From dc7d552705215ac50a0617fcf51bb9c736255b8e Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Thu, 17 Apr 2008 20:05:37 +0200 Subject: kgdb: core kgdb core code. Handles the protocol and the arch details. [ mingo@elte.hu: heavily modified, simplified and cleaned up. ] [ xemul@openvz.org: use find_task_by_pid_ns ] Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar Signed-off-by: Jan Kiszka Reviewed-by: Thomas Gleixner --- kernel/Makefile | 1 + kernel/kgdb.c | 1693 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 1694 insertions(+) create mode 100644 kernel/kgdb.c (limited to 'kernel') diff --git a/kernel/Makefile b/kernel/Makefile index 6c584c55a6e9..05c8003718ee 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -53,6 +53,7 @@ obj-$(CONFIG_AUDIT) += audit.o auditfilter.o obj-$(CONFIG_AUDITSYSCALL) += auditsc.o obj-$(CONFIG_AUDIT_TREE) += audit_tree.o obj-$(CONFIG_KPROBES) += kprobes.o +obj-$(CONFIG_KGDB) += kgdb.o obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_SECCOMP) += seccomp.o diff --git a/kernel/kgdb.c b/kernel/kgdb.c new file mode 100644 index 000000000000..017ee782bc08 --- /dev/null +++ b/kernel/kgdb.c @@ -0,0 +1,1693 @@ +/* + * KGDB stub. + * + * Maintainer: Jason Wessel + * + * Copyright (C) 2000-2001 VERITAS Software Corporation. + * Copyright (C) 2002-2004 Timesys Corporation + * Copyright (C) 2003-2004 Amit S. Kale + * Copyright (C) 2004 Pavel Machek + * Copyright (C) 2004-2006 Tom Rini + * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. + * Copyright (C) 2005-2008 Wind River Systems, Inc. + * Copyright (C) 2007 MontaVista Software, Inc. + * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar + * + * Contributors at various stages not listed above: + * Jason Wessel ( jason.wessel@windriver.com ) + * George Anzinger + * Anurekh Saxena (anurekh.saxena@timesys.com) + * Lake Stevens Instrument Division (Glenn Engel) + * Jim Kingdon, Cygnus Support. + * + * Original KGDB stub: David Grothe , + * Tigran Aivazian + * + * This file is licensed under the terms of the GNU General Public License + * version 2. This program is licensed "as is" without any warranty of any + * kind, whether express or implied. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +static int kgdb_break_asap; + +struct kgdb_state { + int ex_vector; + int signo; + int err_code; + int cpu; + int pass_exception; + long threadid; + long kgdb_usethreadid; + struct pt_regs *linux_regs; +}; + +static struct debuggerinfo_struct { + void *debuggerinfo; + struct task_struct *task; +} kgdb_info[NR_CPUS]; + +/** + * kgdb_connected - Is a host GDB connected to us? + */ +int kgdb_connected; +EXPORT_SYMBOL_GPL(kgdb_connected); + +/* All the KGDB handlers are installed */ +static int kgdb_io_module_registered; + +/* Guard for recursive entry */ +static int exception_level; + +static struct kgdb_io *kgdb_io_ops; +static DEFINE_SPINLOCK(kgdb_registration_lock); + +/* kgdb console driver is loaded */ +static int kgdb_con_registered; +/* determine if kgdb console output should be used */ +static int kgdb_use_con; + +static int __init opt_kgdb_con(char *str) +{ + kgdb_use_con = 1; + return 0; +} + +early_param("kgdbcon", opt_kgdb_con); + +module_param(kgdb_use_con, int, 0644); + +/* + * Holds information about breakpoints in a kernel. These breakpoints are + * added and removed by gdb. + */ +static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { + [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } +}; + +/* + * The CPU# of the active CPU, or -1 if none: + */ +atomic_t kgdb_active = ATOMIC_INIT(-1); + +/* + * We use NR_CPUs not PERCPU, in case kgdb is used to debug early + * bootup code (which might not have percpu set up yet): + */ +static atomic_t passive_cpu_wait[NR_CPUS]; +static atomic_t cpu_in_kgdb[NR_CPUS]; +atomic_t kgdb_setting_breakpoint; + +struct task_struct *kgdb_usethread; +struct task_struct *kgdb_contthread; + +int kgdb_single_step; + +/* Our I/O buffers. */ +static char remcom_in_buffer[BUFMAX]; +static char remcom_out_buffer[BUFMAX]; + +/* Storage for the registers, in GDB format. */ +static unsigned long gdb_regs[(NUMREGBYTES + + sizeof(unsigned long) - 1) / + sizeof(unsigned long)]; + +/* to keep track of the CPU which is doing the single stepping*/ +atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); + +/* + * If you are debugging a problem where roundup (the collection of + * all other CPUs) is a problem [this should be extremely rare], + * then use the nokgdbroundup option to avoid roundup. In that case + * the other CPUs might interfere with your debugging context, so + * use this with care: + */ +int kgdb_do_roundup = 1; + +static int __init opt_nokgdbroundup(char *str) +{ + kgdb_do_roundup = 0; + + return 0; +} + +early_param("nokgdbroundup", opt_nokgdbroundup); + +/* + * Finally, some KGDB code :-) + */ + +/* + * Weak aliases for breakpoint management, + * can be overriden by architectures when needed: + */ +int __weak kgdb_validate_break_address(unsigned long addr) +{ + char tmp_variable[BREAK_INSTR_SIZE]; + + return probe_kernel_read(tmp_variable, (char *)addr, BREAK_INSTR_SIZE); +} + +int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr) +{ + int err; + + err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE); + if (err) + return err; + + return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr, + BREAK_INSTR_SIZE); +} + +int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle) +{ + return probe_kernel_write((char *)addr, + (char *)bundle, BREAK_INSTR_SIZE); +} + +unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) +{ + return instruction_pointer(regs); +} + +int __weak kgdb_arch_init(void) +{ + return 0; +} + +/** + * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. + * @regs: Current &struct pt_regs. + * + * This function will be called if the particular architecture must + * disable hardware debugging while it is processing gdb packets or + * handling exception. + */ +void __weak kgdb_disable_hw_debug(struct pt_regs *regs) +{ +} + +/* + * GDB remote protocol parser: + */ + +static const char hexchars[] = "0123456789abcdef"; + +static int hex(char ch) +{ + if ((ch >= 'a') && (ch <= 'f')) + return ch - 'a' + 10; + if ((ch >= '0') && (ch <= '9')) + return ch - '0'; + if ((ch >= 'A') && (ch <= 'F')) + return ch - 'A' + 10; + return -1; +} + +/* scan for the sequence $# */ +static void get_packet(char *buffer) +{ + unsigned char checksum; + unsigned char xmitcsum; + int count; + char ch; + + do { + /* + * Spin and wait around for the start character, ignore all + * other characters: + */ + while ((ch = (kgdb_io_ops->read_char())) != '$') + /* nothing */; + + kgdb_connected = 1; + checksum = 0; + xmitcsum = -1; + + count = 0; + + /* + * now, read until a # or end of buffer is found: + */ + while (count < (BUFMAX - 1)) { + ch = kgdb_io_ops->read_char(); + if (ch == '#') + break; + checksum = checksum + ch; + buffer[count] = ch; + count = count + 1; + } + buffer[count] = 0; + + if (ch == '#') { + xmitcsum = hex(kgdb_io_ops->read_char()) << 4; + xmitcsum += hex(kgdb_io_ops->read_char()); + + if (checksum != xmitcsum) + /* failed checksum */ + kgdb_io_ops->write_char('-'); + else + /* successful transfer */ + kgdb_io_ops->write_char('+'); + if (kgdb_io_ops->flush) + kgdb_io_ops->flush(); + } + } while (checksum != xmitcsum); +} + +/* + * Send