[PATCH] uml: S390 preparation, abstract host page fault data

This patch removes the arch-specific fault/trap-infos from thread and
skas-regs.

It adds a new struct faultinfo, that is arch-specific defined in
sysdep/faultinfo.h.

The structure is inserted in thread.arch and thread.regs.skas and
thread.regs.tt

Now, segv and other trap-handlers can copy the contents from regs.X.faultinfo
to thread.arch.faultinfo with one simple assignment.

Also, the number of macros necessary is reduced to

FAULT_ADDRESS(struct faultinfo)
    extracts the faulting address from faultinfo

FAULT_WRITE(struct faultinfo)
    extracts the "is_write" flag

SEGV_IS_FIXABLE(struct faultinfo)
    is true for the fixable segvs, i.e. (TRAP == 14)
    on i386

UPT_FAULTINFO(regs)
    result is (struct faultinfo *) to the faultinfo
    in regs->skas.faultinfo

GET_FAULTINFO_FROM_SC(struct faultinfo, struct sigcontext *)
    copies the relevant parts of the sigcontext to
    struct faultinfo.

On SIGSEGV, call user_signal() instead of handle_segv(), if the architecture
provides the information needed in PTRACE_FAULTINFO, or if PTRACE_FAULTINFO is
missing, because segv-stub will provide the info.

The benefit of the change is, that in case of a non-fixable SIGSEGV, we can
give user processes a SIGSEGV, instead of possibly looping on pagefault
handling.

Since handle_segv() sikked arch_fixup() implicitly by passing ip==0 to segv(),
I changed segv() to call arch_fixup() only, if !is_user.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/include/kern_util.h

@@ -8,6 +8,7 @@
 
 #include "linux/threads.h"
 #include "sysdep/ptrace.h"
+#include "sysdep/faultinfo.h"
 
 extern int ncpus;
 extern char *linux_prog;
@@ -31,8 +32,8 @@ extern int current_pid(void);
 extern unsigned long alloc_stack(int order, int atomic);
 extern int do_signal(void);
 extern int is_stack_fault(unsigned long sp);
-extern unsigned long segv(unsigned long address, unsigned long ip, 
-			  int is_write, int is_user, void *sc);
+extern unsigned long segv(struct faultinfo fi, unsigned long ip,
+			  int is_user, void *sc);
 extern int handle_page_fault(unsigned long address, unsigned long ip,
 			     int is_write, int is_user, int *code_out);
 extern void syscall_ready(void);
@@ -82,7 +83,7 @@ extern void timer_irq(union uml_pt_regs *regs);
 extern void unprotect_stack(unsigned long stack);
 extern void do_uml_exitcalls(void);
 extern int attach_debugger(int idle_pid, int pid, int stop);
-extern void bad_segv(unsigned long address, unsigned long ip, int is_write);
+extern void bad_segv(struct faultinfo fi, unsigned long ip);
 extern int config_gdb(char *str);
 extern int remove_gdb(void);
 extern char *uml_strdup(char *string);

arch/um/include/sysdep-i386/faultinfo.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
+ * Author: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
+ * Licensed under the GPL
+ */
+
+#ifndef __FAULTINFO_I386_H
+#define __FAULTINFO_I386_H
+
+/* this structure contains the full arch-specific faultinfo
+ * from the traps.
+ * On i386, ptrace_faultinfo unfortunately doesn't provide
+ * all the info, since trap_no is missing.
+ * All common elements are defined at the same position in
+ * both structures, thus making it easy to copy the
+ * contents without knowledge about the structure elements.
+ */
+struct faultinfo {
+        int error_code; /* in ptrace_faultinfo misleadingly called is_write */
+        unsigned long cr2; /* in ptrace_faultinfo called addr */
+        int trap_no; /* missing in ptrace_faultinfo */
+};
+
+#define FAULT_WRITE(fi) ((fi).error_code & 2)
+#define FAULT_ADDRESS(fi) ((fi).cr2)
+
+#define PTRACE_FULL_FAULTINFO 0
+
+#endif

arch/um/include/sysdep-i386/ptrace.h

@@ -31,6 +31,7 @@ extern int sysemu_supported;
 #ifdef UML_CONFIG_MODE_SKAS
 
 #include "skas_ptregs.h"
+#include "sysdep/faultinfo.h"
 
