[PATCH 08/28] kdb: core for kgdb back end (2 of 2)

[Jason Wessel <jason.wessel@windriver.com>]

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: mort@sgi.com
CC: linux-arch@vger.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
 arch/arm/include/asm/kmap_types.h     |    1 +
 arch/powerpc/include/asm/kmap_types.h |    1 +
 fs/proc/internal.h                    |    4 +-
 fs/proc/meminfo.c                     |   15 ++++++++++--
 fs/proc/mmu.c                         |    8 ++++--
 include/asm-generic/kmap_types.h      |    3 +-
 include/linux/swap.h                  |    2 +
 init/main.c                           |    2 +
 kernel/kallsyms.c                     |   21 +++++++++++++++++
 kernel/module.c                       |    4 +++
 kernel/printk.c                       |   16 +++++++++++++
 kernel/sched.c                        |    7 ++++-
 kernel/signal.c                       |   40 +++++++++++++++++++++++++++++++++
 mm/swapfile.c                         |   10 ++++++-
 14 files changed, 121 insertions(+), 13 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/fs/proc/internal.h b/fs/proc/internal.h
index 1f24a3e..36d55e1 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -32,11 +32,11 @@ extern struct mm_struct *mm_for_maps(struct task_struct *);
 
 #ifdef CONFIG_MMU
 #define VMALLOC_TOTAL (VMALLOC_END - VMALLOC_START)
-extern void get_vmalloc_info(struct vmalloc_info *vmi);
+extern void get_vmalloc_info(struct vmalloc_info *vmi, int lock);
 #else
 
 #define VMALLOC_TOTAL 0UL
-#define get_vmalloc_info(vmi)			\
+#define get_vmalloc_info(vmi, lock)		\
 do {						\
 	(vmi)->used = 0;			\
 	(vmi)->largest_chunk = 0;		\
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index a65239c..b967cf2 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -10,6 +10,7 @@
 #include <linux/seq_file.h>
 #include <linux/swap.h>
 #include <linux/vmstat.h>
+#include <linux/kdb.h>
 #include <asm/atomic.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -19,7 +20,7 @@ void __attribute__((weak)) arch_report_meminfo(struct seq_file *m)
 {
 }
 
-static int meminfo_proc_show(struct seq_file *m, void *v)
+int _meminfo_proc_show(struct seq_file *m, void *v, int lock)
 {
 	struct sysinfo i;
 	unsigned long committed;
@@ -34,7 +35,10 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
  */
 #define K(x) ((x) << (PAGE_SHIFT - 10))
 	si_meminfo(&i);
-	si_swapinfo(&i);
+	if (lock)
+		si_swapinfo(&i);
+	else
+		__si_swapinfo(&i);
 	committed = percpu_counter_read_positive(&vm_committed_as);
 	allowed = ((totalram_pages - hugetlb_total_pages())
 		* sysctl_overcommit_ratio / 100) + total_swap_pages;
@@ -44,7 +48,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 	if (cached < 0)
 		cached = 0;
 
-	get_vmalloc_info(&vmi);
+	get_vmalloc_info(&vmi, lock);
 
 	for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
 		pages[lru] = global_page_state(NR_LRU_BASE + lru);
@@ -161,6 +165,11 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 #undef K
 }
 
+static int meminfo_proc_show(struct seq_file *m, void *v)
+{
+	return _meminfo_proc_show(m, v, 1);
+}
+
 static int meminfo_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, meminfo_proc_show, NULL);
diff --git a/fs/proc/mmu.c b/fs/proc/mmu.c
index 8ae221d..10a0f8b 100644
--- a/fs/proc/mmu.c
+++ b/fs/proc/mmu.c
@@ -14,7 +14,7 @@
 #include <asm/pgtable.h>
 #include "internal.h"
 
-void get_vmalloc_info(struct vmalloc_info *vmi)
+void get_vmalloc_info(struct vmalloc_info *vmi, int lock)
 {
 	struct vm_struct *vma;
 	unsigned long free_area_size;
@@ -30,7 +30,8 @@ void get_vmalloc_info(struct vmalloc_info *vmi)
 
 		prev_end = VMALLOC_START;
 
-		read_lock(&vmlist_lock);
+		if (lock)
+			read_lock(&vmlist_lock);
 
 		for (vma = vmlist; vma; vma = vma->next) {
 			unsigned long addr = (unsigned long) vma->addr;
@@ -55,6 +56,7 @@ void get_vmalloc_info(struct vmalloc_info *vmi)
 		if (VMALLOC_END - prev_end > vmi->largest_chunk)
 			vmi->largest_chunk = VMALLOC_END - prev_end;
 
-		read_unlock(&vmlist_lock);
+		if (lock)
+			read_unlock(&vmlist_lock);
 	}
 }
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/include/linux/swap.h b/include/linux/swap.h
index a2602a8..c326282 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -312,6 +312,7 @@ extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 /* linux/mm/swapfile.c */
 extern long nr_swap_pages;
 extern long total_swap_pages;
+extern void __si_swapinfo(struct sysinfo *);
 extern void si_swapinfo(struct sysinfo *);
 extern swp_entry_t get_swap_page(void);
 extern swp_entry_t get_swap_page_of_type(int);
@@ -377,6 +378,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 
 #define si_swapinfo(val) \
 	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
+#define __si_swapinfo(val) si_swapinfo(val)
 /* only sparc can not include linux/pagemap.h in this file
  * so leave page_cache_release and release_pages undeclared... */
 #define free_page_and_swap_cache(page) \
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 */
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6c0585b..dc2039e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -13,6 +13,7 @@
 #include <linux/swap.h>
 #include <linux/vmalloc.h>
 #include <linux/pagemap.h>
+#include <linux/kdb.h>
 #include <linux/namei.h>
 #include <linux/shm.h>
 #include <linux/blkdev.h>
@@ -2056,12 +2057,11 @@ out:
 	return error;
 }
 
-void si_swapinfo(struct sysinfo *val)
+void __si_swapinfo(struct sysinfo *val)
 {
 	unsigned int type;
 	unsigned long nr_to_be_unused = 0;
 
-	spin_lock(&swap_lock);
 	for (type = 0; type < nr_swapfiles; type++) {
 		struct swap_info_struct *si = swap_info[type];
 
@@ -2070,6 +2070,12 @@ void si_swapinfo(struct sysinfo *val)
 	}
 	val->freeswap = nr_swap_pages + nr_to_be_unused;
 	val->totalswap = total_swap_pages + nr_to_be_unused;
+}
+
+void si_swapinfo(struct sysinfo *val)
+{
+	spin_lock(&swap_lock);
+	__si_swapinfo(val);
 	spin_unlock(&swap_lock);
 }
 
-- 
1.6.4.rc1