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Subject[rfc][patch] reimplement nopfn callers with fault
Hi guys,

I'd like to finally remove nopfn from the tree. So I would really like to get
this patch into -mm soon (or broken out patches into appropriate trees).

Anyway, I don't have a good way to compile mspec or cell changes very easily.
Hopefully if there are any silly typos, they will be easier to fix. More problematic
is actually testing the things; I'm not even sure I'm covering all bases with
drm testing.

So, if I could trouble you for a quick review and/or test at some time.... the
patch is against latest -mm.

Thanks,
Nick

---

From: Nick Piggin <npiggin@suse.de>

Reimplement the existing nopfn handlers with ->fault so we can subsequently remove
nopfn.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jes Sorensen <jes@sgi.com>
Cc: Cliff Wickman <cpw@sgi.com>
Cc: airlied@linux.ie
Cc: benh@kernel.crashing.org
Cc: michael@ellerman.id.au
Cc: jk@ozlabs.org
Cc: Cedric Le Goater <clg@fr.ibm.com>
---

arch/powerpc/platforms/cell/spufs/file.c | 85 ++++++++++++++-----------------
drivers/char/drm/drm_vm.c | 33 +++++-------
drivers/char/mspec.c | 23 +++++---
3 files changed, 68 insertions(+), 73 deletions(-)

Index: linux-2.6/arch/powerpc/platforms/cell/spufs/file.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/spufs/file.c
+++ linux-2.6/arch/powerpc/platforms/cell/spufs/file.c
@@ -237,11 +237,10 @@ spufs_mem_write(struct file *file, const
return size;
}

-static unsigned long spufs_mem_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_mem_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct spu_context *ctx = vma->vm_file->private_data;
- unsigned long pfn, offset, addr0 = address;
+ unsigned long pfn, offset, address = (unsigned long)vmf->virtual_address;
#ifdef CONFIG_SPU_FS_64K_LS
struct spu_state *csa = &ctx->csa;
int psize;
@@ -259,15 +258,14 @@ static unsigned long spufs_mem_mmap_nopf
}
#endif /* CONFIG_SPU_FS_64K_LS */

- offset = (address - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
+ offset = vmf->pgoff << PAGE_SHIFT;
if (offset >= LS_SIZE)
- return NOPFN_SIGBUS;
+ return VM_FAULT_SIGBUS;

- pr_debug("spufs_mem_mmap_nopfn address=0x%lx -> 0x%lx, offset=0x%lx\n",
- addr0, address, offset);
+ pr_debug("spufs_mem_mmap_fault address=0x%lx, offset=0x%lx\n", address, offset);

if (spu_acquire(ctx))
- return NOPFN_REFAULT;
+ return VM_FAULT_NOPAGE;

if (ctx->state == SPU_STATE_SAVED) {
vma->vm_page_prot = __pgprot(pgprot_val(vma->vm_page_prot)
@@ -278,16 +276,16 @@ static unsigned long spufs_mem_mmap_nopf
| _PAGE_NO_CACHE);
pfn = (ctx->spu->local_store_phys + offset) >> PAGE_SHIFT;
}
- vm_insert_pfn(vma, address, pfn);
+ vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);

spu_release(ctx);

- return NOPFN_REFAULT;
+ return VM_FAULT_NOPAGE;
}


static struct vm_operations_struct spufs_mem_mmap_vmops = {
- .nopfn = spufs_mem_mmap_nopfn,
+ .fault = spufs_mem_mmap_fault,
};

static int spufs_mem_mmap(struct file *file, struct vm_area_struct *vma)
@@ -350,28 +348,27 @@ static const struct file_operations spuf
#endif
};

-static unsigned long spufs_ps_nopfn(struct vm_area_struct *vma,
- unsigned long address,
+static int spufs_ps_fault(struct vm_area_struct *vma,
+ struct vm_fault *vmf,
unsigned long ps_offs,
unsigned long ps_size)
{
struct spu_context *ctx = vma->vm_file->private_data;
- unsigned long area, offset = address - vma->vm_start;
+ unsigned long area, offset = vmf->pgoff << PAGE_SHIFT;

