From c3a2654fa248687c66f033fcdb4dd6c50e6d6fdf Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 30 Sep 2016 14:58:48 +0200 Subject: [PATCH] x86emul: defer injection of #DB Move the raising of the single step trap until after registers were updated. This should probably have been that way from the beginning, to allow the inject_hw_exception() hook to see updated register state (in case it cares) - it's a trap, after all. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/x86_emulate/x86_emulate.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c index c3d193ce51..8c6cc50bec 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -2265,6 +2265,7 @@ x86_emulate( struct x86_emulate_state state; int rc; uint8_t b, d; + bool tf = ctxt->regs->eflags & EFLG_TF; struct operand src = { .reg = REG_POISON }; struct operand dst = { .reg = REG_POISON }; enum x86_swint_type swint_type; @@ -5176,11 +5177,6 @@ x86_emulate( } no_writeback: - /* Inject #DB if single-step tracing was enabled at instruction start. */ - if ( (ctxt->regs->eflags & EFLG_TF) && (rc == X86EMUL_OKAY) && - (ops->inject_hw_exception != NULL) ) - rc = ops->inject_hw_exception(EXC_DB, -1, ctxt) ? : X86EMUL_EXCEPTION; - /* Commit shadow register state. */ _regs.eflags &= ~EFLG_RF; @@ -5190,6 +5186,10 @@ x86_emulate( *ctxt->regs = _regs; + /* Inject #DB if single-step tracing was enabled at instruction start. */ + if ( tf && (rc == X86EMUL_OKAY) && ops->inject_hw_exception ) + rc = ops->inject_hw_exception(EXC_DB, -1, ctxt) ? : X86EMUL_EXCEPTION; + done: _put_fpu(); put_stub(stub); -- 2.30.2