x86/debug: Change thread.debugreg6 to thread.virtual_dr6 (d53d9bc0) · Commits · 戴 / test

arch/x86/include/asm/processor.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -517,7 +517,7 @@ struct thread_struct {
		/* Save middle states of ptrace breakpoints */
		struct perf_event *ptrace_bps[HBP_NUM];
		/* Debug status used for traps, single steps, etc... */
		unsigned long debugreg6;
		unsigned long virtual_dr6;
		/* Keep track of the exact dr7 value set by the user */
		unsigned long ptrace_dr7;
		/* Fault info: */

arch/x86/kernel/hw_breakpoint.c

+3 −9

Original line number	Diff line number	Diff line
		@@ -454,7 +454,7 @@ void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
		t->ptrace_bps[i] = NULL;
		}

		t->debugreg6 = 0;
		t->virtual_dr6 = 0;
		t->ptrace_dr7 = 0;
		}

		@@ -489,8 +489,8 @@ static int hw_breakpoint_handler(struct die_args *args)
		{
		int i, rc = NOTIFY_STOP;
		struct perf_event *bp;
		unsigned long dr6;
		unsigned long *dr6_p;
		unsigned long dr6;

		/* The DR6 value is pointed by args->err */
		dr6_p = (unsigned long *)ERR_PTR(args->err);
		@@ -504,12 +504,6 @@ static int hw_breakpoint_handler(struct die_args *args)
		if ((dr6 & DR_TRAP_BITS) == 0)
		return NOTIFY_DONE;

		/*
		* Reset the DRn bits in the virtualized register value.
		* The ptrace trigger routine will add in whatever is needed.
		*/
		current->thread.debugreg6 &= ~DR_TRAP_BITS;

		/* Handle all the breakpoints that were triggered */
		for (i = 0; i < HBP_NUM; ++i) {
		if (likely(!(dr6 & (DR_TRAP0 << i))))
		@@ -554,7 +548,7 @@ static int hw_breakpoint_handler(struct die_args *args)
		* breakpoints (to generate signals) and b) when the system has
		* taken exception due to multiple causes
		*/
		if ((current->thread.debugreg6 & DR_TRAP_BITS) \|\|
		if ((current->thread.virtual_dr6 & DR_TRAP_BITS) \|\|
		(dr6 & (~DR_TRAP_BITS)))
		rc = NOTIFY_DONE;

arch/x86/kernel/kgdb.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -629,9 +629,10 @@ static void kgdb_hw_overflow_handler(struct perf_event *event,
		struct task_struct *tsk = current;
		int i;

		for (i = 0; i < 4; i++)
		for (i = 0; i < 4; i++) {
		if (breakinfo[i].enabled)
		tsk->thread.debugreg6 \|= (DR_TRAP0 << i);
		tsk->thread.virtual_dr6 \|= (DR_TRAP0 << i);
		}
		}

		void kgdb_arch_late(void)

arch/x86/kernel/ptrace.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -465,7 +465,7 @@ static void ptrace_triggered(struct perf_event *bp,
		break;
		}

		thread->debugreg6 \|= (DR_TRAP0 << i);
		thread->virtual_dr6 \|= (DR_TRAP0 << i);
		}

		/*
		@@ -601,7 +601,7 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
		if (bp)
		val = bp->hw.info.address;
		} else if (n == 6) {
		val = thread->debugreg6 ^ DR6_RESERVED; /* Flip back to arch polarity */
		val = thread->virtual_dr6 ^ DR6_RESERVED; /* Flip back to arch polarity */
		} else if (n == 7) {
		val = thread->ptrace_dr7;
		}
		@@ -657,7 +657,7 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n,
		if (n < HBP_NUM) {
		rc = ptrace_set_breakpoint_addr(tsk, n, val);
		} else if (n == 6) {
		thread->debugreg6 = val ^ DR6_RESERVED; /* Flip to positive polarity */
		thread->virtual_dr6 = val ^ DR6_RESERVED; /* Flip to positive polarity */
		rc = 0;
		} else if (n == 7) {
		rc = ptrace_write_dr7(tsk, val);

arch/x86/kernel/traps.c

+16 −9

Original line number	Diff line number	Diff line
		@@ -748,6 +748,12 @@ static __always_inline unsigned long debug_read_clear_dr6(void)
		set_debugreg(DR6_RESERVED, 6);
		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
		@@ -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));

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