[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, 9 insertions, 7 deletions

diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index ffc599bd85c3..ec19fed7c64b 100644
--- a/arch/um/kernel/ptrace.c
+++ b/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;