Objtool reports:
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x36: redundant UACCESS disable
__copy_from_user() already does both STAC and CLAC, so the user_access_end() in its error path adds an extra unnecessary CLAC.
Fixes: 0b2c8f8b6b0c ("i915: fix missing user_access_end() in page fault exception case") Reported-by: Thomas Gleixner tglx@linutronix.de Reported-by: Sedat Dilek sedat.dilek@gmail.com Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Tested-by: Nick Desaulniers ndesaulniers@google.com Tested-by: Sedat Dilek sedat.dilek@gmail.com Link: https://github.com/ClangBuiltLinux/linux/issues/617 Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com --- .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 20 +++++++++---------- 1 file changed, 9 insertions(+), 11 deletions(-)
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); }