[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>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/um/include/kern_util.h b/arch/um/include/kern_util.h
index 15389c886b41..e5fec5570199 100644
--- a/arch/um/include/kern_util.h
+++ b/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);