linux-kernel - [PATCH] riscv: reserve DTB before possible memblock allocation

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Message-ID: <tencent_B15C0F1F3105597D0DCE7DADC96C5EB5CF0A@qq.com>
Date:   Wed,  7 Jun 2023 21:35:19 +0800
From:   Woody Zhang <woodylab@...mail.com>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Woody Zhang <woodylab@...mail.com>
Subject: [PATCH] riscv: reserve DTB before possible memblock allocation

It's possible that early_init_fdt_scan_reserved_mem() allocates memory
from memblock for dynamic reserved memory in `/reserved-memory` node.
Any fixed reservation must be done before that to avoid potential
conflicts.

Reserve the DTB in memblock just after early scanning it.

Signed-off-by: Woody Zhang <woodylab@...mail.com>
---
 arch/riscv/kernel/setup.c | 10 ++++++++++
 arch/riscv/mm/init.c      |  9 ---------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 36b026057503..c147fa8da929 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -16,6 +16,7 @@
 #include <linux/console.h>
 #include <linux/screen_info.h>
 #include <linux/of_fdt.h>
+#include <linux/libfdt.h>
 #include <linux/sched/task.h>
 #include <linux/smp.h>
 #include <linux/efi.h>
@@ -256,6 +257,15 @@ static void __init parse_dtb(void)
 		pr_err("No DTB passed to the kernel\n");
 	}
 
+	/*
+	 * If DTB is built in, no need to reserve its memblock.
+	 * Otherwise, do reserve it but avoid using
+	 * early_init_fdt_reserve_self() since __pa() does
+	 * not work for DTB pointers that are fixmap addresses
+	 */
+	if (!IS_ENABLED(CONFIG_BUILTIN_DTB))
+		memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
+
 #ifdef CONFIG_CMDLINE_FORCE
 	strscpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 	pr_info("Forcing kernel command line to: %s\n", boot_command_line);
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index c6bb966e4123..f8c9a79acd94 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -254,15 +254,6 @@ static void __init setup_bootmem(void)
 	 */
 	early_init_fdt_scan_reserved_mem();
 
-	/*
-	 * If DTB is built in, no need to reserve its memblock.
-	 * Otherwise, do reserve it but avoid using
-	 * early_init_fdt_reserve_self() since __pa() does
-	 * not work for DTB pointers that are fixmap addresses
-	 */
-	if (!IS_ENABLED(CONFIG_BUILTIN_DTB))
-		memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
-
 	dma_contiguous_reserve(dma32_phys_limit);
 	if (IS_ENABLED(CONFIG_64BIT))
 		hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-- 
2.39.2