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Date:      Thu, 11 Mar 2010 07:17:14 +0000 (UTC)
From:      Neel Natu <neel@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r204997 - in head/sys/mips: include mips
Message-ID:  <201003110717.o2B7HEhE097772@svn.freebsd.org>
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Author: neel
Date: Thu Mar 11 07:17:14 2010
New Revision: 204997
URL: http://svn.freebsd.org/changeset/base/204997

Log:
  Stash the context of the running thread at the time an IPI_STOP is received
  in 'stoppcbs[]'. We use the 'stoppcbs[]' context to generate the backtrace
  of such stopped threads.

Modified:
  head/sys/mips/include/kdb.h
  head/sys/mips/include/smp.h
  head/sys/mips/mips/db_trace.c
  head/sys/mips/mips/mp_machdep.c
  head/sys/mips/mips/swtch.S

Modified: head/sys/mips/include/kdb.h
==============================================================================
--- head/sys/mips/include/kdb.h	Thu Mar 11 03:18:16 2010	(r204996)
+++ head/sys/mips/include/kdb.h	Thu Mar 11 07:17:14 2010	(r204997)
@@ -32,6 +32,8 @@
 
 #include <machine/frame.h>
 
+#define	KDB_STOPPEDPCB(pc)	&stoppcbs[pc->pc_cpuid]
+
 static __inline void
 kdb_cpu_clear_singlestep(void)
 {

Modified: head/sys/mips/include/smp.h
==============================================================================
--- head/sys/mips/include/smp.h	Thu Mar 11 03:18:16 2010	(r204996)
+++ head/sys/mips/include/smp.h	Thu Mar 11 07:17:14 2010	(r204997)
@@ -17,6 +17,8 @@
 
 #ifdef _KERNEL
 
+#include <machine/pcb.h>
+
 /*
  * Interprocessor interrupts for SMP.
  */
@@ -31,6 +33,8 @@ void	ipi_selected(cpumask_t cpus, int ip
 void	smp_init_secondary(u_int32_t cpuid);
 void	mpentry(void);
 
+extern struct pcb stoppcbs[];
+
 #endif /* !LOCORE */
 #endif /* _KERNEL */
 

Modified: head/sys/mips/mips/db_trace.c
==============================================================================
--- head/sys/mips/mips/db_trace.c	Thu Mar 11 03:18:16 2010	(r204996)
+++ head/sys/mips/mips/db_trace.c	Thu Mar 11 07:17:14 2010	(r204997)
@@ -169,6 +169,12 @@ loop:
 		subr = (uintptr_t)MipsKernTLBInvalidException;
 	else if (pcBetween(MipsUserTLBInvalidException, MipsTLBMissException))
 		subr = (uintptr_t)MipsUserTLBInvalidException;
+	else if (pcBetween(fork_trampoline, savectx))
+		subr = (uintptr_t)fork_trampoline;
+	else if (pcBetween(savectx, mips_cpu_throw))
+		subr = (uintptr_t)savectx;
+	else if (pcBetween(mips_cpu_throw, cpu_switch))
+		subr = (uintptr_t)cpu_throw;
 	else if (pcBetween(cpu_switch, MipsSwitchFPState))
 		subr = (uintptr_t)cpu_switch;
 	else if (pcBetween(_locore, _locoreEnd)) {
@@ -412,10 +418,8 @@ db_trace_thread(struct thread *thr, int 
                          : "=r" (pc)
 			 : "r" (ra));
 
-	}
-
-	else {
-		ctx = thr->td_pcb;
+	} else {
+		ctx = kdb_thr_ctx(thr);
 		sp = (register_t)ctx->pcb_context[PREG_SP];
 		pc = (register_t)ctx->pcb_context[PREG_PC];
 		ra = (register_t)ctx->pcb_context[PREG_RA];

Modified: head/sys/mips/mips/mp_machdep.c
==============================================================================
--- head/sys/mips/mips/mp_machdep.c	Thu Mar 11 03:18:16 2010	(r204996)
+++ head/sys/mips/mips/mp_machdep.c	Thu Mar 11 07:17:14 2010	(r204997)
@@ -50,6 +50,8 @@ __FBSDID("$FreeBSD$");
 #include <machine/intr_machdep.h>
 #include <machine/cache.h>
 
+struct pcb stoppcbs[MAXCPU];
+
 static void *dpcpu;
 static struct mtx ap_boot_mtx;
 
@@ -88,10 +90,14 @@ ipi_selected(cpumask_t cpus, int ipi)
 static int
 mips_ipi_handler(void *arg)
 {
+	int cpu;
 	cpumask_t cpumask;
 	u_int	ipi, ipi_bitmap;
 	int	bit;
 
+	cpu = PCPU_GET(cpuid);
+	cpumask = PCPU_GET(cpumask);
+
 	platform_ipi_clear();	/* quiesce the pending ipi interrupt */
 
 	ipi_bitmap = atomic_readandclear_int(PCPU_PTR(pending_ipis));
@@ -120,10 +126,16 @@ mips_ipi_handler(void *arg)
 			 * necessary to add it in the switch.
 			 */
 			CTR0(KTR_SMP, "IPI_STOP or IPI_STOP_HARD");
-			cpumask = PCPU_GET(cpumask);
+
+			savectx(&stoppcbs[cpu]);
+
+			/* Indicate we are stopped */
 			atomic_set_int(&stopped_cpus, cpumask);
+
+			/* Wait for restart */
 			while ((started_cpus & cpumask) == 0)
 				cpu_spinwait();
+
 			atomic_clear_int(&started_cpus, cpumask);
 			atomic_clear_int(&stopped_cpus, cpumask);
 			CTR0(KTR_SMP, "IPI_STOP (restart)");

Modified: head/sys/mips/mips/swtch.S
==============================================================================
--- head/sys/mips/mips/swtch.S	Thu Mar 11 03:18:16 2010	(r204996)
+++ head/sys/mips/mips/swtch.S	Thu Mar 11 07:17:14 2010	(r204997)
@@ -245,6 +245,14 @@ LEAF(savectx)
 	SAVE_U_PCB_CONTEXT(ra, PREG_RA, a0)
 	SAVE_U_PCB_CONTEXT(v0, PREG_SR, a0)
 	SAVE_U_PCB_CONTEXT(gp, PREG_GP, a0)
+
+	move	v0, ra			/* save 'ra' before we trash it */
+	jal	1f
+	nop
+1:
+	SAVE_U_PCB_CONTEXT(ra, PREG_PC, a0)
+	move	ra, v0			/* restore 'ra' before returning */
+
 	/*
 	 * FREEBSD_DEVELOPERS_FIXME:
 	 * In case there are CPU-specific registers that need

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