[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, 16 insertions, 8 deletions

diff --git a/arch/um/kernel/skas/trap_user.c b/arch/um/kernel/skas/trap_user.c
index 8e9b46d4702e..0dee1d95c806 100644
--- a/arch/um/kernel/skas/trap_user.c
+++ b/arch/um/kernel/skas/trap_user.c
@@ -5,12 +5,15 @@
 
 #include <signal.h>
 #include <errno.h>
-#include "sysdep/ptrace.h"
 #include "signal_user.h"
 #include "user_util.h"
 #include "kern_util.h"
 #include "task.h"
 #include "sigcontext.h"
+#include "skas.h"
+#include "ptrace_user.h"
+#include "sysdep/ptrace.h"
+#include "sysdep/ptrace_user.h"
 
 void sig_handler_common_skas(int sig, void *sc_ptr)
 {
@@ -31,9 +34,11 @@ void sig_handler_common_skas(int sig, void *sc_ptr)
         r = &TASK_REGS(get_current())->skas;
         save_user = r->is_user;
         r->is_user = 0;
-        r->fault_addr = SC_FAULT_ADDR(sc);
-        r->fault_type = SC_FAULT_TYPE(sc);
-        r->trap_type = SC_TRAP_TYPE(sc);
+        if ( sig == SIGFPE || sig == SIGSEGV ||
+             sig == SIGBUS || sig == SIGILL ||
+             sig == SIGTRAP ) {
+                GET_FAULTINFO_FROM_SC(r->faultinfo, sc);
+        }
 
         change_sig(SIGUSR1, 1);
         info = &sig_info[sig];
@@ -45,14 +50,17 @@ void sig_handler_common_skas(int sig, void *sc_ptr)
         r->is_user = save_user;
 }
 
-void user_signal(int sig, union uml_pt_regs *regs)
+extern int ptrace_faultinfo;
+
+void user_signal(int sig, union uml_pt_regs *regs, int pid)
 {
         struct signal_info *info;
+        int segv = ((sig == SIGFPE) || (sig == SIGSEGV) || (sig == SIGBUS) ||
+                    (sig == SIGILL) || (sig == SIGTRAP));
 
         regs->skas.is_user = 1;
-        regs->skas.fault_addr = 0;
-        regs->skas.fault_type = 0;
-        regs->skas.trap_type = 0;
+        if (segv)
+                get_skas_faultinfo(pid, &regs->skas.faultinfo);
         info = &sig_info[sig];
         (*info->handler)(sig, regs);