- Don't bother traversing trap frames in stack_save(). This fixes panics

  when option DEBUG_LOCKS is used. Trap frames are determined by checking
  whether the caller was one of the tl0_*() or tl1_*() asm functions via
  a newly added pair of dummy symbols in exception.S which mark the begin
  and end of these functions. The tl_trap_* pair marks those in the special
  .trap section and the tl_text_* in the regular .text section. Because
  of their performance penalty db_search_symbol()/db_symbol_values() and
  linker_ddb_search_symbol()/linker_ddb_symbol_values() aren't used here
  for determining the caller, with db_search_symbol()/db_symbol_values()
  additionally not being reentrant.
- For consistency, change db_backtrace() to also use the new markers for
  determining the tl0_*() and tl1_*() asm functions instead of bcmp()'ing
  the symbol name.
- Use FBSDID in db_trace.c.

PR:			93226
Based on a patch by:	Antoine Brodin <antoine.brodin@laposte.net>
Ok'ed by:		jhb

2 files changed, 34 insertions, 4 deletions

diff --git a/sys/sparc64/sparc64/db_trace.c b/sys/sparc64/sparc64/db_trace.c
index 66cc76b..bb5f60c 100644
--- a/sys/sparc64/sparc64/db_trace.c
+++ b/sys/sparc64/sparc64/db_trace.c
@@ -22,10 +22,11 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kdb.h>
@@ -49,6 +50,11 @@
 #include <ddb/db_variables.h>
 #include <ddb/db_watch.h>
 
+extern char tl_trap_begin[];
+extern char tl_trap_end[];
+extern char tl_text_begin[];
+extern char tl_text_end[];
+
 #define	INKERNEL(va) \
 	((va) >= VM_MIN_KERNEL_ADDRESS && (va) <= VM_MAX_KERNEL_ADDRESS)
 
@@ -259,8 +265,10 @@ db_backtrace(struct thread *td, struct frame *fp, int count)
 			name = "(null)";
 		fp = (struct frame *)(db_get_value((db_addr_t)&fp->fr_fp,
 		   sizeof(fp->fr_fp), FALSE) + SPOFF);
-		if (bcmp(name, "tl0_", 4) == 0 ||
-		    bcmp(name, "tl1_", 4) == 0) {
+		if ((value > (u_long)tl_trap_begin &&
+		    value < (u_long)tl_trap_end) ||
+		    (value > (u_long)tl_text_begin &&
+		    value < (u_long)tl_text_end)) {
 			tf = (struct trapframe *)(fp + 1);
 			npc = db_get_value((db_addr_t)&tf->tf_tpc,
 			    sizeof(tf->tf_tpc), FALSE);
@@ -307,6 +315,12 @@ stack_save(struct stack *st)
 		callpc = fp->fr_pc;
 		if (!INKERNEL(callpc))
 			break;
+		/* Don't bother traversing trap frames. */
+		if ((callpc > (u_long)tl_trap_begin &&
+		    callpc < (u_long)tl_trap_end) ||
+		    (callpc > (u_long)tl_text_begin &&
+		    callpc < (u_long)tl_text_end))
+			break;
 		if (stack_put(st, callpc) == -1)
 			break;
 		fp = (struct frame *)(fp->fr_fp + SPOFF);
diff --git a/sys/sparc64/sparc64/exception.S b/sys/sparc64/sparc64/exception.S
index d3fcdb8..830a724 100644
--- a/sys/sparc64/sparc64/exception.S
+++ b/sys/sparc64/sparc64/exception.S
@@ -166,6 +166,10 @@ __FBSDID("$FreeBSD$");
 	ldx	[ASP_REG + 0], %g1 ; \
 	inc	16, ASP_REG
 
+	.globl	tl_text_begin
+tl_text_begin:
+	nop
+
 ENTRY(tl1_kstack_fault)
 	rdpr	%tl, %g1
 1:	cmp	%g1, 2
@@ -1818,6 +1822,10 @@ END(tl1_spill_topcb)
 	.endm
 
 	.sect	.trap
+	.globl	tl_trap_begin
+tl_trap_begin:
+	nop
+
 	.align	0x8000
 	.globl	tl0_base
 
@@ -2015,6 +2023,10 @@ tl1_breakpoint:
 	tl1_gen		T_RSTRWP_VIRT			! 0x303
 	tl1_reserved	252				! 0x304-0x3ff
 
+	.globl	tl_trap_end
+tl_trap_end:
+	nop
+
 /*
  * User trap entry point.
  *
@@ -2901,6 +2913,10 @@ ENTRY(tl1_intr)
 	retry
 END(tl1_intr)
 
+	.globl	tl_text_end
+tl_text_end:
+	nop
+
 /*
  * Freshly forked processes come here when switched to for the first time.
  * The arguments to fork_exit() have been setup in the locals, we must move