linux-kernel - [PATCH] of: Fix reserved-memory overlap detection

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Date:   Tue, 20 Oct 2020 09:35:58 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
CC:     <kernel@...s.com>, <mitchelh@...eaurora.org>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] of: Fix reserved-memory overlap detection

The reserved-memory overlap detection code fails to detect overlaps if
either of the regions starts at address 0x0.  For some reason the code
explicitly checks for and ignores such regions, but this check looks
invalid.  Remove the check and fix this detection.

For example, no overlap is currently reported for this case:

	foo@0 {
		reg = <0x0000 0x2000>;
	};

	bar@...0 {
		reg = <0x1000 0x1000>;
	};

but it is after this patch:

 OF: reserved mem: OVERLAP DETECTED!
 foo@0 (0x00000000--0x00002000) overlaps with bar@...0 (0x00001000--0x00002000)

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
 drivers/of/of_reserved_mem.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 46b9371c8a33..1c5259e3e81f 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -217,8 +217,7 @@ static void __init __rmem_check_for_overlap(void)
 
 		this = &reserved_mem[i];
 		next = &reserved_mem[i + 1];
-		if (!(this->base && next->base))
-			continue;
+
 		if (this->base + this->size > next->base) {
 			phys_addr_t this_end, next_end;
 
-- 
2.28.0