[PATCH] uml: x86_64 ptrace fixes

This patch fixes some missing ptrace bits on x86_64.  PTRACE_ARCH_PRCTL is
hooked up and implemented.  This required generalizing arch_prctl_skas
slightly to take a task_struct to modify.  Previously, it always operated on
current.

Reading and writing the debug registers is also enabled by un-ifdefing the
code that implements that.  It turns out that x86_64 is identical to i386, so
the same code can be used.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 6 deletions

diff --git a/arch/um/sys-x86_64/syscalls.c b/arch/um/sys-x86_64/syscalls.c
index f309fa9bc232..01b91f9fa789 100644
--- a/arch/um/sys-x86_64/syscalls.c
+++ b/arch/um/sys-x86_64/syscalls.c
@@ -59,18 +59,20 @@ static long arch_prctl_tt(int code, unsigned long addr)
 
 #ifdef CONFIG_MODE_SKAS
 
-static long arch_prctl_skas(int code, unsigned long __user *addr)
+long arch_prctl_skas(struct task_struct *task, int code,
+                     unsigned long __user *addr)
 {
         unsigned long *ptr = addr, tmp;
         long ret;
-        int pid = current->mm->context.skas.id.u.pid;
+        int pid = task->mm->context.skas.id.u.pid;
 
         /*
          * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
          * be safe), we need to call arch_prctl on the host because
          * setting %fs may result in something else happening (like a
-         * GDT being set instead).  So, we let the host fiddle the
-         * registers and restore them afterwards.
+         * GDT or thread.fs being set instead).  So, we let the host
+         * fiddle the registers and thread struct and restore the
+         * registers afterwards.
          *
          * So, the saved registers are stored to the process (this
          * needed because a stub may have been the last thing to run),
@@ -118,7 +120,7 @@ static long arch_prctl_skas(int code, unsigned long __user *addr)
 
 long sys_arch_prctl(int code, unsigned long addr)
 {
-        return CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, code,
+        return CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, current, code,
                                 (unsigned long __user *) addr);
 }
 
@@ -141,6 +143,6 @@ void arch_switch_to_skas(struct task_struct *from, struct task_struct *to)
         if(to->thread.arch.fs == 0)
                 return;
 
-        arch_prctl_skas(ARCH_SET_FS, (void __user *) to->thread.arch.fs);
+        arch_prctl_skas(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
 }