new file mode 100644
@@ -0,0 +1,114 @@
+/*
+ * Linux syscalls internals
+ * Copyright (c) 2018 Linaro, Limited.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+typedef struct SyscallDef SyscallDef;
+
+/*
+ * This hook extracts max 6 arguments from max 8 input registers.
+ * In the process, register pairs that store 64-bit arguments are merged.
+ * Finally, syscalls are demultipliexed; e.g. the hook for socketcall will
+ * return the SyscallDef for bind, listen, etc. In the process the hook
+ * may need to read from guest memory, or otherwise validate operands.
+ * On failure, set errno (to a host value) and return NULL;
+ * the (target adjusted) errno will be returned to the guest.
+ */
+typedef const SyscallDef *SyscallArgsFn(const SyscallDef *, int64_t out[6],
+ abi_long in[8]);
+
+/* This hook implements the syscall. */
+typedef abi_long SyscallImplFn(CPUArchState *, int64_t, int64_t, int64_t,
+ int64_t, int64_t, int64_t);
+
+/* This hook prints the arguments to the syscall for strace. */
+typedef void SyscallPrintFn(const SyscallDef *, int64_t arg[6]);
+
+/* This hook print the return value from the syscall for strace. */
+typedef void SyscallPrintRetFn(const SyscallDef *, abi_long);
+
+/*
+ * These flags describe the arguments for the generic fallback to
+ * SyscallPrintFn. ARG_NONE indicates that the argument is not present.
+ */
+typedef enum {
+ ARG_NONE = 0,
+
+ /* These print as numbers of abi_long. */
+ ARG_DEC,
+ ARG_HEX,
+ ARG_OCT,
+
+ /* These print as sets of flags. */
+ ARG_ATDIRFD,
+ ARG_MODEFLAG,
+ ARG_OPENFLAG,
+
+ /* These are interpreted as pointers. */
+ ARG_PTR,
+ ARG_STR,
+ ARG_BUF,
+
+ /* For a 32-bit host, force printing as a 64-bit operand. */
+#if TARGET_ABI_BITS == 32
+ ARG_DEC64,
+#else
+ ARG_DEC64 = ARG_DEC,
+#endif
+} SyscallArgType;
+
+struct SyscallDef {
+ const char *name;
+ SyscallArgsFn *args;
+ SyscallImplFn *impl;
+ SyscallPrintFn *print;
+ SyscallPrintRetFn *print_ret;
+ SyscallArgType arg_type[6];
+};
+
+void print_syscall_def(const SyscallDef *def, int64_t args[6]);
+void print_syscall_def_ret(const SyscallDef *def, abi_long ret);
+void print_syscall_ptr_ret(const SyscallDef *def, abi_long ret);
+
+/* Emit the signature for a SyscallArgsFn. */
+#define SYSCALL_ARGS(NAME) \
+ static const SyscallDef *args_##NAME(const SyscallDef *def, \
+ int64_t out[6], abi_long in[8])
+
+/* Emit the signature for a SyscallImplFn. */
+#define SYSCALL_IMPL(NAME) \
+ static abi_long impl_##NAME(CPUArchState *cpu_env, int64_t arg1, \
+ int64_t arg2, int64_t arg3, int64_t arg4, \
+ int64_t arg5, int64_t arg6)
+
+/*
+ * Emit the definition for a "simple" syscall. Such does not use
+ * SyscallArgsFn and only uses arg_type for strace.
+ */
+#define SYSCALL_DEF(NAME, ...) \
+ static const SyscallDef def_##NAME = { \
+ .name = #NAME, .impl = impl_##NAME, .arg_type = { __VA_ARGS__ } \
+ }
+
+/*
+ * Emit the definition for a syscall that also has an args hook,
+ * and uses arg_type for strace.
