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Date: Tue, 20 Aug 2019 08:47:38 +0400
From: kpark3469@...il.com
To: kernel-hardening@...ts.openwall.com
Cc: keescook@...omium.org,
	re.emese@...il.com,
	keun-o.park@...kmatter.ae
Subject: [PATCH] latent_entropy: make builtin_frame_address implicit

From: Sahara <keun-o.park@...kmatter.ae>

When Android toolchain for aarch64 is used to build this plugin,
builtin_decl_implicit(BUILT_IN_FRAME_ADDRESS) returns NULL_TREE.
Due to this issue, the returned NULL_TREE from builtin_decl_implicit
causes compiler's unexpected fault in the next gimple_build_call.
To avoid this problem, let's make it implicit before calling
builtin_decl_implicit() for the frame address.

Signed-off-by: Sahara <keun-o.park@...kmatter.ae>
---
 scripts/gcc-plugins/latent_entropy_plugin.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/gcc-plugins/latent_entropy_plugin.c b/scripts/gcc-plugins/latent_entropy_plugin.c
index cbe1d6c..7571990 100644
--- a/scripts/gcc-plugins/latent_entropy_plugin.c
+++ b/scripts/gcc-plugins/latent_entropy_plugin.c
@@ -446,6 +446,8 @@ static void init_local_entropy(basic_block bb, tree local_entropy)
 	frame_addr = create_var(ptr_type_node, "local_entropy_frameaddr");
 
 	/* 2. local_entropy_frameaddr = __builtin_frame_address() */
+	if (!builtin_decl_implicit_p(BUILT_IN_FRAME_ADDRESS))
+		set_builtin_decl_implicit_p(BUILT_IN_FRAME_ADDRESS, true);
 	fndecl = builtin_decl_implicit(BUILT_IN_FRAME_ADDRESS);
 	call = gimple_build_call(fndecl, 1, integer_zero_node);
 	gimple_call_set_lhs(call, frame_addr);
-- 
2.7.4

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