the packet in buffer. + * Check for gdb connection if asked for. + */ +static void put_packet(char *buffer) +{ + unsigned char checksum; + int count; + char ch; + + /* + * $#. + */ + while (1) { + kgdb_io_ops->write_char('$'); + checksum = 0; + count = 0; + + while ((ch = buffer[count])) { + kgdb_io_ops->write_char(ch); + checksum += ch; + count++; + } + + kgdb_io_ops->write_char('#'); + kgdb_io_ops->write_char(hexchars[checksum >> 4]); + kgdb_io_ops->write_char(hexchars[checksum & 0xf]); + if (kgdb_io_ops->flush) + kgdb_io_ops->flush(); + + /* Now see what we get in reply. */ + ch = kgdb_io_ops->read_char(); + + if (ch == 3) + ch = kgdb_io_ops->read_char(); + + /* If we get an ACK, we are done. */ + if (ch == '+') + return; + + /* + * If we get the start of another packet, this means + * that GDB is attempting to reconnect. We will NAK + * the packet being sent, and stop trying to send this + * packet. + */ + if (ch == '$') { + kgdb_io_ops->write_char('-'); + if (kgdb_io_ops->flush) + kgdb_io_ops->flush(); + return; + } + } +} + +static char *pack_hex_byte(char *pkt, u8 byte) +{ + *pkt++ = hexchars[byte >> 4]; + *pkt++ = hexchars[byte & 0xf]; + + return pkt; +} + +/* + * Convert the memory pointed to by mem into hex, placing result in buf. + * Return a pointer to the last char put in buf (null). May return an error. + */ +int kgdb_mem2hex(char *mem, char *buf, int count) +{ + char *tmp; + int err; + + /* + * We use the upper half of buf as an intermediate buffer for the + * raw memory copy. Hex conversion will work against this one. + */ + tmp = buf + count; + + err = probe_kernel_read(tmp, mem, count); + if (!err) { + while (count > 0) { + buf = pack_hex_byte(buf, *tmp); + tmp++; + count--; + } + + *buf = 0; + } + + return err; +} + +/* + * Copy the binary array pointed to by buf into mem. Fix $, #, and + * 0x7d escaped with 0x7d. Return a pointer to the character after + * the last byte written. + */ +static int kgdb_ebin2mem(char *buf, char *mem, int count) +{ + int err = 0; + char c; + + while (count-- > 0) { + c = *buf++; + if (c == 0x7d) + c = *buf++ ^ 0x20; + + err = probe_kernel_write(mem, &c, 1); + if (err) + break; + + mem++; + } + + return err; +} + +/* + * Convert the hex array pointed to by buf into binary to be placed in mem. + * Return a pointer to the character AFTER the last byte written. + * May return an error. + */ +int kgdb_hex2mem(char *buf, char *mem, int count) +{ + char *tmp_raw; + char *tmp_hex; + + /* + * We use the upper half of buf as an intermediate buffer for the + * raw memory that is converted from hex. + */ + tmp_raw = buf + count * 2; + + tmp_hex = tmp_raw - 1; + while (tmp_hex >= buf) { + tmp_raw--; + *tmp_raw = hex(*tmp_hex--); + *tmp_raw |= hex(*tmp_hex--) << 4; + } + + return probe_kernel_write(mem, tmp_raw, count); +} + +/* + * While we find nice hex chars, build a long_val. + * Return number of chars processed. + */ +int kgdb_hex2long(char **ptr, long *long_val) +{ + int hex_val; + int num = 0; + + *long_val = 0; + + while (**ptr) { + hex_val = hex(**ptr); + if (hex_val < 0) + break; + + *long_val = (*long_val << 4) | hex_val; + num++; + (*ptr)++; + } + + return num; +} + +/* Write memory due to an 'M' or 'X' packet. */ +static int write_mem_msg(int binary) +{ + char *ptr = &remcom_in_buffer[1]; + unsigned long addr; + unsigned long length; + int err; + + if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' && + kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') { + if (binary) + err = kgdb_ebin2mem(ptr, (char *)addr, length); + else + err = kgdb_hex2mem(ptr, (char *)addr, length); + if (err) + return err; + if (CACHE_FLUSH_IS_SAFE) + flush_icache_range(addr, addr + length + 1); + return 0; + } + + return -EINVAL; +} + +static void error_packet(char *pkt, int error) +{ + error = -error; + pkt[0] = 'E'; + pkt[1] = hexchars[(error / 10)]; + pkt[2] = hexchars[(error % 10)]; + pkt[3] = '\0'; +} + +/* + * Thread ID accessors. We represent a flat TID space to GDB, where + * the per CPU idle threads (which under Linux all have PID 0) are + * remapped to negative TIDs. + */ + +#define BUF_THREAD_ID_SIZE 16 + +static char *pack_threadid(char *pkt, unsigned char *id) +{ + char *limit; + + limit = pkt + BUF_THREAD_ID_SIZE; + while (pkt < limit) + pkt = pack_hex_byte(pkt, *id++); + + return pkt; +} + +static void int_to_threadref(unsigned char *id, int value) +{ + unsigned char *scan; + int i = 4; + + scan = (unsigned char *)id; + while (i--) + *scan++ = 0; + *scan++ = (value >> 24) & 0xff; + *scan++ = (value >> 16) & 0xff; + *scan++ = (value >> 8) & 0xff; + *scan++ = (value & 0xff); +} + +static struct task_struct *getthread(struct pt_regs *regs, int tid) +{ + /* + * Non-positive TIDs are remapped idle tasks: + */ + if (tid <= 0) + return idle_task(-tid); + + /* + * find_task_by_pid_ns() does not take the tasklist lock anymore + * but is nicely RCU locked - hence is a pretty resilient + * thing to use: + */ + return find_task_by_pid_ns(tid, &init_pid_ns); +} + +/* + * CPU debug state control: + */ + +#ifdef CONFIG_SMP +static void kgdb_wait(struct pt_regs *regs) +{ + unsigned long flags; + int cpu; + + local_irq_save(flags); + cpu = raw_smp_processor_id(); + kgdb_info[cpu].debuggerinfo = regs; + kgdb_info[cpu].task = current; + /* + * Make sure the above info reaches the primary CPU before + * our cpu_in_kgdb[] flag setting does: + */ + smp_wmb(); + atomic_set(&cpu_in_kgdb[cpu], 1); + + /* + * The primary CPU must be active to enter here, but this is + * guard in case the primary CPU had not been selected if + * this was an entry via nmi. + */ + while (atomic_read(&kgdb_active) == -1) + cpu_relax(); + + /* Wait till primary CPU goes completely into the debugger. */ + while (!atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) + cpu_relax(); + + /* Wait till primary CPU is done with debugging */ + while (atomic_read(&passive_cpu_wait[cpu])) + cpu_relax(); + + kgdb_info[cpu].debuggerinfo = NULL; + kgdb_info[cpu].task = NULL; + + /* fix up hardware debug registers on local cpu */ + if (arch_kgdb_ops.correct_hw_break) + arch_kgdb_ops.correct_hw_break(); + + /* Signal the primary CPU that we are done: */ + atomic_set(&cpu_in_kgdb[cpu], 0); + local_irq_restore(flags); +} +#endif + +/* + * Some architectures need cache flushes when we set/clear a + * breakpoint: + */ +static void kgdb_flush_swbreak_addr(unsigned long addr) +{ + if (!CACHE_FLUSH_IS_SAFE) + return; + + if (current->mm) { + flush_cache_range(current->mm->mmap_cache, + addr, addr + BREAK_INSTR_SIZE); + } else { + flush_icache_range(addr, addr + BREAK_INSTR_SIZE); + } +} + +/* + * SW breakpoint management: + */ +static int kgdb_activate_sw_breakpoints(void) +{ + unsigned long addr; + int error = 0; + int i; + + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if (kgdb_break[i].state != BP_SET) + continue; + + addr = kgdb_break[i].bpt_addr; + error = kgdb_arch_set_breakpoint(addr, + kgdb_break[i].saved_instr); + if (error) + return error; + + kgdb_flush_swbreak_addr(addr); + kgdb_break[i].state = BP_ACTIVE; + } + return 0; +} + +static int kgdb_set_sw_break(unsigned long addr) +{ + int err = kgdb_validate_break_address(addr); + int breakno = -1; + int i; + + if (err) + return err; + + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if ((kgdb_break[i].state == BP_SET) && + (kgdb_break[i].bpt_addr == addr)) + return -EEXIST; + } + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if (kgdb_break[i].state == BP_REMOVED && + kgdb_break[i].bpt_addr == addr) { + breakno = i; + break; + } + } + + if (breakno == -1) { + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if (kgdb_break[i].state == BP_UNDEFINED) { + breakno = i; + break; + } + } + } + + if (breakno == -1) + return -E2BIG; + + kgdb_break[breakno].state = BP_SET; + kgdb_break[breakno].type = BP_BREAKPOINT; + kgdb_break[breakno].bpt_addr = addr; + + return 0; +} + +static int kgdb_deactivate_sw_breakpoints(void) +{ + unsigned long addr; + int error = 0; + int i; + + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if (kgdb_break[i].state != BP_ACTIVE) + continue; + addr = kgdb_break[i].bpt_addr; + error = kgdb_arch_remove_breakpoint(addr, + kgdb_break[i].saved_instr); + if (error) + return error; + + kgdb_flush_swbreak_addr(addr); + kgdb_break[i].state = BP_SET; + } + return 0; +} + +static int kgdb_remove_sw_break(unsigned long addr) +{ + int i; + + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if ((kgdb_break[i].state == BP_SET) && + (kgdb_break[i].bpt_addr == addr)) { + kgdb_break[i].state = BP_REMOVED; + return 0; + } + } + return -ENOENT; +} + +int kgdb_isremovedbreak(unsigned long addr) +{ + int i; + + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if ((kgdb_break[i].state == BP_REMOVED) && + (kgdb_break[i].bpt_addr == addr)) + return 1; + } + return 0; +} + +int remove_all_break(void) +{ + unsigned long addr; + int error; + int i; + + /* Clear memory breakpoints. */ + for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { + if (kgdb_break[i].state != BP_SET) + continue; + addr = kgdb_break[i].bpt_addr; + error = kgdb_arch_remove_breakpoint(addr, + kgdb_break[i].saved_instr); + if (error) + return error; + kgdb_break[i].state = BP_REMOVED; + } + + /* Clear hardware breakpoints. */ + if (arch_kgdb_ops.remove_all_hw_break) + arch_kgdb_ops.remove_all_hw_break(); + + return 0; +} + +/* + * Remap normal tasks to their real PID, idle tasks to -1 ... -NR_CPUs: + */ +static inline int shadow_pid(int realpid) +{ + if (realpid) + return realpid; + + return -1-raw_smp_processor_id(); +} + +static char gdbmsgbuf[BUFMAX + 1]; + +static void kgdb_msg_write(const char *s, int len) +{ + char *bufptr; + int wcount; + int i; + + /* 'O'utput */ + gdbmsgbuf[0] = 'O'; + + /* Fill and send buffers... */ + while (len > 0) { + bufptr = gdbmsgbuf + 1; + + /* Calculate how many this time */ + if ((len << 1) > (BUFMAX - 2)) + wcount = (BUFMAX - 2) >> 1; + else + wcount = len; + + /* Pack in hex chars */ + for (i = 0; i < wcount; i++) + bufptr = pack_hex_byte(bufptr, s[i]); + *bufptr = '\0'; + + /* Move up */ + s += wcount; + len -= wcount; + + /* Write packet */ + put_packet(gdbmsgbuf); + } +} + +/* + * Return true if there is a valid kgdb I/O module. Also if no + * debugger is attached a message can be printed to the console about + * waiting for the debugger to attach. + * + * The print_wait argument is only to be true when called from inside + * the core kgdb_handle_exception, because it will wait for the + * debugger to attach. + */ +static int kgdb_io_ready(int print_wait) +{ + if (!kgdb_io_ops) + return 0; + if (kgdb_connected) + return 1; + if (atomic_read(&kgdb_setting_breakpoint)) + return 1; + if (print_wait) + printk(KERN_CRIT "KGDB: Waiting for remote debugger\n"); + return 1; +} + +/* + * All the functions that start with gdb_cmd are the various + * operations to implement the handlers for the gdbserial protocol + * where KGDB is communicating with an external debugger + */ + +/* Handle the '?' status packets */ +static void gdb_cmd_status(struct kgdb_state *ks) +{ + /* + * We know that this packet is only sent + * during initial connect. So to be safe, + * we clear out our breakpoints now in case + * GDB is reconnecting. + */ + remove_all_break(); + + remcom_out_buffer[0] = 'S'; + pack_hex_byte(&remcom_out_buffer[1], ks->signo); +} + +/* Handle the 'g' get registers request */ +static void gdb_cmd_getregs(struct kgdb_state *ks) +{ + struct task_struct *thread; + void *local_debuggerinfo; + int i; + + thread = kgdb_usethread; + if (!thread) { + thread = kgdb_info[ks->cpu].task; + local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo; + } else { + local_debuggerinfo = NULL; + for (i = 0; i < NR_CPUS; i++) { + /* + * Try to find the task on some other + * or possibly this node if we do not + * find the matching task then we try + * to approximate the results. + */ + if (thread == kgdb_info[i].task) + local_debuggerinfo = kgdb_info[i].debuggerinfo; + } + } + + /* + * All threads that don't have debuggerinfo should be + * in __schedule() sleeping, since all other CPUs + * are in kgdb_wait, and thus have debuggerinfo. + */ + if (local_debuggerinfo) { + pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo); + } else { + /* + * Pull stuff saved during switch_to; nothing + * else is accessible (or even particularly + * relevant). + * + * This should be enough for a stack trace. + */ + sleeping_thread_to_gdb_regs(gdb_regs, thread); + } + kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES); +} + +/* Handle the 'G' set registers request */ +static void gdb_cmd_setregs(struct kgdb_state *ks) +{ + kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES); + + if (kgdb_usethread && kgdb_usethread != current) { + error_packet(remcom_out_buffer, -EINVAL); + } else { + gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs); + strcpy(remcom_out_buffer, "OK"); + } +} + +/* Handle the 'm' memory read bytes */ +static void gdb_cmd_memread(struct kgdb_state *ks) +{ + char *ptr = &remcom_in_buffer[1]; + unsigned long length; + unsigned long addr; + int err; + + if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' && + kgdb_hex2long(&ptr, &length) > 0) { + err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length); + if (err) + error_packet(remcom_out_buffer, err); + } else { + error_packet(remcom_out_buffer, -EINVAL); + } +} + +/* Handle the 'M' memory write bytes */ +static void gdb_cmd_memwrite(struct kgdb_state *ks) +{ + int err = write_mem_msg(0); + + if (err) + error_packet(remcom_out_buffer, err); + else + strcpy(remcom_out_buffer, "OK"); +} + +/* Handle the 'X' memory binary write bytes */ +static void gdb_cmd_binwrite(struct kgdb_state *ks) +{ + int err = write_mem_msg(1); + + if (err) + error_packet(remcom_out_buffer, err); + else + strcpy(remcom_out_buffer, "OK"); +} + +/* Handle the 'D' or 'k', detach or kill packets */ +static void gdb_cmd_detachkill(struct kgdb_state *ks) +{ + int error; + + /* The detach case */ + if (remcom_in_buffer[0] == 'D') { + error = remove_all_break(); + if (error < 0) { + error_packet(remcom_out_buffer, error); + } else { + strcpy(remcom_out_buffer, "OK"); + kgdb_connected = 0; + } + put_packet(remcom_out_buffer); + } else { + /* + * Assume the kill case, with no exit code checking, + * trying to force detach the debugger: + */ + remove_all_break(); + kgdb_connected = 0; + } +} + +/* Handle the 'R' reboot packets */ +static int gdb_cmd_reboot(struct kgdb_state *ks) +{ + /* For now, only honor R0 */ + if (strcmp(remcom_in_buffer, "R0") == 0) { + printk(KERN_CRIT "Executing emergency reboot\n"); + strcpy(remcom_out_buffer, "OK"); + put_packet(remcom_out_buffer); + + /* + * Execution