| /* BSD Kernel Data Access Library (libkvm) interface. |
| |
| Copyright (C) 2004-2024 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 "cli/cli-cmds.h" |
| #include "command.h" |
| #include "filenames.h" |
| #include "frame.h" |
| #include "regcache.h" |
| #include "target.h" |
| #include "process-stratum-target.h" |
| #include "value.h" |
| #include "gdbcore.h" |
| #include "inferior.h" |
| #include "gdbthread.h" |
| #include "gdbsupport/pathstuff.h" |
| #include "gdbsupport/gdb_tilde_expand.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 std::string 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]; |
| kvm_t *temp_kd; |
| std::string filename; |
| |
| target_preopen (from_tty); |
| |
| if (arg) |
| { |
| filename = gdb_tilde_expand (arg); |
| if (!IS_ABSOLUTE_PATH (filename)) |
| filename = gdb_abspath (filename); |
| } |
| |
| const char *execfile = current_program_space->exec_filename (); |
| temp_kd = kvm_openfiles (execfile, filename.c_str (), 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_thread_regcache (thr), -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; |
| } |
| |
| bsd_kvm_corefile.clear (); |
| switch_to_no_thread (); |
| exit_inferior (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 != _PATH_MEM) |
| gdb_printf (_("\tUsing the kernel crash dump %s.\n"), |
| bsd_kvm_corefile.c_str ()); |
| 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_thread_regcache (inferior_thread ()), -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_thread_regcache (inferior_thread ()), -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); |
| } |