/*
 *  (C) 2003 - 2004  Dominik Brodowski <linux@dominikbrodowski.de>
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *
 * Based on code found in
 * linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
 * and originally developed by Jeremy Fitzhardinge.
 *
 * USAGE: simply run it to decode the current settings on CPU 0,
 *	  or pass the CPU number as argument, or pass the MSR content
 *	  as argument.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>

#include <sys/types.h>
#include <sys/stat.h>

#define MCPU	32

#define MSR_IA32_PERF_STATUS	0x198

static int rdmsr(unsigned int cpu, unsigned int msr,
		 unsigned int *lo, unsigned int *hi)
{
	int fd;
	char file[20];
	unsigned long long val;
	int retval = -1;

	*lo = *hi = 0;

	if (cpu > MCPU)
		goto err1;

	sprintf(file, "/dev/cpu/%d/msr", cpu);
	fd = open(file, O_RDONLY);

	if (fd < 0)
		goto err1;

	if (lseek(fd, msr, SEEK_CUR) == -1)
		goto err2;

	if (read(fd, &val, 8) != 8)
		goto err2;

	*lo = (uint32_t )(val & 0xffffffffull);
	*hi = (uint32_t )(val>>32 & 0xffffffffull);

	retval = 0;
err2:
	close(fd);
err1:
	return retval;
}

static void decode (unsigned int msr)
{
	unsigned int multiplier;
	unsigned int mv;

	multiplier = ((msr >> 8) & 0xFF);

	mv = (((msr & 0xFF) * 16) + 700);

	printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
}

static int decode_live(unsigned int cpu)
{
	unsigned int lo, hi;
	int err;

	err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);

	if (err) {
		printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
		printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
		printf("or you are not root, or the msr driver is not present\n");
		return 1;
	}

	decode(lo);

	return 0;
}

int main (int argc, char **argv)
{
	unsigned int cpu, mode = 0;

	if (argc < 2)
		cpu = 0;
	else {
		cpu = strtoul(argv[1], NULL, 0);
		if (cpu >= MCPU)
			mode = 1;
	}

	if (mode)
		decode(cpu);
	else
		decode_live(cpu);

	return 0;
}
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>tools</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>perf</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/tests?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>tests</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/tests/mmap-thread-lookup.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>mmap-thread-lookup.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='bf29bddf0417a4783da3b24e8c9e017ac649326f'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Jiri Kosina &lt;jkosina@suse.cz&gt;</td><td class='right'>2017-01-27 22:25:52 +0000</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2017-01-28 09:18:56 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/tests/mmap-thread-lookup.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>bf29bddf0417a4783da3b24e8c9e017ac649326f</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/perf/tests/mmap-thread-lookup.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>54a05a4883b73f80e4e1d8c4b15750aa01c39932</a> /<a href='/cgit.cgi/linux/net-next.git/tree/tools/perf/tests/mmap-thread-lookup.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>tools/perf/tests/mmap-thread-lookup.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/tests/mmap-thread-lookup.c?id=883af14e67e8b8702b5560aa64c888c0cd0bd66c'>883af14e67e8b8702b5560aa64c888c0cd0bd66c</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/perf/tests/mmap-thread-lookup.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f&amp;id2=883af14e67e8b8702b5560aa64c888c0cd0bd66c'>diff</a>)</td></tr></table>
<div class='commit-subject'>x86/efi: Always map the first physical page into the EFI pagetables</div><div class='commit-msg'>Commit:

  129766708 ("x86/efi: Only map RAM into EFI page tables if in mixed-mode")

stopped creating 1:1 mappings for all RAM, when running in native 64-bit mode.

It turns out though that there are 64-bit EFI implementations in the wild
(this particular problem has been reported on a Lenovo Yoga 710-11IKB),
which still make use of the first physical page for their own private use,
even though they explicitly mark it EFI_CONVENTIONAL_MEMORY in the memory
map.

In case there is no mapping for this particular frame in the EFI pagetables,
as soon as firmware tries to make use of it, a triple fault occurs and the
system reboots (in case of the Yoga 710-11IKB this is very early during bootup).

Fix that by always mapping the first page of physical memory into the EFI
pagetables. We're free to hand this page to the BIOS, as trim_bios_range()
will reserve the first page and isolate it away from memory allocators anyway.

Note that just reverting 129766708 alone is not enough on v4.9-rc1+ to fix the
regression on affected hardware, as this commit:

   ab72a27da ("x86/efi: Consolidate region mapping logic")

later made the first physical frame not to be mapped anyway.

Reported-by: Hanka Pavlikova &lt;hanka@ucw.cz&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
Signed-off-by: Matt Fleming &lt;matt@codeblueprint.co.uk&gt;
Cc: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Borislav Petkov &lt;bp@suse.de&gt;
Cc: Laura Abbott &lt;labbott@redhat.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vojtech Pavlik &lt;vojtech@ucw.cz&gt;
Cc: Waiman Long &lt;waiman.long@hpe.com&gt;
Cc: linux-efi@vger.kernel.org
Cc: stable@kernel.org # v4.8+
Fixes: 129766708 ("x86/efi: Only map RAM into EFI page tables if in mixed-mode")
Link: http://lkml.kernel.org/r/20170127222552.22336-1-matt@codeblueprint.co.uk
[ Tidied up the changelog and the comment. ]
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>Diffstat</a> (limited to 'tools/perf/tests/mmap-thread-lookup.c')</div><table summary='diffstat' class='diffstat'>