Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: [RFC PATCH v6 3/4] powerpc/fadump: throw proper error message on
 fadump registration failure.
From:   Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
To:     linuxppc-dev <linuxppc-dev@ozlabs.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>
Cc:     Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Anshuman Khandual <khandual@linux.vnet.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Michal Hocko <mhocko@suse.com>,
        Hari Bathini <hbathini@linux.vnet.ibm.com>,
        Ananth Narayan <ananth@in.ibm.com>, kernelfans@gmail.com
Date:   Mon, 16 Jul 2018 11:33:39 +0530
In-Reply-To: <153172096333.29252.4376707071382727345.stgit@jupiter.in.ibm.com>
References: <153172096333.29252.4376707071382727345.stgit@jupiter.in.ibm.com>
User-Agent: StGit/unknown-version
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <153172101748.29252.12590745448233151667.stgit@jupiter.in.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>

fadump fails to register when there are holes in reserved memory area.
This can happen if user has hot-removed a memory that falls in the fadump
reserved memory area. Throw a meaningful error message to the user in
such case.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/fadump.c |   33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index ce333c1d4cb8..d1375f3f48c3 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -170,6 +170,36 @@ static int is_boot_memory_area_contiguous(void)
 	return ret;
 }
 
+/*
+ * Returns 1, if there are no holes in reserved memory area,
+ * 0 otherwise.
+ */
+static int is_reserved_memory_area_contiguous(void)
+{
+	struct memblock_region *reg;
+	unsigned long start, end;
+	unsigned long d_start = fw_dump.reserve_dump_area_start;
+	unsigned long d_end = d_start + fw_dump.reserve_dump_area_size;
+	int ret = 0;
+
+	for_each_memblock(memory, reg) {
+		start = max(d_start, (unsigned long)reg->base);
+		end = min(d_end, (unsigned long)(reg->base + reg->size));
+		if (d_start < end) {
+			/* Memory hole from d_start to start */
+			if (start > d_start)
+				break;
+
+			if (end == d_end) {
+				ret = 1;
+				break;
+			}
+			d_start = end + 1;
+		}
+	}
+	return ret;
+}
+
 /* Print firmware assisted dump configurations for debugging purpose. */
 static void fadump_show_config(void)
 {
@@ -531,6 +561,9 @@ static int register_fw_dump(struct fadump_mem_struct *fdm)
 		if (!is_boot_memory_area_contiguous())
 			pr_err("Can't have holes in boot memory area while "
 			       "registering fadump\n");
+		else if (!is_reserved_memory_area_contiguous())
+			pr_err("Can't have holes in reserved memory area while"
+			       " registering fadump\n");
 
 		printk(KERN_ERR "Failed to register firmware-assisted kernel"
 			" dump. Parameter Error(%d).\n", rc);