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authorTejun Heo <tj@kernel.org>2009-02-09 22:17:40 +0900
committerIngo Molnar <mingo@elte.hu>2009-02-10 00:41:58 +0100
commitd9a89a26e02ef9ed03f74a755a8b4d8f3a066622 (patch)
tree35f3713bca4e6b815f6b9db92dc9d812ec7213ff /arch/x86/kernel
parentf0d96110f9fd98a1a22e03b8adba69508843d910 (diff)
downloadlinux-d9a89a26e02ef9ed03f74a755a8b4d8f3a066622.tar.gz
x86: add %gs accessors for x86_32
Impact: cleanup On x86_32, %gs is handled lazily. It's not saved and restored on kernel entry/exit but only when necessary which usually is during task switch but there are few other places. Currently, it's done by calling savesegment() and loadsegment() explicitly. Define get_user_gs(), set_user_gs() and task_user_gs() and use them instead. While at it, clean up register access macros in signal.c. This cleans up code a bit and will help future changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/process_32.c6
-rw-r--r--arch/x86/kernel/ptrace.c14
-rw-r--r--arch/x86/kernel/signal.c41
-rw-r--r--arch/x86/kernel/vm86_32.c4
4 files changed, 27 insertions, 38 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 1a1ae8edc40c..d58a340e1be3 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -131,7 +131,7 @@ void __show_regs(struct pt_regs *regs, int all)
if (user_mode_vm(regs)) {
sp = regs->sp;
ss = regs->ss & 0xffff;
- savesegment(gs, gs);
+ gs = get_user_gs(regs);
} else {
sp = (unsigned long) (&regs->sp);
savesegment(ss, ss);
@@ -304,7 +304,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
p->thread.ip = (unsigned long) ret_from_fork;
- savesegment(gs, p->thread.gs);
+ task_user_gs(p) = get_user_gs(regs);
tsk = current;
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
@@ -342,7 +342,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
void
start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
{
- __asm__("movl %0, %%gs" : : "r"(0));
+ set_user_gs(regs, 0);
regs->fs = 0;
set_fs(USER_DS);
regs->ds = __USER_DS;
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 0a5df5f82fb9..508b6b57d0c3 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -90,9 +90,10 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
if (offset != offsetof(struct user_regs_struct, gs))
retval = *pt_regs_access(task_pt_regs(task), offset);
else {
- retval = task->thread.gs;
if (task == current)
- savesegment(gs, retval);
+ retval = get_user_gs(task_pt_regs(task));
+ else
+ retval = task_user_gs(task);
}
return retval;
}
@@ -126,13 +127,10 @@ static int set_segment_reg(struct task_struct *task,
break;
case offsetof(struct user_regs_struct, gs):
- task->thread.gs = value;
if (task == current)
- /*
- * The user-mode %gs is not affected by
- * kernel entry, so we must update the CPU.
- */
- loadsegment(gs, value);
+ set_user_gs(task_pt_regs(task), value);
+ else
+ task_user_gs(task) = value;
}
return 0;
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 7fc78b019815..8562387c75a7 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -50,27 +50,23 @@
# define FIX_EFLAGS __FIX_EFLAGS
#endif
-#define COPY(x) { \
- get_user_ex(regs->x, &sc->x); \
-}
+#define COPY(x) do { \
+ get_user_ex(regs->x, &sc->x); \
+} while (0)
-#define COPY_SEG(seg) { \
- unsigned short tmp; \
- get_user_ex(tmp, &sc->seg); \
- regs->seg = tmp; \
-}
+#define GET_SEG(seg) ({ \
+ unsigned short tmp; \
+ get_user_ex(tmp, &sc->seg); \
+ tmp; \
+})
-#define COPY_SEG_CPL3(seg) { \
- unsigned short tmp; \
- get_user_ex(tmp, &sc->seg); \
- regs->seg = tmp | 3; \
-}
+#define COPY_SEG(seg) do { \
+ regs->seg = GET_SEG(seg); \
+} while (0)
-#define GET_SEG(seg) { \
- unsigned short tmp; \
- get_user_ex(tmp, &sc->seg); \
- loadsegment(seg, tmp); \
-}
+#define COPY_SEG_CPL3(seg) do { \
+ regs->seg = GET_SEG(seg) | 3; \
+} while (0)
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
@@ -86,7 +82,7 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
get_user_try {
#ifdef CONFIG_X86_32
- GET_SEG(gs);
+ set_user_gs(regs, GET_SEG(gs));
COPY_SEG(fs);
COPY_SEG(es);
COPY_SEG(ds);
@@ -138,12 +134,7 @@ setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
put_user_try {
#ifdef CONFIG_X86_32
- {
- unsigned int tmp;
-
- savesegment(gs, tmp);
- put_user_ex(tmp, (unsigned int __user *)&sc->gs);
- }
+ put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
put_user_ex(regs->es, (unsigned int __user *)&sc->es);
put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 4eeb5cf9720d..55ea30d2a3d6 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -158,7 +158,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
ret = KVM86->regs32;
ret->fs = current->thread.saved_fs;
- loadsegment(gs, current->thread.saved_gs);
+ set_user_gs(ret, current->thread.saved_gs);
return ret;
}
@@ -323,7 +323,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
info->regs32->ax = 0;
tsk->thread.saved_sp0 = tsk->thread.sp0;
tsk->thread.saved_fs = info->regs32->fs;
- savesegment(gs, tsk->thread.saved_gs);
+ tsk->thread.saved_gs = get_user_gs(info->regs32);
tss = &per_cpu(init_tss, get_cpu());
tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;