 #define REGS_IP(r) ((r)[HOST_IP])
 #define REGS_SP(r) ((r)[HOST_SP])
@@ -53,12 +54,6 @@ extern int sysemu_supported;
 
 #define REGS_RESTART_SYSCALL(r) IP_RESTART_SYSCALL(REGS_IP(r))
 
-#define REGS_SEGV_IS_FIXABLE(r) SEGV_IS_FIXABLE((r)->trap_type)
-
-#define REGS_FAULT_ADDR(r) ((r)->fault_addr)
-
-#define REGS_FAULT_WRITE(r) FAULT_WRITE((r)->fault_type)
-
 #endif
 #ifndef PTRACE_SYSEMU_SINGLESTEP
 #define PTRACE_SYSEMU_SINGLESTEP 32
@@ -71,16 +66,15 @@ union uml_pt_regs {
 	struct tt_regs {
 		long syscall;
 		void *sc;
+                struct faultinfo faultinfo;
 	} tt;
 #endif
 #ifdef UML_CONFIG_MODE_SKAS
 	struct skas_regs {
 		unsigned long regs[HOST_FRAME_SIZE];
 		unsigned long fp[HOST_FP_SIZE];
 		unsigned long xfp[HOST_XFP_SIZE];
-		unsigned long fault_addr;
-		unsigned long fault_type;
-		unsigned long trap_type;
+                struct faultinfo faultinfo;
 		long syscall;
 		int is_user;
 	} skas;
@@ -217,15 +211,8 @@ struct syscall_args {
 #define UPT_SYSCALL_NR(r) UPT_ORIG_EAX(r)
 #define UPT_SYSCALL_RET(r) UPT_EAX(r)
 
-#define UPT_SEGV_IS_FIXABLE(r) \
-	CHOOSE_MODE(SC_SEGV_IS_FIXABLE(UPT_SC(r)), \
-                    REGS_SEGV_IS_FIXABLE(&r->skas))
-
-#define UPT_FAULT_ADDR(r) \
-	__CHOOSE_MODE(SC_FAULT_ADDR(UPT_SC(r)), REGS_FAULT_ADDR(&r->skas))
-
-#define UPT_FAULT_WRITE(r) \
-	CHOOSE_MODE(SC_FAULT_WRITE(UPT_SC(r)), REGS_FAULT_WRITE(&r->skas))
+#define UPT_FAULTINFO(r) \
+        CHOOSE_MODE((&(r)->tt.faultinfo), (&(r)->skas.faultinfo))
 
 #endif
 

arch/um/include/sysdep-i386/sigcontext.h

@@ -13,25 +13,20 @@
 #define SC_RESTART_SYSCALL(sc) IP_RESTART_SYSCALL(SC_IP(sc))
 #define SC_SET_SYSCALL_RETURN(sc, result) SC_EAX(sc) = (result)
 
-#define SC_FAULT_ADDR(sc) SC_CR2(sc)
-#define SC_FAULT_TYPE(sc) SC_ERR(sc)
-
-#define FAULT_WRITE(err) (err & 2)
-#define TO_SC_ERR(is_write) ((is_write) ? 2 : 0)
-
-#define SC_FAULT_WRITE(sc) (FAULT_WRITE(SC_ERR(sc)))
-
-#define SC_TRAP_TYPE(sc) SC_TRAPNO(sc)
+#define GET_FAULTINFO_FROM_SC(fi,sc) \
+	{ \
+		(fi).cr2 = SC_CR2(sc); \
+		(fi).error_code = SC_ERR(sc); \
+		(fi).trap_no = SC_TRAPNO(sc); \
+	}
 
 /* ptrace expects that, at the start of a system call, %eax contains
  * -ENOSYS, so this makes it so.
  */
 #define SC_START_SYSCALL(sc) do SC_EAX(sc) = -ENOSYS; while(0)
 
 /* This is Page Fault */
-#define SEGV_IS_FIXABLE(trap) (trap == 14)
-
-#define SC_SEGV_IS_FIXABLE(sc) (SEGV_IS_FIXABLE(SC_TRAPNO(sc)))
+#define SEGV_IS_FIXABLE(fi) ((fi)->trap_no == 14)
 
 extern unsigned long *sc_sigmask(void *sc_ptr);
 extern int sc_get_fpregs(unsigned long buf, void *sc_ptr);

arch/um/include/sysdep-i386/skas_ptrace.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __SYSDEP_I386_SKAS_PTRACE_H
+#define __SYSDEP_I386_SKAS_PTRACE_H
+
+struct ptrace_faultinfo {
+        int is_write;
+        unsigned long addr;
+};
+
+struct ptrace_ldt {
+        int func;
+        void *ptr;
+        unsigned long bytecount;
+};
+
+#define PTRACE_LDT 54
+
+#endif

arch/um/include/sysdep-ia64/skas_ptrace.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __SYSDEP_IA64_SKAS_PTRACE_H
+#define __SYSDEP_IA64_SKAS_PTRACE_H
+
+struct ptrace_faultinfo {
+        int is_write;
+        unsigned long addr;
+};
+
+struct ptrace_ldt {
+        int func;
+        void *ptr;
+        unsigned long bytecount;
+};
+
+#define PTRACE_LDT 54
+
+#endif

arch/um/include/sysdep-ppc/skas_ptrace.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __SYSDEP_PPC_SKAS_PTRACE_H
+#define __SYSDEP_PPC_SKAS_PTRACE_H
+
+struct ptrace_faultinfo {
+        int is_write;
+        unsigned long addr;
+};
+
+struct ptrace_ldt {
+        int func;
+        void *ptr;
+        unsigned long bytecount;
+};
+
+#define PTRACE_LDT 54
+
+#endif

arch/um/include/sysdep-x86_64/faultinfo.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
+ * Author: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
+ * Licensed under the GPL
+ */
+
+#ifndef __FAULTINFO_X86_64_H
+#define __FAULTINFO_X86_64_H
+
+/* this structure contains the full arch-specific faultinfo
+ * from the traps.
+ * On i386, ptrace_faultinfo unfortunately doesn't provide
+ * all the info, since trap_no is missing.
+ * All common elements are defined at the same position in
+ * both structures, thus making it easy to copy the
+ * contents without knowledge about the structure elements.
+ */
+struct faultinfo {
+        int error_code; /* in ptrace_faultinfo misleadingly called is_write */
+        unsigned long cr2; /* in ptrace_faultinfo called addr */
+        int trap_no; /* missing in ptrace_faultinfo */
+};
+
+#define FAULT_WRITE(fi) ((fi).error_code & 2)
+#define FAULT_ADDRESS(fi) ((fi).cr2)
+
+#define PTRACE_FULL_FAULTINFO 1
+
+#endif

arch/um/include/sysdep-x86_64/ptrace.h

@@ -9,6 +9,7 @@
 
 #include "uml-config.h"
 #include "user_constants.h"
+#include "sysdep/faultinfo.h"
 
 #define MAX_REG_OFFSET (UM_FRAME_SIZE)
 #define MAX_REG_NR ((MAX_REG_OFFSET) / sizeof(unsigned long))
@@ -83,16 +84,15 @@ union uml_pt_regs {
 		long syscall;
 		unsigned long orig_rax;
 		void *sc;
+                struct faultinfo faultinfo;
 	} tt;
 #endif
 #ifdef UML_CONFIG_MODE_SKAS
 	struct skas_regs {
 		/* XXX */
 		unsigned long regs[27];
 		unsigned long fp[65];
-		unsigned long fault_addr;
-		unsigned long fault_type;
-		unsigned long trap_type;
+                struct faultinfo faultinfo;
 		long syscall;
 		int is_user;
 	} skas;
@@ -241,14 +241,8 @@ struct syscall_args {
 	CHOOSE_MODE(SC_SEGV_IS_FIXABLE(UPT_SC(r)), \
                     REGS_SEGV_IS_FIXABLE(&r->skas))
 
-#define UPT_FAULT_ADDR(r) \
-	__CHOOSE_MODE(SC_FAULT_ADDR(UPT_SC(r)), REGS_FAULT_ADDR(&r->skas))
-
-#define UPT_FAULT_WRITE(r) \
-	CHOOSE_MODE(SC_FAULT_WRITE(UPT_SC(r)), REGS_FAULT_WRITE(&r->skas))
-
-#define UPT_TRAP(r) __CHOOSE_MODE(SC_TRAP_TYPE(UPT_SC(r)), REGS_TRAP(&r->skas))
-#define UPT_ERR(r) __CHOOSE_MODE(SC_FAULT_TYPE(UPT_SC(r)), REGS_ERR(&r->skas))
+#define UPT_FAULTINFO(r) \
+        CHOOSE_MODE((&(r)->tt.faultinfo), (&(r)->skas.faultinfo))
 
 #endif
 

arch/um/include/sysdep-x86_64/sigcontext.h

@@ -17,20 +17,21 @@
 #define SC_FAULT_ADDR(sc) SC_CR2(sc)
 #define SC_FAULT_TYPE(sc) SC_ERR(sc)
 
-#define FAULT_WRITE(err) ((err) & 2)
-
-#define SC_FAULT_WRITE(sc) FAULT_WRITE(SC_FAULT_TYPE(sc))
-
-#define SC_TRAP_TYPE(sc) SC_TRAPNO(sc)
+#define GET_FAULTINFO_FROM_SC(fi,sc) \
+	{ \
+		(fi).cr2 = SC_CR2(sc); \
+		(fi).error_code = SC_ERR(sc); \
+		(fi).trap_no = SC_TRAPNO(sc); \
+	}
 
 /* ptrace expects that, at the start of a system call, %eax contains
  * -ENOSYS, so this makes it so.
  */
 
 #define SC_START_SYSCALL(sc) do SC_RAX(sc) = -ENOSYS; while(0)
 
-#define SEGV_IS_FIXABLE(trap) ((trap) == 14)
-#define SC_SEGV_IS_FIXABLE(sc) SEGV_IS_FIXABLE(SC_TRAP_TYPE(sc))
+/* This is Page Fault */
+#define SEGV_IS_FIXABLE(fi) ((fi)->trap_no == 14)
 
 extern unsigned long *sc_sigmask(void *sc_ptr);
 

arch/um/include/sysdep-x86_64/skas_ptrace.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __SYSDEP_X86_64_SKAS_PTRACE_H
+#define __SYSDEP_X86_64_SKAS_PTRACE_H
+
+struct ptrace_faultinfo {
+        int is_write;
+        unsigned long addr;
+};
+
+struct ptrace_ldt {
+        int func;
+        void *ptr;
+        unsigned long bytecount;
+};
+
+#define PTRACE_LDT 54
+
+#endif

arch/um/kernel/ptrace.c

@@ -252,13 +252,13 @@ long sys_ptrace(long request, long pid, long addr, long data)
 		break;
 #endif
 	case PTRACE_FAULTINFO: {
-		struct ptrace_faultinfo fault;
-
-		fault = ((struct ptrace_faultinfo) 
-			{ .is_write	= child->thread.err,
-			  .addr		= child->thread.cr2 });
-		ret = copy_to_user((unsigned long __user *) data, &fault,
-				   sizeof(fault));
+                /* Take the info from thread->arch->faultinfo,
+                 * but transfer max. sizeof(struct ptrace_faultinfo).
+                 * On i386, ptrace_faultinfo is smaller!
+                 */
+                ret = copy_to_user((unsigned long __user *) data,
+                                   &child->thread.arch.faultinfo,
+                                   sizeof(struct ptrace_faultinfo));
 		if(ret)
 			break;
 		break;
@@ -269,6 +269,7 @@ long sys_ptrace(long request, long pid, long addr, long data)
 				   sizeof(child->pending.signal));
 		break;
 
+#ifdef PTRACE_LDT
 	case PTRACE_LDT: {
 		struct ptrace_ldt ldt;
 
@@ -284,6 +285,7 @@ long sys_ptrace(long request, long pid, long addr, long data)
 		ret = -EIO;
 		break;
 	}
+#endif
 #ifdef CONFIG_PROC_MM
 	case PTRACE_SWITCH_MM: {
 		struct mm_struct *old = child->mm;

arch/um/kernel/skas/include/skas.h

@@ -27,9 +27,10 @@ extern void map(int fd, unsigned long virt, unsigned long len, int r, int w,
 extern int unmap(int fd, void *addr, unsigned long len);
 extern int protect(int fd, unsigned long addr, unsigned long len, 
 		   int r, int w, int x);
-extern void user_signal(int sig, union uml_pt_regs *regs);
+extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
 extern int new_mm(int from);
 extern void start_userspace(int cpu);
+extern void get_skas_faultinfo(int pid, struct faultinfo * fi);
 extern long execute_syscall_skas(void *r);
 
 #endif