- offset += vma->vm_pgoff << PAGE_SHIFT;
if (offset >= ps_size)
- return NOPFN_SIGBUS;
+ return VM_FAULT_SIGBUS;

/*
* We have to wait for context to be loaded before we have
* pages to hand out to the user, but we don't want to wait
* with the mmap_sem held.
* It is possible to drop the mmap_sem here, but then we need
- * to return NOPFN_REFAULT because the mappings may have
+ * to return VM_FAULT_NOPAGE because the mappings may have
* hanged.
*/
if (spu_acquire(ctx))
- return NOPFN_REFAULT;
+ return VM_FAULT_NOPAGE;

if (ctx->state == SPU_STATE_SAVED) {
up_read(&current->mm->mmap_sem);
@@ -379,22 +376,23 @@ static unsigned long spufs_ps_nopfn(stru
down_read(&current->mm->mmap_sem);
} else {
area = ctx->spu->problem_phys + ps_offs;
- vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
+ vm_insert_pfn(vma, (unsigned long)vmf->virtual_address,
+ (area + offset) >> PAGE_SHIFT);
}

spu_release(ctx);
- return NOPFN_REFAULT;
+ return VM_FAULT_NOPAGE;
}

#if SPUFS_MMAP_4K
-static unsigned long spufs_cntl_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_cntl_mmap_fault(struct vm_area_struct *vma,
+ struct vm_fault *vmf)
{
- return spufs_ps_nopfn(vma, address, 0x4000, 0x1000);
+ return spufs_ps_fault(vma, vmf, 0x4000, 0x1000);
}

static struct vm_operations_struct spufs_cntl_mmap_vmops = {
- .nopfn = spufs_cntl_mmap_nopfn,
+ .fault = spufs_cntl_mmap_fault,
};

/*
@@ -1074,23 +1072,22 @@ static ssize_t spufs_signal1_write(struc
return 4;
}

-static unsigned long spufs_signal1_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_signal1_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
#if PAGE_SIZE == 0x1000
- return spufs_ps_nopfn(vma, address, 0x14000, 0x1000);
+ return spufs_ps_fault(vma, vmf, 0x14000, 0x1000);
#elif PAGE_SIZE == 0x10000
/* For 64k pages, both signal1 and signal2 can be used to mmap the whole
* signal 1 and 2 area
*/
- return spufs_ps_nopfn(vma, address, 0x10000, 0x10000);
+ return spufs_ps_fault(vma, vmf, 0x10000, 0x10000);
#else
#error unsupported page size
#endif
}

static struct vm_operations_struct spufs_signal1_mmap_vmops = {
- .nopfn = spufs_signal1_mmap_nopfn,
+ .fault = spufs_signal1_mmap_fault,
};

static int spufs_signal1_mmap(struct file *file, struct vm_area_struct *vma)
@@ -1211,23 +1208,22 @@ static ssize_t spufs_signal2_write(struc
}

#if SPUFS_MMAP_4K
-static unsigned long spufs_signal2_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_signal2_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
#if PAGE_SIZE == 0x1000
- return spufs_ps_nopfn(vma, address, 0x1c000, 0x1000);
+ return spufs_ps_fault(vma, vmf, 0x1c000, 0x1000);
#elif PAGE_SIZE == 0x10000
/* For 64k pages, both signal1 and signal2 can be used to mmap the whole
* signal 1 and 2 area
*/
- return spufs_ps_nopfn(vma, address, 0x10000, 0x10000);
+ return spufs_ps_fault(vma, vmf, 0x10000, 0x10000);
#else
#error unsupported page size
#endif
}

static struct vm_operations_struct spufs_signal2_mmap_vmops = {
- .nopfn = spufs_signal2_mmap_nopfn,
+ .fault = spufs_signal2_mmap_fault,
};

static int spufs_signal2_mmap(struct file *file, struct vm_area_struct *vma)
@@ -1339,14 +1335,13 @@ DEFINE_SPUFS_ATTRIBUTE(spufs_signal2_typ
spufs_signal2_type_set, "%llu", SPU_ATTR_ACQUIRE);

