ugh: runtime support for c++ exception handling

(links, but crashes if an exception is thrown).

ugh: runtime support for c++ exception handling
23869406 · Nickolai Zeldovich · 2a78d8e2 · 23869406 · 23869406 · 23869406
--- a/Makefile
+++ b/Makefile
@@ -32,7 +32,7 @@ COMFLAGS  = -static -g -MD -m64 -O3 -Wall -Werror -DHW_$(HW) -DXV6 \
 	    -mno-sse -mcx16 -mno-red-zone $(INCLUDES)
 COMFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector) -nostdinc -I$(shell $(CC) -print-file-name=include)
 CFLAGS   := $(COMFLAGS) -std=c99 $(CFLAGS)
-CXXFLAGS := $(COMFLAGS) -std=c++0x -Wno-sign-compare -fno-exceptions -fno-rtti -fcheck-new -nostdinc++ $(CXXFLAGS)
+CXXFLAGS := $(COMFLAGS) -std=c++0x -Wno-sign-compare -fno-rtti -fcheck-new -nostdinc++ $(CXXFLAGS)
 ASFLAGS   = -Iinclude -I$(O)/include -m64 -gdwarf-2 -MD -DHW_$(HW) -include param.h
 LDFLAGS   = -m elf_x86_64


--- a/bin/Makefrag
+++ b/bin/Makefrag
 $(O)/bin/%.o: CFLAGS:=$(CFLAGS) -DXV6_USER
-$(O)/bin/%.o: CXXFLAGS:=$(CXXFLAGS) -DXV6_USER
+$(O)/bin/%.o: CXXFLAGS:=$(CXXFLAGS) -DXV6_USER -fno-exceptions

 UPROGS= \
        bench \

--- a/include/kernel.hh
+++ b/include/kernel.hh
@@ -219,7 +219,7 @@ char*           safestrcpy(char*, const char*, size_t);
 extern "C" unsigned int strlen(const char*);
 int             strncmp(const char*, const char*, size_t);
 char*           strncpy(char*, const char*, size_t);
-int             strcmp(const char *p, const char *q);
+extern "C" int  strcmp(const char *p, const char *q);

 // swtch.S
 void            swtch(struct context**, struct context*);

--- a/kernel/Makefrag
+++ b/kernel/Makefrag
@@ -58,13 +58,15 @@ KERN = $(O)/kernel.elf
 ALL += $(KERN)

 $(O)/kernel/%.o: CFLAGS+=-mcmodel=kernel -DXV6_KERNEL
-$(O)/kernel/%.o: CXXFLAGS+=-mcmodel=kernel -DXV6_KERNEL
+$(O)/kernel/%.o: CXXFLAGS+=-mcmodel=kernel -DXV6_KERNEL -fno-exceptions

 $(KERN): $(O)/kernel/boot.o $(OBJS) $(LDEPS) kernel/kernel.ld
 	@echo "  LD     $@"
 	$(Q)mkdir -p $(@D)
 	$(Q)$(LD) $(LDFLAGS) -T kernel/kernel.ld -z max-page-size=4096 -e start \
 		-o $@ $(O)/kernel/boot.o $(OBJS) -L$(O) $(LFLAGS)
+                # $(shell $(CC) -print-file-name=libgcc_eh.a) \
+                # $(shell $(CC) -print-file-name=libsupc++.a)

 $(O)/kernel/%.o: lib/%.cc
 	@echo "  CXX    $@"

--- a/kernel/cpprt.cc
+++ b/kernel/cpprt.cc
@@ -26,34 +26,12 @@ __cxa_pure_virtual(void)
  panic("__cxa_pure_virtual");
 }

-int
-__cxa_guard_acquire(s64 *guard)
-{
-  volatile u8 *x = (u8*) guard;
-  volatile u32 *l = (u32*) (x+4);
-
-  pushcli();
-  while (xchg32(l, 1) != 0)
-    ; /* spin */
-
-  if (*x) {
-    xchg32(l, 0);
-    popcli();
-    return 0;
-  }
-  return 1;
-}
-
-void
-__cxa_guard_release(s64 *guard)
+// Ugh: libsupc++ calls syscall(SYS_futex, ...)
+extern "C" u64 syscall(void);
+u64
+syscall(void)
 {
-  volatile u8 *x = (u8*) guard;
-  volatile u32 *l = (u32*) (x+4);
-
-  *x = 1;
-  __sync_synchronize();
-  xchg32(l, 0);
-  popcli();
+  return 0;
 }

 int
@@ -91,3 +69,99 @@ atomic<u128>::compare_exchange_weak(u128 &__i1, u128 i2, memory_order __m)
 }

 };
+
+extern "C" void abort(void);
+void
+abort(void)
+{
+  panic("abort");
+}
+
+extern "C" void* malloc(size_t);
+void*
+malloc(size_t n)
+{
+  u64* p = (u64*) kmalloc(n+8, "cpprt malloc");
+  *p = n;
+  return p+1;
+}
+
+extern "C" void free(void*);
+void
+free(void* vp)
+{
+  u64* p = (u64*) vp;
+  kmfree(vp, p[-1]);
+}
+
+extern "C" void* realloc(void*, size_t);
+void*
+realloc(void* vp, size_t n)
+{
+  u64* p = (u64*) vp;
+  u64* np = (u64*) malloc(n);
+  memcpy(np, p, p[-1]);
+  free(p);
+  return np;
+}
+
+extern "C" int dl_iterate_phdr(void);
+int
+dl_iterate_phdr(void)
+{
+  return -1;
+}
+
+extern "C" int __sprintf_chk(char* buf, int flags, size_t n, const char* fmt, ...);
+int
+__sprintf_chk(char* buf, int flags, size_t n, const char* fmt, ...)
+{
+  va_list ap;
+
+  va_start(ap, fmt);
+  vsnprintf(buf, n, fmt, ap);
+  va_end(ap);
+
+  return 0; // XXX
+}
+
+extern "C" void __stack_chk_fail(void);
+void
+__stack_chk_fail(void)
+{
+  panic("stack_chk_fail");
+}
+
+extern "C" char* strcpy(char*, const char*);
+char*
+strcpy(char* dst, const char* src)
+{
+  return strncpy(dst, src, __SIZE_MAX__);
+}
+
+// stdio stubs to satisfy libsupc++
+int stderr = 1;
+
+extern "C" int fputc(int c, int stream);
+int
+fputc(int c, int stream)
+{
+  cprintf("%c", (u8) c);
+  return (u8) c;
+}
+
+extern "C" size_t fwrite(const void* buf, size_t n, size_t nmemb, int stream);
+size_t
+fwrite(const void* buf, size_t n, size_t nmemb, int stream)
+{
+  cprintf("%s", (char*) buf);
+  return n;
+}
+
+extern "C" int fputs(const char* s, int stream);
+int
+fputs(const char* s, int stream)
+{
+  cprintf("%s", s);
+  return 0;
+}
--- a/lib/Makefrag
+++ b/lib/Makefrag
 $(O)/lib/%.o: CFLAGS:=$(CFLAGS) -DXV6_USER
-$(O)/lib/%.o: CXXFLAGS:=$(CXXFLAGS) -DXV6_USER
+$(O)/lib/%.o: CXXFLAGS:=$(CXXFLAGS) -DXV6_USER -fno-exceptions

 ULIB = ulib.o usys.o printf.o umalloc.o uthread.o fmt.o stream.o ipc.o \
-       threads.o crt.o wqlib.o wquser.o perf.o wqalloc.o rt.o
+       threads.o crt.o wqlib.o wquser.o perf.o wqalloc.o
 ULIB := $(addprefix $(O)/lib/, $(ULIB))

 .PRECIOUS: $(O)/lib/%.o

--- a/lib/rt.c
+++ b/lib/rt.c
-#include "types.h"
-#include "user.h"
-
-void
-abort(void)
-{
-  char* p = (char*) 1;
-  *p = 1;
-  exit();
-}
-
-int
-dl_iterate_phdr(void)
-{
-  return -1;
-}