From 21fc7ec93f8b633b60d5bddef2f1529ff6b36185 Mon Sep 17 00:00:00 2001 From: Yu Peng Date: Wed, 8 Jul 2026 10:35:14 +0800 Subject: [PATCH] arm64: fixmap: Allow 256K early_ioremap() at any offset NR_FIX_BTMAPS is the per-slot page limit for early_ioremap(). Since __early_ioremap() maps the page-aligned physical range, a 256K request can require one extra page when the physical address is not page-aligned. Reserve one extra page per slot so the 256K mapping budget is usable regardless of the initial page offset. Link: https://lore.kernel.org/r/08fd96fa-ee3a-4904-bd11-bb08bd90436f@kylinos.cn Signed-off-by: Yu Peng Signed-off-by: Will Deacon --- arch/arm64/include/asm/fixmap.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h index 65555284446e..7075a3bd2c61 100644 --- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -78,8 +78,12 @@ enum fixed_addresses { /* * Temporary boot-time mappings, used by early_ioremap(), * before ioremap() is functional. + * + * Reserve one extra page so a 256K mapping may start at any + * offset within a page. early_ioremap() maps the page-aligned + * physical range, so the initial offset can consume an extra page. */ -#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE) +#define NR_FIX_BTMAPS ((SZ_256K / PAGE_SIZE) + 1) #define FIX_BTMAPS_SLOTS 7 #define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)