Hi,
> My original concern was the need to upgrade the hypervisor, but since that
> time, we've put in a workaround for the crash utility to allow the
> xen_phys_start value to be passed in as a command line argument.
Yes. There is no problem for us to analyze a dump. I think the makedumpfile
utility can have a workaround too.
I like the Plan A too. So I will send a patch of Plan A to the xen-devel
mailing list.
Thanks.
Itsuro Oda
On Tue, 20 May 2008 08:49:19 -0400
Dave Anderson <anderson@xxxxxxxxxx> wrote:
> Simon Horman wrote:
> > On Tue, Apr 22, 2008 at 05:32:03PM +0900, Itsuro ODA wrote:
> >> Hi all,
> >>
> >> Recent version of xen (ex. RHEL5.2, 3.2.0) on the x86_64
> >> moves the physical(machine) address of xen code/data area after
> >> the system started up. The start address of this is stored in
> >> 'xen_phys_start'. Thus to get a machine address of a xen text symbol
> >> from its virtual address, calculate
> >> "va - __XEN_VIRT_START + xen_phys_start".
> >>
> >> crash and makedumpfile command need the value of xen_phys_start.
> >> They know the virtual address of 'xen_phys_start' symbol but
> >> no way to extract the value of xen_phys_start.
> >>
> >> I think adding the xen_phys_start value to the CRASHINFO ElfNote
> >> section at first. (Plan A: patch for xen hypervisor code attaced)
> >> It is smallest modification necessary over all.
> >>
> >> On the other hand there is a opinion that it is better to upgrade
> >> a user-package than a hypervisor or kernel package.
> >> The xen_phys_start value can be got from /proc/iomem.
> >> -------------------------------------------------------
> >> # cat /proc/iomem
> >> ...
> >> 7e600000-7f5fffff : Hypervisor code and data *** this line
> >> ...
> >> -------------------------------------------------------
> >> So the kexec-tools can handle it theoretically.
> >>
> >> The Plan B is that kexec-tools adds another ElfNote section which
> >> holds the xen_phys_start value. The attached patch works well
> >> though I am concern about it is a bit tricky.
> >>
> >> Which plan is better ? Or more good implementation ?
> >> Please comment.
> >>
> >> (note that crash and makedumpfile modification is same degree
> >> for both plan.)
> >
> > Hi Oda-san,
> >
> > I think that in terms of simplicity plan A is a clear
> > winner. That is assuming tha the changes to crash
> > and makedumpfile are more or less the same for both
> > plan A and plan B.
> >
> > However, if there is a reason that it makes sense to include
> > the change in kexec-tools and make a fresh release, I'm happy to do so.
>
> I was the one who suggested a user-space alternative, but reconsidering it,
> I also agree that plan A is preferable, primarily for simplicity's sake in
> both kexec-tools (no changes) and in the crash utility (a couple lines that
> have already been added in the latest version).
>
> My original concern was the need to upgrade the hypervisor, but since that
> time, we've put in a workaround for the crash utility to allow the
> xen_phys_start value to be passed in as a command line argument.
>
> Dave
>
> >
> >> === Plan A (modify the xen hypervisor. It is for RHEL5.2 but almost same
> >> for other version) ===
> >> --- include/xen/elfcore.h.org 2008-04-17 14:11:41.000000000 +0900
> >> +++ include/xen/elfcore.h 2008-04-17 14:11:57.000000000 +0900
> >> @@ -66,6 +66,7 @@
> >> unsigned long xen_compile_time;
> >> unsigned long tainted;
> >> #ifdef CONFIG_X86
> >> + unsigned long xen_phys_start;
> >> unsigned long dom0_pfn_to_mfn_frame_list_list;
> >> #endif
> >> } crash_xen_info_t;
> >> --- arch/x86/crash.c.org 2008-04-17 14:12:51.000000000 +0900
> >> +++ arch/x86/crash.c 2008-04-17 14:13:13.000000000 +0900
> >> @@ -102,6 +102,7 @@
> >> hvm_disable();
> >>
> >> info = kexec_crash_save_info();
> >> + info->xen_phys_start = xen_phys_start;
> >> info->dom0_pfn_to_mfn_frame_list_list =
> >> arch_get_pfn_to_mfn_frame_list_list(dom0);
> >> }
> >> ================================================================
