latent_entropy: make builtin_frame_address implicit
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Message ID 1566276458-6233-1-git-send-email-kpark3469@gmail.com
State New
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Series
  • latent_entropy: make builtin_frame_address implicit
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Commit Message

kpark3469@gmail.com Aug. 20, 2019, 4:47 a.m. UTC
From: Sahara <keun-o.park@darkmatter.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@darkmatter.ae>
---
 scripts/gcc-plugins/latent_entropy_plugin.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Kees Cook Aug. 20, 2019, 3:23 p.m. UTC | #1
On Tue, Aug 20, 2019 at 08:47:38AM +0400, kpark3469@gmail.com wrote:
> From: Sahara <keun-o.park@darkmatter.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@darkmatter.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);

Interesting! Is this aarch64-specific or something that has changed in
more recent GCC versions?

Thanks!

-Kees

>  	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
>

Patch
diff mbox series

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);