should not return from + * machine_emergency_restart() + */ + machine_emergency_restart(); + kgdb_connected = 0; + + return 1; + } + return 0; +} + +/* Handle the 'q' query packets */ +static void gdb_cmd_query(struct kgdb_state *ks) +{ + struct task_struct *thread; + unsigned char thref[8]; + char *ptr; + int i; + + switch (remcom_in_buffer[1]) { + case 's': + case 'f': + if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) { + error_packet(remcom_out_buffer, -EINVAL); + break; + } + + if (remcom_in_buffer[1] == 'f') + ks->threadid = 1; + + remcom_out_buffer[0] = 'm'; + ptr = remcom_out_buffer + 1; + + for (i = 0; i < 17; ks->threadid++) { + thread = getthread(ks->linux_regs, ks->threadid); + if (thread) { + int_to_threadref(thref, ks->threadid); + pack_threadid(ptr, thref); + ptr += BUF_THREAD_ID_SIZE; + *(ptr++) = ','; + i++; + } + } + *(--ptr) = '\0'; + break; + + case 'C': + /* Current thread id */ + strcpy(remcom_out_buffer, "QC"); + ks->threadid = shadow_pid(current->pid); + int_to_threadref(thref, ks->threadid); + pack_threadid(remcom_out_buffer + 2, thref); + break; + case 'T': + if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) { + error_packet(remcom_out_buffer, -EINVAL); + break; + } + ks->threadid = 0; + ptr = remcom_in_buffer + 17; + kgdb_hex2long(&ptr, &ks->threadid); + if (!getthread(ks->linux_regs, ks->threadid)) { + error_packet(remcom_out_buffer, -EINVAL); + break; + } + if (ks->threadid > 0) { + kgdb_mem2hex(getthread(ks->linux_regs, + ks->threadid)->comm, + remcom_out_buffer, 16); + } else { + static char tmpstr[23 + BUF_THREAD_ID_SIZE]; + + sprintf(tmpstr, "Shadow task %d for pid 0", + (int)(-ks->threadid-1)); + kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr)); + } + break; + } +} + +/* Handle the 'H' task query packets */ +static void gdb_cmd_task(struct kgdb_state *ks) +{ + struct task_struct *thread; + char *ptr; + + switch (remcom_in_buffer[1]) { + case 'g': + ptr = &remcom_in_buffer[2]; + kgdb_hex2long(&ptr, &ks->threadid); + thread = getthread(ks->linux_regs, ks->threadid); + if (!thread && ks->threadid > 0) { + error_packet(remcom_out_buffer, -EINVAL); + break; + } + kgdb_usethread = thread; + ks->kgdb_usethreadid = ks->threadid; + strcpy(remcom_out_buffer, "OK"); + break; + case 'c': + ptr = &remcom_in_buffer[2]; + kgdb_hex2long(&ptr, &ks->threadid); + if (!ks->threadid) { + kgdb_contthread = NULL; + } else { + thread = getthread(ks->linux_regs, ks->threadid); + if (!thread && ks->threadid > 0) { + error_packet(remcom_out_buffer, -EINVAL); + break; + } + kgdb_contthread = thread; + } + strcpy(remcom_out_buffer, "OK"); + break; + } +} + +/* Handle the 'T' thread query packets */ +static void gdb_cmd_thread(struct kgdb_state *ks) +{ + char *ptr = &remcom_in_buffer[1]; + struct task_struct *thread; + + kgdb_hex2long(&ptr, &ks->threadid); + thread = getthread(ks->linux_regs, ks->threadid); + if (thread) + strcpy(remcom_out_buffer, "OK"); + else + error_packet(remcom_out_buffer, -EINVAL); +} + +/* Handle the 'z' or 'Z' breakpoint remove or set packets */ +static void gdb_cmd_break(struct kgdb_state *ks) +{ + /* + * Since GDB-5.3, it's been drafted that '0' is a software + * breakpoint, '1' is a hardware breakpoint, so let's do that. + */ + char *bpt_type = &remcom_in_buffer[1]; + char *ptr = &remcom_in_buffer[2]; + unsigned long addr; + unsigned long length; + int error = 0; + + if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') { + /* Unsupported */ + if (*bpt_type > '4') + return; + } else { + if (*bpt_type != '0' && *bpt_type != '1') + /* Unsupported. */ + return; + } + + /* + * Test if this is a hardware breakpoint, and + * if we support it: + */ + if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT)) + /* Unsupported. */ + return; + + if (*(ptr++) != ',') { + error_packet(remcom_out_buffer, -EINVAL); + return; + } + if (!kgdb_hex2long(&ptr, &addr)) { + error_packet(remcom_out_buffer, -EINVAL); + return; + } + if (*(ptr++) != ',' || + !kgdb_hex2long(&ptr, &length)) { + error_packet(remcom_out_buffer, -EINVAL); + return; + } + + if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0') + error = kgdb_set_sw_break(addr); + else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0') + error = kgdb_remove_sw_break(addr); + else if (remcom_in_buffer[0] == 'Z') + error = arch_kgdb_ops.set_hw_breakpoint(addr, + (int)length, *bpt_type); + else if (remcom_in_buffer[0] == 'z') + error = arch_kgdb_ops.remove_hw_breakpoint(addr, + (int) length, *bpt_type); + + if (error == 0) + strcpy(remcom_out_buffer, "OK"); + else + error_packet(remcom_out_buffer, error); +} + +/* Handle the 'C' signal / exception passing packets */ +static int gdb_cmd_exception_pass(struct kgdb_state *ks) +{ + /* C09 == pass exception + * C15 == detach kgdb, pass exception + */ + if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') { + + ks->pass_exception = 1; + remcom_in_buffer[0] = 'c'; + + } else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') { + + ks->pass_exception = 1; + remcom_in_buffer[0] = 'D'; + remove_all_break(); + kgdb_connected = 0; + return 1; + + } else { + error_packet(remcom_out_buffer, -EINVAL); + return 0; + } + + /* Indicate fall through */ + return -1; +} + +/* + * This function performs all gdbserial command procesing + */ +static int gdb_serial_stub(struct kgdb_state *ks) +{ + int error = 0; + int tmp; + + /* Clear the out buffer. */ + memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer)); + + if (kgdb_connected) { + unsigned char thref[8]; + char *ptr; + + /* Reply to host that an exception has occurred */ + ptr = remcom_out_buffer; + *ptr++ = 'T'; + ptr = pack_hex_byte(ptr, ks->signo); + ptr += strlen(strcpy(ptr, "thread:")); + int_to_threadref(thref, shadow_pid(current->pid)); + ptr = pack_threadid(ptr, thref); + *ptr++ = ';'; + put_packet(remcom_out_buffer); + } + + kgdb_usethread = kgdb_info[ks->cpu].task; + ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid); + ks->pass_exception = 0; + + while (1) { + error = 0; + + /* Clear the out buffer. */ + memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer)); + + get_packet(remcom_in_buffer); + + switch (remcom_in_buffer[0]) { + case '?': /* gdbserial status */ + gdb_cmd_status(ks); + break; + case 'g': /* return the value of the CPU registers */ + gdb_cmd_getregs(ks); + break; + case 'G': /* set the value of the CPU registers - return OK */ + gdb_cmd_setregs(ks); + break; + case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */ + gdb_cmd_memread(ks); + break; + case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */ + gdb_cmd_memwrite(ks); + break; + case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */ + gdb_cmd_binwrite(ks); + break; + /* kill or detach. KGDB should treat this like a + * continue. + */ + case 'D': /* Debugger detach */ + case 'k': /* Debugger detach via kill */ + gdb_cmd_detachkill(ks); + goto default_handle; + case 'R': /* Reboot */ + if (gdb_cmd_reboot(ks)) + goto default_handle; + break; + case 'q': /* query command */ + gdb_cmd_query(ks); + break; + case 'H': /* task related */ + gdb_cmd_task(ks); + break; + case 'T': /* Query thread status */ + gdb_cmd_thread(ks); + break; + case 'z': /* Break point remove */ + case 'Z': /* Break point set */ + gdb_cmd_break(ks); + break; + case 