From 401721ecd1dcb0a428aa5d6832ee05ffbdbffbbe Mon Sep 17 00:00:00 2001
From: Baoquan He <bhe@redhat.com>
Date: Wed, 14 Dec 2016 15:04:20 -0800
Subject: [PATCH] kexec: export the value of phys_base instead of symbol
address
Currently in x86_64, the symbol address of phys_base is exported to
vmcoreinfo. Dave Anderson complained this is really useless for his
Crash implementation. Because in user-space utility Crash and
Makedumpfile which exported vmcore information is mainly used for, value
of phys_base is needed to covert virtual address of exported kernel
symbol to physical address. Especially init_level4_pgt, if we want to
access and go over the page table to look up a PA corresponding to VA,
firstly we need calculate
page_dir = SYMBOL(init_level4_pgt) - __START_KERNEL_map + phys_base;
Now in Crash and Makedumpfile, we have to analyze the vmcore elf program
header to get value of phys_base. As Dave said, it would be preferable
if it were readily availabl in vmcoreinfo rather than depending upon the
PT_LOAD semantics.
Hence in this patch change to export the value of phys_base instead of
its virtual address.
And people also complained that KERNEL_IMAGE_SIZE exporting is x86_64
only, should be moved into arch dependent function
arch_crash_save_vmcoreinfo. Do the moving in this patch.
Link: http://lkml.kernel.org/r/1478568596-30060-2-git-send-email-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Xunlei Pang <xlpang@redhat.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Eugene Surovegin <surovegin@google.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/x86/kernel/machine_kexec_64.c | 3 ++-
kernel/kexec_core.c | 3 ---
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 5a294e48b1852..307b1f4543de4 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -328,7 +328,7 @@ void machine_kexec(struct kimage *image)
void arch_crash_save_vmcoreinfo(void)
{
- VMCOREINFO_SYMBOL(phys_base);
+ VMCOREINFO_NUMBER(phys_base);
VMCOREINFO_SYMBOL(init_level4_pgt);
#ifdef CONFIG_NUMA
@@ -337,6 +337,7 @@ void arch_crash_save_vmcoreinfo(void)
#endif
vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
kaslr_offset());
+ VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
}
/* arch-dependent functionality related to kexec file-based syscall */
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5616755895119..8ad3a29eb7285 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1467,9 +1467,6 @@ static int __init crash_save_vmcoreinfo_init(void)
#endif
VMCOREINFO_NUMBER(PG_head_mask);
VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
-#ifdef CONFIG_X86
- VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
-#endif
#ifdef CONFIG_HUGETLB_PAGE
VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
#endif
--
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