diff mbox series

[v3,3/5] xen: print lock profile info in panic()

Message ID 20190829101846.21369-4-jgross@suse.com (mailing list archive)
State Superseded
Headers show
Series enhance lock debugging | expand

Commit Message

Jürgen Groß Aug. 29, 2019, 10:18 a.m. UTC
Print the lock profile data when the system crashes and add some more
information for each lock data (lock address, cpu holding the lock).
While at it use the PRI_stime format specifier for printing time data.

This is especially beneficial for watchdog triggered crashes in case
of deadlocks.

In order to have the cpu holding the lock available let the
lock profile config option select DEBUG_LOCKS.

As printing the lock profile data will make use of locking, too, we
need to disable spinlock debugging before calling
spinlock_profile_printall() from panic().

While at it remove a superfluous #ifdef CONFIG_LOCK_PROFILE and rename
CONFIG_LOCK_PROFILE to CONFIG_DEBUG_LOCK_PROFILE.

Also move the .lockprofile.data section to init area in linker scripts
as the data is no longer needed after boot.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- rename CONFIG_LOCK_PROFILE to CONFIG_DEBUG_LOCK_PROFILE (Jan Beulich)
- move .lockprofile.data section to init area in linker scripts
- use PRI_stime (Andrew Cooper)
- don't print "cpu=4095", but "not locked" (Andrew Cooper)
---
 xen/Kconfig.debug          |  3 ++-
 xen/arch/arm/xen.lds.S     | 13 +++++++------
 xen/arch/x86/domain.c      |  2 +-
 xen/arch/x86/xen.lds.S     | 13 +++++++------
 xen/common/keyhandler.c    |  2 +-
 xen/common/spinlock.c      | 33 ++++++++++++++++++---------------
 xen/common/sysctl.c        |  2 +-
 xen/drivers/char/console.c |  4 +++-
 xen/include/xen/spinlock.h | 12 +++++++-----
 9 files changed, 47 insertions(+), 37 deletions(-)

Comments

Jan Beulich Sept. 3, 2019, 2:22 p.m. UTC | #1
On 29.08.2019 12:18, Juergen Gross wrote:
> V2:
> - rename CONFIG_LOCK_PROFILE to CONFIG_DEBUG_LOCK_PROFILE (Jan Beulich)
> - move .lockprofile.data section to init area in linker scripts

How can this be correct, when you don't change lock_prof_init() at
all? The function builds a linked list from the entries in the
section, and then hands the head of this list to
_lock_profile_register_struct(). I guess I must be missing
something. Anyway, everything else here looks good to me.

Jan
Jürgen Groß Sept. 3, 2019, 2:38 p.m. UTC | #2
On 03.09.19 16:22, Jan Beulich wrote:
> On 29.08.2019 12:18, Juergen Gross wrote:
>> V2:
>> - rename CONFIG_LOCK_PROFILE to CONFIG_DEBUG_LOCK_PROFILE (Jan Beulich)
>> - move .lockprofile.data section to init area in linker scripts
> 
> How can this be correct, when you don't change lock_prof_init() at
> all? The function builds a linked list from the entries in the
> section, and then hands the head of this list to
> _lock_profile_register_struct(). I guess I must be missing
> something. Anyway, everything else here looks good to me.

The .lockprofile.data section contains only the pointers to the
elements put into the linked list. And those pointers are no longer
needed afterwards.


Juergen
Jan Beulich Sept. 3, 2019, 3:06 p.m. UTC | #3
On 03.09.2019 16:38, Juergen Gross wrote:
> On 03.09.19 16:22, Jan Beulich wrote:
>> On 29.08.2019 12:18, Juergen Gross wrote:
>>> V2:
>>> - rename CONFIG_LOCK_PROFILE to CONFIG_DEBUG_LOCK_PROFILE (Jan Beulich)
>>> - move .lockprofile.data section to init area in linker scripts
>>
>> How can this be correct, when you don't change lock_prof_init() at
>> all? The function builds a linked list from the entries in the
>> section, and then hands the head of this list to
>> _lock_profile_register_struct(). I guess I must be missing
>> something. Anyway, everything else here looks good to me.
> 
> The .lockprofile.data section contains only the pointers to the
> elements put into the linked list. And those pointers are no longer
> needed afterwards.

Oh, yes, I see now. Arguably worth making a separate change,
but since it's this way now
Acked-by: Jan Beulich <jbeulich@suse.com>

Jan
diff mbox series

Patch

diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index 1faaa3ba6a..22573e74db 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -44,8 +44,9 @@  config COVERAGE
 
 	  If unsure, say N here.
 
