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Message-Id: <6da6fa391c0d6344cc9ff99a69fcaa65666f3947.1585811416.git.christophe.leroy@c-s.fr>
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From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH RESEND 3/4] drm/i915/gem: Replace user_access_begin by
 user_write_access_begin
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, airlied@linux.ie,
        daniel@ffwll.ch, torvalds@linux-foundation.org,
        viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
        keescook@chromium.org, hpa@zytor.com
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mm@kvack.org, linux-arch@vger.kernel.org
Date:   Thu,  2 Apr 2020 07:34:18 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When i915_gem_execbuffer2_ioctl() is using user_access_begin(),
that's only to perform unsafe_put_user() so use
user_write_access_begin() in order to only open write access.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 7643a30ba4cd..4be8205a70b6 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1611,14 +1611,14 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb)
 		 * happened we would make the mistake of assuming that the
 		 * relocations were valid.
 		 */
-		if (!user_access_begin(urelocs, size))
+		if (!user_write_access_begin(urelocs, size))
 			goto end;
 
 		for (copied = 0; copied < nreloc; copied++)
 			unsafe_put_user(-1,
 					&urelocs[copied].presumed_offset,
 					end_user);
-		user_access_end();
+		user_write_access_end();
 
 		eb->exec[i].relocs_ptr = (uintptr_t)relocs;
 	}
@@ -1626,7 +1626,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb)
 	return 0;
 
 end_user:
-	user_access_end();
+	user_write_access_end();
 end:
 	kvfree(relocs);
 	err = -EFAULT;
@@ -2991,7 +2991,8 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 		 * And this range already got effectively checked earlier
 		 * when we did the "copy_from_user()" above.
 		 */
-		if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list)))
+		if (!user_write_access_begin(user_exec_list,
+					     count * sizeof(*user_exec_list)))
 			goto end;
 
 		for (i = 0; i < args->buffer_count; i++) {
@@ -3005,7 +3006,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 					end_user);
 		}
 end_user:
-		user_access_end();
+		user_write_access_end();
 end:;
 	}
 
-- 
2.25.0