|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Crash-utility] [PATCH] xen: Add support for domU with Linux kernel 3.19 and newer
----- Original Message ----- > crash patch c3413456599161cabc4e910a0ae91dfe5eec3c21 (xen: Add support for > dom0 with Linux kernel 3.19 and newer) from Daniel made crash utility > support xen dom0 vmcores after linux kernel commit > 054954eb051f35e74b75a566a96fe756015352c8 (xen: switch to linear virtual > mapped sparse p2m list). > > This patch can be deemed as a subsequent and make this utility support Xen > PV domU dumpfiles again. > > Basically speaking, readmem() can't be used to read xen_p2m_addr associate > memory directly during m2p translation. It introduces infinite recursion. > Following call sequence shows the scenario, it comes from a section of > backtrace with only kvaddr, machine addr and mfn left as parameter: > > module_init() > > /* The first readmem() from module_init(). */ > readmem(addr=0xffffffffa02fe4a0) > > /* readmem() needs physical address, so calls kvtop(). */ > kvtop(kvaddr=0xffffffffa02fe4a0) > x86_64_kvtop(kvaddr=ffffffffa02fe4a0) > > /* Calculate physical address by traversing page tables. */ > x86_64_kvtop_xen_wpt(kvaddr=0xffffffffa02fe4a0) > > /* > * x86_64_kvtop_xen_wpt() is going to traverse the page table to > * get the physical address for 0xffffffffa02fe4a0. So, at first it > * is needed to translate the pgd from machine address to physical > * address. So invoke xen_m2p() here to do the translation. 0x58687f000 > * is the pgd machine address in x86_64_kvtop_xen_wpt() and is needed > * to be translated to its physical address. > */ > xen_m2p(machine=0x58687f000) > __xen_m2p(machine=0x58687f000, mfn=0x58687f) > > /* > * __xen_m2p() is going to search mfn 0x58687f in p2m VMA which starts > * at VMA 0xffffc900001cf000. It compares every mfn stored in it with > * 0x58687f. Once it's proved 0x58687f is one mfn in the p2m, its offset > * will be used to calculate the pfn. > * > * readmem() is invoked by __xen_m2p() to read the page from VMA > * 0xffffc900001cf000 here. > */ > readmem(addr=0xffffc900001cf000) > > /* > * readmem() needs physical address of 0xffffc900001cf000 to make the > * reading done. So it invokes kvtop() to get the physical address. > */ > kvtop(kvaddr=0xffffc900001cf000) > x86_64_kvtop(kvaddr=0xffffc900001cf000) > > /* It needs to calculate physical address by traversing page tables. */ > x86_64_kvtop_xen_wpt(kvaddr=0xffffc900001cf000) > > /* > * 0x581b7e000 is the machine address of pgd need to be translated here. > * The mfn is calculated in this way at x86_64_kvtop_xen_wpt(): > * > * pml4 = ((ulong *)machdep->machspec->pml4) + pml4_index(kvaddr); > * pgd_paddr = (*pml4) & PHYSICAL_PAGE_MASK; > * > * The kvaddr 0xffffc900001cf000 here is quite different from the one > * above, so the machine address of pgd is not the same one. And this > * pgd is the one we use to access the VMA of p2m table. > */ > xen_m2p(machine=0x581b7e000) > __xen_m2p(machine=0x581b7e000, mfn=0x581b7e) > > /* > * Looking for mfn 0x581b7e in the range of p2m page which starts at > * VMA 0xffffc900001f5000. > */ > readmem(addr=0xffffc900001f5000) > > /* Need physical address of VMA 0xffffc900001f5000 as same reason above. */ > kvtop(kvaddr=0xffffc900001f5000) > x86_64_kvtop(kvaddr=0xffffc900001f5000) > > /* Need to traverse page tables to calculate physical address for it. */ > x86_64_kvtop_xen_wpt(kvaddr=0xffffc900001f5000) > > /* > * Unfortunately, machine address 0x581b7e000 have to be translated again. > * Endless loop starts from here. > */ > xen_m2p(machine=0x581b7e000) > __xen_m2p(machine=0x581b7e000, mfn=0x581b7e) > readmem(addr=0xffffc900001f5000) > > Fortunately, PV domU p2m mapping is also stored at xd->xfd + xch_index_offset > and organized as struct xen_dumpcore_p2m. We have a chance to read the p2m > stuff directly from there, and then we avoid the loop above. > > So, this patch implements a special reading function read_xc_p2m() to extract > the mfns from xd->xfd + xch_index_offset. This function does not need to read > mfns from p2m