/* BSD Kernel Data Access Library (libkvm) interface. Copyright (C) 2004-2015 Free Software Foundation, Inc. This file is part of GDB. 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 3 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/>. */ #include "defs.h" #include "cli/cli-cmds.h" #include "command.h" #include "frame.h" #include "regcache.h" #include "target.h" #include "value.h" #include "gdbcore.h" /* for get_exec_file */ #include "gdbthread.h" #include <fcntl.h> #include <kvm.h> #ifdef HAVE_NLIST_H #include <nlist.h> #endif #include <paths.h> #include "readline/readline.h" #include <sys/param.h> #include <sys/proc.h> #include <sys/user.h> #include "bsd-kvm.h" /* Kernel memory device file. */ static const char *bsd_kvm_corefile; /* Kernel memory interface descriptor. */ static kvm_t *core_kd; /* Address of process control block. */ static struct pcb *bsd_kvm_paddr; /* Pointer to architecture-specific function that reconstructs the register state from PCB and supplies it to REGCACHE. */ static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb); /* Target ops for libkvm interface. */ static struct target_ops bsd_kvm_ops; /* This is the ptid we use while we're connected to kvm. The kvm target currently doesn't export any view of the running processes, so this represents the kernel task. */ static ptid_t bsd_kvm_ptid; static void bsd_kvm_open (const char *arg, int from_tty) { char errbuf[_POSIX2_LINE_MAX]; char *execfile = NULL; kvm_t *temp_kd; char *filename = NULL; target_preopen (from_tty); if (arg) { char *temp; filename = tilde_expand (arg); if (filename[0] != '/') { temp = concat (current_directory, "/", filename, (char *)NULL); xfree (filename); filename = temp; } } execfile = get_exec_file (0); temp_kd = kvm_openfiles (execfile, filename, NULL, write_files ? O_RDWR : O_RDONLY, errbuf); if (temp_kd == NULL) error (("%s"), errbuf); bsd_kvm_corefile = filename; unpush_target (&bsd_kvm_ops); core_kd = temp_kd; push_target (&bsd_kvm_ops); add_thread_silent (bsd_kvm_ptid); inferior_ptid = bsd_kvm_ptid; target_fetch_registers (get_current_regcache (), -1); reinit_frame_cache (); print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1); } static void bsd_kvm_close (struct target_ops *self) { if (core_kd) { if (kvm_close (core_kd) == -1) warning (("%s"), kvm_geterr(core_kd)); core_kd = NULL; } inferior_ptid = null_ptid; delete_thread_silent (bsd_kvm_ptid); } static LONGEST bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len, gdb_byte *readbuf, const gdb_byte *writebuf) { ssize_t nbytes = len; if (readbuf) nbytes = kvm_read (core_kd, addr, readbuf, nbytes); if (writebuf && nbytes > 0) nbytes = kvm_write (core_kd, addr, writebuf, nbytes); return nbytes; } static enum target_xfer_status bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object, const char *annex, gdb_byte *readbuf, const gdb_byte *writebuf, ULONGEST offset, ULONGEST len, ULONGEST *xfered_len) { switch (object) { case TARGET_OBJECT_MEMORY: { LONGEST ret = bsd_kvm_xfer_memory (offset, len, readbuf, writebuf); if (ret < 0) return TARGET_XFER_E_IO; else if (ret == 0) return TARGET_XFER_EOF; else { *xfered_len = (ULONGEST) ret; return TARGET_XFER_OK; } } default: return TARGET_XFER_E_IO; } } static void bsd_kvm_files_info (struct target_ops *ops) { if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0) printf_filtered (_("\tUsing the kernel crash dump %s.\n"), bsd_kvm_corefile); else printf_filtered (_("\tUsing the currently running kernel.\n")); } /* Fetch process control block at address PADDR. */ static int bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr) { struct pcb pcb; if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1) error (("%s"), kvm_geterr (core_kd)); gdb_assert (bsd_kvm_supply_pcb); return bsd_kvm_supply_pcb (regcache, &pcb); } static void bsd_kvm_fetch_registers (struct target_ops *ops, struct regcache *regcache, int regnum) { struct nlist nl[2]; if (bsd_kvm_paddr) { bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr); return; } /* On dumping core, BSD kernels store the faulting context (PCB) in the variable "dumppcb". */ memset (nl, 0, sizeof nl); nl[0].n_name = "_dumppcb"; if (kvm_nlist (core_kd, nl) == -1) error (("%s"), kvm_geterr (core_kd)); if (nl[0].n_value != 0) { /* Found dumppcb. If it contains a valid context, return immediately. */ if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value)) return; } /* Traditional BSD kernels have a process proc0 that should always be present. The address of proc0's PCB is stored in the variable "proc0paddr". */ memset (nl, 0, sizeof nl); nl[0].n_name = "_proc0paddr"; if (kvm_nlist (core_kd, nl) == -1) error (("%s"), kvm_geterr (core_kd)); if (nl[0].n_value != 0) { struct pcb *paddr; /* Found proc0paddr. */ if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1) error (("%s"), kvm_geterr (core_kd)); bsd_kvm_fetch_pcb (regcache, paddr); return; } #ifdef HAVE_STRUCT_THREAD_TD_PCB /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer lives in `struct proc' but in `struct thread'. The `struct thread' for the initial thread for proc0 can be found in the variable "thread0". */ memset (nl, 0, sizeof nl); nl[0].n_name = "_thread0"; if (kvm_nlist (core_kd, nl) == -1) error (("%s"), kvm_geterr (core_kd)); if (nl[0].n_value != 0) { struct pcb *paddr; /* Found thread0. */ nl[0].n_value += offsetof (struct thread, td_pcb); if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1) error (("%s"), kvm_geterr (core_kd)); bsd_kvm_fetch_pcb (regcache, paddr); return; } #endif /* i18n: PCB == "Process Control Block". */ error (_("Cannot find a valid PCB")); } /* Kernel memory interface commands. */ struct cmd_list_element *bsd_kvm_cmdlist; static void bsd_kvm_cmd (char *arg, int fromtty) { /* ??? Should this become an alias for "target kvm"? */ } #ifndef HAVE_STRUCT_THREAD_TD_PCB static void bsd_kvm_proc_cmd (char *arg, int fromtty) { CORE_ADDR addr; if (arg == NULL) error_no_arg (_("proc address")); if (core_kd == NULL) error (_("No kernel memory image.")); addr = parse_and_eval_address (arg); #ifdef HAVE_STRUCT_LWP addr += offsetof (struct lwp, l_addr); #else addr += offsetof (struct proc, p_addr); #endif if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1) error (("%s"), kvm_geterr (core_kd)); target_fetch_registers (get_current_regcache (), -1); reinit_frame_cache (); print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1); } #endif static void bsd_kvm_pcb_cmd (char *arg, int fromtty) { if (arg == NULL) /* i18n: PCB == "Process Control Block". */ error_no_arg (_("pcb address")); if (core_kd == NULL) error (_("No kernel memory image.")); bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg); target_fetch_registers (get_current_regcache (), -1); reinit_frame_cache (); print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1); } static int bsd_kvm_thread_alive (struct target_ops *ops, ptid_t ptid) { return 1; } static char * bsd_kvm_pid_to_str (struct target_ops *ops, ptid_t ptid) { static char buf[64]; xsnprintf (buf, sizeof buf, "<kvm>"); return buf; } static int bsd_kvm_return_one (struct target_ops *ops) { return 1; } /* Add the libkvm interface to the list of all possible targets and register CUPPLY_PCB as the architecture-specific process control block interpreter. */ void bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *)) { gdb_assert (bsd_kvm_supply_pcb == NULL); bsd_kvm_supply_pcb = supply_pcb; bsd_kvm_ops.to_shortname = "kvm"; bsd_kvm_ops.to_longname = _("Kernel memory interface"); bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\ Optionally specify the filename of a core dump."); bsd_kvm_ops.to_open = bsd_kvm_open; bsd_kvm_ops.to_close = bsd_kvm_close; bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers; bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial; bsd_kvm_ops.to_files_info = bsd_kvm_files_info; bsd_kvm_ops.to_thread_alive = bsd_kvm_thread_alive; bsd_kvm_ops.to_pid_to_str = bsd_kvm_pid_to_str; bsd_kvm_ops.to_stratum = process_stratum; bsd_kvm_ops.to_has_memory = bsd_kvm_return_one; bsd_kvm_ops.to_has_stack = bsd_kvm_return_one; bsd_kvm_ops.to_has_registers = bsd_kvm_return_one; bsd_kvm_ops.to_magic = OPS_MAGIC; add_target (&bsd_kvm_ops); add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\ Generic command for manipulating the kernel memory interface."), &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist); #ifndef HAVE_STRUCT_THREAD_TD_PCB add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd, _("Set current context from proc address"), &bsd_kvm_cmdlist); #endif add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd, /* i18n: PCB == "Process Control Block". */ _("Set current context from pcb address"), &bsd_kvm_cmdlist); /* Some notes on the ptid usage on this target. The pid field represents the kvm inferior instance. Currently, we don't support multiple kvm inferiors, but we start at 1 anyway. The lwp field is set to != 0, in case the core wants to refer to the whole kvm inferior with ptid(1,0,0). If kvm is made to export running processes as gdb threads, the following form can be used: ptid (1, 1, 0) -> kvm inferior 1, in kernel ptid (1, 1, 1) -> kvm inferior 1, process 1 ptid (1, 1, 2) -> kvm inferior 1, process 2 ptid (1, 1, n) -> kvm inferior 1, process n */ bsd_kvm_ptid = ptid_build (1, 1, 0); }