-config LOCK_PROFILE
+config DEBUG_LOCK_PROFILE
 	bool "Lock Profiling"
+	select DEBUG_LOCKS
 	---help---
 	  Lock profiling allows you to see how often locks are taken and blocked.
 	  You can use serial console to print (and reset) using 'l' and 'L'
diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
index 16ce1dd01e..a497f6a48d 100644
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -54,12 +54,6 @@  SECTIONS
        *(.data.rel.ro)
        *(.data.rel.ro.*)
 
-#ifdef CONFIG_LOCK_PROFILE
-       . = ALIGN(POINTER_ALIGN);
-       __lock_profile_start = .;
-       *(.lockprofile.data)
-       __lock_profile_end = .;
-#endif
        . = ALIGN(POINTER_ALIGN);
        __param_start = .;
        *(.data.param)
@@ -173,6 +167,13 @@  SECTIONS
        . = ALIGN(4);
        *(.altinstr_replacement)
 
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
+       . = ALIGN(POINTER_ALIGN);
+       __lock_profile_start = .;
+       *(.lockprofile.data)
+       __lock_profile_end = .;
+#endif
+
        *(.init.data)
        *(.init.data.rel)
        *(.init.data.rel.*)
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index bc082ed827..b1c67c2d28 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -305,7 +305,7 @@  struct domain *alloc_domain_struct(void)
 #endif
 
 
-#ifndef CONFIG_LOCK_PROFILE
+#ifndef CONFIG_DEBUG_LOCK_PROFILE
     BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
 #endif
     d = alloc_xenheap_pages(order, MEMF_bits(bits));
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 87fa02b9b5..111edb5360 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -128,12 +128,6 @@  SECTIONS
        *(.ex_table.pre)
        __stop___pre_ex_table = .;
 
-#ifdef CONFIG_LOCK_PROFILE
-       . = ALIGN(POINTER_ALIGN);
-       __lock_profile_start = .;
-       *(.lockprofile.data)
-       __lock_profile_end = .;
-#endif
        . = ALIGN(POINTER_ALIGN);
        __param_start = .;
        *(.data.param)
@@ -251,6 +245,13 @@  SECTIONS
         *(.altinstructions)
         __alt_instructions_end = .;
 
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
+       . = ALIGN(POINTER_ALIGN);
+       __lock_profile_start = .;
+       *(.lockprofile.data)
+       __lock_profile_end = .;
+#endif
+
        . = ALIGN(8);
        __ctors_start = .;
        *(.ctors)
diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
index 57b360ee4b..c36baa4dff 100644
--- a/xen/common/keyhandler.c
+++ b/xen/common/keyhandler.c
@@ -62,7 +62,7 @@  static struct keyhandler {
     KEYHANDLER('P', perfc_reset, "reset performance counters", 0),
 #endif
 
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
     KEYHANDLER('l', spinlock_profile_printall, "print lock profile info", 1),
     KEYHANDLER('L', spinlock_profile_reset, "reset lock profile info", 0),
 #endif
diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c
index 79e70a9947..c4f706c627 100644
--- a/xen/common/spinlock.c
+++ b/xen/common/spinlock.c
@@ -106,7 +106,7 @@  void spin_debug_disable(void)
 
 #endif
 
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
 
 #define LOCK_PROFILE_REL                                                     \
     if (lock->profile)                                                       \
@@ -243,7 +243,7 @@  int _spin_trylock(spinlock_t *lock)
                  old.head_tail, new.head_tail) != old.head_tail )
         return 0;
     got_lock(&lock->debug);
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
     if (lock->profile)
         lock->profile->time_locked = NOW();
 #endif
@@ -258,7 +258,7 @@  int _spin_trylock(spinlock_t *lock)
 void _spin_barrier(spinlock_t *lock)
 {
     spinlock_tickets_t sample;
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
     s_time_t block = NOW();
 #endif
 
@@ -269,7 +269,7 @@  void _spin_barrier(spinlock_t *lock)
     {
         while ( observe_head(&lock->tickets) == sample.head )
             arch_lock_relax();
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
         if ( lock->profile )
         {
             lock->profile->time_block += NOW() - block;
@@ -327,7 +327,7 @@  void _spin_unlock_recursive(spinlock_t *lock)
     }
 }
 
