diff options
Diffstat (limited to 'gdbstub/syscalls.c')
| -rw-r--r-- | gdbstub/syscalls.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/gdbstub/syscalls.c b/gdbstub/syscalls.c new file mode 100644 index 0000000000..02e3a8f74c --- /dev/null +++ b/gdbstub/syscalls.c @@ -0,0 +1,205 @@ +/* + * GDB Syscall Handling + * + * GDB can execute syscalls on the guests behalf, currently used by + * the various semihosting extensions. + * + * Copyright (c) 2003-2005 Fabrice Bellard + * Copyright (c) 2023 Linaro Ltd + * + * SPDX-License-Identifier: LGPL-2.0+ + */ + +#include "qemu/osdep.h" +#include "qemu/error-report.h" +#include "semihosting/semihost.h" +#include "sysemu/runstate.h" +#include "gdbstub/user.h" +#include "gdbstub/syscalls.h" +#include "trace.h" +#include "internals.h" + +/* Syscall specific state */ +typedef struct { + char syscall_buf[256]; + gdb_syscall_complete_cb current_syscall_cb; +} GDBSyscallState; + +static GDBSyscallState gdbserver_syscall_state; + +/* + * Return true if there is a GDB currently connected to the stub + * and attached to a CPU + */ +static bool gdb_attached(void) +{ + return gdbserver_state.init && gdbserver_state.c_cpu; +} + +static enum { + GDB_SYS_UNKNOWN, + GDB_SYS_ENABLED, + GDB_SYS_DISABLED, +} gdb_syscall_mode; + +/* Decide if either remote gdb syscalls or native file IO should be used. */ +int use_gdb_syscalls(void) +{ + SemihostingTarget target = semihosting_get_target(); + if (target == SEMIHOSTING_TARGET_NATIVE) { + /* -semihosting-config target=native */ + return false; + } else if (target == SEMIHOSTING_TARGET_GDB) { + /* -semihosting-config target=gdb */ + return true; + } + + /* -semihosting-config target=auto */ + /* On the first call check if gdb is connected and remember. */ + if (gdb_syscall_mode == GDB_SYS_UNKNOWN) { + gdb_syscall_mode = gdb_attached() ? GDB_SYS_ENABLED : GDB_SYS_DISABLED; + } + return gdb_syscall_mode == GDB_SYS_ENABLED; +} + +/* called when the stub detaches */ +void gdb_disable_syscalls(void) +{ + gdb_syscall_mode = GDB_SYS_DISABLED; +} + +void gdb_syscall_reset(void) +{ + gdbserver_syscall_state.current_syscall_cb = NULL; +} + +bool gdb_handled_syscall(void) +{ + if (gdbserver_syscall_state.current_syscall_cb) { + gdb_put_packet(gdbserver_syscall_state.syscall_buf); + return true; + } + + return false; +} + +/* + * Send a gdb syscall request. + * This accepts limited printf-style format specifiers, specifically: + * %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, ...) +{ + char *p, *p_end; + va_list va; + + if (!gdb_attached()) { + return; + } + + gdbserver_syscall_state.current_syscall_cb = cb; + va_start(va, fmt); + + p = gdbserver_syscall_state.syscall_buf; + p_end = p + sizeof(gdbserver_syscall_state.syscall_buf); + *(p++) = 'F'; + while (*fmt) { + if (*fmt == '%') { + uint64_t i64; + uint32_t i32; + + fmt++; + switch (*fmt++) { + case 'x': + i32 = va_arg(va, uint32_t); + p += snprintf(p, p_end - p, "%" PRIx32, i32); + break; + case 'l': + if (*(fmt++) != 'x') { + goto bad_format; + } + i64 = va_arg(va, uint64_t); + p += snprintf(p, p_end - p, "%" PRIx64, i64); + break; + case 's': + i64 = va_arg(va, uint64_t); + i32 = va_arg(va, uint32_t); + p += snprintf(p, p_end - p, "%" PRIx64 "/%x" PRIx32, i64, i32); + break; + default: + bad_format: + error_report("gdbstub: Bad syscall format string '%s'", + fmt - 1); + break; + } + } else { + *(p++) = *(fmt++); + } + } + *p = 0; + + va_end(va); + gdb_syscall_handling(gdbserver_syscall_state.syscall_buf); +} + +/* + * GDB Command Handlers + */ + +void gdb_handle_file_io(GArray *params, void *user_ctx) +{ + if (params->len >= 1 && gdbserver_syscall_state.current_syscall_cb) { + uint64_t ret; + int err; + + ret = get_param(params, 0)->val_ull; + if (params->len >= 2) { + err = get_param(params, 1)->val_ull; + } else { + err = 0; + } + + /* Convert GDB error numbers back to host error numbers. */ +#define E(X) case GDB_E##X: err = E##X; break + switch (err) { + case 0: + break; + E(PERM); + E(NOENT); + E(INTR); + E(BADF); + E(ACCES); + E(FAULT); + E(BUSY); + E(EXIST); + E(NODEV); + E(NOTDIR); + E(ISDIR); + E(INVAL); + E(NFILE); + E(MFILE); + E(FBIG); + E(NOSPC); + E(SPIPE); + E(ROFS); + E(NAMETOOLONG); + default: + err = EINVAL; + break; + } +#undef E + + gdbserver_syscall_state.current_syscall_cb(gdbserver_state.c_cpu, + ret, err); + gdbserver_syscall_state.current_syscall_cb = NULL; + } + + if (params->len >= 3 && get_param(params, 2)->opcode == (uint8_t)'C') { + gdb_put_packet("T02"); + return; + } + + gdb_continue(); +} |