Messages in this thread Patch in this message | | | Date | Tue, 23 Jul 2019 21:43:24 -0500 | From | Josh Poimboeuf <> | Subject | Re: x86 - clang / objtool status |
| |
On Thu, Jul 18, 2019 at 10:40:09PM +0200, Thomas Gleixner wrote:
> drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x86: redundant UACCESS disable
Looking at this one, I think I agree with objtool.
PeterZ, Linus, I know y'all discussed this code a few months ago.
__copy_from_user() already does a CLAC in its error path. So isn't the user_access_end() redundant for the __copy_from_user() error path?
Untested fix:
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index 5fae0e50aad0..41dab9ea33cd 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -1628,6 +1628,7 @@ static int check_relocations(const struct drm_i915_gem_exec_object2 *entry) static int eb_copy_relocations(const struct i915_execbuffer *eb) { + struct drm_i915_gem_relocation_entry *relocs; const unsigned int count = eb->buffer_count; unsigned int i; int err; @@ -1635,7 +1636,6 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) for (i = 0; i < count; i++) { const unsigned int nreloc = eb->exec[i].relocation_count; struct drm_i915_gem_relocation_entry __user *urelocs; - struct drm_i915_gem_relocation_entry *relocs; unsigned long size; unsigned long copied; @@ -1663,14 +1663,8 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) if (__copy_from_user((char *)relocs + copied, (char __user *)urelocs + copied, - len)) { -end_user: - user_access_end(); -end: - kvfree(relocs); - err = -EFAULT; - goto err; - } + len)) + goto end; copied += len; } while (copied < size); @@ -1699,10 +1693,14 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) return 0; +end_user: + user_access_end(); +end: + kvfree(relocs); + err = -EFAULT; err: while (i--) { - struct drm_i915_gem_relocation_entry *relocs = - u64_to_ptr(typeof(*relocs), eb->exec[i].relocs_ptr); + relocs = u64_to_ptr(typeof(*relocs), eb->exec[i].relocs_ptr); if (eb->exec[i].relocation_count) kvfree(relocs); }
| |