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[Qemu-devel] [PATCH 3/6] hypertrace: [*-user] Add QEMU-side proxy to "gu
|
From: |
Lluís Vilanova |
|
Subject: |
[Qemu-devel] [PATCH 3/6] hypertrace: [*-user] Add QEMU-side proxy to "guest_hypertrace" event |
|
Date: |
Fri, 5 Aug 2016 18:59:39 +0200 |
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User-agent: |
StGit/0.17.1-dirty |
QEMU detects when the guest uses 'mmap' on hypertrace's control channel
file, and then uses 'mprotect' to detect accesses to it, which are used
to trigger traceing event "guest_hypertrace".
Signed-off-by: Lluís Vilanova <address@hidden>
---
Makefile.objs | 4 +
bsd-user/main.c | 16 +++
bsd-user/mmap.c | 2
bsd-user/syscall.c | 4 +
hypertrace/Makefile.objs | 17 +++
hypertrace/user.c | 292 ++++++++++++++++++++++++++++++++++++++++++++++
hypertrace/user.h | 52 ++++++++
linux-user/main.c | 19 +++
linux-user/mmap.c | 2
linux-user/syscall.c | 3
10 files changed, 411 insertions(+)
create mode 100644 hypertrace/Makefile.objs
create mode 100644 hypertrace/user.c
create mode 100644 hypertrace/user.h
diff --git a/Makefile.objs b/Makefile.objs
index 1c1b03c..f598e0e 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -104,6 +104,10 @@ util-obj-y += trace/
target-obj-y += trace/
######################################################################
+# hypertrace
+target-obj-y += hypertrace/
+
+######################################################################
# guest agent
# FIXME: a few definitions from qapi-types.o/qapi-visit.o are needed
diff --git a/bsd-user/main.c b/bsd-user/main.c
index 315ba1d..9721240 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -30,9 +30,12 @@
#include "tcg.h"
#include "qemu/timer.h"
#include "qemu/envlist.h"
+#include "qemu/error-report.h"
#include "exec/log.h"
#include "trace/control.h"
#include "glib-compat.h"
+#include "hypertrace/user.h"
+
int singlestep;
unsigned long mmap_min_addr;
@@ -692,6 +695,8 @@ static void usage(void)
"-strace log system calls\n"
"-trace
[[enable=]<pattern>][,events=<file>][,file=<file>]\n"
" specify tracing options\n"
+ "-hypertrace [[base=]<path>][,pages=<int>]\n"
+ " specify hypertrace options\n"
"\n"
"Environment variables:\n"
"QEMU_STRACE Print system calls and arguments similar to
the\n"
@@ -742,6 +747,8 @@ int main(int argc, char **argv)
envlist_t *envlist = NULL;
char *trace_file = NULL;
bsd_type = target_openbsd;
+ char *hypertrace_base = NULL;
+ uint64_t hypertrace_size = 0;
if (argc <= 1)
usage();
@@ -761,6 +768,7 @@ int main(int argc, char **argv)
cpu_model = NULL;
qemu_add_opts(&qemu_trace_opts);
+ qemu_add_opts(&qemu_hypertrace_opts);
optind = 1;
for (;;) {
@@ -851,6 +859,9 @@ int main(int argc, char **argv)
} else if (!strcmp(r, "trace")) {
g_free(trace_file);
trace_file = trace_opt_parse(optarg);
+ } else if (!strcmp(r, "hypertrace")) {
+ g_free(hypertrace_file);
+ hypertrace_opt_parse(optarg, &hypertrace_base, &hypertrace_size);
} else {
usage();
}
@@ -985,6 +996,11 @@ int main(int argc, char **argv)
target_set_brk(info->brk);
syscall_init();
signal_init();
+ if (atexit(hypertrace_fini) != 0) {
+ fprintf(stderr, "error: atexit: %s\n", strerror(errno));
+ abort();
+ }
+ hypertrace_init(hypertrace_base, hypertrace_size);
/* Now that we've loaded the binary, GUEST_BASE is fixed. Delay
generating the prologue until now so that the prologue can take
diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index 610f91b..faf255f 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -21,6 +21,7 @@
#include "qemu.h"
#include "qemu-common.h"
#include "bsd-mman.h"
+#include "hypertrace/user.h"
//#define DEBUG_MMAP
@@ -407,6 +408,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
prot,
}
}
the_end1:
+ hypertrace_guest_mmap(fd, (void *)g2h(start));
page_set_flags(start, start + len, prot | PAGE_VALID);
the_end:
#ifdef DEBUG_MMAP
diff --git a/bsd-user/syscall.c b/bsd-user/syscall.c
index 66492aa..275ef61 100644
--- a/bsd-user/syscall.c
+++ b/bsd-user/syscall.c
@@ -26,6 +26,7 @@
#include "qemu.h"
#include "qemu-common.h"
+#include "hypertrace/user.h"
//#define DEBUG
@@ -332,6 +333,7 @@ abi_long do_freebsd_syscall(void *cpu_env, int num,
abi_long arg1,
_mcleanup();
#endif
gdb_exit(cpu_env, arg1);
+ hypertrace_fini();
/* XXX: should free thread stack and CPU env */
_exit(arg1);
ret = 0; /* avoid warning */
@@ -430,6 +432,7 @@ abi_long do_netbsd_syscall(void *cpu_env, int num, abi_long
arg1,
_mcleanup();
#endif
gdb_exit(cpu_env, arg1);
+ hypertrace_fini();
/* XXX: should free thread stack and CPU env */
_exit(arg1);
ret = 0; /* avoid warning */
@@ -505,6 +508,7 @@ abi_long do_openbsd_syscall(void *cpu_env, int num,
abi_long arg1,
_mcleanup();
#endif
gdb_exit(cpu_env, arg1);
+ hypertrace_fini();
/* XXX: should free thread stack and CPU env */
_exit(arg1);
ret = 0; /* avoid warning */
diff --git a/hypertrace/Makefile.objs b/hypertrace/Makefile.objs
new file mode 100644
index 0000000..6eb5acf
--- /dev/null
+++ b/hypertrace/Makefile.objs
@@ -0,0 +1,17 @@
+# -*- mode: makefile -*-
+
+target-obj-$(CONFIG_USER_ONLY) += user.o
+
+$(obj)/user.o: $(obj)/emit.c
+
+$(obj)/emit.c: $(obj)/emit.c-timestamp $(BUILD_DIR)/config-host.mak
+ @cmp $< $@ >/dev/null 2>&1 || cp $< $@
+$(obj)/emit.c-timestamp: $(BUILD_DIR)/config-host.mak
+ @echo "static void hypertrace_emit(CPUState *cpu, uint64_t *data)" >$@
+ @echo "{" >>$@
+ @echo -n " trace_guest_hypertrace(cpu" >>$@
+ @for i in `seq $(CONFIG_HYPERTRACE_ARGS)`; do \
+ echo -n ", data[$$i-1]" >>$@; \
+ done
+ @echo ");" >>$@
+ @echo "}" >>$@
diff --git a/hypertrace/user.c b/hypertrace/user.c
new file mode 100644
index 0000000..55df79d
--- /dev/null
+++ b/hypertrace/user.c
@@ -0,0 +1,292 @@
+/*
+ * QEMU-side management of hypertrace in user-level emulation.
+ *
+ * Copyright (C) 2016 Lluís Vilanova <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+/*
+ * Implementation details
+ * ======================
+ *
+ * Both channels are provided as regular files in the host system, which must
be
+ * mmap'ed by the guest application.
+ *
+ * Data channel
+ * ------------
+ *
+ * The guest must mmap a file named <base>-data, where base is the argument
+ * given to hypertrace_init.
+ *
+ * Regular memory accesses are used on the data channel.
+ *
+ * Control channel
+ * ---------------
+ *
+ * The guest must mmap a file named <base>-control, where base is the argument
+ * given to hypertrace_init.
+ *
+ * The first 64 bits of that memory contain the size of the data channel.
+ *
+ * The control channel is mprotect'ed by QEMU so that guest writes can be
+ * intercepted by QEMU in order to raise the "guest_hypertrace" tracing
+ * event. The guest must perform writes twice, one on each of two consecutive
+ * pages, so that the written data can be both read by QEMU and the access
+ * intercepted.
