diff options
| author | Rusty Russell <rusty@rustcorp.com.au> | 2006-09-26 10:52:39 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-09-26 10:52:39 +0200 |
| commit | 78be3706b21a232310590fe00258b224177ac05f (patch) | |
| tree | 57dbe444e57241613067145b04c0e15c98278cd6 /arch/i386/mm/fault.c | |
| parent | 0da5db313317e3195482d3e660a1074857374a89 (diff) | |
[PATCH] i386: Allow a kernel not to be in ring 0
We allow for the fact that the guest kernel may not run in ring 0. This
requires some abstraction in a few places when setting %cs or checking
privilege level (user vs kernel).
This is Chris' [RFC PATCH 15/33] move segment checks to subarch, except rather
than using #define USER_MODE_MASK which depends on a config option, we use
Zach's more flexible approach of assuming ring 3 == userspace. I also used
"get_kernel_rpl()" over "get_kernel_cs()" because I think it reads better in
the code...
1) Remove the hardcoded 3 and introduce #define SEGMENT_RPL_MASK 3 2) Add a
get_kernel_rpl() macro, and don't assume it's zero.
And:
Clean up of patch for letting kernel run other than ring 0:
a. Add some comments about the SEGMENT_IS_*_CODE() macros.
b. Add a USER_RPL macro. (Code was comparing a value to a mask
in some places and to the magic number 3 in other places.)
c. Add macros for table indicator field and use them.
d. Change the entry.S tests for LDT stack segment to use the macros
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/i386/mm/fault.c')
| -rw-r--r-- | arch/i386/mm/fault.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c index 0ce86168a0b..5e17a3f43b4 100644 --- a/arch/i386/mm/fault.c +++ b/arch/i386/mm/fault.c @@ -27,6 +27,7 @@ #include <asm/uaccess.h> #include <asm/desc.h> #include <asm/kdebug.h> +#include <asm/segment.h> extern void die(const char *,struct pt_regs *,long); @@ -113,10 +114,10 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, } /* The standard kernel/user address space limit. */ - *eip_limit = (seg & 3) ? USER_DS.seg : KERNEL_DS.seg; + *eip_limit = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg; /* By far the most common cases. */ - if (likely(seg == __USER_CS || seg == __KERNEL_CS)) + if (likely(SEGMENT_IS_FLAT_CODE(seg))) return eip; /* Check the segment exists, is within the current LDT/GDT size, @@ -430,11 +431,7 @@ good_area: write = 0; switch (error_code & 3) { default: /* 3: write, present */ -#ifdef TEST_VERIFY_AREA - if (regs->cs == KERNEL_CS) - printk("WP fault at %08lx\n", regs->eip); -#endif - /* fall through */ + /* fall through */ case 2: /* write, not present */ if (!(vma->vm_flags & VM_WRITE)) goto bad_area; |