linux-kernel - [PATCH] fdt: Extend warnings on error paths

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Message-ID: <20250423091018.51831-1-bsz@amazon.de>
Date: Wed, 23 Apr 2025 09:10:17 +0000
From: Bartosz Szczepanek <bsz@...zon.de>
To: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>
CC: <nh-open-source@...zon.com>, Bartosz Szczepanek <bsz@...zon.de>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] fdt: Extend warnings on error paths

Print out adress and size if elfcorehdr is overlapped. Be more verbose
about what went wrong in case early_init_dt_verify fails. Other than
improving logging, no functional change is intended in this commit.

Signed-off-by: Bartosz Szczepanek <bsz@...zon.de>
---
 drivers/of/fdt.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index aedd0e2dcd89..c9b5e056b713 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -469,21 +469,22 @@ static u32 of_fdt_crc32;
  * described in the device tree. This region contains all the
  * information about primary kernel's core image and is used by a dump
  * capture kernel to access the system memory on primary kernel.
  */
 static void __init fdt_reserve_elfcorehdr(void)
 {
 	if (!IS_ENABLED(CONFIG_CRASH_DUMP) || !elfcorehdr_size)
 		return;
 
 	if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
-		pr_warn("elfcorehdr is overlapped\n");
+		pr_warn("elfcorehdr is overlapped (addr=0x%llx, size=%llu)\n",
+			elfcorehdr_addr, elfcorehdr_size);
 		return;
 	}
 
 	memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
 
 	pr_info("Reserving %llu KiB of memory at 0x%llx for elfcorehdr\n",
 		elfcorehdr_size >> 10, elfcorehdr_addr);
 }
 
 /**
@@ -1128,26 +1129,33 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 	memblock_add(base, size);
 }
 
 static void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
 {
 	return memblock_alloc_or_panic(size, align);
 }
 
 bool __init early_init_dt_verify(void *dt_virt, phys_addr_t dt_phys)
 {
-	if (!dt_virt)
+	int rc;
+
+	if (!dt_virt) {
+		pr_warn("FDT wasn't correctly mapped");
 		return false;
+	}
 
 	/* check device tree validity */
-	if (fdt_check_header(dt_virt))
+	rc = fdt_check_header(dt_virt);
+	if (rc) {
+		pr_warn("FDT header is invalid: status=%d", rc);
 		return false;
+	}
 
 	/* Setup flat device-tree pointer */
 	initial_boot_params = dt_virt;
 	initial_boot_params_pa = dt_phys;
 	of_fdt_crc32 = crc32_be(~0, initial_boot_params,
 				fdt_totalsize(initial_boot_params));
 
 	/* Initialize {size,address}-cells info */
 	early_init_dt_scan_root();
 
-- 
2.47.1