Messages in this thread | | | From | Timur Tabi <> | Subject | Re: [PATCH 4/4] hvc_dcc: disable user-space access to DCC | Date | Fri, 3 Jul 2015 10:53:12 -0400 |
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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.
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