diff options
| -rw-r--r-- | docs/specs/vmcoreinfo.txt | 8 | ||||
| -rw-r--r-- | dump.c | 56 |
2 files changed, 62 insertions, 2 deletions
diff --git a/docs/specs/vmcoreinfo.txt b/docs/specs/vmcoreinfo.txt index 2868a77142..821261067f 100644 --- a/docs/specs/vmcoreinfo.txt +++ b/docs/specs/vmcoreinfo.txt @@ -39,3 +39,11 @@ qemu dumps. The note format/class must be of the target bitness and the size must be less than 1Mb. + +If the ELF note name is "VMCOREINFO", it is expected to be the Linux +vmcoreinfo note (see Documentation/ABI/testing/sysfs-kernel-vmcoreinfo +in Linux source). In this case, qemu dump code will read the content +as a key=value text file, looking for "NUMBER(phys_base)" key +value. The value is expected to be more accurate than architecture +guess of the value. This is useful for KASLR-enabled guest with +ancient tools not handling the VMCOREINFO note. @@ -779,6 +779,23 @@ static void get_note_sizes(DumpState *s, const void *note, } } +static bool note_name_equal(DumpState *s, + const uint8_t *note, const char *name) +{ + int len = strlen(name) + 1; + uint64_t head_size, name_size; + + get_note_sizes(s, note, &head_size, &name_size, NULL); + head_size = ROUND_UP(head_size, 4); + + if (name_size != len || + memcmp(note + head_size, "VMCOREINFO", len)) { + return false; + } + + return true; +} + /* write common header, sub header and elf note to vmcore */ static void create_header32(DumpState *s, Error **errp) { @@ -1553,6 +1570,39 @@ static int64_t dump_calculate_size(DumpState *s) return total; } +static void vmcoreinfo_update_phys_base(DumpState *s) +{ + uint64_t size, note_head_size, name_size, phys_base; + char **lines; + uint8_t *vmci; + size_t i; + + if (!note_name_equal(s, s->guest_note, "VMCOREINFO")) { + return; + } + + get_note_sizes(s, s->guest_note, ¬e_head_size, &name_size, &size); + note_head_size = ROUND_UP(note_head_size, 4); + + vmci = s->guest_note + note_head_size + ROUND_UP(name_size, 4); + *(vmci + size) = '\0'; + + lines = g_strsplit((char *)vmci, "\n", -1); + for (i = 0; lines[i]; i++) { + if (g_str_has_prefix(lines[i], "NUMBER(phys_base)=")) { + if (qemu_strtou64(lines[i] + 18, NULL, 16, + &phys_base) < 0) { + warn_report("Failed to read NUMBER(phys_base)="); + } else { + s->dump_info.phys_base = phys_base; + } + break; + } + } + + g_strfreev(lines); +} + static void dump_init(DumpState *s, int fd, bool has_format, DumpGuestMemoryFormat format, bool paging, bool has_filter, int64_t begin, int64_t length, Error **errp) @@ -1636,8 +1686,9 @@ static void dump_init(DumpState *s, int fd, bool has_format, } /* - * The goal of this block is to copy the guest note out of - * the guest. Failure to do so is not fatal for dumping. + * The goal of this block is to (a) update the previously guessed + * phys_base, (b) copy the guest note out of the guest. + * Failure to do so is not fatal for dumping. */ if (vmci) { uint64_t addr, note_head_size, name_size, desc_size; @@ -1670,6 +1721,7 @@ static void dump_init(DumpState *s, int fd, bool has_format, g_free(s->guest_note); s->guest_note = NULL; } else { + vmcoreinfo_update_phys_base(s); s->note_size += s->guest_note_size; } } |