x86, traps: converge do_debug handlers
Make the x86_64-version and the i386-version of do_debug
more similar.
- introduce preempt_conditional_sti/cli to i386. The preempt-count
is now elevated during the trap handler, like on x86_64. It
does not run on a separate stack, however.
- replace an open-coded "send_sigtrap"
- copy some comments
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 7eb1203..953172a 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -88,6 +88,20 @@
local_irq_enable();
}
+static inline void preempt_conditional_sti(struct pt_regs *regs)
+{
+ inc_preempt_count();
+ if (regs->flags & X86_EFLAGS_IF)
+ local_irq_enable();
+}
+
+static inline void preempt_conditional_cli(struct pt_regs *regs)
+{
+ if (regs->flags & X86_EFLAGS_IF)
+ local_irq_disable();
+ dec_preempt_count();
+}
+
static inline void
die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
@@ -498,7 +512,7 @@
dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk = current;
- unsigned int condition;
+ unsigned long condition;
int si_code;
get_debugreg(condition, 6);
@@ -512,9 +526,9 @@
if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
SIGTRAP) == NOTIFY_STOP)
return;
+
/* It's safe to allow irq's after DR6 has been saved */
- if (regs->flags & X86_EFLAGS_IF)
- local_irq_enable();
+ preempt_conditional_sti(regs);
/* Mask out spurious debug traps due to lazy DR7 setting */
if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
@@ -533,16 +547,11 @@
* kernel space (but re-enable TF when returning to user mode).
*/
if (condition & DR_STEP) {
- /*
- * We already checked v86 mode above, so we can
- * check for kernel mode by just checking the CPL
- * of CS.
- */
if (!user_mode(regs))
goto clear_TF_reenable;
}
- si_code = get_si_code((unsigned long)condition);
+ si_code = get_si_code(condition);
/* Ok, finally something we can handle */
send_sigtrap(tsk, regs, error_code, si_code);
@@ -552,15 +561,18 @@
*/
clear_dr7:
set_debugreg(0, 7);
+ preempt_conditional_cli(regs);
return;
debug_vm86:
handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
+ preempt_conditional_cli(regs);
return;
clear_TF_reenable:
set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
regs->flags &= ~X86_EFLAGS_TF;
+ preempt_conditional_cli(regs);
return;
}