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x86: add %gs accessors for x86_32

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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>
This commit is contained in:
Tejun Heo
2009-02-09 22:17:40 +09:00
committed by Ingo Molnar
parent f0d96110f9
commit d9a89a26e0
9 changed files with 41 additions and 45 deletions
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41
arch/x86/kernel/signal.c
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@@ -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);