x86/debug: Sync BTF earlier (c182487d) · Commits · 戴 / test

Move the BTF sync near the DR6 load, as this will be the only common code guaranteed to run on every #DB. Signed-off-by:

arch/x86/kernel/traps.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -749,6 +749,13 @@ static __always_inline unsigned long debug_read_clear_dr6(void)
		/* Filter out all the reserved bits which are preset to 1 */
		dr6 &= ~DR6_RESERVED;

		/*
		* 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.
		*/
		clear_thread_flag(TIF_BLOCKSTEP);

		return dr6;
		}

		@@ -782,13 +789,6 @@ static void handle_debug(struct pt_regs *regs, unsigned long dr6, bool user)
		bool user_icebp;
		int si_code;

		/*
		* 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.
		*/
		clear_thread_flag(TIF_BLOCKSTEP);

		/*
		* If DR6 is zero, no point in trying to handle it. The kernel is
		* not using INT1.