#if SPUFS_MMAP_4K
-static unsigned long spufs_mss_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_mss_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- return spufs_ps_nopfn(vma, address, 0x0000, 0x1000);
+ return spufs_ps_fault(vma, vmf, 0x0000, 0x1000);
}

static struct vm_operations_struct spufs_mss_mmap_vmops = {
- .nopfn = spufs_mss_mmap_nopfn,
+ .fault = spufs_mss_mmap_fault,
};

/*
@@ -1401,14 +1396,13 @@ static const struct file_operations spuf
.mmap = spufs_mss_mmap,
};

-static unsigned long spufs_psmap_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_psmap_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- return spufs_ps_nopfn(vma, address, 0x0000, 0x20000);
+ return spufs_ps_fault(vma, vmf, 0x0000, 0x20000);
}

static struct vm_operations_struct spufs_psmap_mmap_vmops = {
- .nopfn = spufs_psmap_mmap_nopfn,
+ .fault = spufs_psmap_mmap_fault,
};

/*
@@ -1461,14 +1455,13 @@ static const struct file_operations spuf


#if SPUFS_MMAP_4K
-static unsigned long spufs_mfc_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int spufs_mfc_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- return spufs_ps_nopfn(vma, address, 0x3000, 0x1000);
+ return spufs_ps_fault(vma, vmf, 0x3000, 0x1000);
}

static struct vm_operations_struct spufs_mfc_mmap_vmops = {
- .nopfn = spufs_mfc_mmap_nopfn,
+ .fault = spufs_mfc_mmap_fault,
};

/*
Index: linux-2.6/drivers/char/mspec.c
===================================================================
--- linux-2.6.orig/drivers/char/mspec.c
+++ linux-2.6/drivers/char/mspec.c
@@ -193,25 +193,23 @@ mspec_close(struct vm_area_struct *vma)
}

/*
- * mspec_nopfn
+ * mspec_fault
*
* Creates a mspec page and maps it to user space.
*/
-static unsigned long
-mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
+static int
+mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
unsigned long paddr, maddr;
unsigned long pfn;
- int index;
+ pgoff_t index = vmf->pgoff;
struct vma_data *vdata = vma->vm_private_data;

- BUG_ON(address < vdata->vm_start || address >= vdata->vm_end);
- index = (address - vdata->vm_start) >> PAGE_SHIFT;
maddr = (volatile unsigned long) vdata->maddr[index];
if (maddr == 0) {
maddr = uncached_alloc_page(numa_node_id());
if (maddr == 0)
- return NOPFN_OOM;
+ return VM_FAULT_OOM;

spin_lock(&vdata->lock);
if (vdata->maddr[index] == 0) {
@@ -231,13 +229,20 @@ mspec_nopfn(struct vm_area_struct *vma,

pfn = paddr >> PAGE_SHIFT;

- return pfn;
+ /*
+ * vm_insert_pfn can fail with -EBUSY, but in that case it will
+ * be because another thread has installed the pte first, so it
+ * is no problem.
+ */
+ vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
+
+ return VM_FAULT_NOPAGE;
}

static struct vm_operations_struct mspec_vm_ops = {
.open = mspec_open,
.close = mspec_close,
- .nopfn = mspec_nopfn
+ .fault = mspec_fault,
};

