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drm/i915: Remove redundant user_access_end() from __copy_from_user() error path 

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: 0b2c8f8b6b ("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>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://github.com/ClangBuiltLinux/linux/issues/617
Link: https://lkml.kernel.org/r/51a4155c5bc2ca847a9cbe85c1c11918bb193141.1564086017.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2019-07-25 15:29:57 -05:00 committed by Thomas Gleixner
parent 33920f1ec5
commit e6a9522ac3
1 changed files with 9 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
View File

@ -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 @@ end:
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);
}