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
 
 struct lock_profile_anc {
     struct lock_profile_qhead *head_q;   /* first head of this type */
@@ -362,14 +362,19 @@  static void spinlock_profile_iterate(lock_profile_subfunc *sub, void *par)
 static void spinlock_profile_print_elem(struct lock_profile *data,
     int32_t type, int32_t idx, void *par)
 {
-    if ( type == LOCKPROF_TYPE_GLOBAL )
-        printk("%s %s:\n", lock_profile_ancs[type].name, data->name);
+    struct spinlock *lock = data->lock;
+
+    printk("%s ", lock_profile_ancs[type].name);
+    if ( type != LOCKPROF_TYPE_GLOBAL )
+        printk("%d ", idx);
+    printk("%s: addr=%p, lockval=%08x, ", data->name, lock,
+           lock->tickets.head_tail);
+    if ( lock->debug.cpu == SPINLOCK_NO_CPU )
+        printk("not locked\n");
     else
-        printk("%s %d %s:\n", lock_profile_ancs[type].name, idx, data->name);
-    printk("  lock:%12"PRId64"(%08X:%08X), block:%12"PRId64"(%08X:%08X)\n",
-           data->lock_cnt, (u32)(data->time_hold >> 32), (u32)data->time_hold,
-           data->block_cnt, (u32)(data->time_block >> 32),
-           (u32)data->time_block);
+        printk("cpu=%d\n", lock->debug.cpu);
+    printk("  lock:%" PRId64 "(%" PRI_stime "), block:%" PRId64 "(%" PRI_stime ")\n",
+           data->lock_cnt, data->time_hold, data->block_cnt, data->time_block);
 }
 
 void spinlock_profile_printall(unsigned char key)
@@ -488,7 +493,6 @@  void _lock_profile_deregister_struct(
     spin_unlock(&lock_profile_lock);
 }
 
-#ifdef CONFIG_LOCK_PROFILE
 static int __init lock_prof_init(void)
 {
     struct lock_profile **q;
@@ -507,6 +511,5 @@  static int __init lock_prof_init(void)
     return 0;
 }
 __initcall(lock_prof_init);
-#endif
 
-#endif /* LOCK_PROFILE */
+#endif /* CONFIG_DEBUG_LOCK_PROFILE */
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index fcf2d2fd7c..9db94754d3 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -119,7 +119,7 @@  long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
         break;
 #endif
 
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
     case XEN_SYSCTL_lockprof_op:
         ret = spinlock_profile_control(&op->u.lockprof_op);
         break;
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 7f29190eaf..e133534be7 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -1170,7 +1170,9 @@  void panic(const char *fmt, ...)
     unsigned long flags;
     static DEFINE_SPINLOCK(lock);
     static char buf[128];
-    
+
+    spin_debug_disable();
+    spinlock_profile_printall('\0');
     debugtrace_dump();
 
     /* Protects buf[] and ensure multi-line message prints atomically. */
diff --git a/xen/include/xen/spinlock.h b/xen/include/xen/spinlock.h
index 736490f52b..a7c1967ec7 100644
--- a/xen/include/xen/spinlock.h
+++ b/xen/include/xen/spinlock.h
@@ -1,6 +1,7 @@ 
 #ifndef __SPINLOCK_H__
 #define __SPINLOCK_H__
 
+#include <xen/time.h>
 #include <asm/system.h>
 #include <asm/spinlock.h>
 #include <asm/types.h>
@@ -26,7 +27,7 @@  union lock_debug { };
 #define spin_debug_disable() ((void)0)
 #endif
 
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
 
 #include <public/sysctl.h>
 
@@ -72,9 +73,9 @@  struct lock_profile {
     struct spinlock     *lock;       /* the lock itself */
     u64                 lock_cnt;    /* # of complete locking ops */
     u64                 block_cnt;   /* # of complete wait for lock */
-    s64                 time_hold;   /* cumulated lock time */
-    s64                 time_block;  /* cumulated wait time */
-    s64                 time_locked; /* system time of last locking */
+    s_time_t            time_hold;   /* cumulated lock time */
+    s_time_t            time_block;  /* cumulated wait time */
+    s_time_t            time_locked; /* system time of last locking */
 };
 
 struct lock_profile_qhead {
@@ -130,6 +131,7 @@  struct lock_profile_qhead { };
 #define spin_lock_init_prof(s, l) spin_lock_init(&((s)->l))
 #define lock_profile_register_struct(type, ptr, idx, print)
 #define lock_profile_deregister_struct(type, ptr)
+#define spinlock_profile_printall(key)
 
 #endif
 
@@ -150,7 +152,7 @@  typedef struct spinlock {
     u16 recurse_cnt:4;
 #define SPINLOCK_MAX_RECURSE 0xfu
     union lock_debug debug;
-#ifdef CONFIG_LOCK_PROFILE
+#ifdef CONFIG_DEBUG_LOCK_PROFILE
     struct lock_profile *profile;
 #endif
 } spinlock_t;