runtime: traceback from outermost libc call

If we're in a libc call and get a trap, don't try to traceback the libc call.
Start from the state we had at entry to libc.

If there are multiple libc calls outstanding, remember the outermost one.

Fixes #26393

Change-Id: Icfe8794b95bf3bfd1a0679b456dcde2481dcabf3
Reviewed-on: https://go-review.googlesource.com/124195
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 21 insertions, 7 deletions

diff --git a/src/runtime/os_solaris.go b/src/runtime/os_solaris.go
index 703a2e5430..4575b5e641 100644
--- a/src/runtime/os_solaris.go
+++ b/src/runtime/os_solaris.go
@@ -37,12 +37,14 @@ func sysvicall0(fn *libcFunc) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil // See comment in sys_darwin.go:libcCall
 	}
 
 	var libcall libcall
@@ -64,12 +66,14 @@ func sysvicall1(fn *libcFunc, a1 uintptr) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil
 	}
 
 	var libcall libcall
@@ -92,12 +96,14 @@ func sysvicall2(fn *libcFunc, a1, a2 uintptr) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil
 	}
 
 	var libcall libcall
@@ -119,12 +125,14 @@ func sysvicall3(fn *libcFunc, a1, a2, a3 uintptr) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil
 	}
 
 	var libcall libcall
@@ -146,12 +154,14 @@ func sysvicall4(fn *libcFunc, a1, a2, a3, a4 uintptr) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil
 	}
 
 	var libcall libcall
@@ -173,12 +183,14 @@ func sysvicall5(fn *libcFunc, a1, a2, a3, a4, a5 uintptr) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil
 	}
 
 	var libcall libcall
@@ -200,12 +212,14 @@ func sysvicall6(fn *libcFunc, a1, a2, a3, a4, a5, a6 uintptr) uintptr {
 	if gp != nil {
 		mp = gp.m
 	}
-	if mp != nil {
+	if mp != nil && mp.libcallsp == 0 {
 		mp.libcallg.set(gp)
 		mp.libcallpc = getcallerpc()
 		// sp must be the last, because once async cpu profiler finds
 		// all three values to be non-zero, it will use them
 		mp.libcallsp = getcallersp()
+	} else {
+		mp = nil
 	}
 
 	var libcall libcall