diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 114515b26168..df9c6554f83e 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -749,6 +749,12 @@ static __always_inline unsigned long debug_read_clear_dr6(void) dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ /* + * Clear the virtual DR6 value, ptrace routines will set bits here for + * things we want signals for. + */ + current->thread.virtual_dr6 = 0; + + /* * 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. @@ -785,17 +791,16 @@ static __always_inline unsigned long debug_read_clear_dr6(void) static bool notify_debug(struct pt_regs *regs, unsigned long *dr6) { - struct task_struct *tsk = current; - - /* Store the virtualized DR6 value */ - tsk->thread.debugreg6 = *dr6; - + /* + * Notifiers will clear bits in @dr6 to indicate the event has been + * consumed - hw_breakpoint_handler(), single_stop_cont(). + * + * Notifiers will set bits in @virtual_dr6 to indicate the desire + * for signals - ptrace_triggered(), kgdb_hw_overflow_handler(). + */ if (notify_die(DIE_DEBUG, "debug", regs, (long)dr6, 0, SIGTRAP) == NOTIFY_STOP) return true; - /* Reload the DR6 value, the notifier might have changed it */ - *dr6 = tsk->thread.debugreg6; - return false; } @@ -853,7 +858,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, * A known way to trigger this is through QEMU's GDB stub, * which leaks #DB into the guest and causes IST recursion. */ - if (WARN_ON_ONCE(current->thread.debugreg6 & DR_STEP)) + if (WARN_ON_ONCE(dr6 & DR_STEP)) regs->flags &= ~X86_EFLAGS_TF; out: instrumentation_end(); @@ -903,6 +908,8 @@ static __always_inline void exc_debug_user(struct pt_regs *regs, goto out_irq; } + /* Add the virtual_dr6 bits for signals. */ + dr6 |= current->thread.virtual_dr6; if (dr6 & (DR_STEP | DR_TRAP_BITS) || icebp) send_sigtrap(regs, 0, get_si_code(dr6)); |