+ */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+
+#include "hypertrace/user.h"
+#include "qemu/config-file.h"
+#include "qemu/error-report.h"
+#include "trace.h"
+
+
+static char *data_path = NULL;
+static char *control_path = NULL;
+static int data_fd = -1;
+static int control_fd = -1;
+
+static uint64_t *qemu_data = NULL;
+static void *qemu_control_0 = NULL;
+static void *qemu_control_1 = NULL;
+
+static struct stat control_fd_stat;
+
+struct sigaction segv_next;
+static void segv_handler(int signum, siginfo_t *siginfo, void *sigctxt);
+
+
+QemuOptsList qemu_hypertrace_opts = {
+ .name = "hypertrace",
+ .implied_opt_name = "path",
+ .head = QTAILQ_HEAD_INITIALIZER(qemu_hypertrace_opts.head),
+ .desc = {
+ {
+ .name = "path",
+ .type = QEMU_OPT_STRING,
+ },
+ {
+ .name = "pages",
+ .type = QEMU_OPT_NUMBER,
+ .def_value_str = "1",
+ },
+ { /* end of list */ }
+ },
+};
+
+void hypertrace_opt_parse(const char *optarg, char **base, size_t *size)
+{
+ int pages;
+ QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("hypertrace"),
+ optarg, true);
+ if (!opts) {
+ exit(1);
+ }
+ if (qemu_opt_get(opts, "path")) {
+ *base = g_strdup(qemu_opt_get(opts, "path"));
+ } else {
+ *base = NULL;
+ }
+ pages = qemu_opt_get_number(opts, "pages", 1);
+ if (pages <= 0) {
+ error_report("Parameter 'pages' expects a positive number");
+ exit(EXIT_FAILURE);
+ }
+ *size = pages * TARGET_PAGE_SIZE;
+}
+
+static void init_channel(const char *base, const char *suffix, size_t size,
+ char ** path, int *fd, uint64_t **addr)
+{
+ *path = g_malloc(strlen(base) + strlen(suffix) + 1);
+ sprintf(*path, "%s%s", base, suffix);
+
+ *fd = open(*path, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR);
+ if (*fd == -1) {
+ error_report("error: open(%s): %s", *path, strerror(errno));
+ abort();
+ }
+
+ off_t lres = lseek(*fd, size - 1, SEEK_SET);
+ if (lres == (off_t)-1) {
+ error_report("error: lseek(%s): %s", *path, strerror(errno));
+ abort();
+ }
+
+ char tmp;
+ ssize_t wres = write(*fd, &tmp, 1);
+ if (wres == -1) {
+ error_report("error: write(%s): %s", *path, strerror(errno));
+ abort();
+ }
+
+ if (addr) {
+ *addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, *fd, 0);
+ if (*addr == MAP_FAILED) {
+ error_report("error: mmap(%s): %s", *path, strerror(errno));
+ abort();
+ }
+ }
+}
+
+static void fini_handler(int signum, siginfo_t *siginfo, void *sigctxt)
+{
+ hypertrace_fini();
+}
+
+void hypertrace_init(const char *base, uint64_t data_size)
+{
+ if (base == NULL) {
+ return;
+ }
+
+ struct sigaction sigint;
+ memset(&sigint, 0, sizeof(sigint));
+ sigint.sa_sigaction = fini_handler;
+ sigint.sa_flags = SA_SIGINFO | SA_RESTART;
+ if (sigaction(SIGINT, &sigint, NULL) != 0) {
+ error_report("error: sigaction(SIGINT): %s", strerror(errno));
+ abort();
+ }
+ if (sigaction(SIGABRT, &sigint, NULL) != 0) {
+ error_report("error: sigaction(SIGABRT): %s", strerror(errno));
+ abort();
+ }
+
+ init_channel(base, "-data", data_size, &data_path, &data_fd, &qemu_data);
+ uint64_t *control;
+ init_channel(base, "-control", getpagesize() * 2, &control_path,
&control_fd, &control);
+
+ control[0] = tswap64(data_size / (CONFIG_HYPERTRACE_ARGS *
sizeof(uint64_t)));
+
+ if (fstat(control_fd, &control_fd_stat) == -1) {
+ error_report("error: fstat(hypertrace_control): %s", strerror(errno));
+ abort();
+ }
+
+ struct sigaction segv;
+ memset(&segv, 0, sizeof(segv));
+ segv.sa_sigaction = segv_handler;
+ segv.sa_flags = SA_SIGINFO | SA_RESTART;
+ sigemptyset(&segv.sa_mask);
+
