[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, 4 deletions

diff --git a/arch/um/sys-x86_64/signal.c b/arch/um/sys-x86_64/signal.c
index 5bc5a0d796e5..b740177066a0 100644
--- a/arch/um/sys-x86_64/signal.c
+++ b/arch/um/sys-x86_64/signal.c
@@ -57,7 +57,7 @@ static int copy_sc_from_user_skas(struct pt_regs *regs,
 int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
                         struct pt_regs *regs, unsigned long mask)
 {
-        unsigned long eflags;
+        struct faultinfo * fi = &current->thread.arch.faultinfo;
         int err = 0;
 
         err |= __put_user(0, &to->gs);
@@ -84,14 +84,16 @@ int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
         err |= PUTREG(regs, R14, to, r14);
         err |= PUTREG(regs, R15, to, r15);
         err |= PUTREG(regs, CS, to, cs); /* XXX x86_64 doesn't do this */
-        err |= __put_user(current->thread.err, &to->err);
-        err |= __put_user(current->thread.trap_no, &to->trapno);
+
+        err |= __put_user(fi->cr2, &to->cr2);
+        err |= __put_user(fi->error_code, &to->err);
+        err |= __put_user(fi->trap_no, &to->trapno);
+
         err |= PUTREG(regs, RIP, to, rip);
         err |= PUTREG(regs, EFLAGS, to, eflags);
 #undef PUTREG
 
         err |= __put_user(mask, &to->oldmask);
-        err |= __put_user(current->thread.cr2, &to->cr2);
 
         return(err);
 }