+ */
+#define SYSCALL_DEF_ARGS(NAME, ...) \
+ static const SyscallDef def_##NAME = { \
+ .name = #NAME, .args = args_##NAME, .impl = impl_##NAME, \
+ .arg_type = { __VA_ARGS__ } \
+ }
@@ -10,6 +10,7 @@
#include <linux/if_packet.h>
#include <sched.h>
#include "qemu.h"
+#include "syscall.h"
int do_strace=0;
@@ -796,7 +797,7 @@ UNUSED static struct flags unlinkat_flags[] = {
FLAG_END,
};
-UNUSED static struct flags mode_flags[] = {
+static struct flags const mode_flags[] = {
FLAG_GENERIC(S_IFSOCK),
FLAG_GENERIC(S_IFLNK),
FLAG_GENERIC(S_IFREG),
@@ -807,14 +808,14 @@ UNUSED static struct flags mode_flags[] = {
FLAG_END,
};
-UNUSED static struct flags open_access_flags[] = {
+static struct flags const open_access_flags[] = {
FLAG_TARGET(O_RDONLY),
FLAG_TARGET(O_WRONLY),
FLAG_TARGET(O_RDWR),
FLAG_END,
};
-UNUSED static struct flags open_flags[] = {
+static struct flags const open_flags[] = {
FLAG_TARGET(O_APPEND),
FLAG_TARGET(O_CREAT),
FLAG_TARGET(O_DIRECTORY),
@@ -989,84 +990,86 @@ get_comma(int last)
return ((last) ? "" : ",");
}
+static int add_flags(char *buf, int size, const struct flags *f,
+ int flags, bool octal)
+{
+ const char *sep = "";
+ int off = 0;
+
+ if (flags == 0 && f->f_value == 0) {
+ return snprintf(buf, size, "%s", f->f_string);
+ }
+
+ for (; f->f_string != NULL; f++) {
+ if (f->f_value != 0 && (flags & f->f_value) == f->f_value) {
+ off += snprintf(buf + off, size - off, "%s%s", sep, f->f_string);
+ flags &= ~f->f_value;
+ sep = "|";
+ }
+ }
+
+ /* Print rest of the flags as numeric. */
+ if (flags) {
+ if (octal) {
+ off += snprintf(buf + off, size - off, "%s%#o", sep, flags);
+ } else {
+ off += snprintf(buf + off, size - off, "%s%#x", sep, flags);
+ }
+ }
+ return off;
+}
+
static void
print_flags(const struct flags *f, abi_long flags, int last)
{
- const char *sep = "";
- int n;
+ char buf[256];
+ add_flags(buf, sizeof(buf), f, flags, false);
+ gemu_log("%s%s", buf, get_comma(last));
+}
- if ((flags == 0) && (f->f_value == 0)) {
- gemu_log("%s%s", f->f_string, get_comma(last));
- return;
- }
- for (n = 0; f->f_string != NULL; f++) {
- if ((f->f_value != 0) && ((flags & f->f_value) == f->f_value)) {
- gemu_log("%s%s", sep, f->f_string);
- flags &= ~f->f_value;
- sep = "|";
- n++;
- }
- }
-
- if (n > 0) {
- /* print rest of the flags as numeric */
- if (flags != 0) {
- gemu_log("%s%#x%s", sep, (unsigned int)flags, get_comma(last));
- } else {
- gemu_log("%s", get_comma(last));
- }
+static int add_atdirfd(char *buf, int size, int fd)
+{
+ if (fd == AT_FDCWD) {
+ return snprintf(buf, size, "AT_FDCWD");
} else {
- /* no string version of flags found, print them in hex then */
- gemu_log("%#x%s", (unsigned int)flags, get_comma(last));
+ return snprintf(buf, size, "%d", fd);
}
}
static void
print_at_dirfd(abi_long dirfd, int last)
{
-#ifdef AT_FDCWD
- if (dirfd == AT_FDCWD) {
- gemu_log("AT_FDCWD%s", get_comma(last));
- return;
- }
-#endif
- gemu_log("%d%s", (int)dirfd, get_comma(last));
+ char buf[16];
+ add_atdirfd(buf, sizeof(buf), dirfd);
+ gemu_log("%s%s", buf, get_comma(last));
}
static void
print_file_mode(abi_long mode, int last)
{
- const char *sep = "";
- const struct flags *m;
+ char buf[256];
+ add_flags(buf, sizeof(buf), mode_flags, mode, true);
+ gemu_log("%s%s", buf, get_comma(last));
+}
- for (m = &mode_flags[0]; m->f_string != NULL; m++) {
- if ((m->f_value & mode) == m->f_value) {
- gemu_log("%s%s", m->f_string, sep);
- sep = "|";
- mode &= ~m->f_value;
- break;
- }
+static int add_open_flags(char *buf, int size, int flags)
+{
+ int off = add_flags(buf, size, open_access_flags,
+ flags & TARGET_O_ACCMODE, false);
+ flags &= ~TARGET_O_ACCMODE;
+ if (flags == 0 || off + 2 >= size) {
+ return off;
}
-
- mode &= ~S_IFMT;
