Subject: [PATCH v6 13/15] sh: cast away constness from the zero page when flushing it from the cache

From: Ard Biesheuvel <[email-masked]>
Date: Tue, 26 May 2026 19:59:00 +0200

From: Ard Biesheuvel <[email-masked]>

SH performs cache maintenance on the zero page during boot, presumably
to ensure that any clearing of BSS that has occurred at startup is
visible to other CPUs and DMA devices.

The __flush_wback_region() function takes a void* argument, which is
conceptually sound, but given that empty_zero_page[] must never be
modified, it is being repainted as const, making it incompatible with a
void* formal parameter.

Given the above, and the fact that __flush_wback_region() is in fact a
function pointer variable with multiple implementations, take the easy
way out, and cast away the constness in this particular invocation.

Cc: Yoshinori Sato <[email-masked]>
Cc: Rich Felker <[email-masked]>
Cc: John Paul Adrian Glaubitz <[email-masked]>
Signed-off-by: Ard Biesheuvel <[email-masked]>
---
 arch/sh/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index 4e40d5e96be9..acbb481cdbfe 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -332,7 +332,7 @@ void __init mem_init(void)
 	cpu_cache_init();
 
 	/* clear the zero-page */
-	__flush_wback_region(empty_zero_page, PAGE_SIZE);
+	__flush_wback_region((void *)empty_zero_page, PAGE_SIZE);
 
 	vsyscall_init();
 
-- 
2.54.0.794.g4f17f83d09-goog