[Crash-utility] some updates of xencrash
Itsuro ODA
oda at valinux.co.jp
Mon Apr 21 22:21:35 UTC 2008
Hi Dave,
On Mon, 21 Apr 2008 09:09:59 -0400
Dave Anderson <anderson at redhat.com> wrote:
> Itsuro ODA wrote:
> > Hi Dave,
> >
> > I thought it is better to be small value from the view point
> > to save 'xen_phys_start' value in the crashinfo.
> >
> > From the view point of users you are right. It should be
> > '--xen_phys_start=<address>'.
>
> Hi Itsuro,
>
> But even from the kernel viewpoint, I'm not sure why it would be better?
> The xen_phys_start symbol is an unsigned long, and its container in the
> crash_xen_info_t is an unsigned long. So I don't see any benefit or reason
> to make it smaller.
Yes, I was too anxious.
> >
> >> Another theoretical question -- since the /proc/iomem exports the
> >> xen_phys_start variable to user space, is there any way it could
> >> be handled entirely in user space by kexec-tools?
> >
> > Theoretically yes. But it is necessary to add another ElfNote section.
> > I thought it is the smallest modication necessary to add 'xen_phys_start'
> > in the crashinfo.
> > Do you think which is better ?
>
> That's a good question. My concern would be to have an easier way for customers
> to deal with the problem without having to upgrade the kernel package; it's always
> easier to upgrade a user-package.
I see.
> However, whatever gets fixed goes beyond the scope of the crash utility.
> For now, the crash utility will need the --xen-phys_start=xxxx workaround
> because the RHEL5.2 kernel will be released without a fix. And that
> decision will have to made by the kernel kexec/kdump and kexec-tools
> maintainers. Can you bring up this discussion on the kexec list?
Yes, sure.
Thanks.
Itsuro Oda
>
> Thanks,
> Dave
>
> >
> > Thanks.
> > Itsuro Oda
> >
> > On Fri, 18 Apr 2008 10:14:04 -0400
> > Dave Anderson <anderson at redhat.com> wrote:
> >
> >> Itsuro ODA wrote:
> >>> Hi,
> >>>
> >>> The attached is some fixes which are necessary for xencrash to use
> >>> for the newer version of xen (after 3.1.0, ex. 3.1.2, 3.2.0).
> >>>
> >>> * x86
> >>> - add some symbols which are used to know the boundary
> >>> condition at the tracing in 'bt'.
> >>> - fix for the symbol 'idle_pg_table_l3' going away.
> >>>
> >>> * x86_64
> >>> - fix for the virtual address area of xen code/data is added.
> >>> - fix for the symbol 'idle_pg_table_l4' going away.
> >>> - add the option '--xen_phys_start_mfn='
> >>> newer version of xen (ex. RHEL5.2, 3.2.0) moves the
> >>> physical(machine) address of xen code/data area after
> >>> the system started up.
> >>> The relocated physical(machine) address of xen code/data
> >>> area is necessary to use xencrash.
> >>> The value can be got by 'cat /proc/iomem' under dom0.
> >>> -------------------------------------------------------
> >>> # cat /proc/iomem
> >>> ...
> >>> 7e600000-7f5fffff : Hypervisor code and data *** this line
> >>> ...
> >>> -------------------------------------------------------
> >>> ex. to use xencrash:
> >>> # crash --xen_phys_start_mfn=0x7e600 xen-syms vmcore
> >>> - extract 'xen_phys_start_mfn' from the XEN_ELFNOTE_CRASH_INFO
> >>> ElfNote.
> >>> This is experimental code because it is necessary to modify
> >>> the xen to add the xen_phys_start_mfn value in the ElfNote
> >>> at crash time. (the patch is also attached in this mail.)
> >>> A sample dump is availavle in the following URL:
> >>> http://people.valinux.co.jp/~oda/x86_64_dump_080417.tar.gz
> >>>
> >>> This patch is for crash-4.0-6.2.
> >>>
> >>> Thanks.
> >>> Itsuro Oda
> >> Hi Itsuro,
> >>
> >> Thanks very much for the quick response.
