Jan Kiszka wrote:
Philippe Gerum wrote:
Hi Jan,
Based on your previous work, here is a set of patches coupling KGDB and
the I-pipe. Basically, I've attempted to shrink the extra patches needed
against the original KGDB + I-pipe ones to the bare minimum. This has
been obtained by having the I-pipe provide ipipe_current_safe(), and
drastically reduce the amount of fiddling with smp_processor_id().
The key difference with the former implementation is that a domain (e.g.
Xenomai) is now expected to tell the I-pipe when it's switching to a
non-Linux stack, and the I-pipe makes good use of this information to
return the proper "current" value when asked to through
ipipe_safe_current() from the KGDB code. The issue of swapping
This looks nice.
smp_processor_id() with ipipe_processor_id() has been addressed the hard
way: smp_processor_id() is simply defined as ipipe_processor_id() when
CONFIG_IPIPE and CONFIG_KGDB are both enabled in include/linux/smp.h.
This approach was actually used during the old Adeos times when pipeline
domain had their own separate stack. I take for granted that the CPU
penalty taken in doing this is perfectly acceptable, since well, we are
debugging after all.
There is only one drawback: we will not be able to debug
smp_processor_id-related bugs in ipipe/Xenomai anymore...
Good point. Here is an updated patch.
Aside of the small patches attached, you will need the latest I-pipe
1.3-05 patch for x86, adding the foreign stack notifier and the
ipipe_safe_current() support:
http://download.gna.org/adeos/patches/v2.6/i386/adeos-ipipe-2.6.16-i386-1.3-05.patch
Patches should be applied in this order on a vanilla 2.6.16 kernel:
- KGDB 2.4 patch series over 2.6.16 (quilt)
- pre-kgdb-ipipe-i386.patch
- adeos-ipipe-2.6.16-i386-1.3-05.patch
- kgdb-ipipe.patch
- post-kgdb-ipipe-i386.patch
Xenomai's trunk/ should be used. Older code won't work and likely crash
since the I-pipe would not be notified about foreign stack switches.
Now the surprise: I did not test this stuff, I mean, at all. Eh. :o)
That's fair: leave the head banging while debugging debuggers (*) up to
me. ;)
Will try to let this fly, likely not before the weekend.
BTW, there is one pending issue of gcc-4.1 which popped up under kgdb,
see [1] (also for a workaround).
Mm, I'll keep on working with gcc3.4 and 8k stacks on x86 then.
Jan
(*) Actually, that's feasible: kgdb-patched kernel inside qemu - already
done this (to find [1]), it's just a bit sloooow.
[1]http://sourceforge.net/mailarchive/forum.php?thread_id=10452132&forum_id=5557
--
Philippe.
--- 2.6.16-base/kernel/kgdb.c 2006-06-07 16:40:21.000000000 +0200
+++ 2.6.16-kgdb/kernel/kgdb.c 2006-06-07 16:43:36.000000000 +0200
@@ -740,10 +740,10 @@
unsigned long flags;
int processor;
- local_irq_save(flags);
+ local_irq_save_hw(flags);
processor = smp_processor_id();
kgdb_info[processor].debuggerinfo = regs;
- kgdb_info[processor].task = current;
+ kgdb_info[processor].task = ipipe_safe_current();
atomic_set(&procindebug[processor], 1);
/* Wait till master processor goes completely into the debugger.
@@ -769,7 +769,7 @@
/* Signal the master processor that we are done */
atomic_set(&procindebug[processor], 0);
spin_unlock(&slavecpulocks[processor]);
- local_irq_restore(flags);
+ local_irq_restore_hw(flags);
}
#endif
@@ -883,8 +883,8 @@
kgdb_break[i].saved_instr)))
return error;
- if (CACHE_FLUSH_IS_SAFE && current->mm &&
- addr < TASK_SIZE)
+ if (CACHE_FLUSH_IS_SAFE && ipipe_safe_current() == current &&
+ current->mm && addr < TASK_SIZE)
flush_cache_range(current->mm->mmap_cache,
addr, addr + BREAK_INSTR_SIZE);
else if (CACHE_FLUSH_IS_SAFE)
@@ -1032,7 +1032,7 @@
* Interrupts will be restored by the 'trap return' code, except when
* single stepping.
