* TODO: in non-Bypass mode we probably need to just assert the
> * DRQ and wait for DMA to write the pixels. */
> - fprintf(stderr, "%s: Bypass mode unimplemented\n", __func__);
> + qemu_log_mask(LOG_UNIMP, "%s: Bypass mode unimplemented\n", __func__);
> return;
> }
Reviewed-by: Thomas Huth <thuth@redhat.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-05-24 10:38 [PATCH] hw/display/omap_dss: Replace fprintf() call by qemu_log_mask(LOG_UNIMP) Philippe Mathieu-Daudé
2020-05-24 12:41 ` Alexander Bulekov
2020-05-24 13:53 ` Philippe Mathieu-Daudé
2020-05-26 7:23 ` Thomas Huth
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