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- /* BSD Kernel Data Access Library (libkvm) interface.
- Copyright (C) 2004-2022 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/>. */
- #define _KMEMUSER
- #include "defs.h"
- #include "cli/cli-cmds.h"
- #include "command.h"
- #include "frame.h"
- #include "regcache.h"
- #include "target.h"
- #include "process-stratum-target.h"
- #include "value.h"
- #include "gdbcore.h"
- #include "inferior.h" /* for get_exec_file */
- #include "gdbthread.h"
- #include "gdbsupport/pathstuff.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>
- #ifdef HAVE_SYS_USER_H
- #include <sys/user.h>
- #endif
- #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);
- /* 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;
- /* The libkvm target. */
- static const target_info bsd_kvm_target_info = {
- "kvm",
- N_("Kernel memory interface"),
- N_("Use a kernel virtual memory image as a target.\n\
- Optionally specify the filename of a core dump.")
- };
- class bsd_kvm_target final : public process_stratum_target
- {
- public:
- bsd_kvm_target () = default;
- const target_info &info () const override
- { return bsd_kvm_target_info; }
- void close () override;
- void fetch_registers (struct regcache *, int) override;
- enum target_xfer_status xfer_partial (enum target_object object,
- const char *annex,
- gdb_byte *readbuf,
- const gdb_byte *writebuf,
- ULONGEST offset, ULONGEST len,
- ULONGEST *xfered_len) override;
- void files_info () override;
- bool thread_alive (ptid_t ptid) override;
- std::string pid_to_str (ptid_t) override;
- bool has_memory () override { return true; }
- bool has_stack () override { return true; }
- bool has_registers () override { return true; }
- };
- /* Target ops for libkvm interface. */
- static bsd_kvm_target bsd_kvm_ops;
- static void
- bsd_kvm_target_open (const char *arg, int from_tty)
- {
- char errbuf[_POSIX2_LINE_MAX];
- const char *execfile = NULL;
- kvm_t *temp_kd;
- char *filename = NULL;
- target_preopen (from_tty);
- if (arg)
- {
- filename = tilde_expand (arg);
- if (filename[0] != '/')
- {
- gdb::unique_xmalloc_ptr<char> temp (gdb_abspath (filename));
- xfree (filename);
- filename = temp.release ();
- }
- }
- 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;
- current_inferior ()->unpush_target (&bsd_kvm_ops);
- core_kd = temp_kd;
- current_inferior ()->push_target (&bsd_kvm_ops);
- thread_info *thr = add_thread_silent (&bsd_kvm_ops, bsd_kvm_ptid);
- switch_to_thread (thr);
- target_fetch_registers (get_current_regcache (), -1);
- reinit_frame_cache ();
- print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1);
- }
- void
- bsd_kvm_target::close ()
- {
- if (core_kd)
- {
- if (kvm_close (core_kd) == -1)
- warning (("%s"), kvm_geterr(core_kd));
- core_kd = NULL;
- }
- switch_to_no_thread ();
- exit_inferior_silent (current_inferior ());
- }
- 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;
- }
- enum target_xfer_status
- bsd_kvm_target::xfer_partial (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;
- }
- }
- void
- bsd_kvm_target::files_info ()
- {
- if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)
- gdb_printf (_("\tUsing the kernel crash dump %s.\n"),
- bsd_kvm_corefile);
- else
- gdb_printf (_("\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);
- }
- void
- bsd_kvm_target::fetch_registers (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 = (char *) "_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 = (char *) "_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 = (char *) "_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 (const char *arg, int fromtty)
- {
- /* ??? Should this become an alias for "target kvm"? */
- }
- #ifndef HAVE_STRUCT_THREAD_TD_PCB
- static void
- bsd_kvm_proc_cmd (const 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 (const 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);
- }
- bool
- bsd_kvm_target::thread_alive (ptid_t ptid)
- {
- return true;
- }
- std::string
- bsd_kvm_target::pid_to_str (ptid_t ptid)
- {
- return "<kvm>";
- }
- /* 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;
- add_target (bsd_kvm_target_info, bsd_kvm_target_open);
-
- add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
- Generic command for manipulating the kernel memory interface."),
- &bsd_kvm_cmdlist, 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_t (1, 1, 0);
- }
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