linux-kernel - [PATCH v2 2/3] tools/nolibc: stackprotector: mark implicitly used symbols as used

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Message-Id: <20240812-nolibc-lto-v2-2-736af7bbefa8@weissschuh.net>
Date: Mon, 12 Aug 2024 22:50:18 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Willy Tarreau <w@....eu>
Cc: Ammar Faizi <ammarfaizi2@...weeb.org>, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH v2 2/3] tools/nolibc: stackprotector: mark implicitly used
 symbols as used

During LTO the references from the compiler-generated prologue and
epilogues to the stack protector symbols are not visible and the symbols
are removed.
This will then lead to errors during linking.
As those symbols are already #ifdeffed-out if unused mark them as "used"
to prevent their removal.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 tools/include/nolibc/stackprotector.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/include/nolibc/stackprotector.h b/tools/include/nolibc/stackprotector.h
index 13f1d0e60387..1d0d5259ec41 100644
--- a/tools/include/nolibc/stackprotector.h
+++ b/tools/include/nolibc/stackprotector.h
@@ -18,7 +18,7 @@
  * triggering stack protector errors themselves
  */
 
-__attribute__((weak,noreturn,section(".text.nolibc_stack_chk")))
+__attribute__((weak,used,noreturn,section(".text.nolibc_stack_chk")))
 void __stack_chk_fail(void)
 {
 	pid_t pid;
@@ -34,7 +34,7 @@ void __stack_chk_fail_local(void)
 	__stack_chk_fail();
 }
 
-__attribute__((weak,section(".data.nolibc_stack_chk")))
+__attribute__((weak,used,section(".data.nolibc_stack_chk")))
 uintptr_t __stack_chk_guard;
 
 static __no_stack_protector void __stack_chk_init(void)

-- 
2.46.0