[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>

4 files changed, 63 insertions, 30 deletions

diff --git a/arch/um/include/sysdep-i386/faultinfo.h b/arch/um/include/sysdep-i386/faultinfo.h
new file mode 100644
index 0000000..db437cc
--- /dev/null
+++ b/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
diff --git a/arch/um/include/sysdep-i386/ptrace.h b/arch/um/include/sysdep-i386/ptrace.h
index 661d495..84ec7ff 100644
--- a/arch/um/include/sysdep-i386/ptrace.h
+++ b/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
@@ -71,6 +66,7 @@ union uml_pt_regs {
 	struct tt_regs {
 		long syscall;
 		void *sc;
+                struct faultinfo faultinfo;
 	} tt;
 #endif
 #ifdef UML_CONFIG_MODE_SKAS
@@ -78,9 +74,7 @@ union uml_pt_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
 
diff --git a/arch/um/include/sysdep-i386/sigcontext.h b/arch/um/include/sysdep-i386/sigcontext.h
index dfee589..1fe7292 100644
--- a/arch/um/include/sysdep-i386/sigcontext.h
+++ b/arch/um/include/sysdep-i386/sigcontext.h
@@ -13,15 +13,12 @@
 #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.
@@ -29,9 +26,7 @@
 #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);
diff --git a/arch/um/include/sysdep-i386/skas_ptrace.h b/arch/um/include/sysdep-i386/skas_ptrace.h
new file mode 100644
index 0000000..e27b8a7
--- /dev/null
+++ b/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