/*
Index: linux-2.6/drivers/char/drm/drm_vm.c
===================================================================
--- linux-2.6.orig/drivers/char/drm/drm_vm.c
+++ linux-2.6/drivers/char/drm/drm_vm.c
@@ -683,8 +683,8 @@ EXPORT_SYMBOL(drm_mmap);
* \c Pagefault method for buffer objects.
*
* \param vma Virtual memory area.
- * \param address File offset.
- * \return Error or refault. The pfn is manually inserted.
+ * \param vmf vm fault data.
+ * \return Error or VM_FAULT_NOPAGE: the pfn is manually inserted.
*
* It's important that pfns are inserted while holding the bo->mutex lock.
* otherwise we might race with unmap_mapping_range() which is always
@@ -696,8 +696,7 @@ EXPORT_SYMBOL(drm_mmap);
* protected by the bo->mutex lock.
*/

-static unsigned long drm_bo_vm_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static int drm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct drm_buffer_object *bo = (struct drm_buffer_object *) vma->vm_private_data;
unsigned long page_offset;
@@ -709,25 +708,22 @@ static unsigned long drm_bo_vm_nopfn(str
unsigned long bus_base;
unsigned long bus_offset;
unsigned long bus_size;
- unsigned long ret = NOPFN_REFAULT;
-
- if (address > vma->vm_end)
- return NOPFN_SIGBUS;
+ unsigned long ret = VM_FAULT_NOPAGE;

dev = bo->dev;
err = drm_bo_read_lock(&dev->bm.bm_lock);
if (err)
- return NOPFN_REFAULT;
+ return VM_FAULT_NOPAGE;

err = mutex_lock_interruptible(&bo->mutex);
if (err) {
drm_bo_read_unlock(&dev->bm.bm_lock);
- return NOPFN_REFAULT;
+ return VM_FAULT_NOPAGE;
}

err = drm_bo_wait(bo, 0, 0, 0);
if (err) {
- ret = (err != -EAGAIN) ? NOPFN_SIGBUS : NOPFN_REFAULT;
+ ret = (err != -EAGAIN) ? VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
goto out_unlock;
}

@@ -742,7 +738,7 @@ static unsigned long drm_bo_vm_nopfn(str
DRM_BO_FLAG_FORCE_MAPPABLE;
err = drm_bo_move_buffer(bo, new_mask, 0, 0);
if (err) {
- ret = (err != -EAGAIN) ? NOPFN_SIGBUS : NOPFN_REFAULT;
+ ret = (err != -EAGAIN) ? VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
goto out_unlock;
}
}
@@ -751,11 +747,12 @@ static unsigned long drm_bo_vm_nopfn(str
&bus_size);

if (err) {
- ret = NOPFN_SIGBUS;
+ ret = VM_FAULT_SIGBUS;
goto out_unlock;
}

- page_offset = (address - vma->vm_start) >> PAGE_SHIFT;
+ /* XXX: vmf->pgoff may work here, but it adds on vma->vm_pgoff */
+ page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >> PAGE_SHIFT;

if (bus_size) {
struct drm_mem_type_manager *man = &dev->bm.man[bo->mem.mem_type];
@@ -768,7 +765,7 @@ static unsigned long drm_bo_vm_nopfn(str
drm_ttm_fixup_caching(ttm);
page = drm_ttm_get_page(ttm, page_offset);
if (!page) {
- ret = NOPFN_OOM;
+ ret = VM_FAULT_OOM;
goto out_unlock;
}
pfn = page_to_pfn(page);
@@ -777,9 +774,9 @@ static unsigned long drm_bo_vm_nopfn(str
drm_io_prot(_DRM_TTM, vma);
}

- err = vm_insert_pfn(vma, address, pfn);
+ err = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
if (err) {
- ret = (err != -EAGAIN) ? NOPFN_OOM : NOPFN_REFAULT;
+ ret = (err != -EAGAIN) ? VM_FAULT_OOM : VM_FAULT_NOPAGE;
goto out_unlock;
}
out_unlock:
@@ -834,7 +831,7 @@ static void drm_bo_vm_close(struct vm_ar
}

static struct vm_operations_struct drm_bo_vm_ops = {
- .nopfn = drm_bo_vm_nopfn,
+ .fault = drm_bo_vm_fault,
.open = drm_bo_vm_open,
.close = drm_bo_vm_close,
};

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