linux-kernel - [PATCH] ARM: mmu: fix access to illegal address when using earlycon & memblock=debug

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Date:   Wed, 16 Mar 2022 10:33:56 +0800
From:   Victor Hassan <victor@...winnertech.com>
To:     linux@...linux.org.uk, rmk+kernel@...linux.org.uk,
        linus.walleij@...aro.org, yanfei.xu@...driver.com, ardb@...nel.org,
        tglx@...utronix.de, mirq-linux@...e.qmqm.pl, arnd@...db.de
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        allwinner-opensource-support@...winnertech.com,
        Victor Hassan <victor@...winnertech.com>
Subject: [PATCH] ARM: mmu: fix access to illegal address when using earlycon & memblock=debug

earlycon uses fixmap to create a memory map,
So we need to close earlycon before closing fixmap,
otherwise printk will access illegal addresses.
After creating a new memory map, we open earlycon again.

Signed-off-by: Victor Hassan <victor@...winnertech.com>
---
 arch/arm/mm/mmu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 274e4f73fd33..f3511f07a7d0 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -14,6 +14,7 @@
 #include <linux/fs.h>
 #include <linux/vmalloc.h>
 #include <linux/sizes.h>
+#include <linux/console.h>
 
 #include <asm/cp15.h>
 #include <asm/cputype.h>
@@ -1695,6 +1696,9 @@ static void __init early_fixmap_shutdown(void)
 	pmd_clear(fixmap_pmd(va));
 	local_flush_tlb_kernel_page(va);
 
+#ifdef CONFIG_FIX_EARLYCON_MEM
+	console_stop(console_drivers);
+#endif
 	for (i = 0; i < __end_of_permanent_fixed_addresses; i++) {
 		pte_t *pte;
 		struct map_desc map;
@@ -1713,6 +1717,9 @@ static void __init early_fixmap_shutdown(void)
 
 		create_mapping(&map);
 	}
+#ifdef CONFIG_FIX_EARLYCON_MEM
+	console_start(console_drivers);
+#endif
 }
 
 /*
-- 
2.29.0