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From 693375003f594a1d19acd35df19141b92a5c8822 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>
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Date: Wed, 13 Dec 2017 13:39:01 +0100
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Subject: [PATCH 30/41] dump: add guest ELF note
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Marc-André Lureau <marcandre.lureau@redhat.com>
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Message-id: <20171213133912.26176-31-marcandre.lureau@redhat.com>
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Patchwork-id: 78377
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O-Subject: [RHEL-7.5 qemu-kvm PATCH v3 30/41] dump: add guest ELF note
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Bugzilla: 1411490
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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Read the guest ELF PT_NOTE from guest memory when fw_cfg
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etc/vmcoreinfo entry provides the location, and write it as an
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additional note in the dump.
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Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit 903ef7349699dcd932b5981b85c1f1ebe4a4bf2a)
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RHEL: Minor conflicts due to "detach" mode not being backported.
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      Replace warn_report() with error_report().
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Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 dump.c                | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++
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 include/sysemu/dump.h |   2 +
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 2 files changed, 108 insertions(+)
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diff --git a/dump.c b/dump.c
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index d629c8d..823d1ad 100644
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--- a/dump.c
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+++ b/dump.c
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@@ -24,6 +24,7 @@
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 #include "sysemu/cpus.h"
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 #include "qapi/error.h"
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 #include "qmp-commands.h"
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+#include "hw/misc/vmcoreinfo.h"
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 #include <zlib.h>
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 #ifdef CONFIG_LZO
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@@ -36,6 +37,13 @@
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 #define ELF_MACHINE_UNAME "Unknown"
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 #endif
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+#define MAX_GUEST_NOTE_SIZE (1 << 20) /* 1MB should be enough */
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+
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+#define ELF_NOTE_SIZE(hdr_size, name_size, desc_size)   \
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+    ((DIV_ROUND_UP((hdr_size), 4) +                     \
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+      DIV_ROUND_UP((name_size), 4) +                    \
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+      DIV_ROUND_UP((desc_size), 4)) * 4)
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+
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 uint16_t cpu_to_dump16(DumpState *s, uint16_t val)
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 {
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     if (s->dump_info.d_endian == ELFDATA2LSB) {
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@@ -74,6 +82,8 @@ static int dump_cleanup(DumpState *s)
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     guest_phys_blocks_free(&s->guest_phys_blocks);
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     memory_mapping_list_free(&s->list);
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     close(s->fd);
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+    g_free(s->guest_note);
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+    s->guest_note = NULL;
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     if (s->resume) {
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         vm_start();
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     }
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@@ -227,6 +237,19 @@ static inline int cpu_index(CPUState *cpu)
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     return cpu->cpu_index + 1;
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 }
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+static void write_guest_note(WriteCoreDumpFunction f, DumpState *s,
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+                             Error **errp)
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+{
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+    int ret;
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+
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+    if (s->guest_note) {
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+        ret = f(s->guest_note, s->guest_note_size, s);
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+        if (ret < 0) {
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+            error_setg(errp, "dump: failed to write guest note");
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+        }
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+    }
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+}
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+
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 static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
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                               Error **errp)
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 {
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@@ -253,6 +276,8 @@ static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
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             return;
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         }
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     }
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+
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+    write_guest_note(f, s, errp);
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 }
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 static void write_elf32_note(DumpState *s, Error **errp)
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@@ -301,6 +326,8 @@ static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
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             return;
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         }
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     }
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+
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+    write_guest_note(f, s, errp);
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 }
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 static void write_elf_section(DumpState *s, int type, Error **errp)
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@@ -712,6 +739,44 @@ static int buf_write_note(const void *buf, size_t size, void *opaque)
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     return 0;
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 }
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+/*
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+ * This function retrieves various sizes from an elf header.
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+ *
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+ * @note has to be a valid ELF note. The return sizes are unmodified
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+ * (not padded or rounded up to be multiple of 4).
