From ea0b163b13ffc52818c079adb00d55e227a6da6f Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 11 Nov 2019 08:13:24 -0800
Subject: drm/i915/cmdparser: Fix jump whitelist clearing
Git-commit: ea0b163b13ffc52818c079adb00d55e227a6da6f
Patch-mainline: v5.4-rc8
References: bsc#1152489

When a jump_whitelist bitmap is reused, it needs to be cleared.
Currently this is done with memset() and the size calculation assumes
bitmaps are made of 32-bit words, not longs.  So on 64-bit
architectures, only the first half of the bitmap is cleared.

If some whitelist bits are carried over between successive batches
submitted on the same context, this will presumably allow embedding
the rogue instructions that we're trying to reject.

Use bitmap_zero() instead, which gets the calculation right.

Fixes: f8c08d8faee5 ("drm/i915/cmdparser: Add support for backward jumps")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jon Bloomfield <jon.bloomfield@intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/i915/i915_cmd_parser.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index d78debed06e2..f24096e27bef 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -1375,7 +1375,7 @@ static void init_whitelist(struct i915_gem_context *ctx, u32 batch_len)
 		return;
 
 	if (batch_cmds <= ctx->jump_whitelist_cmds) {
-		memset(ctx->jump_whitelist, 0, exact_size * sizeof(u32));
+		bitmap_zero(ctx->jump_whitelist, batch_cmds);
 		return;
 	}
 
@@ -1395,8 +1395,7 @@ static void init_whitelist(struct i915_gem_context *ctx, u32 batch_len)
 	}
 
 	DRM_DEBUG("CMD: Failed to extend whitelist. BB_START may be disallowed\n");
-	memset(ctx->jump_whitelist, 0,
-	       BITS_TO_LONGS(ctx->jump_whitelist_cmds) * sizeof(u32));
+	bitmap_zero(ctx->jump_whitelist, ctx->jump_whitelist_cmds);
 
 	return;
 }
-- 
2.28.0