diff options
| author | Zachary Amsden <zach@vmware.com> | 2005-09-03 15:56:43 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-09-05 00:06:12 -0700 |
| commit | 0998e4228aca046fbd747c3fed909791d52e88eb (patch) | |
| tree | 314cb04a6223100bf468cc420985bfe7e3680d44 /include/asm-i386 | |
| parent | f2ab4461249df85b20930a7a57b54f39c5ae291a (diff) | |
[PATCH] x86: privilege cleanup
Privilege checking cleanup. Originally, these diffs were much greater, but
recent cleanups in Linux have already done much of the cleanup. I added
some explanatory comments in places where the reasoning behind certain
tests is rather subtle.
Also, in traps.c, we can skip the user_mode check in handle_BUG(). The
reason is, there are only two call chains - one via die_if_kernel() and one
via do_page_fault(), both entering from die(). Both of these paths already
ensure that a kernel mode failure has happened. Also, the original check
here, if (user_mode(regs)) was insufficient anyways, since it would not
rule out BUG faults from V8086 mode execution.
Saving the %ss segment in show_regs() rather than assuming a fixed value
also gives better information about the current kernel state in the
register dump.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-i386')
| -rw-r--r-- | include/asm-i386/ptrace.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h index 05532875e39..7e0f2945d17 100644 --- a/include/asm-i386/ptrace.h +++ b/include/asm-i386/ptrace.h @@ -61,6 +61,13 @@ struct pt_regs { struct task_struct; extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code); +/* + * user_mode_vm(regs) determines whether a register set came from user mode. + * This is true if V8086 mode was enabled OR if the register set was from + * protected mode with RPL-3 CS value. This tricky test checks that with + * one comparison. Many places in the kernel can bypass this full check + * if they have already ruled out V8086 mode, so user_mode(regs) can be used. + */ static inline int user_mode(struct pt_regs *regs) { return (regs->xcs & 3) != 0; |