better debuggers:

	- follow through segmented stacks
	- a couple of fixes to db

R=rsc
DELTA=72  (62 added, 0 deleted, 10 changed)
OCL=15713
CL=15717

diff --git a/src/libmach_amd64/8db.c b/src/libmach_amd64/8db.c
index 3984ea4e9c30176d5cfa9bcee416f2af6becd3e1..d4ee633ff4f8f582e89821420a26a81e4d0ac69e 100644 (file)
--- a/src/libmach_amd64/8db.c
+++ b/src/libmach_amd64/8db.c
@@ -30,6 +30,9 @@
 #include <libc.h>
 #include <bio.h>
 #include <mach_amd64.h>
+#include <ureg_amd64.h>
+
+typedef struct Ureg Ureg_amd64;
 
 /*
  * i386-specific debugger interface
@@ -46,8 +49,10 @@ static       int     i386das(Map*, uvlong, char*, int);
 static int     i386instlen(Map*, uvlong);
 
 static char    STARTSYM[] =    "_main";
+static char    GOSTARTSYM[] =  "sys·goexit";
 static char    PROFSYM[] =     "_mainp";
 static char    FRAMENAME[] =   ".frame";
+static char    RETFROMNEWSTACK[] = "retfromnewstack";
 static char *excname[] =
 {
 [0]    "divide error",
@@ -119,13 +124,46 @@ i386excep(Map *map, Rgetter rget)
                return excname[c];
 }
 
+// borrowed from src/runtime/runtime.h
+struct Stktop
+{
+       uint8*  oldbase;
+       uint8*  oldsp;
+       uint64  magic;
+       uint8*  oldguard;
+};
+
+struct G
+{
+       uvlong  stackguard;     // must not move
+       uvlong  stackbase;      // must not move
+       uvlong  stack0;         // first stack segment
+       // rest not needed
+};
+
 static int
 i386trace(Map *map, uvlong pc, uvlong sp, uvlong link, Tracer trace)
 {
        int i;
        uvlong osp;
-       Symbol s, f;
-
+       Symbol s, f, s1;
+       extern Mach mamd64;
+       int isamd64;
+       struct Stktop *stktop;
+       struct G g;
+       uvlong r15;
+       uvlong retfromnewstack;
+
+       isamd64 = (mach == &mamd64);
+       retfromnewstack = 0;
+       if(isamd64) {
+               get8(map, offsetof(Ureg_amd64, r15), &r15);
+               get8(map, r15+offsetof(struct G, stackguard), &g.stackguard);
+               get8(map, r15+offsetof(struct G, stackbase), &g.stackbase);
+               get8(map, r15+offsetof(struct G, stack0), &g.stack0);
+               if(lookup(0, RETFROMNEWSTACK, &s))
+                       retfromnewstack = s.value;
+       }
        USED(link);
        osp = 0;
        i = 0;
@@ -134,9 +172,24 @@ i386trace(Map *map, uvlong pc, uvlong sp, uvlong link, Tracer trace)
                        break;
                osp = sp;
 
-               if(strcmp(STARTSYM, s.name) == 0 || strcmp(PROFSYM, s.name) == 0)
+               if(strcmp(STARTSYM, s.name) == 0 ||
+                  strcmp(GOSTARTSYM, s.name) == 0 ||
+                  strcmp(PROFSYM, s.name) == 0)
                        break;
 
+               if(pc == retfromnewstack) {
+                       stktop = (struct Stktop*)g.stackbase;
+                       get8(map, (uvlong)&stktop->oldbase, &g.stackbase);
+                       get8(map, (uvlong)&stktop->oldguard, &g.stackguard);
+                       get8(map, (uvlong)&stktop->oldsp, &sp);
+                       get8(map, sp+8, &pc);
+                       (*trace)(map, pc, sp +  8, &s1);
+                       sp += 16;  // two irrelevant calls on stack - morestack, plus the call morestack made
+                       continue;
+                       break;
+               }
+               s1 = s;
+
                if(pc != s.value) {     /* not at first instruction */
                        if(findlocal(&s, FRAMENAME, &f) == 0)
                                break;
@@ -148,7 +201,8 @@ i386trace(Map *map, uvlong pc, uvlong sp, uvlong link, Tracer trace)
                if(pc == 0)
                        break;
 
-               (*trace)(map, pc, sp, &s);
+               if (pc != retfromnewstack)
+                       (*trace)(map, pc, sp, &s1);
                sp += mach->szaddr;
 
                if(++i > 1000)