[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>

2 files changed, 9 insertions, 1 deletions

diff --git a/arch/um/kernel/tt/tracer.c b/arch/um/kernel/tt/tracer.c
index 7b5d937e5955..f7b1753a025c 100644
--- a/arch/um/kernel/tt/tracer.c
+++ b/arch/um/kernel/tt/tracer.c
@@ -89,8 +89,10 @@ void tracer_panic(char *format, ...)
 
 static void tracer_segv(int sig, struct sigcontext sc)
 {
+        struct faultinfo fi;
+        GET_FAULTINFO_FROM_SC(fi, &sc);
         printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
-               SC_FAULT_ADDR(&sc), SC_IP(&sc));
+               FAULT_ADDRESS(fi), SC_IP(&sc));
         while(1)
                 pause();
 }
diff --git a/arch/um/kernel/tt/trap_user.c b/arch/um/kernel/tt/trap_user.c
index 92a3820ca543..fc108615beaf 100644
--- a/arch/um/kernel/tt/trap_user.c
+++ b/arch/um/kernel/tt/trap_user.c
@@ -7,6 +7,7 @@
 #include <errno.h>
 #include <signal.h>
 #include "sysdep/ptrace.h"
+#include "sysdep/sigcontext.h"
 #include "signal_user.h"
 #include "user_util.h"
 #include "kern_util.h"
@@ -28,6 +29,11 @@ void sig_handler_common_tt(int sig, void *sc_ptr)
                 change_sig(SIGSEGV, 1);
 
         r = &TASK_REGS(get_current())->tt;
+        if ( sig == SIGFPE || sig == SIGSEGV ||
+             sig == SIGBUS || sig == SIGILL ||
+             sig == SIGTRAP ) {
+                GET_FAULTINFO_FROM_SC(r->faultinfo, sc);
+        }
         save_regs = *r;
         is_user = user_context(SC_SP(sc));
         r->sc = sc;