signal-handling tweaks for mips/mips64

[Alexandre Oliva <aoliva at redhat dot com>]

It was reported to me that ucontext is utterly broken, even in o32
with a stable 32-bit mips kernel.  Indeed, it doesn't match the
ucontext structure defined by the kernel at all.  This means that
programs taking real-time signals in o32 won't be able to extract
correct information from the mcontext_t, since the kernel puts data in
there that's in an entirely different format.

I've looked for any ways in which the current data structures could
possibly be useful, and didn't find any.  gdb and rda thought they
were using the register arrays, but it turned out they were using the
arrays in procps instead.  makecontext(), [sg]etcontext() et al aren't
implemented on mips, so any uses thereof will just return ENOSYS,
without messing with the given data structure.  So, I believe it is
not too late for us to fix it such that it matches the kernel data
structures.

While at that, I fixed a number of incompatibilities introduced by
either differences between kernel headers that we used to include,
whose contents are different depending on whether asm points to
asm-mips or asm-mips64.

With this patch, after some pending kernel patches are checked in, one
will be able to obtain the correct information from signal handlers in
all mips ABIs.  With n64, this is already true.  With o32, it works
with the 32-bit mips kernel, but the mips64 kernel needs a patch to
implement the proper sigcontext ABI.  n32 still a patch to be
developed for it to be possible for ucontext to be POSIX-compliant.
Currently, the kernel uses the same ucontext for n32 and n64, but this
doesn't work in n32 because uc_link must be a pointer and stack_t must
contain a pointer and a size_t, whose sizes differ between n32 and
n64.  I believe Ralf is working on a patch for the kernel to generate
n32-compliant ucontext when invoking signal handlers in n32 processes.
The only uncertainty is whether uc_flags will be a 32- or 64-bit value
in n32; I left it as the latter, just because I already had that in
place; if it changes, a (simplifying) follow-up patch will be posted.
However, I wanted to circulate the idea of fixing ucontext_t for o32
as soon as possible, so I didn't wait for a decision on the exact n32
ABI.

Ok to install?

Index: ChangeLog
from  Alexandre Oliva  <aoliva at redhat dot com>

	* sysdeps/unix/sysv/linux/mips/profil-counter: New.
	* sysdeps/unix/sysv/linux/mips/sigcontextinfo.h: Port to n32/n64.
	* sysdeps/unix/sysv/linux/mips/bits/sigcontext.h: New.
	* sysdeps/unix/sysv/linux/mips/sys/ucontext.h: Port to n32/n64.
	(mcontext_t): Make it match the 32-bit mips kernel in o32.
	* sysdeps/unix/sysv/linux/mips/sys/user.h: Bring in constants from
	the mips and mips64 headers.
	(struct user): Port to n32/n64.

Index: sysdeps/unix/sysv/linux/mips/profil-counter.h
===================================================================
RCS file: sysdeps/unix/sysv/linux/mips/profil-counter.h
diff -N sysdeps/unix/sysv/linux/mips/profil-counter.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ sysdeps/unix/sysv/linux/mips/profil-counter.h 12 Apr 2003 09:13:13 -0000
@@ -0,0 +1,2 @@
+/* We can use the ix86 version.  */
+#include <sysdeps/unix/sysv/linux/i386/profil-counter.h>
Index: sysdeps/unix/sysv/linux/mips/sigcontextinfo.h
===================================================================
RCS file: /cvs/glibc/libc/sysdeps/unix/sysv/linux/mips/sigcontextinfo.h,v
retrieving revision 1.6
diff -u -p -r1.6 sigcontextinfo.h
--- sysdeps/unix/sysv/linux/mips/sigcontextinfo.h 6 Jul 2001 04:56:18 -0000 1.6
+++ sysdeps/unix/sysv/linux/mips/sigcontextinfo.h 12 Apr 2003 09:13:13 -0000
@@ -1,4 +1,4 @@
-/* Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+/* Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Andreas Jaeger <aj at suse dot de>, 2000.
 
@@ -18,6 +18,8 @@
    02111-1307 USA.  */
 
 
+#if _MIPS_SIM == _MIPS_SIM_ABI32
+
 #define SIGCONTEXT unsigned long _code, struct sigcontext *
 #define SIGCONTEXT_EXTRA_ARGS _code,
 #define GET_PC(ctx)	((void *) ctx->sc_pc)
@@ -25,3 +27,15 @@
 #define GET_STACK(ctx)	((void *) ctx->sc_regs[29])
 #define CALL_SIGHANDLER(handler, signo, ctx) \
   (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
+
+#else
+
+#define SIGCONTEXT unsigned long _code, ucontext_t *
+#define SIGCONTEXT_EXTRA_ARGS _code,
+#define GET_PC(ctx)	((void *) ctx->uc_mcontext.pc)
+#define GET_FRAME(ctx)	((void *) ctx->uc_mcontext.gregs[30])
+#define GET_STACK(ctx)	((void *) ctx->uc_mcontext.gregs[29])
+#define CALL_SIGHANDLER(handler, signo, ctx) \
+  (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
+
+#endif
Index: sysdeps/unix/sysv/linux/mips/bits/sigcontext.h
===================================================================
RCS file: sysdeps/unix/sysv/linux/mips/bits/sigcontext.h
diff -N sysdeps/unix/sysv/linux/mips/bits/sigcontext.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ sysdeps/unix/sysv/linux/mips/bits/sigcontext.h 12 Apr 2003 09:13:13 -0000
@@ -0,0 +1,103 @@
+/* Copyright (C) 1996, 1997, 1998, 2003 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
+# error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
+#endif
+
+#ifndef sigcontext_struct
+/* Kernel headers before 2.1.1 define a struct sigcontext_struct, but
+   we need sigcontext.  */
+# define sigcontext_struct sigcontext
+
+/* # include <asm/sigcontext.h> */
+/* Instead of including the kernel header, that will vary depending on
+   whether the 32- or the 64-bit kernel is installed, we paste the
+   contents here.  In case you're wondering about the different
+   licenses, the fact that the file is pasted, instead of included,
+   doesn't really make any difference for the program that includes
+   this header.  */
+#if _MIPS_SIM == _MIPS_SIM_ABI32
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1996, 1997, 2000 by Ralf Baechle
+ */
+#ifndef _ASM_SIGCONTEXT_H
+#define _ASM_SIGCONTEXT_H
+
+/*
+ * Keep this struct definition in sync with the sigcontext fragment
+ * in arch/mips/tools/offset.c
+ */
+struct sigcontext {
+	unsigned int       sc_regmask;		/* Unused */
+	unsigned int       sc_status;
+	unsigned long long sc_pc;
+	unsigned long long sc_regs[32];
+	unsigned long long sc_fpregs[32];
+	unsigned int       sc_ownedfp;		/* Unused */
+	unsigned int       sc_fpc_csr;
+	unsigned int       sc_fpc_eir;		/* Unused */
+	unsigned int       sc_used_math;
+	unsigned int       sc_ssflags;		/* Unused */
+	unsigned long long sc_mdhi;
+	unsigned long long sc_mdlo;
+
+	unsigned int       sc_cause;		/* Unused */
+	unsigned int       sc_badvaddr;		/* Unused */
+
+	unsigned long      sc_sigset[4];	/* kernel's sigset_t */
+};
+
+#endif /* _ASM_SIGCONTEXT_H */
+#else /* _MIPS_SIM != _MIPS_SIM_ABI32 */
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1996, 1997, 1999 by Ralf Baechle
+ * Copyright (C) 1999 Silicon Graphics, Inc.
+ */
+#ifndef _ASM_SIGCONTEXT_H
+#define _ASM_SIGCONTEXT_H
+
+/*
+ * Keep this struct definition in sync with the sigcontext fragment
+ * in arch/mips/tools/offset.c
+ */
+struct sigcontext {
+	unsigned long long sc_regs[32];
+	unsigned long long sc_fpregs[32];
+	unsigned long long sc_mdhi;
+	unsigned long long sc_mdlo;
+	unsigned long long sc_pc;
+	unsigned int       sc_status;
+	unsigned int       sc_fpc_csr;
+	unsigned int       sc_fpc_eir;
+	unsigned int       sc_used_math;
+	unsigned int       sc_cause;
+	unsigned int       sc_badvaddr;
+};
+
+#endif /* _ASM_SIGCONTEXT_H */
+#endif /* _MIPS_SIM != _MIPS_SIM_ABI32 */
+#endif
Index: sysdeps/unix/sysv/linux/mips/sys/ucontext.h
===================================================================
RCS file: /cvs/glibc/libc/sysdeps/unix/sysv/linux/mips/sys/ucontext.h,v
retrieving revision 1.6
diff -u -p -r1.6 ucontext.h
--- sysdeps/unix/sysv/linux/mips/sys/ucontext.h 17 Mar 2003 15:47:13 -0000 1.6
+++ sysdeps/unix/sysv/linux/mips/sys/ucontext.h 12 Apr 2003 09:13:13 -0000
@@ -29,47 +29,72 @@
 #include <bits/sigcontext.h>
 
 
-/* Type for general register.  */
-#if defined _ABIN32 && _MIPS_SIM == _ABIN32
+/* Type for general register.  Even in o32 we assume 64-bit registers,
+   like the kernel.  */
 __extension__ typedef unsigned long long int greg_t;
-#else
-typedef unsigned long int greg_t;
-#endif
 
 /* Number of general registers.  */
-#define NGREG	37
-#define NFPREG	33
+#define NGREG	32
+#define NFPREG	32
 
 /* Container for all general registers.  */
-/* gregset_t must be an array.  The below declared array corresponds to:
-typedef struct gregset {
-	greg_t	g_regs[32];
-	greg_t	g_hi;
-	greg_t	g_lo;
-	greg_t	g_pad[3];
-} gregset_t;  */
 typedef greg_t gregset_t[NGREG];
 
 /* Container for all FPU registers.  */
 typedef struct fpregset {
 	union {
-		double	fp_dregs[32];
+		double	fp_dregs[NFPREG];
 		struct {
 			float		_fp_fregs;
 			unsigned int	_fp_pad;
-		} fp_fregs[32];
+		} fp_fregs[NFPREG];
 	} fp_r;
-	unsigned int	fp_csr;
-	unsigned int	fp_pad;
 } fpregset_t;
 
 
 /* Context to describe whole processor state.  */
+#if _MIPS_SIM == _MIPS_SIM_ABI32
+/* Earlier versions of glibc for mips had an entirely different
+   definition of mcontext_t, that didn't even resemble the
+   corresponding kernel data structure.  Since all legitimate uses of
+   ucontext_t in glibc mustn't have accessed anything beyond
+   uc_mcontext and, even then, taking a pointer to it, casting it to
+   sigcontext_t, and accessing it as such, which is what it has always
+   been, this can still be rectified.  Fortunately, makecontext,
+   [gs]etcontext et all have never been implemented.  */
 typedef struct
   {
+    unsigned int regmask;
+    unsigned int status;
+    greg_t pc;
     gregset_t gregs;
     fpregset_t fpregs;
+    unsigned int fp_owned;
+    unsigned int fpc_csr;
+    unsigned int fpc_eir;
+    unsigned int used_math;
+    unsigned int ssflags;
+    greg_t mdhi;
+    greg_t mdlo;
+    unsigned int cause;
+    unsigned int badvaddr;
   } mcontext_t;
+#else
+typedef struct
+  {
+    gregset_t gregs;
+    fpregset_t fpregs;
+    greg_t mdhi;
+    greg_t mdlo;
+    greg_t pc;
+    unsigned int status;
+    unsigned int fpc_csr;
+    unsigned int fpc_eir;
+    unsigned int used_math;
+    unsigned int cause;
+    unsigned int badvaddr;
+  } mcontext_t;
+#endif
 
 /* Userlevel context.  */
 typedef struct ucontext
Index: sysdeps/unix/sysv/linux/mips/sys/user.h
===================================================================
RCS file: /cvs/glibc/libc/sysdeps/unix/sysv/linux/mips/sys/user.h,v
retrieving revision 1.1
diff -u -p -r1.1 user.h
--- sysdeps/unix/sysv/linux/mips/sys/user.h 8 Feb 2002 16:21:00 -0000 1.1
+++ sysdeps/unix/sysv/linux/mips/sys/user.h 12 Apr 2003 09:13:13 -0000
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -23,7 +23,154 @@
    too much into it.  Don't use it for anything other than GDB unless
    you know what you are doing.  */
 
-#include <asm/reg.h>
+/* #include <asm/reg.h> */
+/* Instead of including the kernel header, that will vary depending on
+   whether the 32- or the 64-bit kernel is installed, we paste its
+   contents here.  Note that the fact that the file is inline here,
+   instead of included separately, doesn't change in any way the
+   licensing status of a program that includes user.h.  Since this is
+   for gdb alone, and gdb is GPLed, no surprises here.  */
+#if _MIPS_SIM == _MIPS_SIM_ABI32
+/*
+ * Various register offset definitions for debuggers, core file
+ * examiners and whatnot.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1995, 1999 by Ralf Baechle
+ */
+#ifndef __ASM_MIPS_REG_H
+#define __ASM_MIPS_REG_H
+
+/*
+ * This defines/structures correspond to the register layout on stack -
+ * if the order here is changed, it needs to be updated in
+ * include/asm-mips/stackframe.h
+ */
+#define EF_REG0			6
+#define EF_REG1			7
+#define EF_REG2			8
+#define EF_REG3			9
+#define EF_REG4			10
+#define EF_REG5			11
+#define EF_REG6			12
+#define EF_REG7			13
+#define EF_REG8			14
+#define EF_REG9			15
+#define EF_REG10		16
+#define EF_REG11		17
+#define EF_REG12		18
+#define EF_REG13		19
+#define EF_REG14		20
+#define EF_REG15		21
+#define EF_REG16		22
+#define EF_REG17		23
+#define EF_REG18		24
+#define EF_REG19		25
+#define EF_REG20		26
+#define EF_REG21		27
+#define EF_REG22		28
+#define EF_REG23		29
+#define EF_REG24		30
+#define EF_REG25		31
+/*
+ * k0/k1 unsaved
+ */
+#define EF_REG28		34
+#define EF_REG29		35
+#define EF_REG30		36
+#define EF_REG31		37
+
+/*
+ * Saved special registers
+ */
+#define EF_LO			38
+#define EF_HI			39
+
+#define EF_CP0_EPC		40
+#define EF_CP0_BADVADDR		41
+#define EF_CP0_STATUS		42
+#define EF_CP0_CAUSE		43
+
+#define EF_SIZE			180	/* size in bytes */
+
+#endif /* __ASM_MIPS_REG_H */
+
+#else /* _MIPS_SIM != _MIPS_SIM_ABI32 */
+
+/*
+ * Various register offset definitions for debuggers, core file
+ * examiners and whatnot.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1995, 1999 Ralf Baechle
+ * Copyright (C) 1995, 1999 Silicon Graphics
+ */
+#ifndef _ASM_REG_H
+#define _ASM_REG_H
+
+/*
+ * This defines/structures correspond to the register layout on stack -
+ * if the order here is changed, it needs to be updated in
+ * include/asm-mips/stackframe.h
+ */
+#define EF_REG0			 0
+#define EF_REG1			 1
+#define EF_REG2			 2
+#define EF_REG3			 3
+#define EF_REG4			 4
+#define EF_REG5			 5
+#define EF_REG6			 6
+#define EF_REG7			 7
+#define EF_REG8			 8
+#define EF_REG9			 9
+#define EF_REG10		10
+#define EF_REG11		11
+#define EF_REG12		12
+#define EF_REG13		13
+#define EF_REG14		14
+#define EF_REG15		15
+#define EF_REG16		16
+#define EF_REG17		17
+#define EF_REG18		18
+#define EF_REG19		19
+#define EF_REG20		20
+#define EF_REG21		21
+#define EF_REG22		22
+#define EF_REG23		23
+#define EF_REG24		24
+#define EF_REG25		25
+/*
+ * k0/k1 unsaved
+ */
+#define EF_REG28		28
+#define EF_REG29		29
+#define EF_REG30		30
+#define EF_REG31		31
+
+/*
+ * Saved special registers
+ */
+#define EF_LO			32
+#define EF_HI			33
+
+#define EF_CP0_EPC		34
+#define EF_CP0_BADVADDR		35
+#define EF_CP0_STATUS		36
+#define EF_CP0_CAUSE		37
+
+#define EF_SIZE			304	/* size in bytes */
+
+#endif /* _ASM_REG_H */
+
+#endif /* _MIPS_SIM != _MIPS_SIM_ABI32 */
+
+#if _MIPS_SIM == _MIPS_SIM_ABI32
 
 struct user
 {
@@ -39,6 +186,24 @@ struct user
   unsigned long	magic;			/* identifies a core file */
   char		u_comm[32];		/* user command name */
 };
+
+#else
+
+struct user {
+  __extension__ unsigned long	regs[EF_SIZE/8+64]; /* integer and fp regs */
+  __extension__ unsigned long	u_tsize;	/* text size (pages) */
+  __extension__ unsigned long	u_dsize;	/* data size (pages) */
+  __extension__ unsigned long	u_ssize;	/* stack size (pages) */
+  __extension__ unsigned long long start_code;	/* text starting address */
+  __extension__ unsigned long long start_data;	/* data starting address */
+  __extension__ unsigned long long start_stack;	/* stack starting address */
+  __extension__ long long	signal;		/* signal causing core dump */
+  __extension__ unsigned long long u_ar0;	/* help gdb find registers */
+  __extension__ unsigned long long magic;	/* identifies a core file */
+  char		u_comm[32];		/* user command name */
+};
+
+#endif
 
 #define PAGE_SHIFT		12
 #define PAGE_SIZE		(1UL << PAGE_SHIFT)

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva at {redhat dot com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva at {lsd dot ic dot unicamp dot br, gnu.org}
Free Software Evangelist                Professional serial bug killer