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Revision 300f786b2683f8bb1ec0afb6e1851183a479c86d authored by Cyrill Gorcunov on 07 June 2012, 21:21:12 UTC, committed by Linus Torvalds on 07 June 2012, 21:43:55 UTC 
c/r: prctl: add ability to get clear_tid_address
 
Zero is written at clear_tid_address when the process exits.  This
functionality is used by pthread_join().

We already have sys_set_tid_address() to change this address for the
current task but there is no way to obtain it from user space.

Without the ability to find this address and dump it we can't restore
pthread'ed apps which call pthread_join() once they have been restored.

This patch introduces the PR_GET_TID_ADDRESS prctl option which allows
the current process to obtain own clear_tid_address.

This feature is available iif CONFIG_CHECKPOINT_RESTORE is set.

[akpm@linux-foundation.org: fix prctl numbering]
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 1ad75b9
Raw File
pci-swiotlb-xen.c 
/* Glue code to lib/swiotlb-xen.c */

#include <linux/dma-mapping.h>
#include <linux/pci.h>
#include <xen/swiotlb-xen.h>

#include <asm/xen/hypervisor.h>
#include <xen/xen.h>
#include <asm/iommu_table.h>

int xen_swiotlb __read_mostly;

static struct dma_map_ops xen_swiotlb_dma_ops = {
	.mapping_error = xen_swiotlb_dma_mapping_error,
	.alloc = xen_swiotlb_alloc_coherent,
	.free = xen_swiotlb_free_coherent,
	.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
	.sync_single_for_device = xen_swiotlb_sync_single_for_device,
	.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
	.sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
	.map_sg = xen_swiotlb_map_sg_attrs,
	.unmap_sg = xen_swiotlb_unmap_sg_attrs,
	.map_page = xen_swiotlb_map_page,
	.unmap_page = xen_swiotlb_unmap_page,
	.dma_supported = xen_swiotlb_dma_supported,
};

/*
 * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
 *
 * This returns non-zero if we are forced to use xen_swiotlb (by the boot
 * option).
 */
int __init pci_xen_swiotlb_detect(void)
{

	/* If running as PV guest, either iommu=soft, or swiotlb=force will
	 * activate this IOMMU. If running as PV privileged, activate it
	 * irregardless.
	 */
	if ((xen_initial_domain() || swiotlb || swiotlb_force) &&
	    (xen_pv_domain()))
		xen_swiotlb = 1;

	/* If we are running under Xen, we MUST disable the native SWIOTLB.
	 * Don't worry about swiotlb_force flag activating the native, as
	 * the 'swiotlb' flag is the only one turning it on. */
	if (xen_pv_domain())
		swiotlb = 0;

	return xen_swiotlb;
}

void __init pci_xen_swiotlb_init(void)
{
	if (xen_swiotlb) {
		xen_swiotlb_init(1);
		dma_ops = &xen_swiotlb_dma_ops;

		/* Make sure ACS will be enabled */
		pci_request_acs();
	}
}
IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
		  0,
		  pci_xen_swiotlb_init,
		  0);
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