Messages in this thread Patch in this message | | | Date | Fri, 21 Aug 2020 11:39:14 +0200 | From | Peter Zijlstra <> | Subject | [PATCH v2 2/8] x86/debug: Sync BTF earlier |
| |
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: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/kernel/traps.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
--- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -749,6 +749,13 @@ static __always_inline unsigned long deb /* 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; } @@ -783,13 +790,6 @@ static void handle_debug(struct pt_regs 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. */
| |