linux-kernel - [PATCH v3 2/3] openrisc: Fix cache API compile issue when not inlining

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Message-Id: <20200910233940.2132107-3-shorne@gmail.com>
Date:   Fri, 11 Sep 2020 08:39:39 +0900
From:   Stafford Horne <shorne@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Stafford Horne <shorne@...il.com>, Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        openrisc@...ts.librecores.org
Subject: [PATCH v3 2/3] openrisc: Fix cache API compile issue when not inlining

I found this when compiling a kbuild random config with GCC 11.  The
config enables CONFIG_DEBUG_SECTION_MISMATCH, which sets CFLAGS
-fno-inline-functions-called-once. This causes the call to cache_loop in
cache.c to not be inlined causing the below compile error.

    In file included from arch/openrisc/mm/cache.c:13:
    arch/openrisc/mm/cache.c: In function 'cache_loop':
    ./arch/openrisc/include/asm/spr.h:16:27: warning: 'asm' operand 0 probably does not match constraints
       16 | #define mtspr(_spr, _val) __asm__ __volatile__ (  \
	  |                           ^~~~~~~
    arch/openrisc/mm/cache.c:25:3: note: in expansion of macro 'mtspr'
       25 |   mtspr(reg, line);
	  |   ^~~~~
    ./arch/openrisc/include/asm/spr.h:16:27: error: impossible constraint in 'asm'
       16 | #define mtspr(_spr, _val) __asm__ __volatile__ (  \
	  |                           ^~~~~~~
    arch/openrisc/mm/cache.c:25:3: note: in expansion of macro 'mtspr'
       25 |   mtspr(reg, line);
	  |   ^~~~~
    make[1]: *** [scripts/Makefile.build:283: arch/openrisc/mm/cache.o] Error 1

The asm constraint "K" requires a immediate constant argument to mtspr,
however because of no inlining a register argument is passed causing a
failure.  Fix this by using __always_inline.

Link: https://lore.kernel.org/lkml/202008200453.ohnhqkjQ%25lkp@intel.com/
Signed-off-by: Stafford Horne <shorne@...il.com>
---
Changes since v2:
 - None
Changes since v1:
 - New

 arch/openrisc/mm/cache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/openrisc/mm/cache.c b/arch/openrisc/mm/cache.c
index 08f56af387ac..534a52ec5e66 100644
--- a/arch/openrisc/mm/cache.c
+++ b/arch/openrisc/mm/cache.c
@@ -16,7 +16,7 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
-static void cache_loop(struct page *page, const unsigned int reg)
+static __always_inline void cache_loop(struct page *page, const unsigned int reg)
 {
 	unsigned long paddr = page_to_pfn(page) << PAGE_SHIFT;
 	unsigned long line = paddr & ~(L1_CACHE_BYTES - 1);
-- 
2.26.2