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SubjectRe: [PATCH] kallsyms: work around bogus -Wrestrict warning
On Tue,  7 Jan 2020 22:40:26 +0100 Arnd Bergmann <arnd@arndb.de> wrote:

> 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.
>
> ...
>
> --- 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;

gee, is that even worth "fixing"? Oleksandr, I've seen a couple of
these false positives. Do we know if anyone is taking them to the gcc
developers?

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