[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, 5 insertions, 18 deletions

diff --git a/arch/um/include/sysdep-i386/ptrace.h b/arch/um/include/sysdep-i386/ptrace.h
index 661d495e2044..84ec7ff5cf8c 100644
--- a/arch/um/include/sysdep-i386/ptrace.h
+++ b/arch/um/include/sysdep-i386/ptrace.h
@@ -31,6 +31,7 @@ extern int sysemu_supported;
 #ifdef UML_CONFIG_MODE_SKAS
 
 #include "skas_ptregs.h"
+#include "sysdep/faultinfo.h"
 
 #define REGS_IP(r) ((r)[HOST_IP])
 #define REGS_SP(r) ((r)[HOST_SP])
@@ -53,12 +54,6 @@ extern int sysemu_supported;
 
 #define REGS_RESTART_SYSCALL(r) IP_RESTART_SYSCALL(REGS_IP(r))
 
-#define REGS_SEGV_IS_FIXABLE(r) SEGV_IS_FIXABLE((r)->trap_type)
-
-#define REGS_FAULT_ADDR(r) ((r)->fault_addr)
-
-#define REGS_FAULT_WRITE(r) FAULT_WRITE((r)->fault_type)
-
 #endif
 #ifndef PTRACE_SYSEMU_SINGLESTEP
 #define PTRACE_SYSEMU_SINGLESTEP 32
@@ -71,6 +66,7 @@ union uml_pt_regs {
         struct tt_regs {
                 long syscall;
                 void *sc;
+                struct faultinfo faultinfo;
         } tt;
 #endif
 #ifdef UML_CONFIG_MODE_SKAS
@@ -78,9 +74,7 @@ union uml_pt_regs {
                 unsigned long regs[HOST_FRAME_SIZE];
                 unsigned long fp[HOST_FP_SIZE];
                 unsigned long xfp[HOST_XFP_SIZE];
-                unsigned long fault_addr;
-                unsigned long fault_type;
-                unsigned long trap_type;
+                struct faultinfo faultinfo;
                 long syscall;
                 int is_user;
         } skas;
@@ -217,15 +211,8 @@ struct syscall_args {
 #define UPT_SYSCALL_NR(r) UPT_ORIG_EAX(r)
 #define UPT_SYSCALL_RET(r) UPT_EAX(r)
 
-#define UPT_SEGV_IS_FIXABLE(r) \
-        CHOOSE_MODE(SC_SEGV_IS_FIXABLE(UPT_SC(r)), \
-                    REGS_SEGV_IS_FIXABLE(&r->skas))
-
-#define UPT_FAULT_ADDR(r) \
-        __CHOOSE_MODE(SC_FAULT_ADDR(UPT_SC(r)), REGS_FAULT_ADDR(&r->skas))
-
-#define UPT_FAULT_WRITE(r) \
-        CHOOSE_MODE(SC_FAULT_WRITE(UPT_SC(r)), REGS_FAULT_WRITE(&r->skas))
+#define UPT_FAULTINFO(r) \
+        CHOOSE_MODE((&(r)->tt.faultinfo), (&(r)->skas.faultinfo))
 
 #endif