VMA like readmem() does, so, we avoid the endless loop > introduced > by the address translation. > > Signed-off-by: Honglei Wang <honglei.wang@xxxxxxxxxx> > Reviewed-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx> Queued for crash-7.2.0: https://github.com/crash-utility/crash/commit/5c52842a58a2602dba81de71831af98b2b53c6e0 Thanks, Dave > --- > kernel.c | 151 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++------ > xendump.c | 2 +- > xendump.h | 2 + > 3 files changed, 140 insertions(+), 15 deletions(-) > > diff --git a/kernel.c b/kernel.c > index 395736c..7a5ce64 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -22,6 +22,7 @@ > #include <libgen.h> > #include <ctype.h> > #include <stdbool.h> > +#include "xendump.h" > > static void do_module_cmd(ulong, char *, ulong, char *, char *); > static void show_module_taint(void); > @@ -67,6 +68,9 @@ static ulong __xen_m2p(ulonglong, ulong); > static ulong __xen_pvops_m2p_l2(ulonglong, ulong); > static ulong __xen_pvops_m2p_l3(ulonglong, ulong); > static ulong __xen_pvops_m2p_hyper(ulonglong, ulong); > +static ulong __xen_pvops_m2p_domU(ulonglong, ulong); > +static int read_xc_p2m(ulonglong addr, void *buffer, long size); > +static void read_p2m(ulong cache_index, int memtype, void *buffer); > static int search_mapping_page(ulong, ulong *, ulong *, ulong *); > static void read_in_kernel_config_err(int, char *); > static void BUG_bytes_init(void); > @@ -181,10 +185,7 @@ kernel_init() > &kt->pvops_xen.p2m_mid_missing); > get_symbol_data("p2m_missing", sizeof(ulong), > &kt->pvops_xen.p2m_missing); > - } else if (symbol_exists("xen_p2m_addr")) { > - if (!XEN_CORE_DUMPFILE()) > - error(FATAL, "p2m array in new format is > unreadable."); > - } else { > + } else if (!symbol_exists("xen_p2m_addr")) { > kt->pvops_xen.p2m_top_entries = > get_array_length("p2m_top", NULL, 0); > kt->pvops_xen.p2m_top = symbol_value("p2m_top"); > kt->pvops_xen.p2m_missing = symbol_value("p2m_missing"); > @@ -9305,13 +9306,7 @@ __xen_m2p(ulonglong machine, ulong mfn) > if (memtype == PHYSADDR) > pc->curcmd_flags |= XEN_MACHINE_ADDR; > > - if (!readmem(kt->p2m_mapping_cache[c].mapping, > memtype, > - mp, PAGESIZE(), "phys_to_machine_mapping > page (cached)", > - RETURN_ON_ERROR)) > - error(FATAL, "cannot access " > - "phys_to_machine_mapping page\n"); > - else > - kt->last_mapping_read = > kt->p2m_mapping_cache[c].mapping; > + read_p2m(c, memtype, mp); > > if (memtype == PHYSADDR) > pc->curcmd_flags &= ~XEN_MACHINE_ADDR; > @@ -9349,9 +9344,12 @@ __xen_m2p(ulonglong machine, ulong mfn) > */ > if (symbol_exists("p2m_mid_missing")) > pfn = __xen_pvops_m2p_l3(machine, mfn); > - else if (symbol_exists("xen_p2m_addr")) > - pfn = __xen_pvops_m2p_hyper(machine, mfn); > - else > + else if (symbol_exists("xen_p2m_addr")) { > + if (XEN_CORE_DUMPFILE()) > + pfn = __xen_pvops_m2p_hyper(machine, mfn); > + else > + pfn = __xen_pvops_m2p_domU(machine, mfn); > + } else > pfn = __xen_pvops_m2p_l2(machine, mfn); > > if (pfn != XEN_MFN_NOT_FOUND) > @@ -9559,6 +9557,131 @@ __xen_pvops_m2p_hyper(ulonglong machine, ulong mfn) > return XEN_MFN_NOT_FOUND; > } > > +static void read_p2m(ulong cache_index, int memtype, void *buffer) > +{ > + /* > + * Use special read function for PV domain p2m reading. > + * See the comments of read_xc_p2m(). > + */ > + if (symbol_exists("xen_p2m_addr") && !XEN_CORE_DUMPFILE()) { > + if (!read_xc_p2m(kt->p2m_mapping_cache[cache_index].mapping, > + buffer, PAGESIZE())) > + error(FATAL, "cannot access phys_to_machine_mapping > page\n"); > + } else if (!readmem(kt->p2m_mapping_cache[cache_index].mapping, memtype, > + buffer, PAGESIZE(), "phys_to_machine_mapping page > (cached)", > + RETURN_ON_ERROR)) > + error(FATAL, "cannot access phys_to_machine_mapping page\n"); > + > + kt->last_mapping_read = kt->p2m_mapping_cache[cache_index].mapping; > +} > + > +/* > + * PV domain p2m mapping info is stored in xd->xfd at xch_index_offset. It > + * is organized as struct xen_dumpcore_p2m and the pfns are progressively > + * increased by 1 from 0. > + * > + * This is a special p2m reading