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From: Jason Yan <yanaijie@huawei.com>
To: <mpe@ellerman.id.au>, <linuxppc-dev@lists.ozlabs.org>,
	<diana.craciun@nxp.com>, <christophe.leroy@c-s.fr>,
	<benh@kernel.crashing.org>, <paulus@samba.org>,
	<npiggin@gmail.com>, <keescook@chromium.org>,
	<kernel-hardening@lists.openwall.com>
Cc: <linux-kernel@vger.kernel.org>, <wangkefeng.wang@huawei.com>,
	<yebin10@huawei.com>, <thunder.leizhen@huawei.com>,
	<jingxiangfeng@huawei.com>, <zhaohongjiang@huawei.com>,
	<oss@buserror.net>, Jason Yan <yanaijie@huawei.com>
Subject: [PATCH v7 10/12] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic
Date: Fri, 20 Sep 2019 17:45:44 +0800
Message-ID: <20190920094546.44948-11-yanaijie@huawei.com> (raw)
In-Reply-To: <20190920094546.44948-1-yanaijie@huawei.com>

When kaslr is enabled, the kernel offset is different for every boot.
This brings some difficult to debug the kernel. Dump out the kernel
offset when panic so that we can easily debug the kernel.

This code is derived from x86/arm64 which has similar functionality.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Cc: Diana Craciun <diana.craciun@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Diana Craciun <diana.craciun@nxp.com>
Tested-by: Diana Craciun <diana.craciun@nxp.com>
---
 arch/powerpc/include/asm/page.h    |  5 +++++
 arch/powerpc/kernel/setup-common.c | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 4d32d1b561d6..b34b9cdd91f1 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -317,6 +317,11 @@ struct vm_area_struct;
 
 extern unsigned long kernstart_virt_addr;
 
+static inline unsigned long kaslr_offset(void)
+{
+	return kernstart_virt_addr - KERNELBASE;
+}
+
 #include <asm-generic/memory_model.h>
 #endif /* __ASSEMBLY__ */
 #include <asm/slice.h>
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 1f8db666468d..ba1a34ab218a 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -715,8 +715,28 @@ static struct notifier_block ppc_panic_block = {
 	.priority = INT_MIN /* may not return; must be done last */
 };
 
+/*
+ * Dump out kernel offset information on panic.
+ */
+static int dump_kernel_offset(struct notifier_block *self, unsigned long v,
+			      void *p)
+{
+	pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+		 kaslr_offset(), KERNELBASE);
+
+	return 0;
+}
+
+static struct notifier_block kernel_offset_notifier = {
+	.notifier_call = dump_kernel_offset
+};
+
 void __init setup_panic(void)
 {
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0)
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &kernel_offset_notifier);
+
 	/* PPC64 always does a hard irq disable in its panic handler */
 	if (!IS_ENABLED(CONFIG_PPC64) && !ppc_md.panic)
 		return;
-- 
2.17.2


  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-20  9:45 [PATCH v7 00/12] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-09-20  9:45 ` [PATCH v7 01/12] powerpc: unify definition of M_IF_NEEDED Jason Yan
2019-09-20  9:45 ` [PATCH v7 02/12] powerpc: move memstart_addr and kernstart_addr to init-common.c Jason Yan
2019-09-20  9:45 ` [PATCH v7 03/12] powerpc: introduce kernstart_virt_addr to store the kernel base Jason Yan
2019-09-20  9:45 ` [PATCH v7 04/12] powerpc/fsl_booke/32: introduce create_kaslr_tlb_entry() helper Jason Yan
2019-09-20  9:45 ` [PATCH v7 05/12] powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper Jason Yan
2019-09-20  9:45 ` [PATCH v7 06/12] powerpc/fsl_booke/32: implement KASLR infrastructure Jason Yan
2019-09-20  9:45 ` [PATCH v7 07/12] powerpc/fsl_booke/32: randomize the kernel image offset Jason Yan
2019-09-20  9:45 ` [PATCH v7 08/12] powerpc/fsl_booke/kaslr: clear the original kernel if randomized Jason Yan
2019-09-20  9:45 ` [PATCH v7 09/12] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter Jason Yan
2019-09-20  9:45 ` Jason Yan [this message]
2019-09-20  9:45 ` [PATCH v7 11/12] powerpc/fsl_booke/kaslr: export offset in VMCOREINFO ELF notes Jason Yan
2019-09-20  9:45 ` [PATCH v7 12/12] powerpc/fsl_booke/32: Document KASLR implementation Jason Yan
2019-09-24  5:52 ` [PATCH v7 00/12] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-10-09  6:10   ` Jason Yan
2019-10-09  7:13     ` Scott Wood
2019-10-09  8:41       ` Jason Yan
2019-10-09 18:46         ` Scott Wood
2019-10-21  3:34           ` Jason Yan
2019-10-22 23:22             ` Scott Wood

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