From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44897) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zn7nM-0002Tn-El for qemu-devel@nongnu.org; Fri, 16 Oct 2015 12:23:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zn7nL-0005WU-5T for qemu-devel@nongnu.org; Fri, 16 Oct 2015 12:23:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41820) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zn7nL-0005WD-0D for qemu-devel@nongnu.org; Fri, 16 Oct 2015 12:23:51 -0400 From: Eduardo Habkost Date: Fri, 16 Oct 2015 13:23:32 -0300 Message-Id: <1445012619-23772-3-git-send-email-ehabkost@redhat.com> In-Reply-To: <1445012619-23772-1-git-send-email-ehabkost@redhat.com> References: <1445012619-23772-1-git-send-email-ehabkost@redhat.com> Subject: [Qemu-devel] [PATCH v2 2/9] target-i386: Re-introduce optimal breakpoint removal List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Paolo Bonzini , Richard Henderson From: Richard Henderson Before the last patch, we had an efficient loop that disabled local breakpoints on task switch. Re-add that, but in a more general way that handles changes to the global enable bits too. Signed-off-by: Richard Henderson Signed-off-by: Paolo Bonzini Signed-off-by: Eduardo Habkost --- Changes v1 -> v2: * Included fix from Paolo to make sure dr7 is updated after hw_breakpoint_remove() call and before hw_breakpoint_insert() call --- target-i386/bpt_helper.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-) diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c index f14788a..23ce828 100644 --- a/target-i386/bpt_helper.c +++ b/target-i386/bpt_helper.c @@ -82,14 +82,36 @@ static void hw_breakpoint_remove(CPUX86State *env, int index) void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7) { + target_ulong old_dr7 = env->dr[7]; int i; - for (i = 0; i < DR7_MAX_BP; i++) { - hw_breakpoint_remove(env, i); - } - env->dr[7] = new_dr7; - for (i = 0; i < DR7_MAX_BP; i++) { - hw_breakpoint_insert(env, i); + /* If nothing is changing except the global/local enable bits, + then we can make the change more efficient. */ + if (((old_dr7 ^ new_dr7) & ~0xff) == 0) { + /* Fold the global and local enable bits together into the + global fields, then xor to show which registers have + changed collective enable state. */ + int mod = ((old_dr7 | old_dr7 * 2) ^ (new_dr7 | new_dr7 * 2)) & 0xff; + + for (i = 0; i < DR7_MAX_BP; i++) { + if ((mod & (2 << i * 2)) && !hw_breakpoint_enabled(new_dr7, i)) { + hw_breakpoint_remove(env, i); + } + } + env->dr[7] = new_dr7; + for (i = 0; i < DR7_MAX_BP; i++) { + if (mod & (2 << i * 2) && hw_breakpoint_enabled(new_dr7, i)) { + hw_breakpoint_insert(env, i); + } + } + } else { + for (i = 0; i < DR7_MAX_BP; i++) { + hw_breakpoint_remove(env, i); + } + env->dr[7] = new_dr7; + for (i = 0; i < DR7_MAX_BP; i++) { + hw_breakpoint_insert(env, i); + } } } #endif -- 2.1.0