From 7a4ce23d655fdc6eb8b971b11fb01e1dafd02db6 Mon Sep 17 00:00:00 2001 From: Luuk van Dijk Date: Wed, 15 Dec 2010 12:00:43 +0100 Subject: [PATCH] [68]l and runtime: GDB support for interfaces and goroutines. R=rsc CC=golang-dev https://golang.org/cl/3477041 --- src/cmd/ld/dwarf.c | 30 +++- src/pkg/runtime/runtime-gdb.py | 250 ++++++++++++++++++++++++++++++-- src/pkg/runtime/runtime_defs.go | 34 ++--- 3 files changed, 280 insertions(+), 34 deletions(-) diff --git a/src/cmd/ld/dwarf.c b/src/cmd/ld/dwarf.c index 21e079a65c5..506c6e5db8d 100644 --- a/src/cmd/ld/dwarf.c +++ b/src/cmd/ld/dwarf.c @@ -11,6 +11,7 @@ // ptype struct '[]uint8' and qualifiers need to be quoted away // - lexical scoping is lost, so gdb gets confused as to which 'main.i' you mean. // - file:line info for variables +// - make strings a typedef so prettyprinters can see the underlying string type // #include "l.h" #include "lib.h" @@ -280,8 +281,9 @@ static struct DWAbbrev { /* IFACETYPE */ { - DW_TAG_interface_type, DW_CHILDREN_no, + DW_TAG_typedef, DW_CHILDREN_yes, DW_AT_name, DW_FORM_string, + DW_AT_type, DW_FORM_ref_addr, 0, 0 }, @@ -957,6 +959,14 @@ decodetype_structfieldoffs(Sym *s, int i) return decode_inuxi(s->p + 10*PtrSize + 0x10 + i*5*PtrSize, 4); // 0x38 / 0x60 } +// InterfaceTYpe.methods.len +static vlong +decodetype_ifacemethodcount(Sym *s) +{ + return decode_inuxi(s->p + 6*PtrSize + 8, 4); +} + + // Fake attributes for slices, maps and channel enum { DW_AT_internal_elem_type = 250, // channels and slices @@ -1095,6 +1105,12 @@ defgotype(Sym *gotype) case KindInterface: die = newdie(&dwtypes, DW_ABRV_IFACETYPE, name); newattr(die, DW_AT_byte_size, DW_CLS_CONSTANT, bytesize, 0); + nfields = decodetype_ifacemethodcount(gotype); + if (nfields == 0) + s = lookup("type.runtime.eface", 0); + else + s = lookup("type.runtime.iface", 0); + newrefattr(die, DW_AT_type, defgotype(s)); break; case KindMap: @@ -1425,9 +1441,14 @@ defdwsymb(Sym* sym, char *s, int t, vlong v, vlong size, int ver, Sym *gotype) return; if (strncmp(s, "string.", 7) == 0) return; - if (strncmp(s, "type.", 5) == 0) + if (strncmp(s, "type._.", 7) == 0) return; + if (strncmp(s, "type.", 5) == 0) { + defgotype(sym); + return; + } + dv = nil; switch (t) { @@ -2291,6 +2312,11 @@ dwarfemitdebugsections(void) newattr(die, DW_AT_encoding, DW_CLS_CONSTANT, DW_ATE_unsigned, 0); newattr(die, DW_AT_byte_size, DW_CLS_CONSTANT, PtrSize, 0); + // Needed by the prettyprinter code for interface inspection. + defgotype(lookup("type.runtime.commonType",0)); + defgotype(lookup("type.runtime.InterfaceType",0)); + defgotype(lookup("type.runtime.itab",0)); + genasmsym(defdwsymb); writeabbrev(); diff --git a/src/pkg/runtime/runtime-gdb.py b/src/pkg/runtime/runtime-gdb.py index 422809e4172..a7ca94cdb0b 100644 --- a/src/pkg/runtime/runtime-gdb.py +++ b/src/pkg/runtime/runtime-gdb.py @@ -9,10 +9,20 @@ section in the compiled binary. The [68]l linkers emit this with a path to this file based on the path to the runtime package. """ +# Known issues: +# - pretty printing only works for the 'native' strings. E.g. 'type +# foo string' will make foo a plain struct in the eyes of gdb, +# circumventing the pretty print triggering. +# - + import sys, re print >>sys.stderr, "Loading Go Runtime support." +# allow to manually reload while developing +goobjfile = gdb.current_objfile() or gdb.objfiles()[0] +goobjfile.pretty_printers = [] + # # Pretty Printers # @@ -95,7 +105,7 @@ class MapTypePrinter: class ChanTypePrinter: """Pretty print chan[T] types. - Map-typed go variables are really pointers. dereference them in gdb + Chan-typed go variables are really pointers. dereference them in gdb to inspect their contents with this pretty printer. """ @@ -117,18 +127,109 @@ class ChanTypePrinter: ptr = ptr['link'] # -# Register all the *Printer classes +# Register all the *Printer classes above. # def makematcher(klass): def matcher(val): try: - if klass.pattern.match(str(val.type)): return klass(val) - except: pass + if klass.pattern.match(str(val.type)): + return klass(val) + except: + pass return matcher -gdb.current_objfile().pretty_printers.extend([makematcher(k) for