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Subject[PATCH 08/28] kdb: core for kgdb back end (2 of 2)
Date
This patch contains the hooks and instrumentation into kernel which
live outside the kernel/debug directory, which the kdb core
will call to run commands like lsmod, dmesg, bt etc...

CC: linux-arch@vger.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Martin Hicks <mort@sgi.com>
---
arch/arm/include/asm/kmap_types.h | 1 +
arch/powerpc/include/asm/kmap_types.h | 1 +
include/asm-generic/kmap_types.h | 3 +-
init/main.c | 2 +
kernel/kallsyms.c | 21 +++++++++++++++++
kernel/module.c | 4 +++
kernel/printk.c | 16 +++++++++++++
kernel/sched.c | 7 ++++-
kernel/signal.c | 40 +++++++++++++++++++++++++++++++++
9 files changed, 92 insertions(+), 3 deletions(-)
diff --git a/arch/arm/include/asm/kmap_types.h b/arch/arm/include/asm/kmap_types.h
index c019949..3a9fb57 100644
--- a/arch/arm/include/asm/kmap_types.h
+++ b/arch/arm/include/asm/kmap_types.h
@@ -19,6 +19,7 @@ enum km_type {
KM_SOFTIRQ0,
KM_SOFTIRQ1,
KM_L2_CACHE,
+ KM_KDB,
KM_TYPE_NR
};

diff --git a/arch/powerpc/include/asm/kmap_types.h b/arch/powerpc/include/asm/kmap_types.h
index 9163695..bca8fdc 100644
--- a/arch/powerpc/include/asm/kmap_types.h
+++ b/arch/powerpc/include/asm/kmap_types.h
@@ -26,6 +26,7 @@ enum km_type {
KM_SOFTIRQ1,
KM_PPC_SYNC_PAGE,
KM_PPC_SYNC_ICACHE,
+ KM_KDB,
KM_TYPE_NR
};

diff --git a/include/asm-generic/kmap_types.h b/include/asm-generic/kmap_types.h
index e5f234a..97e807c 100644
--- a/include/asm-generic/kmap_types.h
+++ b/include/asm-generic/kmap_types.h
@@ -28,7 +28,8 @@ KMAP_D(15) KM_UML_USERCOPY,
KMAP_D(16) KM_IRQ_PTE,
KMAP_D(17) KM_NMI,
KMAP_D(18) KM_NMI_PTE,
-KMAP_D(19) KM_TYPE_NR
+KMAP_D(19) KM_KDB,
+KMAP_D(20) KM_TYPE_NR
};

#undef KMAP_D
diff --git a/init/main.c b/init/main.c
index 4cb47a1..9d415a1 100644
--- a/init/main.c
+++ b/init/main.c
@@ -63,6 +63,7 @@
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/idr.h>
+#include <linux/kdb.h>
#include <linux/ftrace.h>
#include <linux/async.h>
#include <linux/kmemcheck.h>
@@ -659,6 +660,7 @@ asmlinkage void __init start_kernel(void)
key_init();
radix_tree_init();
security_init();
+ kdb_init(KDB_INIT_FULL);
vfs_caches_init(totalram_pages);
signals_init();
/* rootfs populating might need page-writeback */
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 8e5288a..dc08f8b 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -16,6 +16,7 @@
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/fs.h>
+#include <linux/kdb.h>
#include <linux/err.h>
#include <linux/proc_fs.h>
#include <linux/sched.h> /* for cond_resched */
@@ -515,6 +516,26 @@ static int kallsyms_open(struct inode *inode, struct file *file)
return ret;
}

