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From:   Geert Uytterhoeven <geert+renesas@glider.be>
To:     Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 1/3] of: Fix truncation of memory sizes on 32-bit platforms
Date:   Wed, 16 Jun 2021 11:27:44 +0200
Message-Id: <4a1117e72d13d26126f57be034c20dac02f1e915.1623835273.git.geert+renesas@glider.be>
In-Reply-To: <cover.1623835273.git.geert+renesas@glider.be>
References: <cover.1623835273.git.geert+renesas@glider.be>
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Variable "size" has type "phys_addr_t", which can be either 32-bit or
64-bit on 32-bit systems, while "unsigned long" is always 32-bit on
32-bit systems.  Hence the cast in

    (unsigned long)size / SZ_1M

may truncate a 64-bit size to 32-bit, as casts have a higher operator
precedence than divisions.

Fix this by inverting the order of the cast and division, which should
be safe for memory blocks smaller than 4 PiB.  Note that the division is
actually a shift, as SZ_1M is a power-of-two constant, hence there is no
need to use div_u64().

While at it, use "%lu" to format "unsigned long".

Fixes: e8d9d1f5485b52ec ("drivers: of: add initialization code for static reserved memory")
Fixes: 3f0c8206644836e4 ("drivers: of: add initialization code for dynamic reserved memory")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/of/fdt.c             | 8 ++++----
 drivers/of/of_reserved_mem.c | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index a03d43f95495d8e1..970fa8cdc9303195 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -510,11 +510,11 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
 
 		if (size &&
 		    early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
-			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
-				uname, &base, (unsigned long)size / SZ_1M);
+			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %lu MiB\n",
+				uname, &base, (unsigned long)(size / SZ_1M));
 		else
-			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB\n",
-				uname, &base, (unsigned long)size / SZ_1M);
+			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %lu MiB\n",
+				uname, &base, (unsigned long)(size / SZ_1M));
 
 		len -= t_len;
 		if (first) {
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 4592b71aba5cf4a1..333d33bad59d7888 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -136,9 +136,9 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 			ret = early_init_dt_alloc_reserved_memory_arch(size,
 					align, start, end, nomap, &base);
 			if (ret == 0) {
-				pr_debug("allocated memory for '%s' node: base %pa, size %ld MiB\n",
+				pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
 					uname, &base,
-					(unsigned long)size / SZ_1M);
+					(unsigned long)(size / SZ_1M));
 				break;
 			}
 			len -= t_len;
@@ -148,8 +148,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 		ret = early_init_dt_alloc_reserved_memory_arch(size, align,
 							0, 0, nomap, &base);
 		if (ret == 0)
-			pr_debug("allocated memory for '%s' node: base %pa, size %ld MiB\n",
-				uname, &base, (unsigned long)size / SZ_1M);
+			pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
+				uname, &base, (unsigned long)(size / SZ_1M));
 	}
 
 	if (base == 0) {
-- 
2.25.1