linux-hardening - [PATCH 04/15] static_call: Use global functions for the self-test

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Date:   Fri, 16 Apr 2021 13:38:33 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     x86@...nel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH 04/15] static_call: Use global functions for the self-test

With CONFIG_CFI_CLANG, the compiler renames static functions. This
breaks static_call users using static functions, because the current
implementation assumes functions have stable names by hardcoding them
in inline assembly. Make the self-test functions global to prevent the
compiler from renaming them.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
 kernel/static_call.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/static_call.c b/kernel/static_call.c
index 723fcc9d20db..d09f500c2d2a 100644
--- a/kernel/static_call.c
+++ b/kernel/static_call.c
@@ -503,12 +503,12 @@ long __static_call_return0(void)
 
 #ifdef CONFIG_STATIC_CALL_SELFTEST
 
-static int func_a(int x)
+int func_a(int x)
 {
 	return x+1;
 }
 
-static int func_b(int x)
+int func_b(int x)
 {
 	return x+2;
 }
-- 
2.31.1.368.gbe11c130af-goog