[patch v3 20/36] Hexagon: Provide basic debugging and system trap support.

Richard Kuo
2011-09-09T01:11:26Z

[-- Attachment #1: traps.diff --]
[-- Type: text/plain, Size: 10904 bytes --]

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Linas Vepstas <linas@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>

---
arch/hexagon/include/asm/traps.h | 29 +++
arch/hexagon/kernel/traps.c | 356 +++++++++++++++++++++++++++++++++++++++
2 files changed, 385 insertions(+)

Index: linux-hexagon-kernel/arch/hexagon/kernel/traps.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-hexagon-kernel/arch/hexagon/kernel/traps.c 2011-09-03 20:14:59.694981307 -0500
@@ -0,0 +1,356 @@
+/*
+ * Kernel traps/events for Hexagon processor
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/kdebug.h>
+#include <linux/syscalls.h>
+#include <linux/signal.h>
+#include <linux/tracehook.h>
+#include <asm/traps.h>
+#include <asm/vm_fault.h>
+#include <asm/syscall.h>
+#include <asm/registers.h>
+#include <asm/unistd.h>
+#ifdef CONFIG_KGDB
+# include <linux/kgdb.h>
+#endif
+
+#define TRAP_SYSCALL 1
+#define TRAP_DEBUG 0xdb
+
+void __init trap_init(void)
+{
+}
+
+#ifdef CONFIG_GENERIC_BUG
+/* Maybe should resemble arch/sh/kernel/traps.c ?? */
+int is_valid_bugaddr(unsigned long addr)
+{
+ return 1;
+}
+#endif /* CONFIG_GENERIC_BUG */
+
+void show_stack(struct task_struct *task, unsigned long *fp)
+{
+ int kstack_depth_to_print = 20;
+ unsigned long offset, size;
+ const char *name = NULL;
+ unsigned long *newfp;
+ unsigned long ip;
+ char tmpstr[128];
+ char *modname;
+ int i;
+
+ if (task == NULL)
+ task = current;
+
+ if (fp == NULL) {
+ if (task == current) {
+ asm("%0 = r30" : "=r" (fp));
+ } else {
+ fp = (unsigned long *)
+ ((struct hexagon_switch_stack *)
+ task->thread.switch_sp)->fp;
+ }
+ }
+
+ printk(KERN_INFO "CPU#%d, %s/%d, Call Trace:\n",
+ raw_smp_processor_id(), current->comm,
+ task_pid_nr(current));
+ for (i = 0; i < kstack_depth_to_print; i++) {
+ if (0 /* Check irq stack at some point */)
+ printk(KERN_INFO " <EOI> ");
+ else if (((long) fp & (THREAD_SIZE-1)) == 0)
+ break;
+
+ newfp = (unsigned long *) *fp;
+
+ ip = *(unsigned long *)((char *)fp + sizeof(unsigned long));
+ name = kallsyms_lookup(ip, &size, &offset, &modname, tmpstr);
+
+ printk(KERN_INFO "[%p] 0x%lx: %s + 0x%lx", fp, ip, name,
+ offset);
+ if (modname)
+ printk(KERN_CONT " [%s] ", modname);
+ if (i == 0)
+ printk(KERN_CONT " (unreliable)");
+ printk(KERN_CONT "\n");
+
+ /* If newfp isn't larger, we're tracing garbage */
+ if (newfp > fp)
+ fp = newfp;
+ else
+ break;
+ }
+}
+
+void dump_state(struct pt_regs *regs)
+{
+ show_regs(regs);
+ show_stack(current, &regs->r30);
+}
+
+void dump_stack(void)
+{
+ show_stack(current, NULL);
+}
+EXPORT_SYMBOL(dump_stack);
+
+int die(const char *str, struct pt_regs *regs, long err)
+{
+ static struct {
+ spinlock_t lock;
+ int counter;
+ } die = {
+ .lock = __SPIN_LOCK_UNLOCKED(die.lock),
+ .counter = 0
+ };
+
+ spin_lock_irq(&die.lock);