k in vars().values() if hasattr(k, 'pattern')]) +goobjfile.pretty_printers.extend([makematcher(k) for k in vars().values() if hasattr(k, 'pattern')]) +# +# For reference, this is what we're trying to do: +# eface: p *(*(struct 'runtime.commonType'*)'main.e'->type_->data)->string +# iface: p *(*(struct 'runtime.commonType'*)'main.s'->tab->Type->data)->string +# +# interface types can't be recognized by their name, instead we check +# if they have the expected fields. Unfortunately the mapping of +# fields to python attributes in gdb.py isn't complete: you can't test +# for presence other than by trapping. + + +def is_iface(val): + try: + return str(val['tab'].type) == "struct runtime.itab *" \ + and str(val['data'].type) == "void *" + except: + pass + +def is_eface(val): + try: + return str(val['type_'].type) == "runtime.Type *" \ + and str(val['data'].type) == "void *" + except: + pass + +def lookup_type(name): + try: + return gdb.lookup_type(name) + except: + pass + try: + return gdb.lookup_type('struct ' + name) + except: + pass + try: + return gdb.lookup_type('struct ' + name[1:]).pointer() + except: + pass + + +def iface_dtype(obj): + "Decode type of the data field of an eface or iface struct." + + if is_iface(obj): + go_type_ptr = obj['tab']['Type'] + elif is_eface(obj): + go_type_ptr = obj['type_'] + else: + return + + ct = gdb.lookup_type("struct runtime.commonType").pointer() + dynamic_go_type = go_type_ptr['data'].cast(ct).dereference() + dtype_name = dynamic_go_type['string'].dereference()['str'].string() + type_size = int(dynamic_go_type['size']) + uintptr_size = int(dynamic_go_type['size'].type.sizeof) # size is itself an uintptr + dynamic_gdb_type = lookup_type(dtype_name) + if type_size > uintptr_size: + dynamic_gdb_type = dynamic_gdb_type.pointer() + return dynamic_gdb_type + + +class IfacePrinter: + """Pretty print interface values + + Casts the data field to the appropriate dynamic type.""" + + def __init__(self, val): + self.val = val + + def display_hint(self): + return 'string' + + def to_string(self): + try: + dtype = iface_dtype(self.val) + except: + return "" + try: + return self.val['data'].cast(dtype).dereference() + except: + pass + return self.val['data'].cast(dtype) + + +def ifacematcher(val): + if is_iface(val) or is_eface(val): + return IfacePrinter(val) + +goobjfile.pretty_printers.append(ifacematcher) # # Convenience Functions @@ -137,35 +238,158 @@ gdb.current_objfile().pretty_printers.extend([makematcher(k) for k in vars().val class GoLenFunc(gdb.Function): "Length of strings, slices, maps or channels" - how = ((StringTypePrinter, 'len' ), - (SliceTypePrinter, 'len'), - (MapTypePrinter, 'count'), - (ChanTypePrinter, 'qcount')) + how = ((StringTypePrinter, 'len' ), + (SliceTypePrinter, 'len'), + (MapTypePrinter, 'count'), + (ChanTypePrinter, 'qcount')) def __init__(self): super(GoLenFunc, self).__init__("len") def invoke(self, obj): typename = str(obj.type) - for klass, fld in self.how: + for klass, fld in self.how: if klass.pattern.match(typename): return obj[fld] class GoCapFunc(gdb.Function): "Capacity of slices or channels" - how = ((SliceTypePrinter, 'cap'), - (ChanTypePrinter, 'dataqsiz')) + how = ((SliceTypePrinter, 'cap'), + (ChanTypePrinter, 'dataqsiz')) def __init__(self): super(GoCapFunc, self).__init__("cap") def invoke(self, obj): typename = str(obj.type) - for klass, fld in self.how: + for klass, fld in self.how: if klass.pattern.match(typename): return obj[fld] +class DTypeFunc(gdb.Function): + """Cast Interface values to their dynamic type. + + For non-interface types this behaves as the identity operation. + """ + + def __init__(self): + super(DTypeFunc, self).__init__("dtype") + + def invoke(self, obj): + try: + return obj['data'].cast(iface_dtype(obj)) + except: + pass + return obj + +# +# Commands +# + +sts = ( 'idle', 'runnable', 'running', 'syscall', 'waiting', 'moribund', 'dead', 'recovery') + +def linked_list(ptr, linkfield): + while ptr: + yield ptr + ptr = ptr[linkfield] + + +class GoroutinesCmd(gdb.Command): + "List all goroutines." + + def __init__(self): + super(GoroutinesCmd, self).