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x86/debug: Simplify #DB signal code

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There's no point in calculating si_code if it's not going to be used.

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/20200902133200.967434217@infradead.org
This commit is contained in:
Peter Zijlstra 2020-09-02 15:25:55 +02:00 committed by Thomas Gleixner
parent 7043679a98
commit 4182e94369
1 changed files with 9 additions and 6 deletions
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15
arch/x86/kernel/traps.c
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@ -786,15 +786,14 @@ static __always_inline unsigned long debug_read_clear_dr6(void)
static void handle_debug(struct pt_regs *regs, unsigned long dr6)
{
struct task_struct *tsk = current;
bool user_icebp;
int si_code;
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.
*/
user_icebp = !dr6;
icebp = !dr6;
/* Store the virtualized DR6 value */
tsk->thread.debugreg6 = dr6;
@ -813,6 +812,11 @@ static void handle_debug(struct pt_regs *regs, unsigned long dr6)
goto out;
}
/*
* Reload dr6, the notifier might have changed it.
*/
dr6 = tsk->thread.debugreg6;
if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
/*
* Historical junk that used to handle SYSENTER single-stepping.
@ -825,9 +829,8 @@ static void handle_debug(struct pt_regs *regs, unsigned long dr6)
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);
if (dr6 & (DR_STEP | DR_TRAP_BITS) || icebp)
send_sigtrap(regs, 0, get_si_code(dr6));
out:
cond_local_irq_disable(regs);