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From 9a2ab369a3685f85dfa7449c31a2267333cb1468 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>
Date: Wed, 13 Dec 2017 13:39:02 +0100
Subject: [PATCH 31/41] dump: update phys_base header field based on VMCOREINFO
content
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: <20171213133912.26176-32-marcandre.lureau@redhat.com>
Patchwork-id: 78380
O-Subject: [RHEL-7.5 qemu-kvm PATCH v3 31/41] dump: update phys_base header field based on VMCOREINFO content
Bugzilla: 1411490
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@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)
RHEL: replace qemu_strotu64() usage, warn_report()->error_report()
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 | 57 +++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 63 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 823d1ad..3bce730 100644
--- a/dump.c
+++ b/dump.c
@@ -777,6 +777,23 @@ 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)
{
@@ -1553,6 +1570,40 @@ 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;
+
+ 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)=")) {
+ errno = 0;
+ phys_base = strtoull(lines[i] + 18, NULL, 16);
+ if (errno == ERANGE) {
+ error_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)
@@ -1636,8 +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;
@@ -1670,6 +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