From 93d31dbfbf412b8a80d364aac0ff6f5f319e831c Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>

Date: Mon, 27 Nov 2017 22:51:06 +0100

Subject: [PATCH 08/21] dump: add guest ELF note

MIME-Version: 1.0

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RH-Author: Marc-André Lureau <marcandre.lureau@redhat.com>

Message-id: <20171127225111.24518-5-marcandre.lureau@redhat.com>

Patchwork-id: 77925

O-Subject: [RHV7.5 qemu-kvm-rhev PATCH 4/9] dump: add guest ELF note

Bugzilla: 1398633

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Andrew Jones <drjones@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

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 <marcandre.lureau@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit 903ef7349699dcd932b5981b85c1f1ebe4a4bf2a)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 dump.c                | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++

 include/sysemu/dump.h |   2 +

 2 files changed, 109 insertions(+)

diff --git a/dump.c b/dump.c

index 99117ba..a4f175d 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/misc/vmcoreinfo.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)

 {

+    VMCoreInfoState *vmci = vmcoreinfo_find();

     CPUState *cpu;

     int nr_cpus;

     Error *err = NULL;

@@ -1569,6 +1636,46 @@ 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 (vmci) {

+        uint64_t addr, note_head_size, name_size, desc_size;

+        uint32_t size;

+        uint16_t format;

+

+        note_head_size = s->dump_info.d_class == ELFCLASS32 ?

+            sizeof(Elf32_Nhdr) : sizeof(Elf64_Nhdr);

+

+        format = le16_to_cpu(vmci->vmcoreinfo.guest_format);

+        size = le32_to_cpu(vmci->vmcoreinfo.size);

+        addr = le64_to_cpu(vmci->vmcoreinfo.paddr);

+        if (!vmci->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 if (format != VMCOREINFO_FORMAT_ELF) {

+            warn_report("guest note format is unsupported: %" PRIu16, format);

+        } 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;;

diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h

index 2672a15..df43bd0 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);

-- 

1.8.3.1