- /* print rest of the mode as octal */
- if (mode != 0)
- gemu_log("%s%#o", sep, (unsigned int)mode);
-
- gemu_log("%s", get_comma(last));
+ buf[off++] = '|';
+ return off + add_flags(buf + off, size - off, open_flags, flags, true);
}
static void
print_open_flags(abi_long flags, int last)
{
- print_flags(open_access_flags, flags & TARGET_O_ACCMODE, 1);
- flags &= ~TARGET_O_ACCMODE;
- if (flags == 0) {
- gemu_log("%s", get_comma(last));
- return;
- }
- gemu_log("|");
- print_flags(open_flags, flags, last);
+ char buf[256];
+ add_open_flags(buf, sizeof(buf), flags);
+ gemu_log("%s%s", buf, get_comma(last));
}
static void
@@ -1083,48 +1086,86 @@ print_syscall_epilogue(const struct syscallname *sc)
gemu_log(")");
}
-static void
-print_string(abi_long addr, int last)
+static int add_pointer(char *buf, int size, abi_ulong addr)
{
- char *s;
-
- if ((s = lock_user_string(addr)) != NULL) {
- gemu_log("\"%s\"%s", s, get_comma(last));
- unlock_user(s, addr, 0);
+ if (addr) {
+ return snprintf(buf, size, "0x" TARGET_ABI_FMT_lx, addr);
} else {
- /* can't get string out of it, so print it as pointer */
- print_pointer(addr, last);
+ return snprintf(buf, size, "NULL");
}
}
+static int add_string(char *buf, int size, abi_ulong addr)
+{
+ char *s = lock_user_string(addr);
+ if (s) {
+ /* TODO: Escape special characters within the string. */
+ /* TODO: Limit the string length for logging. */
+ int len = snprintf(buf, size, "\"%s\"", s);
+ unlock_user(s, addr, 0);
+ return len;
+ }
+ return add_pointer(buf, size, addr);
+}
+
+static void
+print_string(abi_long addr, int last)
+{
+ char buf[256];
+ add_string(buf, sizeof(buf), addr);
+ gemu_log("%s%s", buf, get_comma(last));
+}
+
#define MAX_PRINT_BUF 40
+
+static int add_buffer(char *buf, int size, abi_long addr, abi_ulong len)
+{
+ unsigned char *p;
+ int off = 0;
+ abi_ulong i;
+
+ p = lock_user(VERIFY_READ, addr, MIN(len, MAX_PRINT_BUF), 1);
+ if (!p) {
+ return add_pointer(buf, size, addr);
+ }
+
+ buf[0] = '"';
+ off = 1;
+
+ for (i = 0; i < MAX_PRINT_BUF; ++i) {
+ int len;
+
+ if (isprint(p[i])) {
+ buf[off] = p[i];
+ len = 1;
+ } else {
+ len = snprintf(buf + off, size - off, "\\%o", p[i]);
+ }
+ off += len;
+ if (off + 2 >= size) {
+ goto overflow;
+ }
+ }
+ unlock_user(p, addr, 0);
+
+ if (i == len && off + 2 < size) {
+ buf[off] = '"';
+ buf[off + 1] = 0;
+ return off + 1;
+ }
+
+ overflow:
+ off = MIN(off, size - 5);
+ strcpy(buf + off, "...\"");
+ return off + 4;
+}
+
static void
print_buf(abi_long addr, abi_long len, int last)
{
- uint8_t *s;
- int i;
-
- s = lock_user(VERIFY_READ, addr, len, 1);
- if (s) {
- gemu_log("\"");
- for (i = 0; i < MAX_PRINT_BUF && i < len; i++) {
- if (isprint(s[i])) {
- gemu_log("%c", s[i]);
- } else {
- gemu_log("\\%o", s[i]);
- }
- }
- gemu_log("\"");
- if (i != len) {
- gemu_log("...");
- }
- if (!last) {
- gemu_log(",");
- }
- unlock_user(s, addr, 0);
- } else {
- print_pointer(addr, last);
- }
+ char buf[256];
+ add_buffer(buf, sizeof(buf), addr, len);
+ gemu_log("%s%s", buf, get_comma(last));
}
/*
@@ -1143,10 +1184,9 @@ print_raw_param(const char *fmt, abi_long param, int last)
static void
print_pointer(abi_long p, int last)
{
- if (p == 0)
- gemu_log("NULL%s", get_comma(last));
- else
- gemu_log("0x" TARGET_ABI_FMT_lx "%s", p, get_comma(last));
+ char buf[24];
+ add_pointer(buf, sizeof(buf), p);
+ gemu_log("%s%s", buf, get_comma(last));
}
/*
@@ -2635,32 +2675,168 @@ print_syscall(int num,
gemu_log("Unknown syscall %d\n", num);
}
+static void print_syscall_def1(const SyscallDef *def, int64_t args[6])
+{
+ char buf[1024], *b = buf;
+ int i, rest = sizeof(buf);
+
+ /* Render the argument list into BUF. This allows us to log the
+ * entire syscall in one write statement at the end.
