Date: Fri, 26 Aug 2011 21:46:36 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r225203 - in head/sys: dev/cfe dev/dcons dev/ofw dev/sio dev/syscons dev/uart kern pc98/cbus powerpc/mambo sys Message-ID: <201108262146.p7QLkaBG072083@svn.freebsd.org>
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Author: rwatson Date: Fri Aug 26 21:46:36 2011 New Revision: 225203 URL: http://svn.freebsd.org/changeset/base/225203 Log: Attempt to make break-to-debugger and alternative break-to-debugger more accessible: (1) Always compile in support for breaking into the debugger if options KDB is present in the kernel. (2) Disable both by default, but allow them to be enabled via tunables and sysctls debug.kdb.break_to_debugger and debug.kdb.alt_break_to_debugger. (3) options BREAK_TO_DEBUGGER and options ALT_BREAK_TO_DEBUGGER continue to behave as before -- only now instead of compiling in break-to-debugger support, they change the default values of the above sysctls to enable those features by default. Current kernel configurations should, therefore, continue to behave as expected. (4) Migrate alternative break-to-debugger state machine logic out of individual device drivers into centralised KDB code. This has a number of upsides, but also one downside: it's now tricky to release sio spin locks when entering the debugger, so we don't. However, similar logic does not exist in other device drivers, including uart. (5) dcons requires some special handling; unlike other console types, it allows overriding KDB's own debugger selection, so we need a new interface to KDB to allow that to work. GENERIC kernels in -CURRENT will now support break-to-debugger as long as appropriate boot/run-time options are set, which should improve the debuggability of BETA kernels significantly. MFC after: 3 weeks Reviewed by: kib, nwhitehorn Approved by: re (bz) Modified: head/sys/dev/cfe/cfe_console.c head/sys/dev/dcons/dcons_os.c head/sys/dev/ofw/ofw_console.c head/sys/dev/sio/sio.c head/sys/dev/syscons/syscons.c head/sys/dev/uart/uart_core.c head/sys/kern/subr_kdb.c head/sys/pc98/cbus/sio.c head/sys/powerpc/mambo/mambo_console.c head/sys/sys/kdb.h Modified: head/sys/dev/cfe/cfe_console.c ============================================================================== --- head/sys/dev/cfe/cfe_console.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/dev/cfe/cfe_console.c Fri Aug 26 21:46:36 2011 (r225203) @@ -67,7 +67,7 @@ static int polltime; static struct callout_handle cfe_timeouthandle = CALLOUT_HANDLE_INITIALIZER(&cfe_timeouthandle); -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) +#if defined(KDB) static int alt_break_state; #endif @@ -191,24 +191,8 @@ cfe_cngetc(struct consdev *cp) unsigned char ch; if (cfe_read(conhandle, &ch, 1) == 1) { -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) - int kdb_brk; - - if ((kdb_brk = kdb_alt_break(ch, &alt_break_state)) != 0) { - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - kdb_enter(KDB_WHY_BREAK, - "Break sequence on console"); - break; - case KDB_REQ_PANIC: - kdb_panic("Panic sequence on console"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - - } - } +#if defined(KDB) + kdb_alt_break(ch, &alt_break_state); #endif return (ch); } Modified: head/sys/dev/dcons/dcons_os.c ============================================================================== --- head/sys/dev/dcons/dcons_os.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/dev/dcons/dcons_os.c Fri Aug 26 21:46:36 2011 (r225203) @@ -133,38 +133,21 @@ static struct ttydevsw dcons_ttydevsw = .tsw_outwakeup = dcons_outwakeup, }; -#if (defined(GDB) || defined(DDB)) && defined(ALT_BREAK_TO_DEBUGGER) +#if (defined(GDB) || defined(DDB)) static int dcons_check_break(struct dcons_softc *dc, int c) { - int kdb_brk; if (c < 0) return (c); - if ((kdb_brk = kdb_alt_break(c, &dc->brk_state)) != 0) { - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - if ((dc->flags & DC_GDB) != 0) { #ifdef GDB - if (gdb_cur == &dcons_gdb_dbgport) { - kdb_dbbe_select("gdb"); - kdb_enter(KDB_WHY_BREAK, - "Break sequence on dcons gdb port"); - } + if ((dc->flags & DC_GDB) != 0 && gdb_cur == &dcons_gdb_dbgport) + kdb_alt_break_gdb(c, &dc->brk_state); + else #endif - } else - kdb_enter(KDB_WHY_BREAK, - "Break sequence on dcons console port"); - break; - case KDB_REQ_PANIC: - kdb_panic("Panic sequence on dcons console port"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - } - } + kdb_alt_break(c, &dc->brk_state); + return (c); } #else Modified: head/sys/dev/ofw/ofw_console.c ============================================================================== --- head/sys/dev/ofw/ofw_console.