+#ifdef CONFIG_KGDB_KDB
+const char *kdb_walk_kallsyms(loff_t *pos)
+{
+ static struct kallsym_iter kdb_walk_kallsyms_iter;
+ if (*pos == 0) {
+ memset(&kdb_walk_kallsyms_iter, 0,
+ sizeof(kdb_walk_kallsyms_iter));
+ reset_iter(&kdb_walk_kallsyms_iter, 0);
+ }
+ while (1) {
+ if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
+ return NULL;
+ ++*pos;
+ /* Some debugging symbols have no name. Ignore them. */
+ if (kdb_walk_kallsyms_iter.name[0])
+ return kdb_walk_kallsyms_iter.name;
+ }
+}
+#endif /* CONFIG_KGDB_KDB */
+
static const struct file_operations kallsyms_operations = {
.open = kallsyms_open,
.read = seq_read,
diff --git a/kernel/module.c b/kernel/module.c
index f82386b..e59aca1 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -79,6 +79,10 @@ EXPORT_TRACEPOINT_SYMBOL(module_get);
DEFINE_MUTEX(module_mutex);
EXPORT_SYMBOL_GPL(module_mutex);
static LIST_HEAD(modules);
+#ifdef CONFIG_KGDB_KDB
+struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
+#endif /* CONFIG_KGDB_KDB */
+

/* Block module loading/unloading? */
int modules_disabled = 0;
diff --git a/kernel/printk.c b/kernel/printk.c
index 1751c45..d86c91a 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -420,6 +420,22 @@ SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
return do_syslog(type, buf, len);
}

+#ifdef CONFIG_KGDB_KDB
+/* kdb dmesg command needs access to the syslog buffer. do_syslog()
+ * uses locks so it cannot be used during debugging. Just tell kdb
+ * where the start and end of the physical and logical logs are. This
+ * is equivalent to do_syslog(3).
+ */
+void kdb_syslog_data(char *syslog_data[4])
+{
+ syslog_data[0] = log_buf;
+ syslog_data[1] = log_buf + log_buf_len;
+ syslog_data[2] = log_buf + log_end -
+ (logged_chars < log_buf_len ? logged_chars : log_buf_len);
+ syslog_data[3] = log_buf + log_end;
+}
+#endif /* CONFIG_KGDB_KDB */
+
/*
* Call the console drivers on a range of log_buf
*/
diff --git a/kernel/sched.c b/kernel/sched.c
index 3a8fb30..92ab8b8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -9802,9 +9802,9 @@ void normalize_rt_tasks(void)

#endif /* CONFIG_MAGIC_SYSRQ */

-#ifdef CONFIG_IA64
+#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
/*
- * These functions are only useful for the IA64 MCA handling.
+ * These functions are only useful for the IA64 MCA handling, or kdb.
*
* They can only be called when the whole system has been
* stopped - every CPU needs to be quiescent, and no scheduling
@@ -9824,6 +9824,9 @@ struct task_struct *curr_task(int cpu)
return cpu_curr(cpu);
}

+#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
+
+#ifdef CONFIG_IA64
/**
* set_curr_task - set the current task for a given cpu.
* @cpu: the processor in question.
diff --git a/kernel/signal.c b/kernel/signal.c
index 934ae5e..96ecbf8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2718,3 +2718,43 @@ void __init signals_init(void)
{
sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
}
+
+#ifdef CONFIG_KGDB_KDB
+#include <linux/kdb.h>
+/*
+ * kdb_send_sig_info - Allows kdb to send signals without exposing
+ * signal internals. This function checks if the required locks are
+ * available before calling the main signal code, to avoid kdb
+ * deadlocks.
+ */
+void
+kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
+{
+ static struct task_struct *kdb_prev_t;
+ int sig, new_t;
+ if (!spin_trylock(&t->sighand->siglock)) {
+ kdb_printf("Can't do kill command now.\n"
+ "The sigmask lock is held somewhere else in "
+ "kernel, try again later\n");
+ return;
+ }
+ spin_unlock(&t->sighand->siglock);
+ new_t = kdb_prev_t != t;
+ kdb_prev_t = t;
+ if (t->state != TASK_RUNNING && new_t) {
+ kdb_printf("Process is not RUNNING, sending a signal from "
+ "kdb risks deadlock\n"
+ "on the run queue locks. "
+ "The signal has _not_ been sent.\n"
+ "Reissue the kill command if you want to risk "
+ "the deadlock.\n");
+ return;
+ }
+ sig = info->si_signo;
+ if (send_sig_info(sig, info, t))
+ kdb_printf("Fail to deliver Signal %d to process %d.\n",
+ sig, t->pid);
+ else
+ kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
+}
+#endif /* CONFIG_KGDB_KDB */
--
1.6.4.rc1


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