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Commit 98481e79 authored by Len Brown's avatar Len Brown
Browse files

tools/power turbostat: relax dependency on root permission 



For turbostat to run as non-root, it needs to permissions:

1. read access to /dev/cpu/*/msr
	via standard user/group/world file permissions

2. CAP_SYS_RAWIO
	eg.  # setcap cap_sys_rawio=ep turbostat

Yes, running as root still works.

Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent bfa76d49

tools/power/x86/turbostat/turbostat.c

+41 −12
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ 
#include <ctype.h>

#include <sched.h>

#include <cpuid.h>

#include <linux/capability.h>

#include <errno.h>



char *proc_stat = "/proc/stat";

unsigned int interval_sec = 5;	/* set with -i interval_sec */
@@ -251,15 +253,13 @@ int get_msr(int cpu, off_t offset, unsigned long long *msr) 
	sprintf(pathname, "/dev/cpu/%d/msr", cpu);

	fd = open(pathname, O_RDONLY);

	if (fd < 0)

		return -1;

		err(-1, "%s open failed, try chown or chmod +r /dev/cpu/*/msr, or run as root", pathname);



	retval = pread(fd, msr, sizeof *msr, offset);

	close(fd);



	if (retval != sizeof *msr) {

		fprintf(stderr, "%s offset 0x%llx read failed\n", pathname, (unsigned long long)offset);

		return -1;

	}

	if (retval != sizeof *msr)

		err(-1, "%s offset 0x%llx read failed", pathname, (unsigned long long)offset);



	return 0;

}
@@ -1462,10 +1462,40 @@ void check_dev_msr() 
		    "Try \"# modprobe msr\"");

}



void check_super_user()

void check_permissions()

{

	struct __user_cap_header_struct cap_header_data;

	cap_user_header_t cap_header = &cap_header_data;

	struct __user_cap_data_struct cap_data_data;

	cap_user_data_t cap_data = &cap_data_data;

	extern int capget(cap_user_header_t hdrp, cap_user_data_t datap);

	int do_exit = 0;



	/* check for CAP_SYS_RAWIO */

	cap_header->pid = getpid();

	cap_header->version = _LINUX_CAPABILITY_VERSION;

	if (capget(cap_header, cap_data) < 0)

		err(-6, "capget(2) failed");



	if ((cap_data->effective & (1 << CAP_SYS_RAWIO)) == 0) {

		do_exit++;

		warnx("capget(CAP_SYS_RAWIO) failed,"

			" try \"# setcap cap_sys_rawio=ep %s\"", progname);

	}



	/* test file permissions */

	if (euidaccess("/dev/cpu/0/msr", R_OK)) {

		do_exit++;

		warn("/dev/cpu/0/msr open failed, try chown or chmod +r /dev/cpu/*/msr");

	}



	/* if all else fails, thell them to be root */

	if (do_exit)

		if (getuid() != 0)

		errx(-6, "must be root");

			warnx("Or simply run as root");



	if (do_exit)

		exit(-6);

}



int has_nehalem_turbo_ratio_limit(unsigned int family, unsigned int model)
@@ -2299,10 +2329,9 @@ void setup_all_buffers(void) 


void turbostat_init()

{

	check_cpuid();



	check_dev_msr();

	check_super_user();

	check_permissions();

	check_cpuid();



	setup_all_buffers();
@@ -2441,7 +2470,7 @@ int main(int argc, char **argv) 
	cmdline(argc, argv);



	if (verbose)

		fprintf(stderr, "turbostat v3.7 Feb 6, 2014"

		fprintf(stderr, "turbostat v3.8 14-Aug 2014"

			" - Len Brown <lenb@kernel.org>\n");



	turbostat_init();