| Message ID | 1435699387-32591-4-git-send-email-timur@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/30/2015 02:23 PM, Timur Tabi wrote: > diff --git a/arch/arm/include/asm/dcc.h b/arch/arm/include/asm/dcc.h > index b74899d..c50056b 100644 > --- a/arch/arm/include/asm/dcc.h > +++ b/arch/arm/include/asm/dcc.h > @@ -9,8 +9,11 @@ > * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > * GNU General Public License for more details. > */ > +#ifndef __ASM_DCC_H > +#define __ASM_DCC_H > > #include <asm/barrier.h> > +#include <asm/hardware/cp14.h> That's new. > > static inline u32 __dcc_getstatus(void) > { > @@ -39,3 +42,15 @@ static inline void __dcc_putchar(char c) > : "r" (c)); > isb(); > } > + > +static inline void __dcc_initialize(void) > +{ > + u32 val; > + > + /* Disable user-space access to DCC */ > + val = MRC14(0, c0, c1, 0); > + val |= 1 << 12; /* DSCR[Comms] */ > + MCR14(val, 0, c0, c1, 0); > +} Nitpick: We do raw cp14 accesses for other functions in this file, so it would be nice to be consistent throughout. > + > +#endif > diff --git a/arch/arm64/include/asm/dcc.h b/arch/arm64/include/asm/dcc.h > index fcb8d7d..7843e62 100644 > --- a/arch/arm64/include/asm/dcc.h > +++ b/arch/arm64/include/asm/dcc.h > @@ -49,4 +49,15 @@ static inline void __dcc_putchar(char c) > isb(); > } > > +static inline void __dcc_initialize(void) > +{ > + u32 val; > + > + /* Disable user-space access to DCC */ > + asm ("mrs %0, mdscr_el1\n" shouldn't this be volatile? > + " orr %0, %0, #4096\n" /* Set the TDCC bit */ arm64 has some #defines in debug-monitors.h which we should probably extend to have this bit as a #define too. > + " msr mdscr_el1, %0\n" > + : "=r" (val)); > +} > + > #endif >
On Jul 1, 2015, at 8:00 PM, Stephen Boyd wrote: >> >> #include <asm/barrier.h> >> +#include <asm/hardware/cp14.h> > > That's new. And no one else is using it either. >> >> + >> +static inline void __dcc_initialize(void) >> +{ >> + u32 val; >> + >> + /* Disable user-space access to DCC */ >> + val = MRC14(0, c0, c1, 0); >> + val |= 1 << 12; /* DSCR[Comms] */ >> + MCR14(val, 0, c0, c1, 0); >> +} > > Nitpick: We do raw cp14 accesses for other functions in this file, so it > would be nice to be consistent throughout. I agree, but I didn't want to expand the scope of this patch beyond what it's supposed to do. >> >> +static inline void __dcc_initialize(void) >> +{ >> + u32 val; >> + >> + /* Disable user-space access to DCC */ >> + asm ("mrs %0, mdscr_el1\n" > > shouldn't this be volatile? Well, I figured it wasn't important exactly why these instructions are executed, since it just disables user-space. I usually get chewed out by someone if I add volatile where it's not needed, so I didn't add it this time. > >> + " orr %0, %0, #4096\n" /* Set the TDCC bit */ > > arm64 has some #defines in debug-monitors.h which we should probably > extend to have this bit as a #define too. Hmmm, the only thing I see in debug_monitors.h that seems applicable are the mdscr_write() and mdscr_read() functions, which seem to overlap cp14.h.
diff --git a/arch/arm/include/asm/dcc.h b/arch/arm/include/asm/dcc.h index b74899d..c50056b 100644 --- a/arch/arm/include/asm/dcc.h +++ b/arch/arm/include/asm/dcc.h @@ -9,8 +9,11 @@ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ +#ifndef __ASM_DCC_H +#define __ASM_DCC_H #include <asm/barrier.h> +#include <asm/hardware/cp14.h> static inline u32 __dcc_getstatus(void) { @@ -39,3 +42,15 @@ static inline void __dcc_putchar(char c) : "r" (c)); isb(); } + +static inline void __dcc_initialize(void) +{ + u32 val; + + /* Disable user-space access to DCC */ + val = MRC14(0, c0, c1, 0); + val |= 1 << 12; /* DSCR[Comms] */ + MCR14(val, 0, c0, c1, 0); +} + +#endif diff --git a/arch/arm64/include/asm/dcc.h b/arch/arm64/include/asm/dcc.h index fcb8d7d..7843e62 100644 --- a/arch/arm64/include/asm/dcc.h +++ b/arch/arm64/include/asm/dcc.h @@ -49,4 +49,15 @@ static inline void __dcc_putchar(char c) isb(); } +static inline void __dcc_initialize(void) +{ + u32 val; + + /* Disable user-space access to DCC */ + asm ("mrs %0, mdscr_el1\n" + " orr %0, %0, #4096\n" /* Set the TDCC bit */ + " msr mdscr_el1, %0\n" + : "=r" (val)); +} + #endif diff --git a/drivers/tty/hvc/hvc_dcc.c b/drivers/tty/hvc/hvc_dcc.c index f8b8cf2..5ccafa4 100644 --- a/drivers/tty/hvc/hvc_dcc.c +++ b/drivers/tty/hvc/hvc_dcc.c @@ -231,6 +231,8 @@ static int __init hvc_dcc_console_init(void) if (!hvc_dcc_check()) return -ENODEV; + __dcc_initialize(); + /* Returns -1 if error */ ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
If the DCC driver loads, then disable user-space access to the DCC so that we don't have two entities trying to access the DCC at the same time. Signed-off-by: Timur Tabi <timur@codeaurora.org> --- arch/arm/include/asm/dcc.h | 15 +++++++++++++++ arch/arm64/include/asm/dcc.h | 11 +++++++++++ drivers/tty/hvc/hvc_dcc.c | 2 ++ 3 files changed, 28 insertions(+)