[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, 7 deletions

diff --git a/arch/um/kernel/trap_user.c b/arch/um/kernel/trap_user.c
index 50a4042a509f..f825a6eda3f5 100644
--- a/arch/um/kernel/trap_user.c
+++ b/arch/um/kernel/trap_user.c
@@ -54,23 +54,22 @@ struct {
 void segv_handler(int sig, union uml_pt_regs *regs)
 {
         int index, max;
+        struct faultinfo * fi = UPT_FAULTINFO(regs);
 
-        if(UPT_IS_USER(regs) && !UPT_SEGV_IS_FIXABLE(regs)){
-                bad_segv(UPT_FAULT_ADDR(regs), UPT_IP(regs), 
-                         UPT_FAULT_WRITE(regs));
+        if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
+                bad_segv(*fi, UPT_IP(regs));
                 return;
         }
         max = sizeof(segfault_record)/sizeof(segfault_record[0]);
         index = next_trap_index(max);
 
         nsegfaults++;
-        segfault_record[index].address = UPT_FAULT_ADDR(regs);
+        segfault_record[index].address = FAULT_ADDRESS(*fi);
         segfault_record[index].pid = os_getpid();
-        segfault_record[index].is_write = UPT_FAULT_WRITE(regs);
+        segfault_record[index].is_write = FAULT_WRITE(*fi);
         segfault_record[index].sp = UPT_SP(regs);
         segfault_record[index].is_user = UPT_IS_USER(regs);
-        segv(UPT_FAULT_ADDR(regs), UPT_IP(regs), UPT_FAULT_WRITE(regs),
-             UPT_IS_USER(regs), regs);
+        segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
 }
 
 void usr2_handler(int sig, union uml_pt_regs *regs)