+ if (sigaction(SIGSEGV, &segv, &segv_next) != 0) {
+ error_report("error: sigaction(SIGSEGV): %s", strerror(errno));
+ abort();
+ }
+}
+
+
+static void fini_channel(int *fd, char **path)
+{
+ if (*fd != -1) {
+ if (close(*fd) == -1) {
+ error_report("error: close: %s", strerror(errno));
+ abort();
+ }
+ if (unlink(*path) == -1) {
+ error_report("error: unlink(%s): %s", *path, strerror(errno));
+ abort();
+ }
+ *fd = -1;
+ }
+ if (*path != NULL) {
+ g_free(*path);
+ *path = NULL;
+ }
+}
+
+void hypertrace_fini(void)
+{
+ static bool atexit_in = false;
+ if (atexit_in) {
+ return;
+ }
+ atexit_in = true;
+
+ if (sigaction(SIGSEGV, &segv_next, NULL) != 0) {
+ error_report("error: sigaction(SIGSEGV): %s", strerror(errno));
+ abort();
+ }
+ fini_channel(&data_fd, &data_path);
+ fini_channel(&control_fd, &control_path);
+}
+
+
+void hypertrace_guest_mmap(int fd, void *qemu_addr)
+{
+ struct stat s;
+ if (fstat(fd, &s) != 0) {
+ return;
+ }
+
+ if (s.st_dev != control_fd_stat.st_dev ||
+ s.st_ino != control_fd_stat.st_ino) {
+ return;
+ }
+
+ /* it's an mmap of the control channel; split it in two and mprotect it to
+ * detect writes (cmd is written once on each part)
+ */
+ qemu_control_0 = qemu_addr;
+ qemu_control_1 = qemu_control_0 + getpagesize();
+ if (mprotect(qemu_control_0, getpagesize(), PROT_READ) == -1) {
+ error_report("error: mprotect(hypertrace_control): %s",
strerror(errno));
+ abort();
+ }
+}
+
+static void swap_control(void *from, void *to)
+{
+ if (mprotect(from, getpagesize(), PROT_READ | PROT_WRITE) == -1) {
+ error_report("error: mprotect(from): %s", strerror(errno));
+ abort();
+ }
+ if (mprotect(to, getpagesize(), PROT_READ) == -1) {
+ error_report("error: mprotect(to): %s", strerror(errno));
+ abort();
+ }
+}
+
+#include "hypertrace/emit.c"
+
+static void segv_handler(int signum, siginfo_t *siginfo, void *sigctxt)
+{
+ if (qemu_control_0 <= siginfo->si_addr &&
+ siginfo->si_addr < qemu_control_1) {
+
+ /* 1st fault (guest will write cmd) */
+ assert(((unsigned long)siginfo->si_addr % getpagesize()) ==
sizeof(uint64_t));
+ swap_control(qemu_control_0, qemu_control_1);
+
+ } else if (qemu_control_1 <= siginfo->si_addr &&
+ siginfo->si_addr < qemu_control_1 + getpagesize()) {
+ uint64_t vcontrol = ((uint64_t*)qemu_control_0)[2];
+ uint64_t *data_ptr = &qemu_data[vcontrol * CONFIG_HYPERTRACE_ARGS *
sizeof(uint64_t)];
+
+ /* 2nd fault (invoke) */
+ assert(((unsigned long)siginfo->si_addr % getpagesize()) ==
sizeof(uint64_t));
+ hypertrace_emit(current_cpu, data_ptr);
+ swap_control(qemu_control_1, qemu_control_0);
+
+ } else {
+ /* proxy to next handler */
+ if (segv_next.sa_sigaction != NULL) {
+ segv_next.sa_sigaction(signum, siginfo, sigctxt);
+ } else if (segv_next.sa_handler != NULL) {
+ segv_next.sa_handler(signum);
+ }
+ }
+}
diff --git a/hypertrace/user.h b/hypertrace/user.h
new file mode 100644
index 0000000..a13bae4
--- /dev/null
+++ b/hypertrace/user.h
@@ -0,0 +1,52 @@
+/*
+ * QEMU-side management of hypertrace in user-level emulation.
+ *
+ * Copyright (C) 2016 Lluís Vilanova <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <stdint.h>
+#include <sys/types.h>
+
+
+/**
+ * Definition of QEMU options describing hypertrace subsystem configuration
+ */
+extern QemuOptsList qemu_hypertrace_opts;
+
+/**
+ * hypertrace_opt_parse:
+ * @optarg: Input arguments.
+ * @base: Output base path for the hypertrace channel files.
+ * @data_size: Output length in bytes for the data channel.
+ *
+ * Parse the commandline arguments for hypertrace.