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/dev/ofw/ofw_console.c Fri Aug 26 21:46:36 2011 (r225203) @@ -64,7 +64,7 @@ static int polltime; static struct callout_handle ofw_timeouthandle = CALLOUT_HANDLE_INITIALIZER(&ofw_timeouthandle); -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) +#if defined(KDB) static int alt_break_state; #endif @@ -199,24 +199,8 @@ ofw_cngetc(struct consdev *cp) unsigned char ch; if (OF_read(stdin, &ch, 1) > 0) { -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) - int kdb_brk; - - if ((kdb_brk = kdb_alt_break(ch, &alt_break_state)) != 0) { - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - kdb_enter(KDB_WHY_BREAK, - "Break sequence on console"); - break; - case KDB_REQ_PANIC: - kdb_panic("Panic sequence on console"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - - } - } +#if defined(KDB) + kdb_alt_break(ch, &alt_break_state); #endif return (ch); } Modified: head/sys/dev/sio/sio.c ============================================================================== --- head/sys/dev/sio/sio.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/dev/sio/sio.c Fri Aug 26 21:46:36 2011 (r225203) @@ -228,7 +228,7 @@ struct com_s { struct pps_state pps; int pps_bit; -#ifdef ALT_BREAK_TO_DEBUGGER +#ifdef KDB int alt_brk_state; #endif @@ -1102,8 +1102,7 @@ determined_type: ; } if (ret) device_printf(dev, "could not activate interrupt\n"); -#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \ - defined(ALT_BREAK_TO_DEBUGGER)) +#if defined(KDB) /* * Enable interrupts for early break-to-debugger support * on the console. @@ -1196,8 +1195,7 @@ comclose(tp) com->poll_output = FALSE; sio_setreg(com, com_cfcr, com->cfcr_image &= ~CFCR_SBREAK); -#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \ - defined(ALT_BREAK_TO_DEBUGGER)) +#if defined(KDB) /* * Leave interrupts enabled and don't clear DTR if this is the * console. This allows us to detect break-to-debugger events @@ -1483,9 +1481,8 @@ siointr1(com) u_char modem_status; u_char *ioptr; u_char recv_data; -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) - int kdb_brk; +#ifdef KDB again: #endif @@ -1518,27 +1515,9 @@ again: else recv_data = inb(com->data_port); #ifdef KDB -#ifdef ALT_BREAK_TO_DEBUGGER if (com->unit == comconsole && - (kdb_brk = kdb_alt_break(recv_data, - &com->alt_brk_state)) != 0) { - mtx_unlock_spin(&sio_lock); - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - kdb_enter(KDB_WHY_BREAK, - "Break sequence on console"); - break; - case KDB_REQ_PANIC: - kdb_panic("panic on console"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - } - mtx_lock_spin(&sio_lock); + kdb_alt_break(recv_data, &com->alt_brk_state) != 0) goto again; - } -#endif /* ALT_BREAK_TO_DEBUGGER */ #endif /* KDB */ if (line_status & (LSR_BI | LSR_FE | LSR_PE)) { /* @@ -1554,10 +1533,9 @@ again: * Note: BI together with FE/PE means just BI. */ if (line_status & LSR_BI) { -#if defined(KDB) && defined(BREAK_TO_DEBUGGER) +#if defined(KDB) if (com->unit == comconsole) { - kdb_enter(KDB_WHY_BREAK, - "Line break on console"); + kdb_break(); goto cont; } #endif Modified: head/sys/dev/syscons/syscons.c ============================================================================== --- head/sys/dev/syscons/syscons.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/dev/syscons/syscons.c Fri Aug 26 21:46:36 2011 (r225203) @@ -3514,7 +3514,7 @@ next_code: case DBG: #ifndef SC_DISABLE_KDBKEY if (enable_kdbkey) - kdb_enter(KDB_WHY_BREAK, "manual escape to debugger"); + kdb_break(); #endif break; Modified: head/sys/dev/uart/uart_core.c ============================================================================== --- head/sys/dev/uart/uart_core.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/dev/uart/uart_core.c Fri Aug 26 21:46:36 2011 (r225203) @@ -118,10 +118,10 @@ uart_intr_break(void *arg) { struct uart_softc *sc = arg; -#if defined(KDB) && defined(BREAK_TO_DEBUGGER) +#if defined(KDB) if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) { - kdb_enter(KDB_WHY_BREAK, "Line break on console"); - return (0); + if (kdb_break()) + return (0); } #endif if (sc->sc_opened) @@ -170,26 +170,10 @@ uart_intr_rxready(void *arg) rxp = sc->sc_rxput; UART_RECEIVE(sc); -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) +#if defined(KDB) if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) { while (rxp != sc->sc_rxput) { - int kdb_brk; - - if ((kdb_brk = kdb_alt_break(sc->sc_rxbuf[rxp++], - &sc->sc_altbrk)) != 0) { - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - kdb_enter(KDB_WHY_BREAK, - "Break sequence on console"); - break; - case KDB_REQ_PANIC: - kdb_panic("Panic sequence on console"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - } - } + kdb_alt_break(sc->sc_rxbuf[rxp++], &sc->sc_altbrk); if (rxp == sc->sc_rxbufsz) rxp = 0; } Modified: head/sys/kern/subr_kdb.c ============================================================================== --- head/sys/kern/subr_kdb.