From 401721ecd1dcb0a428aa5d6832ee05ffbdbffbbe Mon Sep 17 00:00:00 2001 From: Baoquan He 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 Cc: Thomas Garnier Cc: Baoquan He Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H . Peter Anvin" Cc: Eric Biederman Cc: Xunlei Pang Cc: HATAYAMA Daisuke Cc: Kees Cook Cc: Eugene Surovegin Cc: Dave Young Cc: AKASHI Takahiro Cc: Atsushi Kumagai Cc: Dave Anderson Cc: Pratyush Anand Cc: Vivek Goyal Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 5a294e48b185..307b1f4543de 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 561675589511..8ad3a29eb728 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 -- 2.11.0