#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/export.h>
#include <asm/syscall.h>

static int collect_syscall(struct task_struct *target, long *callno,
			   unsigned long args[6], unsigned int maxargs,
			   unsigned long *sp, unsigned long *pc)
{
	struct pt_regs *regs;

	if (!try_get_task_stack(target)) {
		/* Task has no stack, so the task isn't in a syscall. */
		*callno = -1;
		return 0;
	}

	regs = task_pt_regs(target);
	if (unlikely(!regs)) {
		put_task_stack(target);
		return -EAGAIN;
	}

	*sp = user_stack_pointer(regs);
	*pc = instruction_pointer(regs);

	*callno = syscall_get_nr(target, regs);
	if (*callno != -1L && maxargs > 0)
		syscall_get_arguments(target, regs, 0, maxargs, args);

	put_task_stack(target);
	return 0;
}

/**
 * task_current_syscall - Discover what a blocked task is doing.
 * @target:		thread to examine
 * @callno:		filled with system call number or -1
 * @args:		filled with @maxargs system call arguments
 * @maxargs:		number of elements in @args to fill
 * @sp:			filled with user stack pointer
 * @pc:			filled with user PC
 *
 * If @target is blocked in a system call, returns zero with *@callno
 * set to the the call's number and @args filled in with its arguments.
 * Registers not used for system call arguments may not be available and
 * it is not kosher to use &struct user_regset calls while the system
 * call is still in progress.  Note we may get this result if @target
 * has finished its system call but not yet returned to user mode, such
 * as when it's stopped for signal handling or syscall exit tracing.
 *
 * If @target is blocked in the kernel during a fault or exception,
 * returns zero with *@callno set to -1 and does not fill in @args.
 * If so, it's now safe to examine @target using &struct user_regset
 * get() calls as long as we're sure @target won't return to user mode.
 *
 * Returns -%EAGAIN if @target does not remain blocked.
 *
 * Returns -%EINVAL if @maxargs is too large (maximum is six).
 */
int task_current_syscall(struct task_struct *target, long *callno,
			 unsigned long args[6], unsigned int maxargs,
			 unsigned long *sp, unsigned long *pc)
{
	long state;
	unsigned long ncsw;

	if (unlikely(maxargs > 6))
		return -EINVAL;

	if (target == current)
		return collect_syscall(target, callno, args, maxargs, sp, pc);

	state = target->state;
	if (unlikely(!state))
		return -EAGAIN;

	ncsw = wait_task_inactive(target, state);
	if (unlikely(!ncsw) ||
	    unlikely(collect_syscall(target, callno, args, maxargs, sp, pc)) ||
	    unlikely(wait_task_inactive(target, state) != ncsw))
		return -EAGAIN;

	return 0;
}
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/kernel?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>kernel</a>/<a href='/cgit.cgi/linux/net-next.git/commit/kernel/power?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>power</a>/<a href='/cgit.cgi/linux/net-next.git/commit/kernel/power/Kconfig?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>Kconfig</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='dd86e373e09fb16b83e8adf5c48c421a4ca76468'/><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>Thomas Gleixner &lt;tglx@linutronix.de&gt;</td><td class='right'>2017-01-31 23:58:38 +0100</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2017-02-01 08:37:27 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/kernel/power/Kconfig?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>dd86e373e09fb16b83e8adf5c48c421a4ca76468</a> (<a href='/cgit.cgi/linux/net-next.git/patch/kernel/power/Kconfig?id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>55703c2ea8584e303e342090614e0aab3509ab21</a> /<a href='/cgit.cgi/linux/net-next.git/tree/kernel/power/Kconfig?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>kernel/power/Kconfig</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/kernel/power/Kconfig?h=nds-private-remove&amp;id=0b3589be9b98994ce3d5aeca52445d1f5627c4ba'>0b3589be9b98994ce3d5aeca52445d1f5627c4ba</a> (<a href='/cgit.cgi/linux/net-next.git/diff/kernel/power/Kconfig?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468&amp;id2=0b3589be9b98994ce3d5aeca52445d1f5627c4ba'>diff</a>)</td></tr></table>
<div class='commit-subject'>perf/x86/intel/rapl: Make package handling more robust</div><div class='commit-msg'>The package management code in RAPL relies on package mapping being
available before a CPU is started. This changed with:

  9d85eb9119f4 ("x86/smpboot: Make logical package management more robust")

because the ACPI/BIOS information turned out to be unreliable, but that
left RAPL in broken state. This was not noticed because on a regular boot
all CPUs are online before RAPL is initialized.

A possible fix would be to reintroduce the mess which allocates a package
data structure in CPU prepare and when it turns out to already exist in
starting throw it away later in the CPU online callback. But that's a
horrible hack and not required at all because RAPL becomes functional for
perf only in the CPU online callback. That's correct because user space is
not yet informed about the CPU being onlined, so nothing caan rely on RAPL
being available on that particular CPU.

Move the allocation to the CPU online callback and simplify the hotplug
handling. At this point the package mapping is established and correct.

This also adds a missing check for available package data in the
event_init() function.

Reported-by: Yasuaki Ishimatsu &lt;yasu.isimatu@gmail.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Sebastian Siewior &lt;bigeasy@linutronix.de&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Vince Weaver &lt;vincent.weaver@maine.edu&gt;
Fixes: 9d85eb9119f4 ("x86/smpboot: Make logical package management more robust")
Link: http://lkml.kernel.org/r/20170131230141.212593966@linutronix.de
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=dd86e373e09fb16b83e8adf5c48c421a4ca76468'>Diffstat</a> (limited to 'kernel/power/Kconfig')</div><table summary='diffstat' class='diffstat'>