[PATCH 4/4] hvc_dcc: disable user-space access to DCC
flat view
From: Stephen Boyd <hidden>
Date: 2015-07-02 00:00:37
Also in:
lkml
On 06/30/2015 02:23 PM, Timur Tabi wrote:
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
+ +#endifdiff --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.
quoted hunk ↗ jump to hunk
+ " msr mdscr_el1, %0\n" + : "=r" (val)); +} + #endif
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