[PATCH] PPC32: Correct signal handling

[Franz Sirl]

Hi,

as promised, here is the powerpc part to correct libjava signal handling.

Bootstrapped and regtested on powerpc-linux.

OK to commit to mainline and 3.3 branch?

Franz.

gcc/
	* config/rs6000/linux.h (MD_FALLBACK_FRAME_STATE_FOR): Partly revert
	2003-01-23 patch. Corrected to handle kernels with changed ucontext.

libjava/
	* include/powerpc-signal.h: New File.
	* configure.in: Use it.
	* configure: Regenerated.

-------------- next part --------------
Index: gcc/config/rs6000/linux.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/linux.h,v
retrieving revision 1.40
diff -u -p -r1.40 linux.h
--- gcc/config/rs6000/linux.h	7 Jun 2003 17:11:47 -0000	1.40
+++ gcc/config/rs6000/linux.h	17 Jun 2003 11:49:55 -0000
@@ -93,7 +93,18 @@
 
 #ifdef IN_LIBGCC2
 #include <signal.h>
-#include <sys/ucontext.h>
+
+/* During the 2.5 kernel series the kernel ucontext was changed, but
+   the new layout is compatible with the old one, so we just define
+   and use the old one here for simplicity and compatibility.  */
+
+struct kernel_old_ucontext {
+  unsigned long     uc_flags;
+  struct ucontext  *uc_link;
+  stack_t           uc_stack;
+  struct sigcontext_struct uc_mcontext;
+  sigset_t          uc_sigmask;
+};
 
 enum { SIGNAL_FRAMESIZE = 64 };
 #endif
@@ -129,7 +140,7 @@ enum { SIGNAL_FRAMESIZE = 64 };
 	  struct siginfo *pinfo;					\
 	  void *puc;							\
 	  struct siginfo info;						\
-	  struct ucontext uc;						\
+	  struct kernel_old_ucontext uc;				\
 	} *rt_ = (CONTEXT)->cfa;					\
 	sc_ = &rt_->uc.uc_mcontext;					\
       }									\
@@ -153,15 +164,9 @@ enum { SIGNAL_FRAMESIZE = 64 };
     (FS)->regs.reg[LINK_REGISTER_REGNUM].loc.offset 			\
       = (long)&(sc_->regs->link) - new_cfa_;				\
 									\
-    /* The unwinder expects the IP to point to the following insn,	\
-       whereas the kernel returns the address of the actual		\
-       faulting insn. We store NIP+4 in an unused register slot to	\
-       get the same result for multiple evaluation of the same signal	\
-       frame.  */							\
-    sc_->regs->gpr[47] = sc_->regs->nip + 4;  				\
     (FS)->regs.reg[CR0_REGNO].how = REG_SAVED_OFFSET;			\
     (FS)->regs.reg[CR0_REGNO].loc.offset 				\
-      = (long)&(sc_->regs->gpr[47]) - new_cfa_;				\
+      = (long)&(sc_->regs->nip) - new_cfa_;				\
     (FS)->retaddr_column = CR0_REGNO;					\
     goto SUCCESS;							\
   } while (0)
Index: libjava/configure.in
===================================================================
RCS file: /cvs/gcc/gcc/libjava/configure.in,v
retrieving revision 1.156
diff -u -p -r1.156 configure.in
--- libjava/configure.in	28 Mar 2003 23:40:51 -0000	1.156
+++ libjava/configure.in	17 Jun 2003 11:49:55 -0000
@@ -1004,7 +1004,7 @@ case "${host}" in
     SIGNAL_HANDLER=include/dwarf2-signal.h
     ;;
  powerpc-*-linux*)
-    SIGNAL_HANDLER=include/dwarf2-signal.h
+    SIGNAL_HANDLER=include/powerpc-signal.h
     ;;
  alpha*-*-linux*)
     SIGNAL_HANDLER=include/dwarf2-signal.h
--- /dev/null	2003-06-04 20:59:54.000000000 +0200
+++ libjava/include/powerpc-signal.h	2003-06-17 13:49:45.675745519 +0200
@@ -0,0 +1,87 @@
+// powerpc-signal.h - Catch runtime signals and turn them into exceptions
+// on a powerpc based Linux system.
+
+/* Copyright (C) 2003  Free Software Foundation
+
+   This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
+details.  */
+
+
+#ifndef JAVA_SIGNAL_H
+# define JAVA_SIGNAL_H 1
+
+# include <signal.h>
+# include <sys/syscall.h>
+
+# define HANDLE_SEGV 1
+# undef HANDLE_FPE
+
+# define SIGNAL_HANDLER(_name)						\
+  static void _name (int /* _signal */, struct sigcontext *_sc)
+
+/* PPC either leaves PC pointing at a faulting instruction or the
+   following instruction, depending on the signal.  SEGV always does
+   the former, so we adjust the saved PC to point to the following
+   instruction. This is what the handler in libgcc expects.  */
+
+# define MAKE_THROW_FRAME(_exception)					\
+do									\
+  {									\
+    _sc->regs->nip += 4;						\
+  }									\
+while (0)
+  
+/* For an explanation why we cannot simply use sigaction to
+   install the handlers, see i386-signal.h.  */
+
+/* We use kernel_old_sigaction here because we're calling the kernel
+   directly rather than via glibc. The sigaction structure that the
+   syscall uses is a different shape from the one in userland and not
+   visible to us in a header file so we define it here.
+   Additionally we want a proper prototype for the handler function
+   with the struct sigcontext pointer passed by the kernel as the 2nd
+   argument, which isn't there in userland headers.
+
+   Note that we explicitly avoid the SA_SIGINFO flag in INIT_SEGV and
+   INIT_FPE below. Using the ucontext pointer passed as 3rd argument
+   of a SA_SIGINFO type handler would need complicated backwards
+   compatibility hacks in MAKE_THROW_FRAME, as the ucontext layout
+   on PPC changed during the 2.5 kernel series.  */
+
+struct kernel_old_sigaction {
+  void (*k_sa_handler) (int, struct sigcontext *);
+  unsigned long k_sa_mask;
+  unsigned long k_sa_flags;
+  void (*k_sa_restorer) (void);
+};
+
+# define INIT_SEGV							\
+do									\
+  {									\
+    nullp = new java::lang::NullPointerException ();			\
+    struct kernel_old_sigaction kact;					\
+    kact.k_sa_handler = catch_segv;					\
+    kact.k_sa_mask = 0;							\
+    kact.k_sa_flags = 0;						\
+    syscall (SYS_sigaction, SIGSEGV, &kact, NULL);			\
+  }									\
+while (0)  
+
+# define INIT_FPE							\
+do									\
+  {									\
+    arithexception = new java::lang::ArithmeticException		\
+      (JvNewStringLatin1 ("/ by zero"));				\
+    struct kernel_old_sigaction kact;					\
+    kact.k_sa_handler = catch_fpe;					\
+    kact.k_sa_mask = 0;							\
+    kact.k_sa_flags = 0;						\
+    syscall (SYS_sigaction, SIGFPE, &kact, NULL);			\
+  }									\
+while (0)  
+
+#endif /* JAVA_SIGNAL_H */
+