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[Qemu-devel] [PATCH v5 4/8] dump: add guest ELF note
From: |
Marc-André Lureau |
Subject: |
[Qemu-devel] [PATCH v5 4/8] dump: add guest ELF note |
Date: |
Mon, 7 Aug 2017 20:16:14 +0200 |
Read the guest ELF PT_NOTE from guest memory when fw_cfg
etc/vmcoreinfo entry provides the location, and write it as an
additional note in the dump.
Signed-off-by: Marc-André Lureau <address@hidden>
---
include/sysemu/dump.h | 2 +
dump.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 105 insertions(+)
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index 2672a15f8b..df43bd0e07 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 *guest_note; /* ELF note content */
+ size_t guest_note_size;
} DumpState;
uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
diff --git a/dump.c b/dump.c
index d9090a24cc..7fe1044280 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/nvram/fw_cfg.h"
#include <zlib.h>
#ifdef CONFIG_LZO
@@ -38,6 +40,13 @@
#define ELF_MACHINE_UNAME "Unknown"
#endif
+#define MAX_GUEST_NOTE_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->guest_note);
+ s->guest_note = 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_guest_note(WriteCoreDumpFunction f, DumpState *s,
+ Error **errp)
+{
+ int ret;
+
+ if (s->guest_note) {
+ ret = f(s->guest_note, s->guest_note_size, s);
+ if (ret < 0) {
+ error_setg(errp, "dump: failed to write guest note");
+ }
+ }
+}
+
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_guest_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_guest_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)
{
@@ -1492,6 +1558,7 @@ 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)
{
+ FWCfgState *fw_cfg = fw_cfg_find();
CPUState *cpu;
int nr_cpus;
Error *err = NULL;
@@ -1563,6 +1630,42 @@ static void dump_init(DumpState *s, int fd, bool
has_format,
goto cleanup;
}
+ /*
+ * The goal of this block is to copy the guest note out of
+ * the guest. Failure to do so is not fatal for dumping.
+ */
+ if (fw_cfg) {
+ 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);
+
+ size = le32_to_cpu(fw_cfg->vmcoreinfo.size);
+ addr = le64_to_cpu(fw_cfg->vmcoreinfo.paddr);
+ if (!fw_cfg->has_vmcoreinfo) {
+ warn_report("guest note is not present");
+ } else if (size < note_head_size || size > MAX_GUEST_NOTE_SIZE) {
+ warn_report("guest note size is invalid: %" PRIu32, size);
+ } else {
+ s->guest_note = g_malloc(size + 1); /* +1 for adding \0 */
+ cpu_physical_memory_read(addr, s->guest_note, size);
+
+ get_note_sizes(s, s->guest_note, NULL, &name_size, &desc_size);
+ s->guest_note_size = ELF_NOTE_SIZE(note_head_size, name_size,
+ desc_size);
+ if (name_size > MAX_GUEST_NOTE_SIZE ||
+ desc_size > MAX_GUEST_NOTE_SIZE ||
+ s->guest_note_size > size) {
+ warn_report("Invalid guest note header");
+ g_free(s->guest_note);
+ s->guest_note = NULL;
+ } else {
+ s->note_size += s->guest_note_size;
+ }
+ }
+ }
+
/* get memory mapping */
if (paging) {
qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, &err);
--
2.14.0.1.geff633fa0
- [Qemu-devel] [PATCH v5 0/8] KASLR kernel dump support, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 1/8] fw_cfg: rename read callback, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 2/8] fw_cfg: add write callback, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 3/8] fw_cfg: add vmcoreinfo file, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 4/8] dump: add guest ELF note,
Marc-André Lureau <=
- [Qemu-devel] [PATCH v5 5/8] dump: update phys_base header field based on VMCOREINFO content, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 6/8] kdump: set vmcoreinfo location, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 7/8] scripts/dump-guest-memory.py: add vmcoreinfo, Marc-André Lureau, 2017/08/07
- [Qemu-devel] [PATCH v5 8/8] MAINTAINERS: add Dump maintainers, Marc-André Lureau, 2017/08/07
- Re: [Qemu-devel] [PATCH v5 0/8] KASLR kernel dump support, Michael S. Tsirkin, 2017/08/16