Re: [PATCH] ARM: mmu: fix access to illegal address when using earlycon & memblock=debug
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2022-08-31 11:53:14
Also in:
lkml
Hi Victor, On 16.03.2022 03:33, Victor Hassan wrote:
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 <redacted>
This patch landed in linux next-20220831 as commit a76886d117cb ("ARM:
9223/1: mmu: fix access to illegal address when using earlycon &
memblock=debug"). Unfortunately it breaks booting of all my test boards
which *do not* use earlycon. It can be easily reproduced even with QEMU.
With kernel compiled from multi_v7_defconfig the following setup boots:
$ qemu-system-arm -nographic -kernel arch/arm/boot/zImage -append
"console=ttyAMA0 earlycon" -M virt -smp 2 -m 512
while this one doesn't:
$ qemu-system-arm -nographic -kernel arch/arm/boot/zImage -append
"console=ttyAMA0" -M virt -smp 2 -m 512
quoted hunk ↗ jump to hunk
--- 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 } /*
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel