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x86/debug: Remove handle_debug(.user) argument 

The handle_debug(.user) argument is used to terminate the #DB handler early
for the INT1-from-kernel case, since the kernel doesn't use INT1.

Remove the argument and handle this explicitly in #DB-from-kernel.

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>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200902133200.907020598@infradead.org
This commit is contained in:
Peter Zijlstra 2020-09-02 15:25:54 +02:00 committed by Thomas Gleixner
parent 20a6e35a94
commit 7043679a98
1 changed files with 10 additions and 11 deletions
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21
arch/x86/kernel/traps.c
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@ -783,25 +783,18 @@ static __always_inline unsigned long debug_read_clear_dr6(void)
*
* May run on IST stack.
*/
static void handle_debug(struct pt_regs *regs, unsigned long dr6, bool user)
static void handle_debug(struct pt_regs *regs, unsigned long dr6)
{
struct task_struct *tsk = current;
bool user_icebp;
int si_code;
/*
* If DR6 is zero, no point in trying to handle it. The kernel is
* not using INT1.
*/
if (!user && !dr6)
return;
/*
* 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 = user && !dr6;
user_icebp = !dr6;
/* Store the virtualized DR6 value */
tsk->thread.debugreg6 = dr6;
@ -874,7 +867,13 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
if (kprobe_debug_handler(regs))
goto out;
handle_debug(regs, dr6, false);
/*
* The kernel doesn't use INT1
*/
if (!dr6)
goto out;
handle_debug(regs, dr6);
out:
instrumentation_end();
@ -904,7 +903,7 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
irqentry_enter_from_user_mode(regs);
instrumentation_begin();
handle_debug(regs, dr6, true);
handle_debug(regs, dr6);
instrumentation_end();
irqentry_exit_to_user_mode(regs);