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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>, <fanchengyang@huawei.com>,
	Jason Yan <yanaijie@huawei.com>
Subject: [RFC PATCH 10/10] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic
Date: Wed, 17 Jul 2019 16:06:21 +0800
Message-ID: <20190717080621.40424-11-yanaijie@huawei.com> (raw)
In-Reply-To: <20190717080621.40424-1-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.

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>
---
 arch/powerpc/include/asm/page.h     |  5 +++++
 arch/powerpc/kernel/machine_kexec.c |  1 +
 arch/powerpc/kernel/setup-common.c  | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 60a68d3a54b1..cd3ac530e58d 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 kimage_vaddr;
 
+static inline unsigned long kaslr_offset(void)
+{
+	return kimage_vaddr - KERNELBASE;
+}
+
 #include <asm-generic/memory_model.h>
 #endif /* __ASSEMBLY__ */
 #include <asm/slice.h>
diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index c4ed328a7b96..078fe3d76feb 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -86,6 +86,7 @@ void arch_crash_save_vmcoreinfo(void)
 	VMCOREINFO_STRUCT_SIZE(mmu_psize_def);
 	VMCOREINFO_OFFSET(mmu_psize_def, shift);
 #endif
+	vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
 }
 
 /*
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 1f8db666468d..49e540c0adeb 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -715,12 +715,35 @@ 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)
+{
+	const unsigned long offset = kaslr_offset();
+
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && offset > 0)
+		pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+			 offset, KERNELBASE);
+	else
+		pr_emerg("Kernel Offset: disabled\n");
+
+	return 0;
+}
+
+static struct notifier_block kernel_offset_notifier = {
+	.notifier_call = dump_kernel_offset
+};
+
 void __init setup_panic(void)
 {
 	/* PPC64 always does a hard irq disable in its panic handler */
 	if (!IS_ENABLED(CONFIG_PPC64) && !ppc_md.panic)
 		return;
 	atomic_notifier_chain_register(&panic_notifier_list, &ppc_panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &kernel_offset_notifier);
 }
 
 #ifdef CONFIG_CHECK_CACHE_COHERENCY
-- 
2.17.2


  parent reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-17  8:06 [RFC PATCH 00/10] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-07-17  8:06 ` [RFC PATCH 01/10] powerpc: unify definition of M_IF_NEEDED Jason Yan
2019-07-29 10:59   ` Christophe Leroy
2019-07-17  8:06 ` [RFC PATCH 02/10] powerpc: move memstart_addr and kernstart_addr to init-common.c Jason Yan
2019-07-29 11:00   ` Christophe Leroy
2019-07-29 14:31   ` Christoph Hellwig
2019-07-30  0:47     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 03/10] powerpc: introduce kimage_vaddr to store the kernel base Jason Yan
2019-07-29 11:00   ` Christophe Leroy
2019-07-29 14:32   ` Christoph Hellwig
2019-07-17  8:06 ` [RFC PATCH 04/10] powerpc/fsl_booke/32: introduce create_tlb_entry() helper Jason Yan
2019-07-29 11:05   ` Christophe Leroy
2019-07-29 13:26     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 05/10] powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper Jason Yan
2019-07-29 11:08   ` Christophe Leroy
2019-07-29 13:35     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 06/10] powerpc/fsl_booke/32: implement KASLR infrastructure Jason Yan
2019-07-29 11:16   ` Christophe Leroy
2019-07-17  8:06 ` [RFC PATCH 07/10] powerpc/fsl_booke/32: randomize the kernel image offset Jason Yan
2019-07-29 11:33   ` Christophe Leroy
2019-07-29 13:53     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 08/10] powerpc/fsl_booke/kaslr: clear the original kernel if randomized Jason Yan
2019-07-29 11:19   ` Christophe Leroy
2019-07-29 13:43     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter Jason Yan
2019-07-29 11:38   ` Christophe Leroy
2019-07-29 14:04     ` Jason Yan
2019-07-17  8:06 ` Jason Yan [this message]
2019-07-29 11:43   ` [RFC PATCH 10/10] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic Christophe Leroy
2019-07-29 14:08     ` Jason Yan
2019-07-25  7:16 ` [RFC PATCH 00/10] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-07-25 19:58   ` Kees Cook
2019-07-26  7:20     ` Jason Yan
2019-07-26 16:15       ` Kees Cook
2019-07-26  7:04   ` Diana Madalina Craciun
2019-07-26  7:26     ` Jason Yan
2019-07-29 14:30 ` Diana Madalina Craciun

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