[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, 10 insertions, 2 deletions

diff --git a/include/asm-um/processor-x86_64.h b/include/asm-um/processor-x86_64.h
index a1ae3a4cd938..0beb9a42ae05 100644
--- a/include/asm-um/processor-x86_64.h
+++ b/include/asm-um/processor-x86_64.h
@@ -7,9 +7,13 @@
 #ifndef __UM_PROCESSOR_X86_64_H
 #define __UM_PROCESSOR_X86_64_H
 
-#include "asm/arch/user.h"
+/* include faultinfo structure */
+#include "sysdep/faultinfo.h"
 
 struct arch_thread {
+        unsigned long debugregs[8];
+        int debugregs_seq;
+        struct faultinfo faultinfo;
 };
 
 /* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
@@ -20,7 +24,11 @@ extern inline void rep_nop(void)
 
 #define cpu_relax()   rep_nop()
 
-#define INIT_ARCH_THREAD { }
+#define INIT_ARCH_THREAD { .debugregs           = { [ 0 ... 7 ] = 0 }, \
+                           .debugregs_seq       = 0, \
+                           .faultinfo           = { 0, 0, 0 } }
+
+#include "asm/arch/user.h"
 
 #define current_text_addr() \
         ({ void *pc; __asm__("movq $1f,%0\n1:":"=g" (pc)); pc; })