> >>
> >> I have one relatively minor issue. I understand that the previously existing
> >> "--p2m_mfn" option was expressed as an mfn, and that made sense because its value
> >> exists in the xen hypervisor code as an mfn value (actually a xen_pfn_t).
> >>
> >> But it seems unnecessary to bother going through the translation of the
> >> hypservisors's "xen_phys_start" physical address into an mfn? And then
> >> only to have the crash utility have to turn it back into a physical address
> >> when it uses it? Why not just leave it as a physical address in both the
> >> kernel patch, and when passing it to the crash utility?
> >>
> >> From a user's standpoint, when it's necessary to pre-determine the argument from
> >> a hypervisor/dom0 vmcore that doesn't contain it, the xen_phys_start can be determined
> >> by either reading /proc/iomem on the live system, where as you've shown in
> >> the example above, it's 7e600000:
> >>
> >> > # cat /proc/iomem
> >> > ...
> >> > 7e600000-7f5fffff : Hypervisor code and data *** this line
> >> > ...
> >>
> >> Alternatively, the same dom0/HV kdump vmcore can be run in a crash session using
> >> the dom0 vmlinux, where in this example vmcore, it's 0x3f000000:
> >>
> >> crash> px xen_hypervisor_res
> >> xen_hypervisor_res = $3 = {
> >> start = 0x3f000000,
> >> end = 0x3fffffff,
> >> name = 0xffffffff8049ab72 "Hypervisor code and data",
> >> flags = 0x80000200,
> >> parent = 0xffff880000001180,
> >> sibling = 0x0,
> >> child = 0xffff8800000000a8
> >> }
> >>
> >> For convenience sake, I'd prefer to just leave it as that, without
> >> needlessly forcing the user to translate the above into an mfn, so
> >> that they can simply enter: "crash --xen_phys_start=0x3f000000 ..."
> >>
> >> The same thing applies to the kernel patch -- just leave it in its
> >> natural state as a physical (machine) address.
> >>
> >> Unfortunately it's already going to be an annoyance to have to pre-determine
> >> the xen_phys_start value -- so why bother making it even more cryptic by
> >> forcing the user to turn it into an mfn?
> >>
> >> Another theoretical question -- since the /proc/iomem exports the
> >> xen_phys_start variable to user space, is there any way it could
> >> be handled entirely in user space by kexec-tools?
> >>
> >> Dave
> >>
> >>
> >>> === for x86 ===
> >>> --- lkcd_x86_trace.c.org 2008-04-17 10:13:05.000000000 +0900
> >>> +++ lkcd_x86_trace.c 2008-04-17 10:13:17.000000000 +0900
> >>> @@ -1423,6 +1423,7 @@
> >>> if (XEN_HYPER_MODE()) {
> >>> func_name = kl_funcname(pc);
> >>> if (STREQ(func_name, "idle_loop") || STREQ(func_name, "hypercall")
> >>> + || STREQ(func_name, "tracing_off")
> >>> || STREQ(func_name, "handle_exception")) {
> >>> UPDATE_FRAME(func_name, pc, 0, sp, bp, asp, 0, 0, bp - sp, 0);
> >>> return(trace->nframes);
> >>> @@ -1682,6 +1683,7 @@
> >>> if (func_name && XEN_HYPER_MODE()) {
> >>> if (STREQ(func_name, "continue_nmi") ||
