[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, 6 insertions, 11 deletions

diff --git a/arch/um/sys-i386/signal.c b/arch/um/sys-i386/signal.c
index 76ba87254b25..03913ca5d256 100644
--- a/arch/um/sys-i386/signal.c
+++ b/arch/um/sys-i386/signal.c
@@ -47,9 +47,6 @@ static int copy_sc_from_user_skas(struct pt_regs *regs,
         REGS_CS(regs->regs.skas.regs) = sc.cs;
         REGS_EFLAGS(regs->regs.skas.regs) = sc.eflags;
         REGS_SS(regs->regs.skas.regs) = sc.ss;
-        regs->regs.skas.fault_addr = sc.cr2;
-        regs->regs.skas.fault_type = FAULT_WRITE(sc.err);
-        regs->regs.skas.trap_type = sc.trapno;
 
         err = restore_fp_registers(userspace_pid[0], fpregs);
         if(err < 0){
@@ -62,11 +59,11 @@ static int copy_sc_from_user_skas(struct pt_regs *regs,
 }
 
 int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
-                         struct pt_regs *regs, unsigned long fault_addr,
-                         int fault_type)
+                         struct pt_regs *regs)
 {
         struct sigcontext sc;
         unsigned long fpregs[HOST_FP_SIZE];
+        struct faultinfo * fi = &current->thread.arch.faultinfo;
         int err;
 
         sc.gs = REGS_GS(regs->regs.skas.regs);
@@ -86,9 +83,9 @@ int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
         sc.eflags = REGS_EFLAGS(regs->regs.skas.regs);
         sc.esp_at_signal = regs->regs.skas.regs[UESP];
         sc.ss = regs->regs.skas.regs[SS];
-        sc.cr2 = fault_addr;
-        sc.err = TO_SC_ERR(fault_type);
-        sc.trapno = regs->regs.skas.trap_type;
+        sc.cr2 = fi->cr2;
+        sc.err = fi->error_code;
+        sc.trapno = fi->trap_no;
 
         err = save_fp_registers(userspace_pid[0], fpregs);
         if(err < 0){
@@ -167,9 +164,7 @@ static int copy_sc_to_user(struct sigcontext *to, struct _fpstate *fp,
 {
         return(CHOOSE_MODE(copy_sc_to_user_tt(to, fp, UPT_SC(&from->regs),
                                               sizeof(*fp)),
-                           copy_sc_to_user_skas(to, fp, from,
-                                                current->thread.cr2,
-                                                current->thread.err)));
+                           copy_sc_to_user_skas(to, fp, from)));
 }
 
 static int copy_ucontext_to_user(struct ucontext *uc, struct _fpstate *fp,