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+ */
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+static void get_note_sizes(DumpState *s, const void *note,
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+                           uint64_t *note_head_size,
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+                           uint64_t *name_size,
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+                           uint64_t *desc_size)
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+{
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+    uint64_t note_head_sz;
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+    uint64_t name_sz;
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+    uint64_t desc_sz;
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+
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+    if (s->dump_info.d_class == ELFCLASS64) {
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+        const Elf64_Nhdr *hdr = note;
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+        note_head_sz = sizeof(Elf64_Nhdr);
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+        name_sz = tswap64(hdr->n_namesz);
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+        desc_sz = tswap64(hdr->n_descsz);
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+    } else {
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+        const Elf32_Nhdr *hdr = note;
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+        note_head_sz = sizeof(Elf32_Nhdr);
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+        name_sz = tswap32(hdr->n_namesz);
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+        desc_sz = tswap32(hdr->n_descsz);
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+    }
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+
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+    if (note_head_size) {
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+        *note_head_size = note_head_sz;
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+    }
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+    if (name_size) {
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+        *name_size = name_sz;
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+    }
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+    if (desc_size) {
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+        *desc_size = desc_sz;
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+    }
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+}
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+
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 /* write common header, sub header and elf note to vmcore */
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 static void create_header32(DumpState *s, Error **errp)
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 {
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@@ -1493,6 +1558,7 @@ static void dump_init(DumpState *s, int fd, bool has_format,
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                       int64_t begin, int64_t length, Error **errp)
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 {
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     CPUArchState *env;
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+    VMCoreInfoState *vmci = vmcoreinfo_find();
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     int nr_cpus;
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     Error *err = NULL;
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     int ret;
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@@ -1569,6 +1635,46 @@ static void dump_init(DumpState *s, int fd, bool has_format,
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         goto cleanup;
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     }
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+    /*
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+     * The goal of this block is to copy the guest note out of
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+     * the guest.  Failure to do so is not fatal for dumping.
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+     */
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+    if (vmci) {
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+        uint64_t addr, note_head_size, name_size, desc_size;
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+        uint32_t size;
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+        uint16_t format;
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+
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+        note_head_size = s->dump_info.d_class == ELFCLASS32 ?
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+            sizeof(Elf32_Nhdr) : sizeof(Elf64_Nhdr);
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+
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+        format = le16_to_cpu(vmci->vmcoreinfo.guest_format);
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+        size = le32_to_cpu(vmci->vmcoreinfo.size);
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+        addr = le64_to_cpu(vmci->vmcoreinfo.paddr);
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+        if (!vmci->has_vmcoreinfo) {
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+            error_report("guest note is not present");
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+        } else if (size < note_head_size || size > MAX_GUEST_NOTE_SIZE) {
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+            error_report("guest note size is invalid: %" PRIu32, size);
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+        } else if (format != VMCOREINFO_FORMAT_ELF) {
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+            error_report("guest note format is unsupported: %" PRIu16, format);
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+        } else {
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+            s->guest_note = g_malloc(size + 1); /* +1 for adding \0 */
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+            cpu_physical_memory_read(addr, s->guest_note, size);
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+
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+            get_note_sizes(s, s->guest_note, NULL, &name_size, &desc_size);
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+            s->guest_note_size = ELF_NOTE_SIZE(note_head_size, name_size,
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+                                               desc_size);
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+            if (name_size > MAX_GUEST_NOTE_SIZE ||
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+                desc_size > MAX_GUEST_NOTE_SIZE ||
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+                s->guest_note_size > size) {
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+                error_report("Invalid guest note header");
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+                g_free(s->guest_note);
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+                s->guest_note = NULL;
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+            } else {
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+                s->note_size += s->guest_note_size;
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+            }
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+        }
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+    }
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+
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     /* get memory mapping */
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     if (paging) {
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         qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, &err;;
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diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
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index b5ebb0a..343dad4 100644
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--- a/include/sysemu/dump.h
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+++ b/include/sysemu/dump.h
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@@ -189,6 +189,8 @@ typedef struct DumpState {
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                                   * this could be used to calculate
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                                   * how much work we have
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                                   * finished. */
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+    uint8_t *guest_note;         /* ELF note content */
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+    size_t guest_note_size;
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 } DumpState;
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 uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
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-- 
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1.8.3.1
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