+ */
+void hypertrace_opt_parse(const char *optarg, char **base, size_t *size);
+
+/**
+ * hypertrace_init:
+ * @base: Base path for the hypertrace channel files.
+ * @data_size: Length in bytes for the data channel.
+ *
+ * Initialize the backing files for the hypertrace channel.
+ */
+void hypertrace_init(const char *base, uint64_t data_size);
+
+/**
+ * hypertrace_guest_mmap:
+ *
+ * Check if this mmap is for the control channel and act accordingly.
+ *
+ * Precondition: defined(CONFIG_USER_ONLY)
+ */
+void hypertrace_guest_mmap(int fd, void *qemu_addr);
+
+/**
+ * hypertrace_fini:
+ *
+ * Remove the backing files for the hypertrace channel.
+ */
+void hypertrace_fini(void);
diff --git a/linux-user/main.c b/linux-user/main.c
index 462e820..8f3d9cf 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -32,10 +32,12 @@
#include "tcg.h"
#include "qemu/timer.h"
#include "qemu/envlist.h"
+#include "qemu/error-report.h"
#include "elf.h"
#include "exec/log.h"
#include "trace/control.h"
#include "glib-compat.h"
+#include "hypertrace/user.h"
char *exec_path;
@@ -4011,6 +4013,14 @@ static void handle_arg_trace(const char *arg)
trace_file = trace_opt_parse(arg);
}
+static char *hypertrace_base;
+static size_t hypertrace_size;
+static void handle_arg_hypertrace(const char *arg)
+{
+ g_free(hypertrace_base);
+ hypertrace_opt_parse(arg, &hypertrace_base, &hypertrace_size);
+}
+
struct qemu_argument {
const char *argv;
const char *env;
@@ -4060,6 +4070,8 @@ static const struct qemu_argument arg_table[] = {
"", "Seed for pseudo-random number generator"},
{"trace", "QEMU_TRACE", true, handle_arg_trace,
"", "[[enable=]<pattern>][,events=<file>][,file=<file>]"},
+ {"hypertrace", "QEMU_HYPERTRACE", true, handle_arg_hypertrace,
+ "", "[[base=]<path>][,pages=<int>]"},
{"version", "QEMU_VERSION", false, handle_arg_version,
"", "display version information and exit"},
{NULL, NULL, false, NULL, NULL, NULL}
@@ -4250,6 +4262,7 @@ int main(int argc, char **argv, char **envp)
srand(time(NULL));
qemu_add_opts(&qemu_trace_opts);
+ qemu_add_opts(&qemu_hypertrace_opts);
optind = parse_args(argc, argv);
@@ -4448,6 +4461,12 @@ int main(int argc, char **argv, char **envp)
syscall_init();
signal_init();
+ if (atexit(hypertrace_fini)) {
+ fprintf(stderr, "error: atexit: %s\n", strerror(errno));
+ abort();
+ }
+ hypertrace_init(hypertrace_base, hypertrace_size);
+
/* Now that we've loaded the binary, GUEST_BASE is fixed. Delay
generating the prologue until now so that the prologue can take
the real value of GUEST_BASE into account. */
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index c4371d9..3207d98 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -23,6 +23,7 @@
#include "qemu.h"
#include "qemu-common.h"
#include "translate-all.h"
+#include "hypertrace/user.h"
//#define DEBUG_MMAP
@@ -553,6 +554,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
prot,
}
}
the_end1:
+ hypertrace_guest_mmap(fd, (void *)g2h(start));
page_set_flags(start, start + len, prot | PAGE_VALID);
the_end:
#ifdef DEBUG_MMAP
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ca6a2b4..e73ec5d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -111,6 +111,7 @@ int __clone2(int (*fn)(void *), void *child_stack_base,
#include "uname.h"
#include "qemu.h"
+#include "hypertrace/user.h"
#define CLONE_NPTL_FLAGS2 (CLONE_SETTLS | \
CLONE_PARENT_SETTID | CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID)
@@ -7214,6 +7215,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
_mcleanup();
#endif
gdb_exit(cpu_env, arg1);
+ hypertrace_fini();
_exit(arg1);
ret = 0; /* avoid warning */
break;
@@ -9219,6 +9221,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
_mcleanup();
#endif
gdb_exit(cpu_env, arg1);
+ hypertrace_fini();
ret = get_errno(exit_group(arg1));
break;
#endif