diff options
| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2006-12-07 02:14:02 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-12-07 02:14:02 +0100 |
| commit | f95d47caae5302a63d92be9a0292abc90e2a14e1 (patch) | |
| tree | cfa963975d104c56aba28df6c941759175ed4b98 /include/asm-i386/processor.h | |
| parent | 62111195800d80c66cdc69063ea3145878c99fbf (diff) | |
[PATCH] i386: Use %gs as the PDA base-segment in the kernel
This patch is the meat of the PDA change. This patch makes several related
changes:
1: Most significantly, %gs is now used in the kernel. This means that on
entry, the old value of %gs is saved away, and it is reloaded with
__KERNEL_PDA.
2: entry.S constructs the stack in the shape of struct pt_regs, and this
is passed around the kernel so that the process's saved register
state can be accessed.
Unfortunately struct pt_regs doesn't currently have space for %gs
(or %fs). This patch extends pt_regs to add space for gs (no space
is allocated for %fs, since it won't be used, and it would just
complicate the code in entry.S to work around the space).
3: Because %gs is now saved on the stack like %ds, %es and the integer
registers, there are a number of places where it no longer needs to
be handled specially; namely context switch, and saving/restoring the
register state in a signal context.
4: And since kernel threads run in kernel space and call normal kernel
code, they need to be created with their %gs == __KERNEL_PDA.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Diffstat (limited to 'include/asm-i386/processor.h')
| -rw-r--r-- | include/asm-i386/processor.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index a9f2041c7c87..f73cf836e649 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -473,6 +473,7 @@ struct thread_struct { .vm86_info = NULL, \ .sysenter_cs = __KERNEL_CS, \ .io_bitmap_ptr = NULL, \ + .gs = __KERNEL_PDA, \ } /* @@ -500,7 +501,8 @@ static inline void load_esp0(struct tss_struct *tss, struct thread_struct *threa } #define start_thread(regs, new_eip, new_esp) do { \ - __asm__("movl %0,%%fs ; movl %0,%%gs": :"r" (0)); \ + __asm__("movl %0,%%fs": :"r" (0)); \ + regs->xgs = 0; \ set_fs(USER_DS); \ regs->xds = __USER_DS; \ regs->xes = __USER_DS; \ |