> >>> STREQ(func_name, "vmx_asm_vmexit_handler") ||
> >>> + STREQ(func_name, "handle_nmi_mce") ||
> >>> STREQ(func_name, "deferred_nmi")) {
> >>> /* Interrupt frame */
> >>> sp = curframe->fp + 4;
> >>> --- x86.c.org 2008-04-17 10:29:21.000000000 +0900
> >>> +++ x86.c 2008-04-17 10:31:51.000000000 +0900
> >>> @@ -2846,7 +2846,10 @@
> >>> *paddr = kvaddr - DIRECTMAP_VIRT_START;
> >>> return TRUE;
> >>> }
> >>> - pgd = (ulonglong *)symbol_value("idle_pg_table_l3");
> >>> + if (symbol_exists("idle_pg_table_l3"))
> >>> + pgd = (ulonglong *)symbol_value("idle_pg_table_l3");
> >>> + else
> >>> + pgd = (ulonglong *)symbol_value("idle_pg_table");
> >>> } else {
> >>> if (!vt->vmalloc_start) {
> >>> *paddr = VTOP(kvaddr);
> >>> @@ -4965,7 +4968,8 @@
> >>> break;
> >>>
> >>> case PRE_GDB:
> >>> - if (symbol_exists("idle_pg_table_l3")) {
> >>> + if (symbol_exists("create_pae_xen_mappings") ||
> >>> + symbol_exists("idle_pg_table_l3")) {
> >>> machdep->flags |= PAE;
> >>> PGDIR_SHIFT = PGDIR_SHIFT_3LEVEL;
> >>> PTRS_PER_PTE = PTRS_PER_PTE_3LEVEL;
> >>>
> >>> === for x86_64 ===
> >>> --- defs.h.org 2008-04-17 15:03:14.000000000 +0900
> >>> +++ defs.h 2008-04-17 15:41:10.000000000 +0900
> >>> @@ -2162,10 +2162,13 @@
> >>>
> >>> #define FILL_PML4_HYPER() { \
> >>> if (!machdep->machspec->last_pml4_read) { \
> >>> - readmem(symbol_value("idle_pg_table_4"), KVADDR, \
> >>> - machdep->machspec->pml4, PAGESIZE(), "idle_pg_table_4", \
> >>> + unsigned long idle_pg_table = \
> >>> + symbol_exists("idle_pg_table_4") ? symbol_value("idle_pg_table_4") : \
> >>> + symbol_value("idle_pg_table"); \
> >>> + readmem(idle_pg_table, KVADDR, \
> >>> + machdep->machspec->pml4, PAGESIZE(), "idle_pg_table", \
> >>> FAULT_ON_ERROR); \
> >>> - machdep->machspec->last_pml4_read = symbol_value("idle_pg_table_4"); \
> >>> + machdep->machspec->last_pml4_read = idle_pg_table; \
> >>> }\
> >>> }
> >>>
> >>> @@ -4081,6 +4084,8 @@
> >>> void get_kdump_regs(struct bt_info *, ulong *, ulong *);
> >>> void xen_kdump_p2m_mfn(char *);
> >>> int is_sadump_xen(void);
> >>> +void set_xen_phys_start_mfn(char *);
> >>> +ulong xen_phys_start_mfn(void);
> >>>
> >>> /*
> >>> * diskdump.c
> >>> --- main.c.org 2008-04-17 15:26:37.000000000 +0900
> >>> +++ main.c 2008-04-17 15:45:18.000000000 +0900
> >>> @@ -48,6 +48,7 @@
> >>> {"no_ikconfig", 0, 0, 0},
> >>> {"hyper", 0, 0, 0},
> >>> {"p2m_mfn", required_argument, 0, 0},
> >>> + {"xen_phys_start_mfn", required_argument, 0, 0},
> >>> {"zero_excluded", 0, 0, 0},
> >>> {"no_panic", 0, 0, 0},
> >>> {"more", 0, 0, 0},
> >>> @@ -155,6 +156,9 @@
> >>> else if (STREQ(long_options[option_index].name, "p2m_mfn"))
> >>> xen_kdump_p2m_mfn(optarg);
> >>>
> >>> + else if (STREQ(long_options[option_index].name, "xen_phys_start_mfn"))
> >>> + set_xen_phys_start_mfn(optarg);
> >>> +
> >>> else if (STREQ(long_options[option_index].name, "zero_excluded"))
> >>> *diskdump_flags |= ZERO_EXCLUDED;
> >>>
