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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>
This commit is contained in:
Alexander van Heukelum 2008-09-30 18:41:37 +02:00 committed by Ingo Molnar
parent e407d62088
commit 3d2a71a596
3 changed files with 30 additions and 21 deletions
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30
arch/x86/kernel/traps_32.c
View File

@ -88,6 +88,20 @@ static inline void conditional_sti(struct pt_regs *regs)
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_int3(struct pt_regs *regs, long error_code)
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 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
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 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
* 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 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
*/
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;
}

17
arch/x86/kernel/traps_64.c
View File

@ -380,7 +380,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk = current;
unsigned long condition;
siginfo_t info;
int si_code;
get_debugreg(condition, 6);
@ -394,6 +394,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
SIGTRAP) == NOTIFY_STOP)
return;
/* It's safe to allow irq's after DR6 has been saved */
preempt_conditional_sti(regs);
/* Mask out spurious debug traps due to lazy DR7 setting */
@ -402,6 +403,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
goto clear_dr7;
}
/* Save debug status register where ptrace can see it */
tsk->thread.debugreg6 = condition;
/*
@ -413,15 +415,14 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
goto clear_TF_reenable;
}
si_code = get_si_code(condition);
/* Ok, finally something we can handle */
tsk->thread.trap_no = 1;
tsk->thread.error_code = error_code;
info.si_signo = SIGTRAP;
info.si_errno = 0;
info.si_code = get_si_code(condition);
info.si_addr = user_mode(regs) ? (void __user *)regs->ip : NULL;
force_sig_info(SIGTRAP, &info, tsk);
send_sigtrap(tsk, regs, error_code, si_code);
/*
* Disable additional traps. They'll be re-enabled when
* the signal is delivered.
*/
clear_dr7:
set_debugreg(0, 7);
preempt_conditional_cli(regs);

4
include/asm-x86/ptrace.h
View File

@ -174,12 +174,8 @@ extern unsigned long profile_pc(struct pt_regs *regs);
extern unsigned long
convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
#ifdef CONFIG_X86_32
extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
int error_code, int si_code);
#endif
void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
extern long syscall_trace_enter(struct pt_regs *);