+ bust_spinlocks(1);
+ printk(KERN_INFO "%s[#%d]:\n", str, ++die.counter);
+
+ if (notify_die(DIE_OOPS, str, regs, err, pt_cause(regs), SIGSEGV) ==
+ NOTIFY_STOP)
+ return 1;
+
+ print_modules();
+ dump_state(regs);
+
+ do_exit(err);
+ return 0;
+}
+
+int die_if_kernel(char *str, struct pt_regs *regs, long err)
+{
+ if (!user_mode(regs))
+ return die(str, regs, err);
+ else
+ return 0;
+}
+
+/*
+ * It's not clear that misaligned fetches are ever recoverable.
+ */
+static void misaligned_instruction(struct pt_regs *regs)
+{
+ die_if_kernel("Misaligned Instruction", regs, 0);
+ force_sig(SIGBUS, current);
+}
+
+/*
+ * Misaligned loads and stores, on the other hand, can be
+ * emulated, and probably should be, some day. But for now
+ * they will be considered fatal.
+ */
+static void misaligned_data_load(struct pt_regs *regs)
+{
+ die_if_kernel("Misaligned Data Load", regs, 0);
+ force_sig(SIGBUS, current);
+}
+
+static void misaligned_data_store(struct pt_regs *regs)
+{
+ die_if_kernel("Misaligned Data Store", regs, 0);
+ force_sig(SIGBUS, current);
+}
+
+static void illegal_instruction(struct pt_regs *regs)
+{
+ die_if_kernel("Illegal Instruction", regs, 0);
+ force_sig(SIGILL, current);
+}
+
+/*
+ * Precise bus errors may be recoverable with a a retry,
+ * but for now, treat them as irrecoverable.
+ */
+static void precise_bus_error(struct pt_regs *regs)
+{
+ die_if_kernel("Precise Bus Error", regs, 0);
+ force_sig(SIGBUS, current);
+}
+
+/*
+ * If anything is to be done here other than panic,
+ * it will probably be complex and migrate to another
+ * source module. For now, just die.
+ */
+static void cache_error(struct pt_regs *regs)
+{
+ die("Cache Error", regs, 0);
+}
+
+/*
+ * General exception handler
+ */
+void do_genex(struct pt_regs *regs)
+{
+
+ /*
+ * Decode Cause and Dispatch
+ */
+ switch (pt_cause(regs)) {
+ case HVM_GE_C_XPROT:
+ case HVM_GE_C_XUSER:
+ execute_protection_fault(regs);
+ break;
+ case HVM_GE_C_RPROT:
+ case HVM_GE_C_RUSER:
+ read_protection_fault(regs);
+ break;
+ case HVM_GE_C_WPROT:
+ case HVM_GE_C_WUSER:
+ write_protection_fault(regs);
+ break;
+ case HVM_GE_C_XMAL:
+ misaligned_instruction(regs);
+ break;
+ case HVM_GE_C_RMAL:
+ misaligned_data_load(regs);
+ break;
+ case HVM_GE_C_WMAL:
+ misaligned_data_store(regs);
+ break;
+ case HVM_GE_C_INVI:
+ case HVM_GE_C_PRIVI:
+ illegal_instruction(regs);
+ break;
+ case HVM_GE_C_BUS:
+ precise_bus_error(regs);
+ break;
+ case HVM_GE_C_CACHE:
+ cache_error(regs);
+ break;
+ default:
+ /* Halt and catch fire */
+ panic("Unrecognized exception 0x%lx\n", pt_cause(regs));
+ break;
+ }
+}
+
+/* Indirect system call dispatch */
+long sys_syscall(void)
+{
+ printk(KERN_ERR "sys_syscall invoked!\n");
+ return -ENOSYS;
+}
+
+void do_trap0(struct pt_regs *regs)
+{
+ unsigned long syscallret = 0;
+ syscall_fn syscall;
+
+ switch (pt_cause(regs)) {
+ case TRAP_SYSCALL:
+ /* System call is trap0 #1 */
+
+ /* allow strace to catch syscall args */
+ if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE) &&
