#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;
}
e>
<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/tools?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>tools</a>/<a href='/cgit.cgi/linux/net-next.git/log/tools/perf?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>perf</a>/<a href='/cgit.cgi/linux/net-next.git/log/tools/perf/arch?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>arch</a>/<a href='/cgit.cgi/linux/net-next.git/log/tools/perf/arch/sh?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>sh</a>/<a href='/cgit.cgi/linux/net-next.git/log/tools/perf/arch/sh/Build?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>Build</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/tools/perf/arch/sh/Build?id=3ad7a4b141ebd6091494913672d7166d5c2764e4&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
8177f91b'>asm-generic</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='d7df2443cd5f67fc6ee7c05a88e4996e8177f91b'/><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>Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;</td><td class='right'>2017-02-03 17:10:28 +1100</td></tr>
<tr><th>committer</th><td>Michael Ellerman &lt;mpe@ellerman.id.au&gt;</td><td class='right'>2017-02-08 23:36:29 +1100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/include/uapi/asm-generic?h=nds-private-remove&amp;id=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b'>d7df2443cd5f67fc6ee7c05a88e4996e8177f91b</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/include/uapi/asm-generic?id=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b'>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=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b'>098a7c0ca4fceb8a65cb1f693c9d71990388933d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/tools/include/uapi/asm-generic?h=nds-private-remove&amp;id=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b'>tools/include/uapi/asm-generic</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/include/uapi/asm-generic?h=nds-private-remove&amp;id=a0615a16f7d0ceb5804d295203c302d496d8ee91'>a0615a16f7d0ceb5804d295203c302d496d8ee91</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/include/uapi/asm-generic?h=nds-private-remove&amp;id=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b&amp;id2=a0615a16f7d0ceb5804d295203c302d496d8ee91'>diff</a>)</td></tr></table>
<div class='commit-subject'>powerpc/mm: Fix spurrious segfaults on radix with autonuma</div><div class='commit-msg'>When autonuma (Automatic NUMA balancing) marks a PTE inaccessible it
clears all the protection bits but leave the PTE valid.

With the Radix MMU, an attempt at executing from such a PTE will
take a fault with bit 35 of SRR1 set "SRR1_ISI_N_OR_G".

It is thus incorrect to treat all such faults as errors. We should
pass them to handle_mm_fault() for autonuma to deal with. The case
of pages that are really not executable is handled by the existing
test for VM_EXEC further down.

That leaves us with catching the kernel attempts at executing user
pages. We can catch that earlier, even before we do find_vma.

It is never valid on powerpc for the kernel to take an exec fault
to begin with. So fold that test with the existing test for the
kernel faulting on kernel addresses to bail out early.

Fixes: 1d18ad026844 ("powerpc/mm: Detect instruction fetch denied and report")
Signed-off-by: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Reviewed-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.vnet.ibm.com&gt;
Acked-by: Balbir Singh &lt;bsingharora@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b'>Diffstat</a> (limited to 'tools/include/uapi/asm-generic')</div><table summary='diffstat' class='diffstat'>