From: Baoquan He <bhe@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> Cc: Thomas Garnier <thgarnie@xxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: "H . Peter Anvin" <hpa@xxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Cc: Xunlei Pang <xlpang@xxxxxxxxxx> Cc: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Eugene Surovegin <surovegin@xxxxxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx> Cc: Atsushi Kumagai <ats-kumagai@xxxxxxxxxxxxx> Cc: Dave Anderson <anderson@xxxxxxxxxx> Cc: Pratyush Anand <panand@xxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/machine_kexec_64.c | 3 ++- kernel/kexec_core.c | 3 --- 2 files changed, 2 insertions(+), 4 deletions(-) diff -puN arch/x86/kernel/machine_kexec_64.c~kexec-change-to-export-the-value-of-phys_base-instead-of-symbol-address arch/x86/kernel/machine_kexec_64.c --- a/arch/x86/kernel/machine_kexec_64.c~kexec-change-to-export-the-value-of-phys_base-instead-of-symbol-address +++ a/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 -puN kernel/kexec_core.c~kexec-change-to-export-the-value-of-phys_base-instead-of-symbol-address kernel/kexec_core.c --- a/kernel/kexec_core.c~kexec-change-to-export-the-value-of-phys_base-instead-of-symbol-address +++ a/kernel/kexec_core.c @@ -1467,9 +1467,6 @@ static int __init crash_save_vmcoreinfo_ #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 _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
