Read the vmcoreinfo ELF PT_NOTE from guest memory when vmcoreinfo
device provides the location, and write it as an ELF note in the dump.
There are now 2 possible sources of phys_base information.
(1) arch guessed value from cpu_get_dump_info()
(2) vmcoreinfo ELF note NUMBER(phys_base)= field
NUMBER(phys_base) in vmcoreinfo has only been recently introduced
in Linux 4.10 (401721ecd1dc "kexec: export the value of phys_base
instead of symbol address").
Since (2) has better chances to be accurate, the guessed value is
replaced by the value from the vmcoreinfo ELF note.
The phys_base value is stored in the same dump field locations as
before, and may duplicate the information available in the vmcoreinfo
ELF PT_NOTE. Crash tools should be prepared to handle this case.
Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Reviewed-by: Laszlo Ersek <ler...@redhat.com>
---
include/sysemu/dump.h | 2 +
dump.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 136 insertions(+)
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index 2672a15f8b..111a7dcaa4 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -192,6 +192,8 @@ typedef struct DumpState {
* this could be used to calculate
* how much work we have
* finished. */
+ uint8_t *vmcoreinfo; /* ELF note content */
+ size_t vmcoreinfo_size;
} DumpState;
uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
diff --git a/dump.c b/dump.c
index d9090a24cc..d86b601248 100644
--- a/dump.c
+++ b/dump.c
@@ -26,6 +26,8 @@
#include "qapi/qmp/qerror.h"
#include "qmp-commands.h"
#include "qapi-event.h"
+#include "qemu/error-report.h"
+#include "hw/acpi/vmcoreinfo.h"
#include <zlib.h>
#ifdef CONFIG_LZO
@@ -38,6 +40,13 @@
#define ELF_MACHINE_UNAME "Unknown"
#endif
+#define MAX_VMCOREINFO_SIZE (1 << 20) /* 1MB should be enough */
+
+#define ELF_NOTE_SIZE(hdr_size, name_size, desc_size) \
+ ((DIV_ROUND_UP((hdr_size), 4) + \
+ DIV_ROUND_UP((name_size), 4) + \
+ DIV_ROUND_UP((desc_size), 4)) * 4)
+
uint16_t cpu_to_dump16(DumpState *s, uint16_t val)
{
if (s->dump_info.d_endian == ELFDATA2LSB) {
@@ -76,6 +85,8 @@ static int dump_cleanup(DumpState *s)
guest_phys_blocks_free(&s->guest_phys_blocks);
memory_mapping_list_free(&s->list);
close(s->fd);
+ g_free(s->vmcoreinfo);
+ s->vmcoreinfo = NULL;
if (s->resume) {
if (s->detached) {
qemu_mutex_lock_iothread();
@@ -235,6 +246,19 @@ static inline int cpu_index(CPUState *cpu)
return cpu->cpu_index + 1;
}
+static void write_vmcoreinfo_note(WriteCoreDumpFunction f, DumpState *s,
+ Error **errp)
+{
+ int ret;
+
+ if (s->vmcoreinfo) {
+ ret = f(s->vmcoreinfo, s->vmcoreinfo_size, s);
+ if (ret < 0) {
+ error_setg(errp, "dump: failed to write vmcoreinfo");
+ }
+ }
+}
+
static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
Error **errp)
{
@@ -258,6 +282,8 @@ static void write_elf64_notes(WriteCoreDumpFunction f,
DumpState *s,
return;
}
}
+
+ write_vmcoreinfo_note(f, s, errp);
}
static void write_elf32_note(DumpState *s, Error **errp)
@@ -303,6 +329,8 @@ static void write_elf32_notes(WriteCoreDumpFunction f,
DumpState *s,
return;
}
}
+
+ write_vmcoreinfo_note(f, s, errp);
}
static void write_elf_section(DumpState *s, int type, Error **errp)
@@ -714,6 +742,44 @@ static int buf_write_note(const void *buf, size_t size,
void *opaque)
return 0;
}
+/*
+ * This function retrieves various sizes from an elf header.
+ *
+ * @note has to be a valid ELF note. The return sizes are unmodified
+ * (not padded or rounded up to be multiple of 4).
+ */
+static void get_note_sizes(DumpState *s, const void *note,
+ uint64_t *note_head_size,
+ uint64_t *name_size,
+ uint64_t *desc_size)
+{
+ uint64_t note_head_sz;
+ uint64_t name_sz;
+ uint64_t desc_sz;
+
+ if (s->dump_info.d_class == ELFCLASS64) {
+ const Elf64_Nhdr *hdr = note;
+ note_head_sz = sizeof(Elf64_Nhdr);
+ name_sz = tswap64(hdr->n_namesz);
+ desc_sz = tswap64(hdr->n_descsz);
+ } else {
+ const Elf32_Nhdr *hdr = note;
+ note_head_sz = sizeof(Elf32_Nhdr);
+ name_sz = tswap32(hdr->n_namesz);
+ desc_sz = tswap32(hdr->n_descsz);
+ }
+
+ if (note_head_size) {
+ *note_head_size = note_head_sz;
+ }
+ if (name_size) {
+ *name_size = name_sz;
+ }
+ if (desc_size) {
+ *desc_size = desc_sz;
+ }
+}
+
/* write common header, sub header and elf note to vmcore */
static void create_header32(DumpState *s, Error **errp)
{
@@ -1488,10 +1554,40 @@ 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;
+
+ get_note_sizes(s, s->vmcoreinfo, ¬e_head_size, &name_size, &size);
+ note_head_size = ROUND_UP(note_head_size, 4);
+ name_size = ROUND_UP(name_size, 4);
+ vmci = s->vmcoreinfo + note_head_size + name_size;
+ *(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)
{
+ Object *vmcoreinfo_dev = find_vmcoreinfo_dev();
CPUState *cpu;
int nr_cpus;
Error *err = NULL;
@@ -1563,6 +1659,44 @@ static void dump_init(DumpState *s, int fd, bool
has_format,
goto cleanup;
}
+ /*
+ * The goal of this block is to (a) update the previously guessed
+ * phys_base, (b) copy the vmcoreinfo note out of the guest.
+ * Failure to do so is not fatal for dumping.
+ */
+ if (vmcoreinfo_dev) {
+ uint64_t addr, note_head_size, name_size, desc_size;
+ uint32_t size;
+
+ note_head_size = s->dump_info.d_class == ELFCLASS32 ?
+ sizeof(Elf32_Nhdr) : sizeof(Elf64_Nhdr);
+
+ if (!vmcoreinfo_get(VMCOREINFO(vmcoreinfo_dev),
+ &addr, &size, &err)) {
+ warn_report_err(err);
+ err = NULL;
+ } else if (size < note_head_size || size > MAX_VMCOREINFO_SIZE) {
+ warn_report("vmcoreinfo size is invalid: %" PRIu32, size);
+ } else {
+ s->vmcoreinfo = g_malloc(size + 1); /* +1 for adding \0 */
+ cpu_physical_memory_read(addr, s->vmcoreinfo, size);
+
+ get_note_sizes(s, s->vmcoreinfo, NULL, &name_size, &desc_size);
+ s->vmcoreinfo_size = ELF_NOTE_SIZE(note_head_size, name_size,
+ desc_size);
+ if (name_size > MAX_VMCOREINFO_SIZE ||
+ desc_size > MAX_VMCOREINFO_SIZE ||
+ s->vmcoreinfo_size > size) {
+ warn_report("Invalid vmcoreinfo header");
+ g_free(s->vmcoreinfo);
+ s->vmcoreinfo = NULL;
+ } else {
+ vmcoreinfo_update_phys_base(s);
+ s->note_size += s->vmcoreinfo_size;
+ }
+ }
+ }
+
/* get memory mapping */
if (paging) {
qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, &err);
--
2.13.1.395.gf7b71de06
