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 | |
| parent | f2ab4461249df85b20930a7a57b54f39c5ae291a (diff) | |
| download | kernel_samsung_crespo-0998e4228aca046fbd747c3fed909791d52e88eb.zip kernel_samsung_crespo-0998e4228aca046fbd747c3fed909791d52e88eb.tar.gz kernel_samsung_crespo-0998e4228aca046fbd747c3fed909791d52e88eb.tar.bz2 | |
[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>
| -rw-r--r-- | arch/i386/kernel/signal.c | 4 | ||||
| -rw-r--r-- | arch/i386/kernel/traps.c | 5 | ||||
| -rw-r--r-- | include/asm-i386/ptrace.h | 7 |
3 files changed, 11 insertions, 5 deletions
diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c index 7bcda6d..61eb0c8 100644 --- a/arch/i386/kernel/signal.c +++ b/arch/i386/kernel/signal.c @@ -604,7 +604,9 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset) * We want the common case to go fast, which * is why we may in certain cases get here from * kernel mode. Just return without doing anything - * if so. + * if so. vm86 regs switched out by assembly code + * before reaching here, so testing against kernel + * CS suffices. */ if (!user_mode(regs)) return 1; diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c index 1144df0..b2b4bb8 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -210,7 +210,7 @@ void show_registers(struct pt_regs *regs) unsigned short ss; esp = (unsigned long) (®s->esp); - ss = __KERNEL_DS; + savesegment(ss, ss); if (user_mode(regs)) { in_kernel = 0; esp = regs->esp; @@ -267,9 +267,6 @@ static void handle_BUG(struct pt_regs *regs) char c; unsigned long eip; - if (user_mode(regs)) - goto no_bug; /* Not in kernel */ - eip = regs->eip; if (eip < PAGE_OFFSET) diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h index 0553287..7e0f294 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; |