From a1b9c54811a4fc6797259dae98548229dba53d76 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 22:51:07 +0100

Subject: [PATCH 09/21] dump: update phys_base header field based on VMCOREINFO

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

Message-id: <20171127225111.24518-6-marcandre.lureau@redhat.com>

Patchwork-id: 77928

O-Subject: [RHV7.5 qemu-kvm-rhev PATCH 5/9] dump: update phys_base header field based on VMCOREINFO content

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>

If the guest note is VMCOREINFO, try to get phys_base from it.

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 d9feb51772b4ade9700c7fa54529327a6c8183a7)

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

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

---

 docs/specs/vmcoreinfo.txt |  8 +++++++

 dump.c                    | 56 +++++++++++++++++++++++++++++++++++++++++++++--

 2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/docs/specs/vmcoreinfo.txt b/docs/specs/vmcoreinfo.txt

index 2868a77..8212610 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.

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

index a4f175d..e3175d7 100644

--- a/dump.c

+++ b/dump.c

@@ -780,6 +780,23 @@ 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)

 {

@@ -1554,6 +1571,39 @@ 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, &note_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)

@@ -1637,8 +1687,9 @@ 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;

@@ -1671,6 +1722,7 @@ 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;

             }

         }

-- 

1.8.3.1