lib/ubsan: remove returns-nonnull-attribute checks

Web:        https://git.kernel.org/torvalds/c/bac7a1fff7926fb9891a18fe33650884b0e13e41
Commit:     bac7a1fff7926fb9891a18fe33650884b0e13e41
Parent:     42440c1f9911b4b7b8ba3dc4e90c1197bc561211
Refname:    refs/heads/master
Author:     Andrey Ryabinin <[email protected]>
AuthorDate: Tue Feb 6 15:40:45 2018 -0800
Committer:  Linus Torvalds <[email protected]>
CommitDate: Tue Feb 6 18:32:46 2018 -0800

    lib/ubsan: remove returns-nonnull-attribute checks
    
    Similarly to type mismatch checks, new GCC 8.x and Clang also changed for
    ABI for returns_nonnull checks.  While we can update our code to conform
    the new ABI it's more reasonable to just remove it.  Because it's just
    dead code, we don't have any single user of returns_nonnull attribute in
    the whole kernel.
    
    And AFAIU the advantage that this attribute could bring would be mitigated
    by -fno-delete-null-pointer-checks cflag that we use to build the kernel.
    So it's unlikely we will have a lot of returns_nonnull attribute in
    future.
    
    So let's just remove the code, it has no use.
    
    [[email protected]: fix warning]
      Link: http://lkml.kernel.org/r/[email protected]
    Link: http://lkml.kernel.org/r/[email protected]
    Signed-off-by: Andrey Ryabinin <[email protected]>
    Cc: Sodagudi Prasad <[email protected]>
    Signed-off-by: Andrew Morton <[email protected]>
    Signed-off-by: Linus Torvalds <[email protected]>
---
 lib/ubsan.c            | 24 ------------------------
 lib/ubsan.h            |  5 -----
 scripts/Makefile.ubsan |  1 -
 3 files changed, 30 deletions(-)

diff --git a/lib/ubsan.c b/lib/ubsan.c
index 50d1d5c25deb..59fee96c29a0 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -141,11 +141,6 @@ static void val_to_string(char *str, size_t size, struct type_descriptor *type,
 	}
 }
 
-static bool location_is_valid(struct source_location *loc)
-{
-	return loc->file_name != NULL;
-}
-
 static DEFINE_SPINLOCK(report_lock);
 
 static void ubsan_prologue(struct source_location *location,
@@ -356,25 +351,6 @@ void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
 }
 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
 
-void __ubsan_handle_nonnull_return(struct nonnull_return_data *data)
-{
-	unsigned long flags;
-
-	if (suppress_report(&data->location))
-		return;
-
-	ubsan_prologue(&data->location, &flags);
-
-	pr_err("null pointer returned from function declared to never return null\n");
-
-	if (location_is_valid(&data->attr_location))
-		print_source_location("returns_nonnull attribute specified in",
-				&data->attr_location);
-
-	ubsan_epilogue(&flags);
-}
-EXPORT_SYMBOL(__ubsan_handle_nonnull_return);
-
 void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
 					unsigned long bound)
 {
diff --git a/lib/ubsan.h b/lib/ubsan.h
index 7e30b26497e0..f4d8d0bd4016 100644
--- a/lib/ubsan.h
+++ b/lib/ubsan.h
@@ -57,11 +57,6 @@ struct nonnull_arg_data {
 	int arg_index;
 };
 
-struct nonnull_return_data {
-	struct source_location location;
-	struct source_location attr_location;
-};