diff options
Diffstat (limited to 'sys/kern/subr_kdb.c')
-rw-r--r-- | sys/kern/subr_kdb.c | 675 |
1 files changed, 675 insertions, 0 deletions
diff --git a/sys/kern/subr_kdb.c b/sys/kern/subr_kdb.c new file mode 100644 index 0000000..59d6258 --- /dev/null +++ b/sys/kern/subr_kdb.c @@ -0,0 +1,675 @@ +/*- + * Copyright (c) 2004 The FreeBSD Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_kdb.h" +#include "opt_stack.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/cons.h> +#include <sys/kdb.h> +#include <sys/kernel.h> +#include <sys/malloc.h> +#include <sys/pcpu.h> +#include <sys/proc.h> +#include <sys/sbuf.h> +#include <sys/smp.h> +#include <sys/stack.h> +#include <sys/sysctl.h> + +#include <machine/kdb.h> +#include <machine/pcb.h> + +#ifdef SMP +#include <machine/smp.h> +#endif + +int kdb_active = 0; +static void *kdb_jmpbufp = NULL; +struct kdb_dbbe *kdb_dbbe = NULL; +static struct pcb kdb_pcb; +struct pcb *kdb_thrctx = NULL; +struct thread *kdb_thread = NULL; +struct trapframe *kdb_frame = NULL; + +#ifdef BREAK_TO_DEBUGGER +#define KDB_BREAK_TO_DEBUGGER 1 +#else +#define KDB_BREAK_TO_DEBUGGER 0 +#endif + +#ifdef ALT_BREAK_TO_DEBUGGER +#define KDB_ALT_BREAK_TO_DEBUGGER 1 +#else +#define KDB_ALT_BREAK_TO_DEBUGGER 0 +#endif + +static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER; +static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER; + +KDB_BACKEND(null, NULL, NULL, NULL, NULL); +SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); + +static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS); +static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS); +static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS); +static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS); +static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS); +static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS); + +static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes"); + +SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL, + 0, kdb_sysctl_available, "A", "list of available KDB backends"); + +SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL, + 0, kdb_sysctl_current, "A", "currently selected KDB backend"); + +SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0, + kdb_sysctl_enter, "I", "set to enter the debugger"); + +SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0, + kdb_sysctl_panic, "I", "set to panic the kernel"); + +SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0, + kdb_sysctl_trap, "I", "set to cause a page fault via data access"); + +SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0, + kdb_sysctl_trap_code, "I", "set to cause a page fault via code access"); + +SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_TUN | CTLFLAG_SECURE, + &kdb_break_to_debugger, 0, "Enable break to debugger"); +TUNABLE_INT("debug.kdb.break_to_debugger", &kdb_break_to_debugger); + +SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_TUN | CTLFLAG_SECURE, + &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger"); +TUNABLE_INT("debug.kdb.alt_break_to_debugger", &kdb_alt_break_to_debugger); + +/* + * Flag to indicate to debuggers why the debugger was entered. + */ +const char * volatile kdb_why = KDB_WHY_UNSET; + +static int +kdb_sysctl_available(SYSCTL_HANDLER_ARGS) +{ + struct kdb_dbbe **iter; + struct sbuf sbuf; + int error; + + sbuf_new_for_sysctl(&sbuf, NULL, 64, req); + SET_FOREACH(iter, kdb_dbbe_set) { + if ((*iter)->dbbe_active == 0) + sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name); + } + error = sbuf_finish(&sbuf); + sbuf_delete(&sbuf); + return (error); +} + +static int +kdb_sysctl_current(SYSCTL_HANDLER_ARGS) +{ + char buf[16]; + int error; + + if (kdb_dbbe != NULL) + strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf)); + else + *buf = '\0'; + error = sysctl_handle_string(oidp, buf, sizeof(buf), req); + if (error != 0 || req->newptr == NULL) + return (error); + if (kdb_active) + return (EBUSY); + return (kdb_dbbe_select(buf)); +} + +static int +kdb_sysctl_enter(SYSCTL_HANDLER_ARGS) +{ + int error, i; + + error = sysctl_wire_old_buffer(req, sizeof(int)); + if (error == 0) { + i = 0; + error = sysctl_handle_int(oidp, &i, 0, req); + } + if (error != 0 || req->newptr == NULL) + return (error); + if (kdb_active) + return (EBUSY); + kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter"); + return (0); +} + +static int +kdb_sysctl_panic(SYSCTL_HANDLER_ARGS) +{ + int error, i; + + error = sysctl_wire_old_buffer(req, sizeof(int)); + if (error == 0) { + i = 0; + error = sysctl_handle_int(oidp, &i, 0, req); + } + if (error != 0 || req->newptr == NULL) + return (error); + panic("kdb_sysctl_panic"); + return (0); +} + +static int +kdb_sysctl_trap(SYSCTL_HANDLER_ARGS) +{ + int error, i; + int *addr = (int *)0x10; + + error = sysctl_wire_old_buffer(req, sizeof(int)); + if (error == 0) { + i = 0; + error = sysctl_handle_int(oidp, &i, 0, req); + } + if (error != 0 || req->newptr == NULL) + return (error); + return (*addr); +} + +static int +kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS) +{ + int error, i; + void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de; + + error = sysctl_wire_old_buffer(req, sizeof(int)); + if (error == 0) { + i = 0; + error = sysctl_handle_int(oidp, &i, 0, req); + } + if (error != 0 || req->newptr == NULL) + return (error); + (*fp)(0x11111111, 0x22222222, 0x33333333); + return (0); +} + +void +kdb_panic(const char *msg) +{ + + printf("KDB: panic\n"); + panic("%s", msg); +} + +void +kdb_reboot(void) +{ + + printf("KDB: reboot requested\n"); + shutdown_nice(0); +} + +/* + * Solaris implements a new BREAK which is initiated by a character sequence + * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the + * Remote Console. + * + * Note that this function may be called from almost anywhere, with interrupts + * disabled and with unknown locks held, so it must not access data other than + * its arguments. Its up to the caller to ensure that the state variable is + * consistent. + */ + +#define KEY_CR 13 /* CR '\r' */ +#define KEY_TILDE 126 /* ~ */ +#define KEY_CRTLB 2 /* ^B */ +#define KEY_CRTLP 16 /* ^P */ +#define KEY_CRTLR 18 /* ^R */ + +/* States of th KDB "alternate break sequence" detecting state machine. */ +enum { + KDB_ALT_BREAK_SEEN_NONE, + KDB_ALT_BREAK_SEEN_CR, + KDB_ALT_BREAK_SEEN_CR_TILDE, +}; + +int +kdb_break(void) +{ + + if (!kdb_break_to_debugger) + return (0); + kdb_enter(KDB_WHY_BREAK, "Break to debugger"); + return (KDB_REQ_DEBUGGER); +} + +static int +kdb_alt_break_state(int key, int *state) +{ + int brk; + + /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */ + if (key == KEY_CR) { + *state = KDB_ALT_BREAK_SEEN_CR; + return (0); + } + + brk = 0; + switch (*state) { + case KDB_ALT_BREAK_SEEN_CR: + *state = KDB_ALT_BREAK_SEEN_NONE; + if (key == KEY_TILDE) + *state = KDB_ALT_BREAK_SEEN_CR_TILDE; + break; + case KDB_ALT_BREAK_SEEN_CR_TILDE: + *state = KDB_ALT_BREAK_SEEN_NONE; + if (key == KEY_CRTLB) + brk = KDB_REQ_DEBUGGER; + else if (key == KEY_CRTLP) + brk = KDB_REQ_PANIC; + else if (key == KEY_CRTLR) + brk = KDB_REQ_REBOOT; + break; + case KDB_ALT_BREAK_SEEN_NONE: + default: + *state = KDB_ALT_BREAK_SEEN_NONE; + break; + } + return (brk); +} + +static int +kdb_alt_break_internal(int key, int *state, int force_gdb) +{ + int brk; + + if (!kdb_alt_break_to_debugger) + return (0); + brk = kdb_alt_break_state(key, state); + switch (brk) { + case KDB_REQ_DEBUGGER: + if (force_gdb) + kdb_dbbe_select("gdb"); + kdb_enter(KDB_WHY_BREAK, "Break to debugger"); + break; + + case KDB_REQ_PANIC: + if (force_gdb) + kdb_dbbe_select("gdb"); + kdb_panic("Panic sequence on console"); + break; + + case KDB_REQ_REBOOT: + kdb_reboot(); + break; + } + return (0); +} + +int +kdb_alt_break(int key, int *state) +{ + + return (kdb_alt_break_internal(key, state, 0)); +} + +/* + * This variation on kdb_alt_break() is used only by dcons, which has its own + * configuration flag to force GDB use regardless of the global KDB + * configuration. + */ +int +kdb_alt_break_gdb(int key, int *state) +{ + + return (kdb_alt_break_internal(key, state, 1)); +} + +/* + * Print a backtrace of the calling thread. The backtrace is generated by + * the selected debugger, provided it supports backtraces. If no debugger + * is selected or the current debugger does not support backtraces, this + * function silently returns. + */ + +void +kdb_backtrace(void) +{ + + if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) { + printf("KDB: stack backtrace:\n"); + kdb_dbbe->dbbe_trace(); + } +#ifdef STACK + else { + struct stack st; + + printf("KDB: stack backtrace:\n"); + stack_zero(&st); + stack_save(&st); + stack_print_ddb(&st); + } +#endif +} + +/* + * Similar to kdb_backtrace() except that it prints a backtrace of an + * arbitrary thread rather than the calling thread. + */ +void +kdb_backtrace_thread(struct thread *td) +{ + + if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) { + printf("KDB: stack backtrace of thread %d:\n", td->td_tid); + kdb_dbbe->dbbe_trace_thread(td); + } +#ifdef STACK + else { + struct stack st; + + printf("KDB: stack backtrace of thread %d:\n", td->td_tid); + stack_zero(&st); + stack_save_td(&st, td); + stack_print_ddb(&st); + } +#endif +} + +/* + * Set/change the current backend. + */ + +int +kdb_dbbe_select(const char *name) +{ + struct kdb_dbbe *be, **iter; + + SET_FOREACH(iter, kdb_dbbe_set) { + be = *iter; + if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) { + kdb_dbbe = be; + return (0); + } + } + return (EINVAL); +} + +/* + * Enter the currently selected debugger. If a message has been provided, + * it is printed first. If the debugger does not support the enter method, + * it is entered by using breakpoint(), which enters the debugger through + * kdb_trap(). The 'why' argument will contain a more mechanically usable + * string than 'msg', and is relied upon by DDB scripting to identify the + * reason for entering the debugger so that the right script can be run. + */ +void +kdb_enter(const char *why, const char *msg) +{ + + if (kdb_dbbe != NULL && kdb_active == 0) { + if (msg != NULL) + printf("KDB: enter: %s\n", msg); + kdb_why = why; + breakpoint(); + kdb_why = KDB_WHY_UNSET; + } +} + +/* + * Initialize the kernel debugger interface. + */ + +void +kdb_init(void) +{ + struct kdb_dbbe *be, **iter; + int cur_pri, pri; + + kdb_active = 0; + kdb_dbbe = NULL; + cur_pri = -1; + SET_FOREACH(iter, kdb_dbbe_set) { + be = *iter; + pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1; + be->dbbe_active = (pri >= 0) ? 