linux-kernel - [PATCH 10/46] static_call, lto: Mark func_a() as __visible_on

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Date:   Mon, 14 Nov 2022 12:43:08 +0100
From:   "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Andi Kleen <andi@...stfloor.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Jason Baron <jbaron@...mai.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Martin Liska <mliska@...e.cz>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 10/46] static_call, lto: Mark func_a() as __visible_on_lto

From: Andi Kleen <andi@...stfloor.org>

Symbols referenced from assembler (either directly or e.f. from
DEFINE_STATIC_KEY()) need to be global and visible in gcc LTO because
they could end up in a different object file than the assembler. This
can lead to linker errors without this patch.

So mark func_a() as __visible_on_lto as it was static.

[js] use __visible_on_lto

Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Andi Kleen <andi@...stfloor.org>
Signed-off-by: Martin Liska <mliska@...e.cz>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 kernel/static_call_inline.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
index dc5665b62814..6933b4437597 100644
--- a/kernel/static_call_inline.c
+++ b/kernel/static_call_inline.c
@@ -501,7 +501,7 @@ early_initcall(static_call_init);
 
 #ifdef CONFIG_STATIC_CALL_SELFTEST
 
-static int func_a(int x)
+__visible_on_lto int sc_func_a(int x)
 {
 	return x+1;
 }
@@ -511,7 +511,7 @@ static int func_b(int x)
 	return x+2;
 }
 
-DEFINE_STATIC_CALL(sc_selftest, func_a);
+DEFINE_STATIC_CALL(sc_selftest, sc_func_a);
 
 static struct static_call_data {
       int (*func)(int);
@@ -520,7 +520,7 @@ static struct static_call_data {
 } static_call_data [] __initdata = {
       { NULL,   2, 3 },
       { func_b, 2, 4 },
-      { func_a, 2, 3 }
+      { sc_func_a, 2, 3 }
 };
 
 static int __init test_static_call_init(void)
-- 
2.38.1