gdbstub: move syscall handling to new file

Our GDB syscall support is the last chunk of code that needs target
specific support so move it to a new file. We take the opportunity to
move the syscall state into its own singleton instance and add in a
few helpers for the main gdbstub to interact with the module.

I also moved the gdb_exit() declaration into syscalls.h as it feels
pretty related and most of the callers of it treat it as such.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Message-Id: <20230302190846.2593720-22-alex.bennee@linaro.org>
Message-Id: <20230303025805.625589-22-richard.henderson@linaro.org>

1 files changed, 124 insertions, 0 deletions

diff --git a/include/gdbstub/syscalls.h b/include/gdbstub/syscalls.h
new file mode 100644
index 0000000..5851a2c
--- /dev/null
+++ b/include/gdbstub/syscalls.h
@@ -0,0 +1,124 @@
+/*
+ * GDB Syscall support
+ *
+ * Copyright (c) 2023 Linaro Ltd
+ *
+ * SPDX-License-Identifier: LGPL-2.0+
+ */
+
+#ifndef _SYSCALLS_H_
+#define _SYSCALLS_H_
+
+/* For gdb file i/o remote protocol open flags. */
+#define GDB_O_RDONLY  0
+#define GDB_O_WRONLY  1
+#define GDB_O_RDWR    2
+#define GDB_O_APPEND  8
+#define GDB_O_CREAT   0x200
+#define GDB_O_TRUNC   0x400
+#define GDB_O_EXCL    0x800
+
+/* For gdb file i/o remote protocol errno values */
+#define GDB_EPERM           1
+#define GDB_ENOENT          2
+#define GDB_EINTR           4
+#define GDB_EBADF           9
+#define GDB_EACCES         13
+#define GDB_EFAULT         14
+#define GDB_EBUSY          16
+#define GDB_EEXIST         17
+#define GDB_ENODEV         19
+#define GDB_ENOTDIR        20
+#define GDB_EISDIR         21
+#define GDB_EINVAL         22
+#define GDB_ENFILE         23
+#define GDB_EMFILE         24
+#define GDB_EFBIG          27
+#define GDB_ENOSPC         28
+#define GDB_ESPIPE         29
+#define GDB_EROFS          30
+#define GDB_ENAMETOOLONG   91
+#define GDB_EUNKNOWN       9999
+
+/* For gdb file i/o remote protocol lseek whence. */
+#define GDB_SEEK_SET  0
+#define GDB_SEEK_CUR  1
+#define GDB_SEEK_END  2
+
+/* For gdb file i/o stat/fstat. */
+typedef uint32_t gdb_mode_t;
+typedef uint32_t gdb_time_t;
+
+struct gdb_stat {
+  uint32_t    gdb_st_dev;     /* device */
+  uint32_t    gdb_st_ino;     /* inode */
+  gdb_mode_t  gdb_st_mode;    /* protection */
+  uint32_t    gdb_st_nlink;   /* number of hard links */
+  uint32_t    gdb_st_uid;     /* user ID of owner */
+  uint32_t    gdb_st_gid;     /* group ID of owner */
+  uint32_t    gdb_st_rdev;    /* device type (if inode device) */
+  uint64_t    gdb_st_size;    /* total size, in bytes */
+  uint64_t    gdb_st_blksize; /* blocksize for filesystem I/O */
+  uint64_t    gdb_st_blocks;  /* number of blocks allocated */
+  gdb_time_t  gdb_st_atime;   /* time of last access */
+  gdb_time_t  gdb_st_mtime;   /* time of last modification */
+  gdb_time_t  gdb_st_ctime;   /* time of last change */
+} QEMU_PACKED;
+
+struct gdb_timeval {
+  gdb_time_t tv_sec;  /* second */
+  uint64_t tv_usec;   /* microsecond */
+} QEMU_PACKED;
+
+typedef void (*gdb_syscall_complete_cb)(CPUState *cpu, uint64_t ret, int err);
+
+/**
+ * gdb_do_syscall:
+ * @cb: function to call when the system call has completed
+ * @fmt: gdb syscall format string
+ * ...: list of arguments to interpolate into @fmt
+ *
+ * Send a GDB syscall request. This function will return immediately;
+ * the callback function will be called later when the remote system
+ * call has completed.
+ *
+ * @fmt should be in the 'call-id,parameter,parameter...' format documented
+ * for the F request packet in the GDB remote protocol. A limited set of
+ * printf-style format specifiers is supported:
+ *   %x  - target_ulong argument printed in hex
+ *   %lx - 64-bit argument printed in hex
+ *   %s  - string pointer (target_ulong) and length (int) pair
+ */
+void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...);
+
+/**
+ * gdb_do_syscallv:
+ * @cb: function to call when the system call has completed
+ * @fmt: gdb syscall format string
+ * @va: arguments to interpolate into @fmt
+ *
+ * As gdb_do_syscall, but taking a va_list rather than a variable
+ * argument list.
+ */
+void gdb_do_syscallv(gdb_syscall_complete_cb cb, const char *fmt, va_list va);
+
+/**
+ * use_gdb_syscalls() - report if GDB should be used for syscalls
+ *
+ * This is mostly driven by the semihosting mode the user configures
+ * but assuming GDB is allowed by that we report true if GDB is
+ * connected to the stub.
+ */
+int use_gdb_syscalls(void);
+
+/**
+ * gdb_exit: exit gdb session, reporting inferior status
+ * @code: exit code reported
+ *
+ * This closes the session and sends a final packet to GDB reporting
+ * the exit status of the program. It also cleans up any connections
+ * detritus before returning.
+ */
+void gdb_exit(int code);
+
+#endif /* _SYSCALLS_H_ */