> >>> --- netdump.c.org 2008-04-17 15:09:06.000000000 +0900
> >>> +++ netdump.c 2008-04-17 15:48:44.000000000 +0900
> >>> @@ -1521,6 +1521,8 @@
> >>> */
> >>> if (!nd->xen_kdump_data->p2m_mfn)
> >>> nd->xen_kdump_data->p2m_mfn = *(uptr+(words-1));
> >>> + if (words > 9 && !nd->xen_kdump_data->xen_phys_start_mfn)
> >>> + nd->xen_kdump_data->xen_phys_start_mfn = *(uptr+(words-2));
> >>> }
> >>> }
> >>> break;
> >>> @@ -1724,6 +1726,8 @@
> >>> */
> >>> if (!nd->xen_kdump_data->p2m_mfn)
> >>> nd->xen_kdump_data->p2m_mfn = *(up+(words-1));
> >>> + if (words > 9 && !nd->xen_kdump_data->xen_phys_start_mfn)
> >>> + nd->xen_kdump_data->xen_phys_start_mfn = *(up+(words-2));
> >>> }
> >>> }
> >>> break;
> >>> @@ -2312,3 +2316,22 @@
> >>>
> >>> return FALSE;
> >>> }
> >>> +
> >>> +void
> >>> +set_xen_phys_start_mfn(char *arg)
> >>> +{
> >>> + ulong value;
> >>> + int errflag = 0;
> >>> +
> >>> + value = htol(arg, RETURN_ON_ERROR|QUIET, &errflag);
> >>> + if (!errflag)
> >>> + xen_kdump_data.xen_phys_start_mfn = value;
> >>> + else
> >>> + error(WARNING, "invalid xen_phys_start_mfn argument: %s\n", arg);
> >>> +}
> >>> +
> >>> +ulong
> >>> +xen_phys_start_mfn(void)
> >>> +{
> >>> + return nd->xen_kdump_data->xen_phys_start_mfn;
> >>> +}
> >>> --- netdump.h.org 2008-04-17 15:38:59.000000000 +0900
> >>> +++ netdump.h 2008-04-17 15:39:38.000000000 +0900
> >>> @@ -109,6 +109,7 @@
> >>> ulong accesses;
> >>> int p2m_frames;
> >>> ulong *p2m_mfn_frame_list;
> >>> + ulong xen_phys_start_mfn;
> >>> };
> >>>
> >>> #define KDUMP_P2M_INIT (0x1)
> >>> --- x86_64.c.org 2008-04-17 15:34:32.000000000 +0900
> >>> +++ x86_64.c 2008-04-17 15:36:53.000000000 +0900
> >>> @@ -1401,6 +1401,10 @@
> >>> return FALSE;
> >>>
> >>> if (XEN_HYPER_MODE()) {
> >>> + if (XENTEXT_VIRT_ADDR(kvaddr)) {
> >>> + *paddr = kvaddr - __XEN_VIRT_START + (xen_phys_start_mfn() << PAGESHIFT());
> >>> + return TRUE;
> >>> + }
> >>> if (DIRECTMAP_VIRT_ADDR(kvaddr)) {
> >>> *paddr = kvaddr - DIRECTMAP_VIRT_START;
> >>> return TRUE;
> >>> --- xen_hyper_defs.h.org 2008-04-17 15:31:23.000000000 +0900
> >>> +++ xen_hyper_defs.h 2008-04-17 15:34:15.000000000 +0900
> >>> @@ -64,6 +64,9 @@
> >>> #define DIRECTMAP_VIRT_START (0xffff830000000000)
> >>> #define DIRECTMAP_VIRT_END (0xffff840000000000)
> >>> #define PAGE_OFFSET_XEN_HYPER DIRECTMAP_VIRT_START
> >>> +#define __XEN_VIRT_START (0xFFFF828C80000000)
> >>> +#define XENTEXT_VIRT_ADDR(vaddr) \
> >>> + (((vaddr) >= __XEN_VIRT_START) && ((vaddr) < DIRECTMAP_VIRT_START))
> >>> #endif
> >>>
> >>> #ifdef IA64
> >>>
> >>> === Xen (explanation purpose) ===
> >>> --- 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_mfn;
> >>> 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_mfn = xen_phys_start >> PAGE_SHIFT;
> >>> info->dom0_pfn_to_mfn_frame_list_list =
> >>> arch_get_pfn_to_mfn_frame_list_list(dom0);
> >>> }
> >
>
--
Itsuro ODA <oda at valinux.co.jp>
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