> >>
> >> === Plan B (modify the kexec-tools. proof of concept version) ===
> >> diff -ru
> >> kexec-tools-testing-20080324.org/kexec/arch/x86_64/crashdump-x86_64.c
> >> kexec-tools-testing-20080324/kexec/arch/x86_64/crashdump-x86_64.c
> >> --- kexec-tools-testing-20080324.org/kexec/arch/x86_64/crashdump-x86_64.c
> >> 2008-03-21 13:16:28.000000000 +0900
> >> +++ kexec-tools-testing-20080324/kexec/arch/x86_64/crashdump-x86_64.c
> >> 2008-04-22 15:15:08.000000000 +0900
> >> @@ -73,6 +73,25 @@
> >> return -1;
> >> }
> >>
> >> +static int get_hypervisor_paddr(struct kexec_info *info)
> >> +{
> >> + uint64_t start;
> >> +
> >> + if (!xen_present())
> >> + return 0;
> >> +
> >> + if (parse_iomem_single("Hypervisor code and data\n", &start, NULL) ==
> >> 0) {
> >> + info->hypervisor_paddr_start = start;
> >> +#ifdef DEBUG
> >> + printf("kernel load physical addr start = 0x%016Lx\n", start);
> >> +#endif
> >> + return 0;
> >> + }
> >> +
> >> + fprintf(stderr, "Cannot determine hypervisor physical load addr\n");
> >> + return -1;
> >> +}
> >> +
> >> /* Retrieve info regarding virtual address kernel has been compiled for
> >> and
> >> * size of the kernel from /proc/kcore. Current /proc/kcore parsing from
> >> * from kexec-tools fails because of malformed elf notes. A kernel patch
> >> has
> >> @@ -581,6 +600,9 @@
> >> if (get_kernel_paddr(info))
> >> return -1;
> >>
> >> + if (get_hypervisor_paddr(info))
> >> + return -1;
> >> +
> >> if (get_kernel_vaddr_and_size(info))
> >> return -1;
> >>
> >> @@ -620,6 +642,9 @@
> >> */
> >> elfcorehdr = add_buffer(info, tmp, sz, 16*1024, align, min_base,
> >> max_addr, -1);
> >> + if (info->hypervisor_paddr_start && xen_present()) {
> >> + *(info->hypervisor_paddr_loc) += elfcorehdr;
> >> + }
> >> if (delete_memmap(memmap_p, elfcorehdr, sz) < 0)
> >> return -1;
> >> cmdline_add_memmap(mod_cmdline, memmap_p);
> >> diff -ru kexec-tools-testing-20080324.org/kexec/crashdump.c
> >> kexec-tools-testing-20080324/kexec/crashdump.c
> >> --- kexec-tools-testing-20080324.org/kexec/crashdump.c 2008-03-21
> >> 13:16:28.000000000 +0900
> >> +++ kexec-tools-testing-20080324/kexec/crashdump.c 2008-04-22
> >> 15:33:47.000000000 +0900
> >> @@ -36,8 +36,10 @@
> >> #define FUNC crash_create_elf64_headers
> >> #define EHDR Elf64_Ehdr
> >> #define PHDR Elf64_Phdr
> >> +#define NHDR Elf64_Nhdr
> >> #include "crashdump-elf.c"
> >> #undef ELF_WIDTH
> >> +#undef NHDR
> >> #undef PHDR
> >> #undef EHDR
> >> #undef FUNC
> >> @@ -46,8 +48,10 @@
> >> #define FUNC crash_create_elf32_headers
> >> #define EHDR Elf32_Ehdr
> >> #define PHDR Elf32_Phdr
> >> +#define NHDR Elf32_Nhdr
> >> #include "crashdump-elf.c"
> >> #undef ELF_WIDTH
> >> +#undef NHDR
> >> #undef PHDR
> >> #undef EHDR
> >> #undef FUNC
> >> diff -ru kexec-tools-testing-20080324.org/kexec/crashdump-elf.c
> >> kexec-tools-testing-20080324/kexec/crashdump-elf.c
> >> --- kexec-tools-testing-20080324.org/kexec/crashdump-elf.c 2008-01-11
> >> 12:13:48.000000000 +0900
> >> +++ kexec-tools-testing-20080324/kexec/crashdump-elf.c 2008-04-22
> >> 15:35:16.000000000 +0900
> >> @@ -1,6 +1,6 @@
> >>
> >> -#if !defined(FUNC) || !defined(EHDR) || !defined(PHDR)
> >> -#error FUNC, EHDR and PHDR must be defined
> >> +#if !defined(FUNC) || !defined(EHDR) || !defined(PHDR) || !defined(NHDR)
> >> +#error FUNC, EHDR, PHDR and NHDR must be defined
> >> #endif
> >>
> >> #if (ELF_WIDTH == 64)
> >> @@ -37,6 +37,7 @@
> >> uint64_t vmcoreinfo_addr, vmcoreinfo_len;
> >> int has_vmcoreinfo = 0;
> >> int (*get_note_info)(int cpu, uint64_t *addr, uint64_t *len);
> >> + int has_hypervisor_paddr_start = 0;
> >>
> >> if (xen_present())
> >> nr_cpus = xen_get_nr_phys_cpus();
> >> @@ -78,6 +79,11 @@
> >> sz += sizeof(PHDR);
> >> }
> >>
> >> + if (info->hypervisor_paddr_start && xen_present()) {
> >> + sz += sizeof(PHDR) + sizeof(NHDR) + 4 + sizeof(unsigned long);
> >> + has_hypervisor_paddr_start = 1;
> >> + }
> >> +
> >> /*
> >> * Make sure the ELF core header is aligned to at least 1024.
