* [PATCH] plugins: new syscalls plugin
@ 2020-08-12 11:58 Matthias Weckbecker
2021-03-10 18:26 ` Alex Bennée
0 siblings, 1 reply; 2+ messages in thread
From: Matthias Weckbecker @ 2020-08-12 11:58 UTC (permalink / raw)
To: qemu-devel; +Cc: Matthias Weckbecker
This commit adds a new syscalls plugin that displays the syscalls
as they are executed and returned. This plugin outputs the number
of the syscall as well as the syscall return value.
Works in *-user only.
Essentially, this commit restores:
https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg00846.html
by using the new QEMU plugin API.
Signed-off-by: Matthias Weckbecker <matthias@weckbecker.name>
---
tests/plugin/Makefile | 1 +
tests/plugin/syscall.c | 49 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 50 insertions(+)
create mode 100644 tests/plugin/syscall.c
diff --git a/tests/plugin/Makefile b/tests/plugin/Makefile
index e9348fde4a..fc176909e9 100644
--- a/tests/plugin/Makefile
+++ b/tests/plugin/Makefile
@@ -21,6 +21,7 @@ NAMES += hotblocks
NAMES += howvec
NAMES += hotpages
NAMES += lockstep
+NAMES += syscall
SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
diff --git a/tests/plugin/syscall.c b/tests/plugin/syscall.c
new file mode 100644
index 0000000000..53ee2ab6c4
--- /dev/null
+++ b/tests/plugin/syscall.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2020, Matthias Weckbecker <matthias@weckbecker.name>
+ *
+ * License: GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include <inttypes.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <glib.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+static void vcpu_syscall(qemu_plugin_id_t id, unsigned int vcpu_index,
+ int64_t num, uint64_t a1, uint64_t a2,
+ uint64_t a3, uint64_t a4, uint64_t a5,
+ uint64_t a6, uint64_t a7, uint64_t a8)
+{
+ g_autofree gchar *out = g_strdup_printf("syscall #%" PRIi64 "\n", num);
+ qemu_plugin_outs(out);
+}
+
+static void vcpu_syscall_ret(qemu_plugin_id_t id, unsigned int vcpu_idx,
+ int64_t num, int64_t ret)
+{
+ g_autofree gchar *out;
+ out = g_strdup_printf("syscall #%" PRIi64 " returned -> %" PRIi64 "\n",
+ num, ret);
+ qemu_plugin_outs(out);
+}
+
+/* ************************************************************************* */
+
+static void plugin_exit(qemu_plugin_id_t id, void *p) {}
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
+ const qemu_info_t *info,
+ int argc, char **argv)
+{
+ qemu_plugin_register_vcpu_syscall_cb(id, vcpu_syscall);
+ qemu_plugin_register_vcpu_syscall_ret_cb(id, vcpu_syscall_ret);
+ qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
+ return 0;
+}
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] plugins: new syscalls plugin
2020-08-12 11:58 [PATCH] plugins: new syscalls plugin Matthias Weckbecker
@ 2021-03-10 18:26 ` Alex Bennée
0 siblings, 0 replies; 2+ messages in thread
From: Alex Bennée @ 2021-03-10 18:26 UTC (permalink / raw)
To: Matthias Weckbecker; +Cc: qemu-devel
Matthias Weckbecker <matthias@weckbecker.name> writes:
> This commit adds a new syscalls plugin that displays the syscalls
> as they are executed and returned. This plugin outputs the number
> of the syscall as well as the syscall return value.
>
> Works in *-user only.
>
> Essentially, this commit restores:
>
> https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg00846.html
>
> by using the new QEMU plugin API.
Sorry I missed this last year, I've queued to plugins/next. That said in
it's current form you basically replicate what you already have with
-strace:
./qemu-aarch64 -strace -d plugin -plugin ./tests/plugin/libsyscall.so ./tests/tcg/aarch64-linux-user/testthread
syscall #214
13165 brk(NULL) = 0x000000000049a000
syscall #214 returned -> 4825088
syscall #214
13165 brk(0x000000000049af90) = 0x000000000049af90
syscall #214 returned -> 4829072
syscall #160
13165 uname(0x5500800498) = 0
syscall #160 returned -> 0
syscall #96
13165 set_tid_address(4825296,0,4294967293,4826880,4825088,253) = 13165
syscall #96 returned -> 13165
So it would be nice to make the default maybe do something more useful
(like emulate strace -C output). You could certainly keep the verbose
output controlled by a flag.
Still as it is it at least ensures we exercise the code ;-)
--
Alex Bennée
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2021-03-10 18:26 ` Alex Bennée
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