0 : -1; + if (pri > cur_pri) { + cur_pri = pri; + kdb_dbbe = be; + } + } + if (kdb_dbbe != NULL) { + printf("KDB: debugger backends:"); + SET_FOREACH(iter, kdb_dbbe_set) { + be = *iter; + if (be->dbbe_active == 0) + printf(" %s", be->dbbe_name); + } + printf("\n"); + printf("KDB: current backend: %s\n", + kdb_dbbe->dbbe_name); + } +} + +/* + * Handle contexts. + */ + +void * +kdb_jmpbuf(jmp_buf new) +{ + void *old; + + old = kdb_jmpbufp; + kdb_jmpbufp = new; + return (old); +} + +void +kdb_reenter(void) +{ + + if (!kdb_active || kdb_jmpbufp == NULL) + return; + + longjmp(kdb_jmpbufp, 1); + /* NOTREACHED */ +} + +/* + * Thread related support functions. + */ + +struct pcb * +kdb_thr_ctx(struct thread *thr) +{ +#if defined(SMP) && defined(KDB_STOPPEDPCB) + struct pcpu *pc; +#endif + + if (thr == curthread) + return (&kdb_pcb); + +#if defined(SMP) && defined(KDB_STOPPEDPCB) + STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) { + if (pc->pc_curthread == thr && + CPU_ISSET(pc->pc_cpuid, &stopped_cpus)) + return (KDB_STOPPEDPCB(pc)); + } +#endif + return (thr->td_pcb); +} + +struct thread * +kdb_thr_first(void) +{ + struct proc *p; + struct thread *thr; + + p = LIST_FIRST(&allproc); + while (p != NULL) { + if (p->p_flag & P_INMEM) { + thr = FIRST_THREAD_IN_PROC(p); + if (thr != NULL) + return (thr); + } + p = LIST_NEXT(p, p_list); + } + return (NULL); +} + +struct thread * +kdb_thr_from_pid(pid_t pid) +{ + struct proc *p; + + p = LIST_FIRST(&allproc); + while (p != NULL) { + if (p->p_flag & P_INMEM && p->p_pid == pid) + return (FIRST_THREAD_IN_PROC(p)); + p = LIST_NEXT(p, p_list); + } + return (NULL); +} + +struct thread * +kdb_thr_lookup(lwpid_t tid) +{ + struct thread *thr; + + thr = kdb_thr_first(); + while (thr != NULL && thr->td_tid != tid) + thr = kdb_thr_next(thr); + return (thr); +} + +struct thread * +kdb_thr_next(struct thread *thr) +{ + struct proc *p; + + p = thr->td_proc; + thr = TAILQ_NEXT(thr, td_plist); + do { + if (thr != NULL) + return (thr); + p = LIST_NEXT(p, p_list); + if (p != NULL && (p->p_flag & P_INMEM)) + thr = FIRST_THREAD_IN_PROC(p); + } while (p != NULL); + return (NULL); +} + +int +kdb_thr_select(struct thread *thr) +{ + if (thr == NULL) + return (EINVAL); + kdb_thread = thr; + kdb_thrctx = kdb_thr_ctx(thr); + return (0); +} + +/* + * Enter the debugger due to a trap. + */ + +int +kdb_trap(int type, int code, struct trapframe *tf) +{ +#ifdef SMP + cpuset_t other_cpus; +#endif + struct kdb_dbbe *be; + register_t intr; + int handled; +#ifdef SMP + int did_stop_cpus; +#endif + + be = kdb_dbbe; + if (be == NULL || be->dbbe_trap == NULL) + return (0); + + /* We reenter the debugger through kdb_reenter(). */ + if (kdb_active) + return (0); + + intr = intr_disable(); + +#ifdef SMP + if (!SCHEDULER_STOPPED()) { + other_cpus = all_cpus; + CPU_CLR(PCPU_GET(cpuid), &other_cpus); + stop_cpus_hard(other_cpus); + did_stop_cpus = 1; + } else + did_stop_cpus = 0; +#endif + + kdb_active++; + + kdb_frame = tf; + + /* Let MD code do its thing first... */ + kdb_cpu_trap(type, code); + + makectx(tf, &kdb_pcb); + kdb_thr_select(curthread); + + cngrab(); + + for (;;) { + handled = be->dbbe_trap(type, code); + if (be == kdb_dbbe) + break; + be = kdb_dbbe; + if (be == NULL || be->dbbe_trap == NULL) + break; + printf("Switching to %s back-end\n", be->dbbe_name); + } + + cnungrab(); + + kdb_active--; + +#ifdef SMP + if (did_stop_cpus) + restart_cpus(stopped_cpus); +#endif + + intr_restore(intr); + + return (handled); +} |