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/kern/subr_kdb.c Fri Aug 26 21:46:36 2011 (r225203) @@ -57,6 +57,21 @@ 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); SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe); @@ -87,6 +102,15 @@ SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, 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, &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, &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. */ @@ -241,7 +265,17 @@ enum { }; int -kdb_alt_break(int key, int *state) +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; @@ -275,6 +309,53 @@ kdb_alt_break(int key, int *state) 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 Modified: head/sys/pc98/cbus/sio.c ============================================================================== --- head/sys/pc98/cbus/sio.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/pc98/cbus/sio.c Fri Aug 26 21:46:36 2011 (r225203) @@ -310,7 +310,7 @@ struct com_s { struct pps_state pps; int pps_bit; -#ifdef ALT_BREAK_TO_DEBUGGER +#ifdef KDB int alt_brk_state; #endif @@ -1752,8 +1752,7 @@ determined_type: ; } if (ret) device_printf(dev, "could not activate interrupt\n"); -#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \ - defined(ALT_BREAK_TO_DEBUGGER)) +#if defined(KDB) /* * Enable interrupts for early break-to-debugger support * on the console. @@ -1896,8 +1895,7 @@ comclose(tp) sio_setreg(com, com_cfcr, com->cfcr_image &= ~CFCR_SBREAK); #endif -#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \ - defined(ALT_BREAK_TO_DEBUGGER)) +#if defined(KDB) /* * Leave interrupts enabled and don't clear DTR if this is the * console. This allows us to detect break-to-debugger events @@ -2272,7 +2270,7 @@ siointr1(com) u_char rsa_buf_status = 0; int rsa_tx_fifo_size = 0; #endif /* PC98 */ -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) +#if defined(KDB) int kdb_brk; again: @@ -2369,27 +2367,11 @@ more_intr: else recv_data = inb(com->data_port); #ifdef KDB -#ifdef ALT_BREAK_TO_DEBUGGER if (com->unit == comconsole && (kdb_brk = kdb_alt_break(recv_data, &com->alt_brk_state)) != 0) { - mtx_unlock_spin(&sio_lock); - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - kdb_enter(KDB_WHY_BREAK, - "Break sequence on console"); - break; - case KDB_REQ_PANIC: - kdb_panic("panic on console"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - } - mtx_lock_spin(&sio_lock); goto again; } -#endif /* ALT_BREAK_TO_DEBUGGER */ #endif /* KDB */ if (line_status & (LSR_BI | LSR_FE | LSR_PE)) { /* @@ -2405,7 +2387,7 @@ more_intr: * Note: BI together with FE/PE means just BI. */ if (line_status & LSR_BI) { -#if defined(KDB) && defined(BREAK_TO_DEBUGGER) +#if defined(KDB) if (com->unit == comconsole) { kdb_enter(KDB_WHY_BREAK, "Line break on console"); Modified: head/sys/powerpc/mambo/mambo_console.c ============================================================================== --- head/sys/powerpc/mambo/mambo_console.c Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/powerpc/mambo/mambo_console.c Fri Aug 26 21:46:36 2011 (r225203) @@ -60,7 +60,7 @@ static int polltime; static struct callout mambo_callout; static struct tty *tp = NULL; -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) +#if defined(KDB) static int alt_break_state; #endif @@ -156,24 +156,8 @@ mambo_cngetc(struct consdev *cp) ch = mambocall(MAMBO_CONSOLE_READ); if (ch > 0 && ch < 0xff) { -#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER) - int kdb_brk; - - if ((kdb_brk = kdb_alt_break(ch, &alt_break_state)) != 0) { - switch (kdb_brk) { - case KDB_REQ_DEBUGGER: - kdb_enter(KDB_WHY_BREAK, - "Break sequence on console"); - break; - case KDB_REQ_PANIC: - kdb_panic("Panic sequence on console"); - break; - case KDB_REQ_REBOOT: - kdb_reboot(); - break; - - } - } +#if defined(KDB) + kdb_alt_break(ch, &alt_break_state); #endif return (ch); } Modified: head/sys/sys/kdb.h ============================================================================== --- head/sys/sys/kdb.h Fri Aug 26 21:27:21 2011 (r225202) +++ head/sys/sys/kdb.h Fri Aug 26 21:46:36 2011 (r225203) @@ -64,6 +64,8 @@ extern struct pcb *kdb_thrctx; /* Curre extern struct thread *kdb_thread; /* Current thread. */ int kdb_alt_break(int, int *); +int kdb_alt_break_gdb(int, int *); +int kdb_break(void); void kdb_backtrace(void); int kdb_dbbe_select(const char *); void kdb_enter(const char *, const char *);
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