+ tracehook_report_syscall_entry(regs)))
+ return; /* return -ENOSYS somewhere? */
+
+ /* Interrupts should be re-enabled for syscall processing */
+ __vmsetie(VM_INT_ENABLE);
+
+ /*
+ * System call number is in r6, arguments in r0..r5.
+ * Fortunately, no Linux syscall has more than 6 arguments,
+ * and Hexagon ABI passes first 6 arguments in registers.
+ * 64-bit arguments are passed in odd/even register pairs.
+ * Fortunately, we have no system calls that take more
+ * than three arguments with more than one 64-bit value.
+ * Should that change, we'd need to redesign to copy
+ * between user and kernel stacks.
+ */
+ regs->syscall_nr = regs->r06;
+
+ /*
+ * GPR R0 carries the first parameter, and is also used
+ * to report the return value. We need a backup of
+ * the user's value in case we need to do a late restart
+ * of the system call.
+ */
+ regs->restart_r0 = regs->r00;
+
+ if ((unsigned long) regs->syscall_nr >= __NR_syscalls) {
+ regs->r00 = -1;
+ } else {
+ syscall = (syscall_fn)
+ (sys_call_table[regs->syscall_nr]);
+ syscallret = syscall(regs->r00, regs->r01,
+ regs->r02, regs->r03,
+ regs->r04, regs->r05);
+ }
+
+ /*
+ * If it was a sigreturn system call, don't overwrite
+ * r0 value in stack frame with return value.
+ *
+ * __NR_sigreturn doesn't seem to exist in new unistd.h
+ */
+
+ if (regs->syscall_nr != __NR_rt_sigreturn)
+ regs->r00 = syscallret;
+
+ /* allow strace to get the syscall return state */
+ if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE)))
+ tracehook_report_syscall_exit(regs, 0);
+
+ break;
+ case TRAP_DEBUG:
+ /* Trap0 0xdb is debug breakpoint */
+ if (user_mode(regs)) {
+ struct siginfo info;
+
+ info.si_signo = SIGTRAP;
+ info.si_errno = 0;
+ /*
+ * Some architecures add some per-thread state
+ * to distinguish between breakpoint traps and
+ * trace traps. We may want to do that, and
+ * set the si_code value appropriately, or we
+ * may want to use a different trap0 flavor.
+ */
+ info.si_code = TRAP_BRKPT;
+ info.si_addr = (void __user *) pt_elr(regs);
+ send_sig_info(SIGTRAP, &info, current);
+ } else {
+#ifdef CONFIG_KGDB
+ kgdb_handle_exception(pt_cause(regs), SIGTRAP,
+ TRAP_BRKPT, regs);
+#endif
+ }
+ break;
+ }
+ /* Ignore other trap0 codes for now, especially 0 (Angel calls) */
+}
+
+/*
+ * Machine check exception handler
+ */
+void do_machcheck(struct pt_regs *regs)
+{
+ /* Halt and catch fire */
+ __vmstop();
+}
Index: linux-hexagon-kernel/arch/hexagon/include/asm/traps.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-hexagon-kernel/arch/hexagon/include/asm/traps.h 2011-09-03 20:14:59.694981307 -0500
@@ -0,0 +1,29 @@
+/*
+ * Trap support for Hexagon
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef _ASM_HEXAGON_TRAPS_H
+#define _ASM_HEXAGON_TRAPS_H
+
+#include <asm/registers.h>
+
+extern int die(const char *str, struct pt_regs *regs, long err);
+extern int die_if_kernel(char *str, struct pt_regs *regs, long err);
+
+#endif /* _ASM_HEXAGON_TRAPS_H */