2022-05-20 23:18:35

by Dmitry Osipenko

[permalink] [raw]
Subject: [PATCH v1] ARM: Silence proc-v7-bugs.c spam about disabled Spectre workarounds

Print message about disabled Spectre workarounds only once to stop
endless spam into KSMG each time CPU goes out from idling state.
This spam makes system unusable with CONFIG_HARDEN_BRANCH_PREDICTOR=n
for those who don't care about security and wants maximum performance.

Signed-off-by: Dmitry Osipenko <[email protected]>
---
arch/arm/mm/proc-v7-bugs.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c
index fb9f3eb6bf48..f9730eba0632 100644
--- a/arch/arm/mm/proc-v7-bugs.c
+++ b/arch/arm/mm/proc-v7-bugs.c
@@ -108,8 +108,7 @@ static unsigned int spectre_v2_install_workaround(unsigned int method)
#else
static unsigned int spectre_v2_install_workaround(unsigned int method)
{
- pr_info("CPU%u: Spectre V2: workarounds disabled by configuration\n",
- smp_processor_id());
+ pr_info_once("Spectre V2: workarounds disabled by configuration\n");

return SPECTRE_VULNERABLE;
}
--
2.35.3



2022-06-28 07:30:42

by Dmitry Osipenko

[permalink] [raw]
Subject: Re: [PATCH v1] ARM: Silence proc-v7-bugs.c spam about disabled Spectre workarounds

On 5/19/22 19:13, Dmitry Osipenko wrote:
> Print message about disabled Spectre workarounds only once to stop
> endless spam into KSMG each time CPU goes out from idling state.
> This spam makes system unusable with CONFIG_HARDEN_BRANCH_PREDICTOR=n
> for those who don't care about security and wants maximum performance.
>
> Signed-off-by: Dmitry Osipenko <[email protected]>
> ---
> arch/arm/mm/proc-v7-bugs.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c
> index fb9f3eb6bf48..f9730eba0632 100644
> --- a/arch/arm/mm/proc-v7-bugs.c
> +++ b/arch/arm/mm/proc-v7-bugs.c
> @@ -108,8 +108,7 @@ static unsigned int spectre_v2_install_workaround(unsigned int method)
> #else
> static unsigned int spectre_v2_install_workaround(unsigned int method)
> {
> - pr_info("CPU%u: Spectre V2: workarounds disabled by configuration\n",
> - smp_processor_id());
> + pr_info_once("Spectre V2: workarounds disabled by configuration\n");
>
> return SPECTRE_VULNERABLE;
> }

Hello Russell,

Could you please apply this patch? I tried to use yours patch tracker
today and it doesn't allow me to recover my password (server error: MAIL
FROM command failed Detail: Space shortage).

Thanks!

--
Best regards,
Dmitry

2022-06-28 07:37:44

by Russell King (Oracle)

[permalink] [raw]
Subject: Re: [PATCH v1] ARM: Silence proc-v7-bugs.c spam about disabled Spectre workarounds

On Tue, Jun 28, 2022 at 10:23:06AM +0300, Dmitry Osipenko wrote:
> On 5/19/22 19:13, Dmitry Osipenko wrote:
> > Print message about disabled Spectre workarounds only once to stop
> > endless spam into KSMG each time CPU goes out from idling state.
> > This spam makes system unusable with CONFIG_HARDEN_BRANCH_PREDICTOR=n
> > for those who don't care about security and wants maximum performance.
> >
> > Signed-off-by: Dmitry Osipenko <[email protected]>
> > ---
> > arch/arm/mm/proc-v7-bugs.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c
> > index fb9f3eb6bf48..f9730eba0632 100644
> > --- a/arch/arm/mm/proc-v7-bugs.c
> > +++ b/arch/arm/mm/proc-v7-bugs.c
> > @@ -108,8 +108,7 @@ static unsigned int spectre_v2_install_workaround(unsigned int method)
> > #else
> > static unsigned int spectre_v2_install_workaround(unsigned int method)
> > {
> > - pr_info("CPU%u: Spectre V2: workarounds disabled by configuration\n",
> > - smp_processor_id());
> > + pr_info_once("Spectre V2: workarounds disabled by configuration\n");
> >
> > return SPECTRE_VULNERABLE;
> > }
>
> Hello Russell,
>
> Could you please apply this patch? I tried to use yours patch tracker
> today and it doesn't allow me to recover my password (server error: MAIL
> FROM command failed Detail: Space shortage).

That should now be working - thanks to apt needlessly consuming 200MB of
space. Please use the patch system, thanks.

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!