'C': /* Exception passing */ + tmp = gdb_cmd_exception_pass(ks); + if (tmp > 0) + goto default_handle; + if (tmp == 0) + break; + /* Fall through on tmp < 0 */ + case 'c': /* Continue packet */ + case 's': /* Single step packet */ + if (kgdb_contthread && kgdb_contthread != current) { + /* Can't switch threads in kgdb */ + error_packet(remcom_out_buffer, -EINVAL); + break; + } + kgdb_activate_sw_breakpoints(); + /* Fall through to default processing */ + default: +default_handle: + error = kgdb_arch_handle_exception(ks->ex_vector, + ks->signo, + ks->err_code, + remcom_in_buffer, + remcom_out_buffer, + ks->linux_regs); + /* + * Leave cmd processing on error, detach, + * kill, continue, or single step. + */ + if (error >= 0 || remcom_in_buffer[0] == 'D' || + remcom_in_buffer[0] == 'k') { + error = 0; + goto kgdb_exit; + } + + } + + /* reply to the request */ + put_packet(remcom_out_buffer); + } + +kgdb_exit: + if (ks->pass_exception) + error = 1; + return error; +} + +static int kgdb_reenter_check(struct kgdb_state *ks) +{ + unsigned long addr; + + if (atomic_read(&kgdb_active) != raw_smp_processor_id()) + return 0; + + /* Panic on recursive debugger calls: */ + exception_level++; + addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); + kgdb_deactivate_sw_breakpoints(); + + /* + * If the break point removed ok at the place exception + * occurred, try to recover and print a warning to the end + * user because the user planted a breakpoint in a place that + * KGDB needs in order to function. + */ + if (kgdb_remove_sw_break(addr) == 0) { + exception_level = 0; + kgdb_skipexception(ks->ex_vector, ks->linux_regs); + kgdb_activate_sw_breakpoints(); + printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed\n"); + WARN_ON_ONCE(1); + + return 1; + } + remove_all_break(); + kgdb_skipexception(ks->ex_vector, ks->linux_regs); + + if (exception_level > 1) { + dump_stack(); + panic("Recursive entry to debugger"); + } + + printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n"); + dump_stack(); + panic("Recursive entry to debugger"); + + return 1; +} + +/* + * kgdb_handle_exception() - main entry point from a kernel exception + * + * Locking hierarchy: + * interface locks, if any (begin_session) + * kgdb lock (kgdb_active) + */ +int +kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) +{ + struct kgdb_state kgdb_var; + struct kgdb_state *ks = &kgdb_var; + unsigned long flags; + int error = 0; + int i, cpu; + + ks->cpu = raw_smp_processor_id(); + ks->ex_vector = evector; + ks->signo = signo; + ks->ex_vector = evector; + ks->err_code = ecode; + ks->kgdb_usethreadid = 0; + ks->linux_regs = regs; + + if (kgdb_reenter_check(ks)) + return 0; /* Ouch, double exception ! */ + +acquirelock: + /* + * Interrupts will be restored by the 'trap return' code, except when + * single stepping. + */ + local_irq_save(flags); + + cpu = raw_smp_processor_id(); + + /* + * Acquire the kgdb_active lock: + */ + while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1) + cpu_relax(); + + /* + * Do not start the debugger connection on this CPU if the last + * instance of the exception handler wanted to come into the + * debugger on a different CPU via a single step + */ + if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && + atomic_read(&kgdb_cpu_doing_single_step) != cpu) { + + atomic_set(&kgdb_active, -1); + local_irq_restore(flags); + + goto acquirelock; + } + + if (!kgdb_io_ready(1)) { + error = 1; + goto kgdb_restore; /* No I/O connection, so resume the system */ + } + + /* + * Don't enter if we have hit a removed breakpoint. + */ + if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) + goto kgdb_restore; + + /* Call the I/O driver's pre_exception routine */ + if (kgdb_io_ops->pre_exception) + kgdb_io_ops->pre_exception(); + + kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs; + kgdb_info[ks->cpu].task = current; + + kgdb_disable_hw_debug(ks->linux_regs); + + /* + * Get the passive CPU lock which will hold all the non-primary + * CPU in a spin state while the debugger is active + */ + if (!kgdb_single_step || !kgdb_contthread) { + for (i = 0; i < NR_CPUS; i++) + atomic_set(&passive_cpu_wait[i], 1); + } + +#ifdef CONFIG_SMP + /* Signal the other CPUs to enter kgdb_wait() */ + if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup) + kgdb_roundup_cpus(flags); +#endif + + /* + * spin_lock code is good enough as a barrier so we don't + * need one here: + */ + atomic_set(&cpu_in_kgdb[ks->cpu], 1); + + /* + * Wait for the other CPUs to be notified and be waiting for us: + */ + for_each_online_cpu(i) { + while (!atomic_read(&cpu_in_kgdb[i])) + cpu_relax(); + } + + /* + * At this point the primary processor is completely + * in the debugger and all secondary CPUs are quiescent + */ + kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code); + kgdb_deactivate_sw_breakpoints(); + kgdb_single_step = 0; + kgdb_contthread = NULL; + exception_level = 0; + + /* Talk to debugger with gdbserial protocol */ + error = gdb_serial_stub(ks); + + /* Call the I/O driver's post_exception routine */ + if (kgdb_io_ops->post_exception) + kgdb_io_ops->post_exception(); + + kgdb_info[ks->cpu].debuggerinfo = NULL; + kgdb_info[ks->cpu].task = NULL; + atomic_set(&cpu_in_kgdb[ks->cpu], 0); + + if (!kgdb_single_step || !kgdb_contthread) { + for (i = NR_CPUS-1; i >= 0; i--) + atomic_set(&passive_cpu_wait[i], 0); + /* + * Wait till all the CPUs have quit + * from the debugger. + */ + for_each_online_cpu(i) { + while (atomic_read(&cpu_in_kgdb[i])) + cpu_relax(); + } + } + +kgdb_restore: + /* Free kgdb_active */ + atomic_set(&kgdb_active, -1); + local_irq_restore(flags); + + return error; +} + +int kgdb_nmicallback(int cpu, void *regs) +{ +#ifdef CONFIG_SMP + if (!atomic_read(&cpu_in_kgdb[cpu]) && + atomic_read(&kgdb_active) != cpu) { + kgdb_wait((struct pt_regs *)regs); + return 0; + } +#endif + return 1; +} + +void kgdb_console_write(struct console *co, const char *s, unsigned count) +{ + unsigned long flags; + + /* If we're debugging, or KGDB has not connected, don't try + * and print. */ + if (!kgdb_connected || atomic_read(&kgdb_active) != -1) + return; + + local_irq_save(flags); + kgdb_msg_write(s, count); + local_irq_restore(flags); +} + +static struct console kgdbcons = { + .name = "kgdb", + .write = kgdb_console_write, + .flags = CON_PRINTBUFFER | CON_ENABLED, + .index = -1, +}; + +#ifdef CONFIG_MAGIC_SYSRQ +static void sysrq_handle_gdb(int key, struct tty_struct *tty) +{ + if (!kgdb_io_ops) { + printk(KERN_CRIT "ERROR: No KGDB I/O module available\n"); + return; + } + if (!kgdb_connected) + printk(KERN_CRIT "Entering KGDB\n"); + + kgdb_breakpoint(); +} + +static struct sysrq_key_op sysrq_gdb_op = { + .handler = sysrq_handle_gdb, + .help_msg = "Gdb", + .action_msg = "GDB", +}; +#endif + +static void kgdb_register_callbacks(void) +{ + if (!kgdb_io_module_registered) { + kgdb_io_module_registered = 1; + kgdb_arch_init(); +#ifdef CONFIG_MAGIC_SYSRQ + register_sysrq_key('g', &sysrq_gdb_op); +#endif + if (kgdb_use_con && !kgdb_con_registered) { + register_console(&kgdbcons); + kgdb_con_registered = 1; + } + } +} + +static void kgdb_unregister_callbacks(void) +{ + /* + * When this routine is called KGDB should unregister from the + * panic handler and clean up, making sure it is not handling any + * break exceptions at the time. + */ + if (kgdb_io_module_registered) { + kgdb_io_module_registered = 0; + kgdb_arch_exit(); +#ifdef CONFIG_MAGIC_SYSRQ + unregister_sysrq_key('g', &sysrq_gdb_op); +#endif + if (kgdb_con_registered) { + unregister_console(&kgdbcons); + kgdb_con_registered = 0; + } + } +} + +static void kgdb_initial_breakpoint(void) +{ + kgdb_break_asap = 0; + + printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n"); + kgdb_breakpoint(); +} + +/** + * kkgdb_register_io_module - register KGDB IO module + * @new_kgdb_io_ops: the io ops vector + * + * Register it with the KGDB core. + */ +int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops) +{ + int err; + + spin_lock(&kgdb_registration_lock); + + if (kgdb_io_ops) { + spin_unlock(&kgdb_registration_lock); + + printk(KERN_ERR "kgdb: Another I/O driver is already " + "registered with KGDB.