+ * While this is still not quite as good as separate files, a-la
+ * strace -ff, it can minimize confusion with a multithreaded guest.
+ */
+ buf[0] = 0;
+ for (i = 0; i < 6; ++i) {
+ SyscallArgType type = def->arg_type[i];
+ int64_t arg = args[i];
+ int len;
+
+ if (type == ARG_NONE) {
+ break;
+ }
+
+ /* Validate remaining space. */
+ if (rest < 4) {
+ goto overflow;
+ }
+
+ /* Add separator. */
+ if (i > 0) {
+ b[0] = ',';
+ b[1] = ' ';
+ b += 2;
+ rest -= 2;
+ }
+
+ switch (type) {
+#if TARGET_ABI_BITS == 32
+ /* ??? We don't have TARGET_ABI_FMT_* macros for exactly
+ * what we want here. For this case it probably makes
+ * most sense to just special case.
+ */
+ case ARG_DEC:
+ len = snprintf(b, rest, "%d", (int32_t)arg);
+ break;
+ case ARG_HEX:
+ len = snprintf(b, rest, "%#x", (uint32_t)arg);
+ break;
+ case ARG_OCT:
+ len = snprintf(b, rest, "%#o", (uint32_t)arg);
+ break;
+ case ARG_DEC64:
+ len = snprintf(b, rest, "%" PRId64, arg);
+ break;
+#else
+ case ARG_DEC:
+ len = snprintf(b, rest, "%" PRId64, arg);
+ break;
+ case ARG_OCT:
+ len = snprintf(b, rest, "%" PRIo64, arg);
+ break;
+ case ARG_HEX:
+ len = snprintf(b, rest, "%" PRIx64, arg);
+ break;
+#endif
+ case ARG_ATDIRFD:
+ len = add_atdirfd(b, rest, arg);
+ break;
+ case ARG_MODEFLAG:
+ len = add_flags(b, rest, mode_flags, arg, true);
+ break;
+ case ARG_OPENFLAG:
+ len = add_open_flags(b, rest, arg);
+ break;
+ case ARG_PTR:
+ len = add_pointer(b, rest, arg);
+ break;
+ case ARG_STR:
+ len = add_string(b, rest, arg);
+ break;
+ case ARG_BUF:
+ len = add_buffer(b, rest, arg, MAX_PRINT_BUF);
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ b += len;
+ rest -= len;
+ if (rest == 0) {
+ goto overflow;
+ }
+ }
+ goto done;
+
+ overflow:
+ strcpy(buf + sizeof(buf) - 4, "...");
+ done:
+ gemu_log("%d %s(%s)", getpid(), def->name, buf);
+}
+
+void print_syscall_def(const SyscallDef *def, int64_t args[6])
+{
+ SyscallPrintFn *print = def->print;
+ if (!print) {
+ print = print_syscall_def1;
+ }
+ print(def, args);
+}
+
+static void print_syscall_def_ret1(const SyscallDef *def, abi_long ret)
+{
+ if (is_error(ret)) {
+ const char *errstr = target_strerror(-ret);
+ if (errstr) {
+ gemu_log(" = -1 errno=" TARGET_ABI_FMT_ld " (%s)\n",
+ -ret, errstr);
+ } else {
+ gemu_log(" = -1 errno=" TARGET_ABI_FMT_ld "\n", -ret);
+ }
+ } else {
+ gemu_log(" = " TARGET_ABI_FMT_ld "\n", ret);
+ }
+}
void
print_syscall_ret(int num, abi_long ret)
{
int i;
- const char *errstr = NULL;
for(i=0;i<nsyscalls;i++)
if( scnames[i].nr == num ) {
if( scnames[i].result != NULL ) {
scnames[i].result(&scnames[i],ret);
} else {
- if (ret < 0) {
- errstr = target_strerror(-ret);
- }
- if (errstr) {
- gemu_log(" = -1 errno=" TARGET_ABI_FMT_ld " (%s)\n",
- -ret, errstr);
- } else {
- gemu_log(" = " TARGET_ABI_FMT_ld "\n", ret);
- }
+ print_syscall_def_ret1(NULL, ret);
}
break;
}
}
+void print_syscall_ptr_ret(const SyscallDef *def, abi_long ret)
+{
+ if (is_error(ret)) {
+ const char *errstr = target_strerror(-ret);
+ if (errstr) {
+ gemu_log(" = -1 errno=" TARGET_ABI_FMT_ld " (%s)\n",
+ -ret, errstr);
+ } else {
