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From:   Alexandre Ghiti <alexghiti@rivosinc.com>
To:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Ard Biesheuvel <ardb@kernel.org>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     Alexandre Ghiti <alexghiti@rivosinc.com>,
        Zong Li <zong.li@sifive.com>
Subject: [PATCH v2 2/4] riscv: Dump out kernel offset information on panic
Date:   Wed, 29 Mar 2023 07:29:24 +0200
Message-Id: <20230329052926.69632-3-alexghiti@rivosinc.com>
In-Reply-To: <20230329052926.69632-1-alexghiti@rivosinc.com>
References: <20230329052926.69632-1-alexghiti@rivosinc.com>
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Dump out the KASLR virtual kernel offset when panic to help debug kernel.

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/kernel/setup.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 376d2827e736..c6937839bbd8 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -20,6 +20,7 @@
 #include <linux/smp.h>
 #include <linux/efi.h>
 #include <linux/crash_dump.h>
+#include <linux/panic_notifier.h>
 
 #include <asm/alternative.h>
 #include <asm/cacheflush.h>
@@ -333,3 +334,27 @@ void free_initmem(void)
 
 	free_initmem_default(POISON_FREE_INITMEM);
 }
+
+static int dump_kernel_offset(struct notifier_block *self,
+			      unsigned long v, void *p)
+{
+	pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+		 kernel_map.virt_offset,
+		 KERNEL_LINK_ADDR);
+
+	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))
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &kernel_offset_notifier);
+
+	return 0;
+}
+device_initcall(register_kernel_offset_dumper);
-- 
2.37.2