linux-kernel - [PATCH] kallsyms: work around bogus -Wrestrict warning

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Message-Id: <20200107214042.855757-1-arnd@arndb.de>
Date:   Tue,  7 Jan 2020 22:40:26 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Oleksandr Natalenko <oleksandr@...hat.com>, linux-mm@...ck.org,
        Arnd Bergmann <arnd@...db.de>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Will Deacon <will@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Song Liu <songliubraving@...com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] kallsyms: work around bogus -Wrestrict warning

gcc -O3 produces some really odd warnings for this file:

kernel/kallsyms.c: In function 'sprint_symbol':
kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict]
   strcpy(buffer, name);
   ^~~~~~~~~~~~~~~~~~~~
kernel/kallsyms.c: In function 'sprint_symbol_no_offset':
kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict]
   strcpy(buffer, name);
   ^~~~~~~~~~~~~~~~~~~~
kernel/kallsyms.c: In function 'sprint_backtrace':
kernel/kallsyms.c:369:3: error: 'strcpy' source argument is the same as destination [-Werror=restrict]
   strcpy(buffer, name);
   ^~~~~~~~~~~~~~~~~~~~

This obviously cannot be since it is preceded by an 'if (name != buffer)'
check.

Using sprintf() instead of strcpy() is a bit wasteful but is
the best workaround I could come up with.

Fixes: mmtom ("init/Kconfig: enable -O3 for all arches")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 kernel/kallsyms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index d812b90f4c86..726b8eeb223e 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -366,7 +366,7 @@ static int __sprint_symbol(char *buffer, unsigned long address,
 		return sprintf(buffer, "0x%lx", address - symbol_offset);
 
 	if (name != buffer)
-		strcpy(buffer, name);
+		sprintf(buffer, "%s", name);
 	len = strlen(buffer);
 	offset -= symbol_offset;
 
-- 
2.20.0