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v0.8.1
Revision f383219674b72f390911c60e1d8ae95e32622398 authored by James Hogan on 19 April 2016, 08:25:06 UTC, committed by Ralf Baechle on 13 May 2016, 13:30:25 UTC 
MIPS: mm: Don't clobber $1 on XPA TLB refill
 
For XPA kernels build_update_entries() uses $1 (at) as a scratch
register, but doesn't arrange for it to be preserved, so it will always
be clobbered by the TLB refill exception. Although this register
normally has a very short lifetime that doesn't cross memory accesses,
TLB refills due to instruction fetches (either on a page boundary or
after preemption) could clobber live data, and its easy to reproduce
the clobber with a little bit of assembler code.

Note that the use of a hardware page table walker will partly mask the
problem, as the TLB refill handler will not always be invoked.

This is fixed by avoiding the use of the extra scratch register. The
pte_high parts (going into the lower half of the EntryLo registers) are
loaded and manipulated separately so as to keep the PTE pointer around
for the other halves (instead of storing in the scratch register), and
the pte_low parts (going into the high half of the EntryLo registers)
are masked with 0x00ffffff using an ext instruction (instead of loading
0x00ffffff into the scratch register and AND'ing).

[paul.burton@imgtec.com:
  - Rebase atop other TLB work.
  - Use ext instead of an sll, srl sequence.
  - Use cpu_has_xpa instead of #ifdefs.
  - Modify commit subject to include "mm".]

Fixes: c5b367835cfc ("MIPS: Add support for XPA.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13120/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
1 parent 7b2cb64
Raw File
drm_agpsupport.h 
#ifndef _DRM_AGPSUPPORT_H_
#define _DRM_AGPSUPPORT_H_

#include <linux/agp_backend.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/types.h>
#include <uapi/drm/drm.h>

struct drm_device;
struct drm_file;

struct drm_agp_head {
	struct agp_kern_info agp_info;
	struct list_head memory;
	unsigned long mode;
	struct agp_bridge_data *bridge;
	int enabled;
	int acquired;
	unsigned long base;
	int agp_mtrr;
	int cant_use_aperture;
	unsigned long page_mask;
};

#if IS_ENABLED(CONFIG_AGP)

void drm_free_agp(struct agp_memory * handle, int pages);
int drm_bind_agp(struct agp_memory * handle, unsigned int start);
int drm_unbind_agp(struct agp_memory * handle);
struct agp_memory *drm_agp_bind_pages(struct drm_device *dev,
				struct page **pages,
				unsigned long num_pages,
				uint32_t gtt_offset,
				uint32_t type);

struct drm_agp_head *drm_agp_init(struct drm_device *dev);
void drm_agp_clear(struct drm_device *dev);
int drm_agp_acquire(struct drm_device *dev);
int drm_agp_acquire_ioctl(struct drm_device *dev, void *data,
			  struct drm_file *file_priv);
int drm_agp_release(struct drm_device *dev);
int drm_agp_release_ioctl(struct drm_device *dev, void *data,
			  struct drm_file *file_priv);
int drm_agp_enable(struct drm_device *dev, struct drm_agp_mode mode);
int drm_agp_enable_ioctl(struct drm_device *dev, void *data,
			 struct drm_file *file_priv);
int drm_agp_info(struct drm_device *dev, struct drm_agp_info *info);
int drm_agp_info_ioctl(struct drm_device *dev, void *data,
		       struct drm_file *file_priv);
int drm_agp_alloc(struct drm_device *dev, struct drm_agp_buffer *request);
int drm_agp_alloc_ioctl(struct drm_device *dev, void *data,
			struct drm_file *file_priv);
int drm_agp_free(struct drm_device *dev, struct drm_agp_buffer *request);
int drm_agp_free_ioctl(struct drm_device *dev, void *data,
		       struct drm_file *file_priv);
int drm_agp_unbind(struct drm_device *dev, struct drm_agp_binding *request);
int drm_agp_unbind_ioctl(struct drm_device *dev, void *data,
			 struct drm_file *file_priv);
int drm_agp_bind(struct drm_device *dev, struct drm_agp_binding *request);
int drm_agp_bind_ioctl(struct drm_device *dev, void *data,
		       struct drm_file *file_priv);

#else /* CONFIG_AGP */

static inline void drm_free_agp(struct agp_memory * handle, int pages)
{
}

static inline int drm_bind_agp(struct agp_memory * handle, unsigned int start)
{
	return -ENODEV;
}

static inline int drm_unbind_agp(struct agp_memory * handle)
{
	return -ENODEV;
}

static inline struct agp_memory *drm_agp_bind_pages(struct drm_device *dev,
					      struct page **pages,
					      unsigned long num_pages,
					      uint32_t gtt_offset,
					      uint32_t type)
{
	return NULL;
}

static inline struct drm_agp_head *drm_agp_init(struct drm_device *dev)
{
	return NULL;
}

static inline void drm_agp_clear(struct drm_device *dev)
{
}

static inline int drm_agp_acquire(struct drm_device *dev)
{
	return -ENODEV;
}

static inline int drm_agp_release(struct drm_device *dev)
{
	return -ENODEV;
}

static inline int drm_agp_enable(struct drm_device *dev,
				 struct drm_agp_mode mode)
{
	return -ENODEV;
}

static inline int drm_agp_info(struct drm_device *dev,
			       struct drm_agp_info *info)
{
	return -ENODEV;
}

static inline int drm_agp_alloc(struct drm_device *dev,
				struct drm_agp_buffer *request)
{
	return -ENODEV;
}

static inline int drm_agp_free(struct drm_device *dev,
			       struct drm_agp_buffer *request)
{
	return -ENODEV;
}

static inline int drm_agp_unbind(struct drm_device *dev,
				 struct drm_agp_binding *request)
{
	return -ENODEV;
}

static inline int drm_agp_bind(struct drm_device *dev,
			       struct drm_agp_binding *request)
{
	return -ENODEV;
}

#endif /* CONFIG_AGP */

#endif /* _DRM_AGPSUPPORT_H_ */
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