linux-kernel - [PATCH RFC 8/8] riscv/kaslr: dump out kernel offset information on panic

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Date:   Tue, 24 Mar 2020 15:30:53 +0800
From:   Zong Li <zong.li@...ive.com>
To:     palmer@...belt.com, paul.walmsley@...ive.com, alex@...ti.fr,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Zong Li <zong.li@...ive.com>
Subject: [PATCH RFC 8/8] riscv/kaslr: dump out kernel offset information on panic

Dump out the kernel offset when panic to help debug kernel.

Signed-off-by: Zong Li <zong.li@...ive.com>
---
 arch/riscv/kernel/setup.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 913d25e4b9fa..3ce50bf628ba 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -85,3 +85,26 @@ void __init setup_arch(char **cmdline_p)
 
 	riscv_fill_hwcap();
 }
+
+static int dump_kernel_offset(struct notifier_block *self, unsigned long v,
+			      void *p)
+{
+	pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+		 get_kaslr_offset(), PAGE_OFFSET);
+
+	return 0;
+}
+
+static struct notifier_block kernel_offset_notifier = {
+	.notifier_call = dump_kernel_offset
+};
+
+static int __init register_kernel_offset_dumper(void)
+{
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && get_kaslr_offset() > 0)
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &kernel_offset_notifier);
+
+	return 0;
+}
+__initcall(register_kernel_offset_dumper);
-- 
2.25.1