mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-24 17:59:32 +00:00
x86/traps: Restructure #DB handling
Now that there are separate entry points, move the kernel/user_mode specifc checks into the entry functions so the common handling code does not need the extra mode checks. Make the code more readable while at it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135315.283276272@linutronix.de
This commit is contained in:
parent
4c0dcd8350
commit
9347f41352
1 changed files with 35 additions and 34 deletions
|
@ -775,39 +775,12 @@ static __always_inline void debug_exit(unsigned long dr7)
|
|||
*
|
||||
* May run on IST stack.
|
||||
*/
|
||||
static noinstr void handle_debug(struct pt_regs *regs, unsigned long dr6)
|
||||
static void noinstr handle_debug(struct pt_regs *regs, unsigned long dr6,
|
||||
bool user_icebp)
|
||||
{
|
||||
struct task_struct *tsk = current;
|
||||
int user_icebp = 0;
|
||||
int si_code;
|
||||
|
||||
/*
|
||||
* The SDM says "The processor clears the BTF flag when it
|
||||
* generates a debug exception." Clear TIF_BLOCKSTEP to keep
|
||||
* TIF_BLOCKSTEP in sync with the hardware BTF flag.
|
||||
*/
|
||||
clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
|
||||
|
||||
if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
|
||||
is_sysenter_singlestep(regs))) {
|
||||
dr6 &= ~DR_STEP;
|
||||
if (!dr6)
|
||||
return;
|
||||
/*
|
||||
* else we might have gotten a single-step trap and hit a
|
||||
* watchpoint at the same time, in which case we should fall
|
||||
* through and handle the watchpoint.
|
||||
*/
|
||||
}
|
||||
|
||||
/*
|
||||
* If dr6 has no reason to give us about the origin of this trap,
|
||||
* then it's very likely the result of an icebp/int01 trap.
|
||||
* User wants a sigtrap for that.
|
||||
*/
|
||||
if (!dr6 && user_mode(regs))
|
||||
user_icebp = 1;
|
||||
|
||||
/* Store the virtualized DR6 value */
|
||||
tsk->thread.debugreg6 = dr6;
|
||||
|
||||
|
@ -832,9 +805,7 @@ static noinstr void handle_debug(struct pt_regs *regs, unsigned long dr6)
|
|||
if (v8086_mode(regs)) {
|
||||
handle_vm86_trap((struct kernel_vm86_regs *) regs, 0,
|
||||
X86_TRAP_DB);
|
||||
cond_local_irq_disable(regs);
|
||||
debug_stack_usage_dec();
|
||||
return;
|
||||
goto out;
|
||||
}
|
||||
|
||||
if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
|
||||
|
@ -848,9 +819,12 @@ static noinstr void handle_debug(struct pt_regs *regs, unsigned long dr6)
|
|||
set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
|
||||
regs->flags &= ~X86_EFLAGS_TF;
|
||||
}
|
||||
|
||||
si_code = get_si_code(tsk->thread.debugreg6);
|
||||
if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
|
||||
send_sigtrap(regs, 0, si_code);
|
||||
|
||||
out:
|
||||
cond_local_irq_disable(regs);
|
||||
debug_stack_usage_dec();
|
||||
}
|
||||
|
@ -859,7 +833,27 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
|
|||
unsigned long dr6)
|
||||
{
|
||||
nmi_enter();
|
||||
handle_debug(regs, dr6);
|
||||
/*
|
||||
* The SDM says "The processor clears the BTF flag when it
|
||||
* generates a debug exception." Clear TIF_BLOCKSTEP to keep
|
||||
* TIF_BLOCKSTEP in sync with the hardware BTF flag.
|
||||
*/
|
||||
clear_thread_flag(TIF_BLOCKSTEP);
|
||||
|
||||
/*
|
||||
* Catch SYSENTER with TF set and clear DR_STEP. If this hit a
|
||||
* watchpoint at the same time then that will still be handled.
|
||||
*/
|
||||
if ((dr6 & DR_STEP) && is_sysenter_singlestep(regs))
|
||||
dr6 &= ~DR_STEP;
|
||||
|
||||
/*
|
||||
* If DR6 is zero, no point in trying to handle it. The kernel is
|
||||
* not using INT1.
|
||||
*/
|
||||
if (dr6)
|
||||
handle_debug(regs, dr6, false);
|
||||
|
||||
nmi_exit();
|
||||
}
|
||||
|
||||
|
@ -867,7 +861,14 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
|
|||
unsigned long dr6)
|
||||
{
|
||||
idtentry_enter(regs);
|
||||
handle_debug(regs, dr6);
|
||||
clear_thread_flag(TIF_BLOCKSTEP);
|
||||
|
||||
/*
|
||||
* If dr6 has no reason to give us about the origin of this trap,
|
||||
* then it's very likely the result of an icebp/int01 trap.
|
||||
* User wants a sigtrap for that.
|
||||
*/
|
||||
handle_debug(regs, dr6, !dr6);
|
||||
idtentry_exit(regs);
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue