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Commit 8fb402bc authored by Erik Bosman's avatar Erik Bosman Committed by Ingo Molnar
Browse files

generic, x86: add prctl commands PR_GET_TSC and PR_SET_TSC 



This patch adds prctl commands that make it possible
to deny the execution of timestamp counters in userspace.
If this is not implemented on a specific architecture,
prctl will return -EINVAL.

ned-off-by: default avatarErik Bosman <ejbosman@cs.vu.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5deb45e3

include/linux/prctl.h

+6 −0
Original line number Diff line number Diff line
@@ -67,4 +67,10 @@ 
#define PR_CAPBSET_READ 23

#define PR_CAPBSET_DROP 24



/* Get/set the process' ability to use the timestamp counter instruction */

#define PR_GET_TSC 25

#define PR_SET_TSC 26

# define PR_TSC_ENABLE		1	/* allow the use of the timestamp counter */

# define PR_TSC_SIGSEGV		2	/* throw a SIGSEGV instead of reading the TSC */



#endif /* _LINUX_PRCTL_H */

kernel/sys.c

+12 −1
Original line number Diff line number Diff line
@@ -67,6 +67,12 @@ 
#ifndef SET_ENDIAN

# define SET_ENDIAN(a,b)	(-EINVAL)

#endif

#ifndef GET_TSC_CTL

# define GET_TSC_CTL(a)		(-EINVAL)

#endif

#ifndef SET_TSC_CTL

# define SET_TSC_CTL(a)		(-EINVAL)

#endif



/*

 * this is where the system-wide overflow UID and GID are defined, for
@@ -1737,7 +1743,12 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3, 
#else

			return -EINVAL;

#endif



		case PR_GET_TSC:

			error = GET_TSC_CTL(arg2);

			break;

		case PR_SET_TSC:

			error = SET_TSC_CTL(arg2);

			break;

		default:

			error = -EINVAL;

			break;