+ gemu_log(" = -1 errno=" TARGET_ABI_FMT_ld "\n", -ret);
+ }
+ } else {
+ gemu_log(" = 0x" TARGET_ABI_FMT_lx "\n", ret);
+ }
+}
+
+void print_syscall_def_ret(const SyscallDef *def, abi_long ret)
+{
+ SyscallPrintRetFn *print = def->print_ret;
+ if (!print) {
+ print = print_syscall_def_ret1;
+ }
+ print(def, ret);
+}
+
void print_taken_signal(int target_signum, const target_siginfo_t *tinfo)
{
/* Print the strace output for a signal being taken:
@@ -111,6 +111,7 @@
#include "uname.h"
#include "qemu.h"
+#include "syscall.h"
#ifndef CLONE_IO
#define CLONE_IO 0x80000000 /* Clone io context */
@@ -12481,12 +12482,26 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
return ret;
}
+static const SyscallDef *syscall_table(int num)
+{
+#define S(NAME) case TARGET_NR_##NAME: return &def_##NAME;
+
+ switch (num) {
+ }
+ return NULL;
+
+#undef S
+}
+
abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
abi_long arg2, abi_long arg3, abi_long arg4,
abi_long arg5, abi_long arg6, abi_long arg7,
abi_long arg8)
{
CPUState *cpu = ENV_GET_CPU(cpu_env);
+ const SyscallDef *def, *orig_def;
+ abi_long raw_args[8] = { arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8 };
+ int64_t out_args[6] = { arg1, arg2, arg3, arg4, arg5, arg6 };
abi_long ret;
#ifdef DEBUG_ERESTARTSYS
@@ -12506,16 +12521,44 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4,
arg5, arg6, arg7, arg8);
- if (unlikely(do_strace)) {
- print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
- ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4,
- arg5, arg6, arg7, arg8);
- print_syscall_ret(num, ret);
- } else {
- ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4,
- arg5, arg6, arg7, arg8);
+ orig_def = def = syscall_table(num);
+ if (def == NULL) {
+ /* Unconverted. */
+ if (unlikely(do_strace)) {
+ print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6);
+ ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4,
+ arg5, arg6, arg7, arg8);
+ print_syscall_ret(num, ret);
+ } else {
+ ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4,
+ arg5, arg6, arg7, arg8);
+ }
+ goto fini;
}
+ if (def->args) {
+ def = def->args(def, out_args, raw_args);
+ if (unlikely(def == NULL)) {
+ ret = -host_to_target_errno(errno);
+ if (unlikely(do_strace)) {
+ print_syscall_def(orig_def, out_args);
+ print_syscall_def_ret(orig_def, ret);
+ }
+ goto fini;
+ }
+ }
+
+ if (unlikely(do_strace)) {
+ print_syscall_def(def, out_args);
+ ret = def->impl(cpu_env, out_args[0], out_args[1], out_args[2],
+ out_args[3], out_args[4], out_args[5]);
+ print_syscall_def_ret(def, ret);
+ } else {
+ ret = def->impl(cpu_env, out_args[0], out_args[1], out_args[2],
+ out_args[3], out_args[4], out_args[5]);
+ }
+
+ fini:
trace_guest_user_syscall_ret(cpu, num, ret);
return ret;
}
Defines a unified structure for implementation and strace. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- linux-user/syscall.h | 114 +++++++++++++ linux-user/strace.c | 386 +++++++++++++++++++++++++++++++------------ linux-user/syscall.c | 59 ++++++- 3 files changed, 446 insertions(+), 113 deletions(-) create mode 100644 linux-user/syscall.h -- 2.17.1