\n"); + return -EBUSY; + } + + if (new_kgdb_io_ops->init) { + err = new_kgdb_io_ops->init(); + if (err) { + spin_unlock(&kgdb_registration_lock); + return err; + } + } + + kgdb_io_ops = new_kgdb_io_ops; + + spin_unlock(&kgdb_registration_lock); + + printk(KERN_INFO "kgdb: Registered I/O driver %s.\n", + new_kgdb_io_ops->name); + + /* Arm KGDB now. */ + kgdb_register_callbacks(); + + if (kgdb_break_asap) + kgdb_initial_breakpoint(); + + return 0; +} +EXPORT_SYMBOL_GPL(kgdb_register_io_module); + +/** + * kkgdb_unregister_io_module - unregister KGDB IO module + * @old_kgdb_io_ops: the io ops vector + * + * Unregister it with the KGDB core. + */ +void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops) +{ + BUG_ON(kgdb_connected); + + /* + * KGDB is no longer able to communicate out, so + * unregister our callbacks and reset state. + */ + kgdb_unregister_callbacks(); + + spin_lock(&kgdb_registration_lock); + + WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops); + kgdb_io_ops = NULL; + + spin_unlock(&kgdb_registration_lock); + + printk(KERN_INFO + "kgdb: Unregistered I/O driver %s, debugger disabled.\n", + old_kgdb_io_ops->name); +} +EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); + +/** + * kgdb_breakpoint - generate breakpoint exception + * + * This function will generate a breakpoint exception. It is used at the + * beginning of a program to sync up with a debugger and can be used + * otherwise as a quick means to stop program execution and "break" into + * the debugger. + */ +void kgdb_breakpoint(void) +{ + atomic_set(&kgdb_setting_breakpoint, 1); + wmb(); /* Sync point before breakpoint */ + arch_kgdb_breakpoint(); + wmb(); /* Sync point after breakpoint */ + atomic_set(&kgdb_setting_breakpoint, 0); +} +EXPORT_SYMBOL_GPL(kgdb_breakpoint); + +static int __init opt_kgdb_wait(char *str) +{ + kgdb_break_asap = 1; + + if (kgdb_io_module_registered) + kgdb_initial_breakpoint(); + + return 0; +} + +early_param("kgdbwait", opt_kgdb_wait); -- cgit v1.2.3 From 7c3078b637882303b1dcf6a16229d0e35f6b60a5 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 15 Feb 2008 14:55:54 -0600 Subject: kgdb: clocksource watchdog In order to not trip the clocksource watchdog, kgdb must touch the clocksource watchdog on the return to normal system run state. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- include/linux/clocksource.h | 1 + kernel/kgdb.c | 4 ++++ kernel/time/clocksource.c | 12 ++++++++++++ 3 files changed, 17 insertions(+) (limited to 'kernel') diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 85778a4b1209..35094479ca55 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -216,6 +216,7 @@ static inline void clocksource_calculate_interval(struct clocksource *c, /* used to install a new clocksource */ extern int clocksource_register(struct clocksource*); extern void clocksource_unregister(struct clocksource*); +extern void clocksource_touch_watchdog(void); extern struct clocksource* clocksource_get_next(void); extern void clocksource_change_rating(struct clocksource *cs, int rating); extern void clocksource_resume(void); diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 017ee782bc08..e3f603740425 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -28,6 +28,7 @@ * kind, whether express or implied. */ #include +#include #include #include #include @@ -574,6 +575,7 @@ static void kgdb_wait(struct pt_regs *regs) /* Signal the primary CPU that we are done: */ atomic_set(&cpu_in_kgdb[cpu], 0); + clocksource_touch_watchdog(); local_irq_restore(flags); } #endif @@ -1396,6 +1398,7 @@ acquirelock: atomic_read(&kgdb_cpu_doing_single_step) != cpu) { atomic_set(&kgdb_active, -1); + clocksource_touch_watchdog(); local_irq_restore(flags); goto acquirelock; @@ -1487,6 +1490,7 @@ acquirelock: kgdb_restore: /* Free kgdb_active */ atomic_set(&kgdb_active, -1); + clocksource_touch_watchdog(); local_irq_restore(flags); return error; diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 7f60097d443a..f61402b1f2d0 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -221,6 +221,18 @@ void clocksource_resume(void) spin_unlock_irqrestore(&clocksource_lock, flags); } +/** + * clocksource_touch_watchdog - Update watchdog + * + * Update the watchdog after exception contexts such as kgdb so as not + * to incorrectly trip the watchdog. + * + */ +void clocksource_touch_watchdog(void) +{ + clocksource_resume_watchdog(); +} + /** * clocksource_get_next - Returns the selected clocksource * -- cgit v1.2.3 From 67baf94cd260dc37504dbd15ba3faa2d8cf8a444 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 15 Feb 2008 14:55:55 -0600 Subject: kgdb: print breakpoint removed on exception If kgdb does remove a breakpoint that had a problem on the recursion check, it should also print the address of the breakpoint. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- kernel/kgdb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/kgdb.c b/kernel/kgdb.c index e3f603740425..319c08c92ee2 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -1327,7 +1327,8 @@ static int kgdb_reenter_check(struct kgdb_state *ks) exception_level = 0; kgdb_skipexception(ks->ex_vector, ks->linux_regs); kgdb_activate_sw_breakpoints(); - printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed\n"); + printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n", + addr); WARN_ON_ONCE(1); return 1; -- cgit v1.2.3 From 64e9ee3095b61d0300ea548216a57d2536611309 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 15 Feb 2008 14:55:56 -0600 Subject: kgdb: add x86 HW breakpoints Add HW breakpoints into the arch specific portion of x86 kgdb. In the current x86 kernel.org kernels HW breakpoints are changed out in lazy fashion because there is no infrastructure around changing them when changing to a kernel task or entering the kernel mode via a system call. This lazy approach means that if a user process uses HW breakpoints the kgdb will loose out. This is an acceptable trade off because the developer debugging the kernel is assumed to know what is going on system wide and would be aware of this trade off. There is a minor bug fix to the kgdb core so as to correctly call the hw breakpoint functions with a valid value from the enum. There is also a minor change to the x86_64 startup code when using early HW breakpoints. When the debugger is connected, the cpu startup code must not zero out the HW breakpoint registers or you cannot hit the breakpoints you are interested in, in the first place. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- arch/x86/kernel/kgdb.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++ arch/x86/kernel/setup64.c | 16 ++++++ kernel/kgdb.c | 4 +- 3 files changed, 156 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 5d7a21119bf8..7d651adcb222 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -182,6 +182,122 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs) #endif } +static struct hw_breakpoint { + unsigned enabled; + unsigned type; + unsigned len; + unsigned long addr; +} breakinfo[4]; + +static void kgdb_correct_hw_break(void) +{ + unsigned long dr7; + int correctit = 0; + int breakbit; + int breakno; + + get_debugreg(dr7, 7); + for (breakno = 0; breakno < 4; breakno++) { + breakbit = 2 << (breakno << 1); + if (!(dr7 & breakbit) && breakinfo[breakno].enabled) { + correctit = 1; + dr7 |= breakbit; + dr7 &= ~(0xf0000 << (breakno << 2)); + dr7 |= ((breakinfo[breakno].len << 2) | + breakinfo[breakno].type) << + ((breakno << 2) + 16); + if (breakno >= 0 && breakno <= 3) + set_debugreg(breakinfo[breakno].addr, breakno); + + } else { + if ((dr7 & breakbit) && !breakinfo[breakno].enabled) { + correctit = 1; + dr7 &= ~breakbit; + dr7 &= ~(0xf0000 << (breakno << 2)); + } + } + } + if (correctit) + set_debugreg(dr7, 7); +} + +static int +kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) +{ + int i; + + for (i = 0; i < 4; i++) + if (breakinfo[i].addr == addr && breakinfo[i].enabled) + break; + if (i == 4) + return -1; + + breakinfo[i].enabled = 0; + + return 0; +} + +static void kgdb_remove_all_hw_break(void) +{ + int i; + + for (i = 0; i < 4; i++) + memset(&breakinfo[i], 0, sizeof(struct hw_breakpoint)); +} + +static int +kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) +{ + unsigned type; + int i; + + for (i = 0; i < 4; i++) + if (!breakinfo[i].enabled) + break; + if (i == 4) + return -1; + + switch (bptype) { + case BP_HARDWARE_BREAKPOINT: + type = 0; + len = 1; + break; + case BP_WRITE_WATCHPOINT: + type = 1; + break; + case BP_ACCESS_WATCHPOINT: + type = 3; + break; + default: + return -1; + } + + if (len == 1 || len == 2 || len == 4) + breakinfo[i].len = len - 1; + else + return -1; + + breakinfo[i].enabled = 1; + breakinfo[i].addr = addr; + breakinfo[i].type = type; + + return 0; +} + +/** + * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. + * @regs: Current &struct pt_regs. + * + * This function will be called if the particular architecture must + * disable hardware debugging while it is processing gdb packets or + * handling exception. + */ +void kgdb_disable_hw_debug(struct pt_regs *regs) +{ + /* Disable hardware debugging while we are in kgdb: */ + set_debugreg(0UL, 7); +} + /** * kgdb_post_primary_code - Save error vector/code numbers. * @regs: Original pt_regs. @@ -243,6 +359,7 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, struct pt_regs *linux_regs) { unsigned long addr; + unsigned long dr6; char *ptr; int newPC; @@ -269,6 +386,22 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, } } + get_debugreg(dr6, 6); + if (!(dr6 & 0x4000)) { + int breakno; + + for (breakno = 0; breakno < 4; breakno++) { + if (dr6 & (1 << breakno) && + breakinfo[breakno].type == 0) { + /* Set restore flag: */ + linux_regs->flags |= X86_EFLAGS_RF; + break; + } + } + } + set_debugreg(0UL, 6); + kgdb_correct_hw_break(); + return 0; } @@ -426,4 +559,9 @@ unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) struct kgdb_arch arch_kgdb_ops = { /* Breakpoint instruction: */ .gdb_bpt_instr = { 0xcc }, + .flags = KGDB_HW_BREAKPOINT, + .set_hw_breakpoint = kgdb_set_hw_break, + .remove_hw_breakpoint = kgdb_remove_hw_break, + .remove_all_hw_break = kgdb_remove_all_hw_break, + .correct_hw_break = kgdb_correct_hw_break, }; diff --git a/arch/x86/kernel/setup64.c b/arch/x86/kernel/setup64.c index e24c45677094..143aa78c566b 100644 --- a/arch/x86/kernel/setup64.c +++ b/arch/x86/kernel/setup64.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -327,6 +328,17 @@ void __cpuinit cpu_init (void) load_TR_desc(); load_LDT(&init_mm.context); +#ifdef CONFIG_KGDB + /* + * If the kgdb is connected no debug regs should be altered. This + * is only applicable when KGDB and a KGDB I/O module are built + * into the kernel and you are using early debugging with + * kgdbwait. KGDB will control the kernel HW breakpoint registers. + */ + if (kgdb_connected && arch_kgdb_ops.correct_hw_break) + arch_kgdb_ops.correct_hw_break(); + else { +#endif /* * Clear all 6 debug registers: */ @@ -337,6 +349,10 @@ void __cpuinit cpu_init (void) set_debugreg(0UL, 3); set_debugreg(0UL, 6); set_debugreg(0UL, 7); +#ifdef CONFIG_KGDB + /* If the kgdb is connected no debug regs should be altered. */ + } +#endif fpu_init(); diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 319c08c92ee2..68aea78407e4 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -1139,10 +1139,10 @@ static void gdb_cmd_break(struct kgdb_state *ks) error = kgdb_remove_sw_break(addr); else if (remcom_in_buffer[0] == 'Z') error = arch_kgdb_ops.set_hw_breakpoint(addr, - (int)length, *bpt_type); + (int)length, *bpt_type - '0'); else if (remcom_in_buffer[0] == 'z') error = arch_kgdb_ops.remove_hw_breakpoint(addr, - (int) length, *bpt_type); + (int) length, *bpt_type - '0'); if (error == 0) strcpy(remcom_out_buffer, "OK"); -- cgit v1.2.3 From b4b8ac524d9b6ed7229017145afa1d7afbea4a48 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Wed, 20 Feb 2008 13:33:38 -0600 Subject: kgdb: fix optional arch functions and probe_kernel_* Fix two regressions dealing with the kgdb core. 1) kgdb_skipexception and kgdb_post_primary_code are optional functions that are only required on archs that need special exception fixups. 2) The kernel address space scope must be set on any probe_kernel_* function or archs such as ARCH=arm will not allow access to the kernel memory space. As an example, it is required to allow the full kernel address space is when you the kernel debugger to inspect a system call. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- kernel/kgdb.c | 11 +++++++++++ mm/maccess.c | 6 ++++++ 2 files changed, 17 insertions(+) (limited to 'kernel') diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 68aea78407e4..31425e0fbf20 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -200,6 +200,17 @@ int __weak kgdb_arch_init(void) return 0; } +int __weak kgdb_skipexception(int exception, struct pt_regs *regs) +{ + return 0; +} + +void __weak +kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code) +{ + return; +} + /** * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. * @regs: Current &struct pt_regs. diff --git a/mm/maccess.c b/mm/maccess.c index 24f81b971403..ac40796cfb15 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -17,11 +17,14 @@ long probe_kernel_read(void *dst, void *src, size_t size) { long ret; + mm_segment_t old_fs = get_fs(); + set_fs(KERNEL_DS); pagefault_disable(); ret = __copy_from_user_inatomic(dst, (__force const void __user *)src, size); pagefault_enable(); + set_fs(old_fs); return ret ? -EFAULT : 0; } @@ -39,10 +42,13 @@ EXPORT_SYMBOL_GPL(probe_kernel_read); long probe_kernel_write(void *dst, void *src, size_t size) { long ret; + mm_segment_t old_fs = get_fs(); + set_fs(KERNEL_DS); pagefault_disable(); ret = __copy_to_user_inatomic((__force void __user *)dst, src, size); pagefault_enable(); + set_fs(old_fs); return ret ? -EFAULT : 0; } -- cgit v1.2.3 From 737a460f21febe551ff1d2299b63bae9b154078f Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 7 Mar 2008 16:34:16 -0600 Subject: kgdb: fix several kgdb regressions kgdb core fixes: - Check to see that mm->mmap_cache is not null before calling flush_cache_range(), else on arch=ARM it will cause a fatal fault. - Breakpoints should only be restored if they are in the BP_ACTIVE state. - Fix a typo in comments to "kgdb_register_io_module" x86 kgdb fixes: - Fix the x86 arch handler such that on a kill or detach that the appropriate cleanup on the single stepping flags gets run. - Add in the DIE_NMIWATCHDOG call for x86_64 - Touch the nmi watchdog before returning the system to normal operation after performing any kind of kgdb operation, else the possibility exists to trigger the watchdog. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- arch/x86/kernel/kgdb.c | 4 ++++ arch/x86/kernel/traps_64.c | 7 ++++++- kernel/kgdb.c | 14 ++++++++------ 3 files changed, 18 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 7d651adcb222..8c7e555f6d39 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -370,6 +370,8 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, ptr = &remcomInBuffer[1]; if (kgdb_hex2long(&ptr, &addr)) linux_regs->ip = addr; + case 'D': + case 'k': newPC = linux_regs->ip; /* clear the trace bit */ @@ -480,6 +482,8 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd) if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs)) return NOTIFY_DONE; + /* Must touch watchdog before return to normal operation */ + touch_nmi_watchdog(); return NOTIFY_STOP; } diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c index 055b1650c69d..4e073320e70a 100644 --- a/arch/x86/kernel/traps_64.c +++ b/arch/x86/kernel/traps_64.c @@ -600,8 +600,13 @@ void die(const char * str, struct pt_regs * regs, long err) void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic) { - unsigned long flags = oops_begin(); + unsigned long flags; + + if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) == + NOTIFY_STOP) + return; + flags = oops_begin(); /* * We are in trouble anyway, lets at least try * to get a message out. diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 31425e0fbf20..85b7e5b934a7 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -600,7 +600,7 @@ static void kgdb_flush_swbreak_addr(unsigned long addr) if (!CACHE_FLUSH_IS_SAFE) return; - if (current->mm) { + if (current->mm && current->mm->mmap_cache) { flush_cache_range(current->mm->mmap_cache, addr, addr + BREAK_INSTR_SIZE); } else { @@ -729,14 +729,16 @@ int remove_all_break(void) /* Clear memory breakpoints. */ for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { - if (kgdb_break[i].state != BP_SET) - continue; + if (kgdb_break[i].state != BP_ACTIVE) + goto setundefined; addr = kgdb_break[i].bpt_addr; error = kgdb_arch_remove_breakpoint(addr, kgdb_break[i].saved_instr); if (error) - return error; - kgdb_break[i].state = BP_REMOVED; + printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n", + addr); +setundefined: + kgdb_break[i].state = BP_UNDEFINED; } /* Clear hardware breakpoints. */ @@ -1605,7 +1607,7 @@ static void kgdb_initial_breakpoint(void) } /** - * kkgdb_register_io_module - register KGDB IO module + * kgdb_register_io_module - register KGDB IO module * @new_kgdb_io_ops: the io ops vector * * Register it with the KGDB core. -- cgit v1.2.3 From 56fb70932964927597ce30bbd820471633c72adc Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Tue, 1 Apr 2008 16:55:27 -0500 Subject: kgdb: fix SMP NMI kgdb_handle_exception exit race Fix the problem of protecting the kgdb handle_exception exit which had an NMI race condition, while trying to restore normal system operation. There was a small window after the master processor sets cpu_in_debug to zero but before it has set kgdb_active to zero where a non-master processor in an SMP system could receive an NMI and re-enter the kgdb_wait() loop. As long as the master processor sets the cpu_in_debug before sending the cpu roundup the cpu_in_debug variable can also be used to guard against the race condition. The kgdb_wait() function no longer needs to check kgdb_active because it is done in the arch specific code and handled along with the nmi traps at the low level. This also allows kgdb_wait() to exit correctly if it was entered for some unknown reason due to a spurious NMI that could not be handled by the arch specific code. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- kernel/kgdb.c | 27 ++++++++------------------- 1 file changed, 8 insertions(+), 19 deletions(-) (limited to 'kernel') diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 85b7e5b934a7..4d1b3c232377 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -561,18 +561,6 @@ static void kgdb_wait(struct pt_regs *regs) smp_wmb(); atomic_set(&cpu_in_kgdb[cpu], 1); - /* - * The primary CPU must be active to enter here, but this is - * guard in case the primary CPU had not been selected if - * this was an entry via nmi. - */ - while (atomic_read(&kgdb_active) == -1) - cpu_relax(); - - /* Wait till primary CPU goes completely into the debugger. */ - while (!atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) - cpu_relax(); - /* Wait till primary CPU is done with debugging */ while (atomic_read(&passive_cpu_wait[cpu])) cpu_relax(); @@ -1447,18 +1435,18 @@ acquirelock: atomic_set(&passive_cpu_wait[i], 1); } -#ifdef CONFIG_SMP - /* Signal the other CPUs to enter kgdb_wait() */ - if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup) - kgdb_roundup_cpus(flags); -#endif - /* * spin_lock code is good enough as a barrier so we don't * need one here: */ atomic_set(&cpu_in_kgdb[ks->cpu], 1); +#ifdef CONFIG_SMP + /* Signal the other CPUs to enter kgdb_wait() */ + if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup) + kgdb_roundup_cpus(flags); +#endif + /* * Wait for the other CPUs to be notified and be waiting for us: */ @@ -1514,7 +1502,8 @@ int kgdb_nmicallback(int cpu, void *regs) { #ifdef CONFIG_SMP if (!atomic_read(&cpu_in_kgdb[cpu]) && - atomic_read(&kgdb_active) != cpu) { + atomic_read(&kgdb_active) != cpu && + atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) { kgdb_wait((struct pt_regs *)regs); return 0; } -- cgit v1.2.3 From 1a9a3e76dde191f82f7a8a66059dcbb4a9f63ff3 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Tue, 1 Apr 2008 16:55:28 -0500 Subject: kgdb: always use icache flush for sw breakpoints On the ppc 4xx architecture the instruction cache must be flushed as well as the data cache. This patch just makes it generic for all architectures where CACHE_FLUSH_IS_SAFE is set to 1. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- kernel/kgdb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 4d1b3c232377..1bd0ec1c80b2 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -591,9 +591,9 @@ static void kgdb_flush_swbreak_addr(unsigned long addr) if (current->mm && current->mm->mmap_cache) { flush_cache_range(current->mm->mmap_cache, addr, addr + BREAK_INSTR_SIZE); - } else { - flush_icache_range(addr, addr + BREAK_INSTR_SIZE); } + /* Force flush instruction cache if it was outside the mm */ + flush_icache_range(addr, addr + BREAK_INSTR_SIZE); } /* -- cgit v1.2.3