linux-kernel - [PATCH] arm: export memblock_reserve()d regions via /proc/iomem

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Message-Id: <1569070969-5168-1-git-send-email-33988979@163.com>
Date:   Sat, 21 Sep 2019 21:02:49 +0800
From:   Yu Chen <33988979@....com>
To:     rmk+kernel@...linux.org.uk, linux@...linux.org.uk
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        yu.chen3@....com.cn
Subject: [PATCH] arm: export memblock_reserve()d regions via /proc/iomem

From: Yu Chen <yu.chen3@....com.cn>

memblock reserved regions are not reported via /proc/iomem on ARM, kexec's
user-space doesn't know about memblock_reserve()d regions and thus
possible for kexec to overwrite with the new kernel or initrd.

[    0.000000] Booting Linux on physical CPU 0xf00
[    0.000000] Linux version 4.9.115-rt93-dirty (yuchen@...alhost.localdomain) (gcc version 6.2.0 (ZTE Embsys-TSP V3.07.2
0) ) #62 SMP PREEMPT Fri Sep 20 10:39:29 CST 2019
[    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=30c5387d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt:Machine model: LS1021A TWR Board
[    0.000000] INITRD: 0x80f7f000+0x03695e40 overlaps in-use memory region - disabling initrd

Signed-off-by: Yu Chen <yu.chen3@....com.cn>
Reviewed-by: Junhua Huang <huang.junhua@....com.cn>
---
 arch/arm/kernel/setup.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d0a464e..606d1ac 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -911,6 +911,34 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
 		request_resource(&ioport_resource, &lp2);
 }
 
+static int __init reserve_memblock_reserved_regions(void)
+{
+	u64 i, j;
+
+	for (i = 0; i < num_standard_resources; ++i) {
+		struct resource *mem = &standard_resources[i];
+		phys_addr_t r_start, r_end, mem_size = resource_size(mem);
+
+		if (!memblock_is_region_reserved(mem->start, mem_size))
+			continue;
+
+		for_each_reserved_mem_region(j, &r_start, &r_end) {
+			resource_size_t start, end;
+
+			start = max(PFN_PHYS(PFN_DOWN(r_start)), mem->start);
+			end = min(PFN_PHYS(PFN_UP(r_end)) - 1, mem->end);
+
+			if (start > mem->end || end < mem->start)
+				continue;
+
+			reserve_region_with_split(mem, start, end, "reserved");
+		}
+	}
+
+	return 0;
+}
+arch_initcall(reserve_memblock_reserved_regions);
+
 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE) || \
     defined(CONFIG_EFI)
 struct screen_info screen_info = {
-- 
2.7.4