__init__("info goroutines", gdb.COMMAND_STACK, gdb.COMPLETE_NONE) + + def invoke(self, arg, from_tty): + # args = gdb.string_to_argv(arg) + vp = gdb.lookup_type('void').pointer() + for ptr in linked_list(gdb.parse_and_eval("'runtime.allg'"), 'alllink'): + if ptr['status'] == 6: # 'gdead' + continue + m = ptr['m'] + s = ' ' + if m: + pc = m['sched']['pc'].cast(vp) + sp = m['sched']['sp'].cast(vp) + s = '*' + else: + pc = ptr['sched']['pc'].cast(vp) + sp = ptr['sched']['sp'].cast(vp) + blk = gdb.block_for_pc(long((pc))) + print s, ptr['goid'], "%8s" % sts[long((ptr['status']))], blk.function + +def find_goroutine(goid): + vp = gdb.lookup_type('void').pointer() + for ptr in linked_list(gdb.parse_and_eval("'runtime.allg'"), 'alllink'): + if ptr['status'] == 6: # 'gdead' + continue + if ptr['goid'] == goid: + return [(ptr['m'] or ptr)['sched'][x].cast(vp) for x in 'pc', 'sp'] + return None, None + + +class GoroutineCmd(gdb.Command): + """Execute gdb command in the context of goroutine . + + Switch PC and SP to the ones in the goroutine's G structure, + execute an arbitrary gdb command, and restore PC and SP. + + Usage: (gdb) goroutine + + Note that it is ill-defined to modify state in the context of a goroutine. + Restrict yourself to inspecting values. + """ + + def __init__(self): + super(GoroutineCmd, self).__init__("goroutine", gdb.COMMAND_STACK, gdb.COMPLETE_NONE) + + def invoke(self, arg, from_tty): + goid, cmd = arg.split(None, 1) + pc, sp = find_goroutine(int(goid)) + if not pc: + print "No such goroutine: ", goid + return + save_frame = gdb.selected_frame() + gdb.parse_and_eval('$save_pc = $pc') + gdb.parse_and_eval('$save_sp = $sp') + gdb.parse_and_eval('$pc = 0x%x' % long(pc)) + gdb.parse_and_eval('$sp = 0x%x' % long(sp)) + try: + gdb.execute(cmd) + finally: + gdb.parse_and_eval('$pc = $save_pc') + gdb.parse_and_eval('$sp = $save_sp') + save_frame.select() + + +class GoIfaceCmd(gdb.Command): + "Print Static and dynamic interface types" + + def __init__(self): + super(GoIfaceCmd, self).__init__("iface", gdb.COMMAND_DATA, gdb.COMPLETE_SYMBOL) + + def invoke(self, arg, from_tty): + for obj in gdb.string_to_argv(arg): + try: + #TODO fix quoting for qualified variable names + obj = gdb.parse_and_eval("%s" % obj) + except Exception, e: + print "Can't parse ", obj, ": ", e + continue + + dtype = iface_dtype(obj) + if not dtype: + print "Not an interface: ", obj.type + continue + + print "%s: %s" % (obj.type, dtype) + +# TODO: print interface's methods and dynamic type's func pointers thereof. +#rsc: "to find the number of entries in the itab's Fn field look at itab.inter->numMethods +#i am sure i have the names wrong but look at the interface type and its method count" +# so Itype will start with a commontype which has kind = interface + # # Register all convience functions and CLI commands # diff --git a/src/pkg/runtime/runtime_defs.go b/src/pkg/runtime/runtime_defs.go index 3591444fa37..ba3c3ed7514 100644 --- a/src/pkg/runtime/runtime_defs.go +++ b/src/pkg/runtime/runtime_defs.go @@ -55,19 +55,19 @@ type slice struct { } type gobuf struct { - sp *byte - pc *byte + sp unsafe.Pointer + pc unsafe.Pointer g *g_ } type g_ struct { - stackguard *byte - stackbase *byte + stackguard unsafe.Pointer + stackbase unsafe.Pointer defer_ *defer_ panic_ *panic_ sched gobuf - stack0 *byte - entry *byte + stack0 unsafe.Pointer + entry unsafe.Pointer alllink *g_ param unsafe.Pointer status int16 @@ -168,31 +168,29 @@ const ( type defer_ struct { siz int32 - sp *byte - pc *byte - fn *byte + sp unsafe.Pointer + pc unsafe.Pointer + fn unsafe.Pointer link *defer_ args [8]byte // padded to actual size } type panic_ struct { arg eface - stackbase *byte + stackbase unsafe.Pointer link *panic_ recovered bool } /* - * external data - -// extern register G* g; -// extern register M* m; + * External data. + */ var ( - algarray [amax]Alg - emptystring String + algarray [amax]alg + emptystring string allg *g_ - allm *M + allm *m_ goidgen int32 gomaxprocs int32 panicking int32 @@ -200,5 +198,3 @@ var ( gcwaiting int32 goos *int8 ) - -*/