*/
- local_irq_save(flags);
+ local_irq_save_hw(flags);
/* Hold debugger_active */
procid = smp_processor_id();
@@ -1055,7 +1055,7 @@
if (atomic_read(&cpu_doing_single_step) != -1 &&
atomic_read(&cpu_doing_single_step) != procid) {
atomic_set(&debugger_active, 0);
- local_irq_restore(flags);
+ local_irq_restore_hw(flags);
goto acquirelock;
}
@@ -1068,7 +1068,7 @@
goto kgdb_restore;
kgdb_info[processor].debuggerinfo = linux_regs;
- kgdb_info[processor].task = current;
+ kgdb_info[processor].task = ipipe_safe_current();
kgdb_disable_hw_debug(linux_regs);
@@ -1120,7 +1120,8 @@
*ptr++ = hexchars[(signo >> 4) % 16];
*ptr++ = hexchars[signo % 16];
ptr += strlen(strcpy(ptr, "thread:"));
- int_to_threadref(&thref, shadow_pid(current->pid));
+ int_to_threadref(&thref,
+ shadow_pid(ipipe_safe_current()->pid));
ptr = pack_threadid(ptr, &thref);
*ptr++ = ';';
@@ -1212,7 +1213,8 @@
kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs,
NUMREGBYTES);
- if (kgdb_usethread && kgdb_usethread != current)
+ if (kgdb_usethread &&
+ kgdb_usethread != ipipe_safe_current())
error_packet(remcom_out_buffer, -EINVAL);
else {
gdb_regs_to_regs(gdb_regs, linux_regs);
@@ -1333,7 +1335,8 @@
/* Current thread id */
strcpy(remcom_out_buffer, "QC");
- threadid = shadow_pid(current->pid);
+ threadid =
+ shadow_pid(ipipe_safe_current()->pid);
int_to_threadref(&thref, threadid);
pack_threadid(remcom_out_buffer + 2, &thref);
@@ -1487,7 +1490,8 @@
break;
case 'c':
case 's':
- if (kgdb_contthread && kgdb_contthread != current) {
+ if (kgdb_contthread &&
+ kgdb_contthread != ipipe_safe_current()) {
/* Can't switch threads in kgdb */
error_packet(remcom_out_buffer, -EINVAL);
break;
@@ -1555,7 +1559,7 @@
kgdb_restore:
/* Free debugger_active */
atomic_set(&debugger_active, 0);
- local_irq_restore(flags);
+ local_irq_restore_hw(flags);
return error;
}
@@ -1924,9 +1928,9 @@
if (!kgdb_connected || atomic_read(&debugger_active) != 0)
return 0;
if ((code == SYS_RESTART) || (code == SYS_HALT) || (code == SYS_POWER_OFF)){
- local_irq_save(flags);
+ local_irq_save_hw(flags);
put_packet("X00");
- local_irq_restore(flags);
+ local_irq_restore_hw(flags);
}
return NOTIFY_DONE;
}
@@ -1941,10 +1945,10 @@
if (!kgdb_connected || atomic_read(&debugger_active) != 0)
return;
- local_irq_save(flags);
+ local_irq_save_hw(flags);
kgdb_msg_write(s, count);
- local_irq_restore(flags);
+ local_irq_restore_hw(flags);
}
static struct console kgdbcons = {
--- 2.6.16-base/lib/Kconfig.debug 2006-06-07 16:40:21.000000000 +0200
+++ 2.6.16-kgdb/lib/Kconfig.debug 2006-06-06 16:01:26.000000000 +0200
@@ -250,7 +250,7 @@
config KGDB_ONLY_MODULES
bool "KGDB: Use only kernel modules for I/O"
- depends on MODULES
+ depends on MODULES && !IPIPE
help
Use only kernel modules to configure KGDB I/O after the
kernel is booted.
@@ -295,8 +295,8 @@
endchoice
config KGDBOE
- tristate "KGDB: On ethernet" if !KGDBOE_NOMODULE
+ tristate "KGDB: On ethernet" if !KGDBOE_NOMODULE && !IPIPE
depends on m && KGDB
select NETPOLL
select NETPOLL_TRAP
--- 2.6.16-base/drivers/serial/8250_kgdb.c 2006-06-07 16:40:20.000000000 +0200
+++ 2.6.16-kgdb/drivers/serial/8250_kgdb.c 2006-06-06 16:01:26.000000000 +0200
@@ -301,6 +301,10 @@
"GDB-stub", current_port) < 0)
printk(KERN_ERR "KGDB failed to request the serial IRQ (%d)\n",
current_port->irq);
+#ifdef CONFIG_IPIPE
+ ipipe_control_irq(current_port->irq, 0,
+ IPIPE_HANDLE_MASK|IPIPE_STICKY_MASK|IPIPE_SYSTEM_MASK);
+#endif /* CONFIG_IPIPE */
}
static __init int kgdb_init_io(void)
--- 2.6.16-base/include/asm-i386/smp.h 2006-03-20 06:53:29.000000000 +0100
+++ 2.6.16-kgdb/include/asm-i386/smp.h 2006-06-08 09:49:07.000000000 +0200
@@ -57,7 +57,11 @@
* from the initial startup. We map APIC_BASE very early in page_setup(),
* so this is correct in the x86 case.
*/
+#if defined(CONFIG_KGDB) && defined(CONFIG_IPIPE)
+#define raw_smp_processor_id() ipipe_processor_id()
+#else
#define raw_smp_processor_id() (current_thread_info()->cpu)
+#endif
extern cpumask_t cpu_callout_map;
extern cpumask_t cpu_callin_map;
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