function for xen PV domain vmcores after > + * kernel commit 054954eb051f35e74b75a566a96fe756015352c8 (xen: switch > + * to linear virtual mapped sparse p2m list). It is invoked for reading > + * p2m associate stuff by read_p2m(). > + */ > +static int read_xc_p2m(ulonglong addr, void *buffer, long size) > +{ > + ulong i, new_p2m_buf_size; > + off_t offset; > + struct xen_dumpcore_p2m *new_p2m_buf; > + static struct xen_dumpcore_p2m *p2m_buf; > + static ulong p2m_buf_size = 0; > + > + if (size <= 0) { > + if ((CRASHDEBUG(1) && !STREQ(pc->curcmd, "search")) || > + CRASHDEBUG(2)) > + error(INFO, "invalid size request: %ld\n", size); > + return FALSE; > + } > + > + /* > + * We extract xen_dumpcore_p2m.gmfn and copy them into the > + * buffer. So, we need temporary p2m_buf whose size is > + * (size * (sizeof(struct xen_dumpcore_p2m) / sizeof(ulong))) > + * to put xen_dumpcore_p2m structures read from xd->xfd. > + */ > + new_p2m_buf_size = size * (sizeof(struct xen_dumpcore_p2m) / > sizeof(ulong)); > + > + if (p2m_buf_size != new_p2m_buf_size) { > + p2m_buf_size = new_p2m_buf_size; > + > + new_p2m_buf = realloc(p2m_buf, p2m_buf_size); > + if (new_p2m_buf == NULL) { > + free(p2m_buf); > + error(FATAL, "cannot realloc p2m buffer\n"); > + } > + p2m_buf = new_p2m_buf; > + } > + > + offset = addr * (sizeof(struct xen_dumpcore_p2m) / sizeof(ulong)); > + offset += xd->xc_core.header.xch_index_offset; > + > + if (lseek(xd->xfd, offset, SEEK_SET) == -1) > + error(FATAL, > + "cannot lseek to xch_index_offset offset 0x%lx\n", offset); > + if (read(xd->xfd, (void*)p2m_buf, p2m_buf_size) != p2m_buf_size) > + error(FATAL, > + "cannot read from xch_index_offset offset 0x%lx\n", offset); > + > + for (i = 0; i < size / sizeof(ulong); i++) > + *((ulong *)buffer + i) = p2m_buf[i].gmfn; > + > + return TRUE; > +} > + > +static ulong > +__xen_pvops_m2p_domU(ulonglong machine, ulong mfn) > +{ > + ulong c, end, i, mapping, p, pfn, start; > + > + /* > + * xch_nr_pages is the number of pages of p2m mapping. It is composed > + * of struct xen_dumpcore_p2m. The stuff we want to copy into the > mapping > + * page is mfn whose type is unsigned long. > + * So actual number of p2m pages should be: > + * > + * xch_nr_pages / (sizeof(struct xen_dumpcore_p2m) / sizeof(ulong)) > + */ > + for (p = 0; > + p < xd->xc_core.header.xch_nr_pages / > + (sizeof(struct xen_dumpcore_p2m) / sizeof(ulong)); > + ++p) { > + > + mapping = p * PAGESIZE(); > + > + if (mapping != kt->last_mapping_read) { > + if (!read_xc_p2m(mapping, (void *)kt->m2p_page, > PAGESIZE())) > + error(FATAL, "cannot read the last mapping > page\n"); > + kt->last_mapping_read = mapping; > + } > + kt->p2m_pages_searched++; > + > + if (search_mapping_page(mfn, &i, &start, &end)) { > + pfn = p * XEN_PFNS_PER_PAGE + i; > + c = kt->p2m_cache_index; > + if (CRASHDEBUG (1)) > + console("mfn: %lx (%llx) i: %ld pfn: %lx > (%llx)\n", > + mfn, machine, i, pfn, > XEN_PFN_TO_PSEUDO(pfn)); > + > + kt->p2m_mapping_cache[c].start = start; > + kt->p2m_mapping_cache[c].end = end; > + kt->p2m_mapping_cache[c].mapping = mapping; > + kt->p2m_mapping_cache[c].pfn = p * XEN_PFNS_PER_PAGE; > + kt->p2m_cache_index = (c+1) % P2M_MAPPING_CACHE; > + > + return pfn; > + } > + } > + > + return XEN_MFN_NOT_FOUND; > +} > + > /* > * Search for an mfn in the current mapping page, and if found, > * determine the range of contiguous mfns that it's contained > diff --git a/xendump.c b/xendump.c > index 8170b22..4bd59b5 100644 > --- a/xendump.c > +++ b/xendump.c > @@ -19,7 +19,7 @@ > #include "xendump.h" > > static struct xendump_data xendump_data = { 0 }; > -static struct xendump_data *xd = &xendump_data; > +struct xendump_data *xd = &xendump_data; > > static int xc_save_verify(char *); > static int xc_core_verify(char *, char *); > diff --git a/xendump.h b/xendump.h > index 08d41b4..b7bae65 100644 > --- a/xendump.h > +++ b/xendump.h > @@ -192,3 +192,5 @@ struct xen_dumpcore_p2m { > uint64_t pfn; > uint64_t gmfn; > }; > + > +extern struct xendump_data *xd; > -- > 1.7.1 > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |