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x86/debug: Move cond_local_irq_enable() block into exc_debug_user()

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The cond_local_irq_enable() block, dealing with vm86 and sending
signals is only relevant for #DB-from-user, move it there.

This then reduces handle_debug() to only the notifier call, so rename
it to notify_debug().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.094265982@infradead.org
This commit is contained in:
Peter Zijlstra 2020-09-02 15:25:57 +02:00 committed by Thomas Gleixner
parent 4eb5acc391
commit f0b67c39c1
1 changed files with 29 additions and 29 deletions
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58
arch/x86/kernel/traps.c
View file

@ -783,17 +783,10 @@ static __always_inline unsigned long debug_read_clear_dr6(void)
*
* May run on IST stack.
*/
static bool handle_debug(struct pt_regs *regs, unsigned long *dr6)
static bool notify_debug(struct pt_regs *regs, unsigned long *dr6)
{
struct task_struct *tsk = current;
bool icebp;
/*
* 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.
*/
icebp = !*dr6;
/* Store the virtualized DR6 value */
tsk->thread.debugreg6 = *dr6;
@ -801,26 +794,9 @@ static bool handle_debug(struct pt_regs *regs, unsigned long *dr6)
if (notify_die(DIE_DEBUG, "debug", regs, (long)dr6, 0, SIGTRAP) == NOTIFY_STOP)
return true;
/* It's safe to allow irq's after DR6 has been saved */
cond_local_irq_enable(regs);
if (v8086_mode(regs)) {
handle_vm86_trap((struct kernel_vm86_regs *) regs, 0,
X86_TRAP_DB);
goto out;
}
/*
* Reload dr6, the notifier might have changed it.
*/
/* Reload the DR6 value, the notifier might have changed it */
*dr6 = tsk->thread.debugreg6;
if (*dr6 & (DR_STEP | DR_TRAP_BITS) || icebp)
send_sigtrap(regs, 0, get_si_code(*dr6));
out:
cond_local_irq_disable(regs);
return false;
}
@ -864,7 +840,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
if (!dr6)
goto out;
if (handle_debug(regs, &dr6))
if (notify_debug(regs, &dr6))
goto out;
if (WARN_ON_ONCE(dr6 & DR_STEP)) {
@ -889,6 +865,8 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
static __always_inline void exc_debug_user(struct pt_regs *regs,
unsigned long dr6)
{
bool icebp;
/*
* If something gets miswired and we end up here for a kernel mode
* #DB, we will malfunction.
@ -907,8 +885,30 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
irqentry_enter_from_user_mode(regs);
instrumentation_begin();
handle_debug(regs, &dr6);
/*
* 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.
*/
icebp = !dr6;
if (notify_debug(regs, &dr6))
goto out;
/* It's safe to allow irq's after DR6 has been saved */
local_irq_enable();
if (v8086_mode(regs)) {
handle_vm86_trap((struct kernel_vm86_regs *)regs, 0, X86_TRAP_DB);
goto out_irq;
}
if (dr6 & (DR_STEP | DR_TRAP_BITS) || icebp)
send_sigtrap(regs, 0, get_si_code(dr6));
out_irq:
local_irq_disable();
out:
instrumentation_end();
irqentry_exit_to_user_mode(regs);
}