From fddcd00a49e9122a3579247151e9cb3ce5a1a36e Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 3 Sep 2018 09:33:35 +0100 Subject: [PATCH] drm/i915: Force the slow path after a user-write error If we fail to write the user relocation back when it is changed, force ourselves to take the slow relocation path where we can handle faults in the write path. There is still an element of dubiousness as having patched up the batch to use the correct offset, it no longer matches the presumed_offset in the relocation, so a second pass may miss any changes in layout. Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20180903083337.13134-3-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_execbuffer.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 020a2394fc85..43706c1db31a 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -1491,8 +1491,10 @@ static int eb_relocate_vma(struct i915_execbuffer *eb, struct i915_vma *vma) * can read from this userspace address. */ offset = gen8_canonical_addr(offset & ~UPDATE); - __put_user(offset, - &urelocs[r-stack].presumed_offset); + if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) { + remain = -EFAULT; + goto out; + } } } while (r++, --count); urelocs += ARRAY_SIZE(stack); @@ -1577,7 +1579,6 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) relocs = kvmalloc_array(size, 1, GFP_KERNEL); if (!relocs) { - kvfree(relocs); err = -ENOMEM; goto err; } @@ -1591,6 +1592,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) if (__copy_from_user((char *)relocs + copied, (char __user *)urelocs + copied, len)) { +end_user: kvfree(relocs); err = -EFAULT; goto err; @@ -1614,7 +1616,6 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) unsafe_put_user(-1, &urelocs[copied].presumed_offset, end_user); -end_user: user_access_end(); eb->exec[i].relocs_ptr = (uintptr_t)relocs; -- 2.11.0