> >> * We do this because the secondary kernel gets the ELF core
> >> @@ -168,6 +174,22 @@
> >> dbgprintf_phdr("vmcoreinfo header", phdr);
> >> }
> >>
> >> + if (has_hypervisor_paddr_start) {
> >> + phdr = (PHDR *) bufp;
> >> + bufp += sizeof(PHDR);
> >> + phdr->p_type = PT_NOTE;
> >> + phdr->p_flags = 0;
> >> + phdr->p_offset = phdr->p_paddr = 0;
> >> + phdr->p_vaddr = 0;
> >> + phdr->p_filesz = phdr->p_memsz = sizeof(NHDR) + 4 +
> >> sizeof(unsigned long);
> >> + phdr->p_align = 0;
> >> +
> >> + (elf->e_phnum)++;
> >> + dbgprintf_phdr("hypervisor phys addr header", phdr);
> >> +
> >> + info->hypervisor_paddr_loc = (unsigned long *)&phdr->p_offset;
> >> + }
> >> +
> >> /* Setup an PT_LOAD type program header for the region where
> >> * Kernel is mapped if info->kern_size is non-zero.
> >> */
> >> @@ -225,6 +247,24 @@
> >> (elf->e_phnum)++;
> >> dbgprintf_phdr("Elf header", phdr);
> >> }
> >> +
> >> + if (has_hypervisor_paddr_start) {
> >> + NHDR *nhdr;
> >> + unsigned int offset = (void *)bufp - *buf;
> >> +
> >> + nhdr = (NHDR *) bufp;
> >> + bufp += sizeof(NHDR);
> >> + nhdr->n_namesz = 4;
> >> + nhdr->n_descsz = sizeof(unsigned long);
> >> + nhdr->n_type = 0x1000003;
> >> + memcpy(bufp, "Xen", 4);
> >> + bufp += 4;
> >> + *((unsigned long *)bufp) = info->hypervisor_paddr_start;
> >> + bufp += sizeof(unsigned long);
> >> +
> >> + *(info->hypervisor_paddr_loc) = offset;
> >> + }
> >> +
> >> return 0;
> >> }
> >>
> >> diff -ru kexec-tools-testing-20080324.org/kexec/kexec.h
> >> kexec-tools-testing-20080324/kexec/kexec.h
> >> --- kexec-tools-testing-20080324.org/kexec/kexec.h 2008-03-21
> >> 13:16:28.000000000 +0900
> >> +++ kexec-tools-testing-20080324/kexec/kexec.h 2008-04-22
> >> 15:08:57.000000000 +0900
> >> @@ -123,6 +123,8 @@
> >> unsigned long kern_vaddr_start;
> >> unsigned long kern_paddr_start;
> >> unsigned long kern_size;
> >> + unsigned long hypervisor_paddr_start;
> >> + unsigned long *hypervisor_paddr_loc;
> >> };
> >>
> >> void usage(void);
> >> ======================================================================================
> >> --
> >> Itsuro ODA <oda@xxxxxxxxxxxxx>
> >>
> >>
> >> _______________________________________________
> >> kexec mailing list
> >> kexec@xxxxxxxxxxxxxxxxxxx
> >> http://lists.infradead.org/mailman/listinfo/kexec
> >
>
--
Itsuro ODA <oda@xxxxxxxxxxxxx>
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