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Commit 08aa0d1f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf tools: Add x86 RDPMC, RDTSC test 



Implement a simple test for the self-monitoring data from the
perf mmap data area control page:

 6: x86 rdpmc test:

             0:           6053
             1:          60053
             2:         600059
             3:        6000059
             4:       60000075
             5:      600000247
    Ok

The counts are expected to increase monotonically - these
are recovered via RDPMC, without calling into the kernel.

It might be nice to add logic to automagically turn these numbers into OK/FAIL.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arun Sharma <asharma@fb.com>
Link: http://lkml.kernel.org/n/tip-evf5yii88ljdgmaihccbxxw1@git.kernel.org


[ various small improvements ]
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e3f3541c

tools/perf/builtin-test.c

+175 −2
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ 
#include "util/thread_map.h"

#include "../../include/linux/hw_breakpoint.h"



#include <sys/mman.h>



static int vmlinux_matches_kallsyms_filter(struct map *map __used, struct symbol *sym)

{

	bool *visited = symbol__priv(sym);
@@ -1296,6 +1298,173 @@ out: 
	return (err < 0 || errs > 0) ? -1 : 0;

}





#if defined(__x86_64__) || defined(__i386__)



#define barrier() asm volatile("" ::: "memory")



static u64 rdpmc(unsigned int counter)

{

	unsigned int low, high;



	asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));



	return low | ((u64)high) << 32;

}



static u64 rdtsc(void)

{

	unsigned int low, high;



	asm volatile("rdtsc" : "=a" (low), "=d" (high));



	return low | ((u64)high) << 32;

}



static u64 mmap_read_self(void *addr)

{

	struct perf_event_mmap_page *pc = addr;

	u32 seq, idx, time_mult = 0, time_shift = 0;

	u64 count, cyc = 0, time_offset = 0, enabled, running, delta;



	do {

		seq = pc->lock;

		barrier();



		enabled = pc->time_enabled;

		running = pc->time_running;



		if (enabled != running) {

			cyc = rdtsc();

			time_mult = pc->time_mult;

			time_shift = pc->time_shift;

			time_offset = pc->time_offset;

		}



		idx = pc->index;

		count = pc->offset;

		if (idx)

			count += rdpmc(idx - 1);



		barrier();

	} while (pc->lock != seq);



	if (enabled != running) {

		u64 quot, rem;



		quot = (cyc >> time_shift);

		rem = cyc & ((1 << time_shift) - 1);

		delta = time_offset + quot * time_mult +

			((rem * time_mult) >> time_shift);



		enabled += delta;

		if (idx)

			running += delta;



		quot = count / running;

		rem = count % running;

		count = quot * enabled + (rem * enabled) / running;

	}



	return count;

}



/*

 * If the RDPMC instruction faults then signal this back to the test parent task:

 */

static void segfault_handler(int sig __used, siginfo_t *info __used, void *uc __used)

{

	exit(-1);

}



static int __test__rdpmc(void)

{

	long page_size = sysconf(_SC_PAGE_SIZE);

	volatile int tmp = 0;

	u64 i, loops = 1000;

	int n;

	int fd;

	void *addr;

	struct perf_event_attr attr = {

		.type = PERF_TYPE_HARDWARE,

		.config = PERF_COUNT_HW_INSTRUCTIONS,

		.exclude_kernel = 1,

	};

	u64 delta_sum = 0;

        struct sigaction sa;



	sigfillset(&sa.sa_mask);

	sa.sa_sigaction = segfault_handler;

	sigaction(SIGSEGV, &sa, NULL);



	fprintf(stderr, "\n\n");



	fd = sys_perf_event_open(&attr, 0, -1, -1, 0);

	if (fd < 0) {

		die("Error: sys_perf_event_open() syscall returned "

		    "with %d (%s)\n", fd, strerror(errno));

	}



	addr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);

	if (addr == (void *)(-1)) {

		die("Error: mmap() syscall returned "

		    "with (%s)\n", strerror(errno));

	}



	for (n = 0; n < 6; n++) {

		u64 stamp, now, delta;



		stamp = mmap_read_self(addr);



		for (i = 0; i < loops; i++)

			tmp++;



		now = mmap_read_self(addr);

		loops *= 10;



		delta = now - stamp;

		fprintf(stderr, "%14d: %14Lu\n", n, (long long)delta);



		delta_sum += delta;

	}



	munmap(addr, page_size);

	close(fd);



	fprintf(stderr, "   ");



	if (!delta_sum)

		return -1;



	return 0;

}



static int test__rdpmc(void)

{

	int status = 0;

	int wret = 0;

	int ret;

	int pid;



	pid = fork();

	if (pid < 0)

		return -1;



	if (!pid) {

		ret = __test__rdpmc();



		exit(ret);

	}



	wret = waitpid(pid, &status, 0);

	if (wret < 0 || status)

		return -1;



	return 0;

}



#endif



static struct test {

	const char *desc;

	int (*func)(void);
@@ -1320,6 +1489,12 @@ static struct test { 
		.desc = "parse events tests",

		.func = test__parse_events,

	},

#if defined(__x86_64__) || defined(__i386__)

	{

		.desc = "x86 rdpmc test",

		.func = test__rdpmc,

	},

#endif

	{

		.desc = "Validate PERF_RECORD_* events & perf_sample fields",

		.func = test__PERF_RECORD,
@@ -1412,7 +1587,5 @@ int cmd_test(int argc, const char **argv, const char *prefix __used) 
	if (symbol__init() < 0)

		return -1;



	setup_pager();



	return __cmd_test(argc, argv);

}