linux-kernel - Re: Remaining randconfig objtool warnings, linux-next-20200428

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Message-ID: <20200501123319.GC3762@hirez.programming.kicks-ass.net>
Date:   Fri, 1 May 2020 14:33:19 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Remaining randconfig objtool warnings, linux-next-20200428

On Thu, Apr 30, 2020 at 08:07:33PM -0500, Josh Poimboeuf wrote:
> On Thu, Apr 30, 2020 at 04:05:07PM +0200, Arnd Bergmann wrote:
> > lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x133: call to do_strncpy_from_user() with UACCESS enabled
> > lib/strnlen_user.o: warning: objtool: strnlen_user()+0x122: call to do_strnlen_user() with UACCESS enabled
> 
> Does this fix it?
> 

GCC is a moron, a static function with inline and a single callsite,
let's out-of-line it, shees!, try this instead:

diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 706020b06617..be420c8c0fdd 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -24,7 +24,7 @@
  * hit it), 'max' is the address space maximum (and we return
  * -EFAULT if we hit it).
  */
-static inline long do_strncpy_from_user(char *dst, const char __user *src,
+static __always_inline long do_strncpy_from_user(char *dst, const char __user *src,
 					unsigned long count, unsigned long max)
 {
 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index 41670d4a5816..c996b745733e 100644
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -20,7 +20,7 @@
  * if it fits in a aligned 'long'. The caller needs to check
  * the return value against "> max".
  */
-static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
+static __always_inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
 {
 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
 	unsigned long align, res = 0;