From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40918) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ewrg3-0001I4-Iz for qemu-devel@nongnu.org; Fri, 16 Mar 2018 11:53:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ewrfy-0006IK-OL for qemu-devel@nongnu.org; Fri, 16 Mar 2018 11:53:55 -0400 Received: from mail-pg0-x242.google.com ([2607:f8b0:400e:c05::242]:35238) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1ewrfy-0006I5-HM for qemu-devel@nongnu.org; Fri, 16 Mar 2018 11:53:50 -0400 Received: by mail-pg0-x242.google.com with SMTP id d1so4233125pgv.2 for ; Fri, 16 Mar 2018 08:53:50 -0700 (PDT) From: Richard Henderson Date: Fri, 16 Mar 2018 23:53:40 +0800 Message-Id: <20180316155340.25734-1-richard.henderson@linaro.org> Subject: [Qemu-devel] [PATCH] tcg: fix cpu_io_recompile List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Pavel.Dovgaluk@ispras.ru, peter.maydell@linaro.org, pbonzini@redhat.com We have confused the number of instructions that have been executed in the TB with the number of instructions needed to repeat the I/O instruction. We have used cpu_restore_state_from_tb, which means that the guest pc is pointing to the I/O instruction. The only time the answer to the later question is not 1 is when MIPS or SH4 need to re-execute the branch for the delay slot as well. Signed-off-by: Richard Henderson --- accel/tcg/translate-all.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index 67795cd78c..d4190602d1 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -1736,37 +1736,32 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) cpu_abort(cpu, "cpu_io_recompile: could not find TB for pc=%p", (void *)retaddr); } - n = cpu->icount_decr.u16.low + tb->icount; cpu_restore_state_from_tb(cpu, tb, retaddr); - /* Calculate how many instructions had been executed before the fault - occurred. */ - n = n - cpu->icount_decr.u16.low; - /* Generate a new TB ending on the I/O insn. */ - n++; + /* On MIPS and SH, delay slot instructions can only be restarted if they were already the first instruction in the TB. If this is not the first instruction in a TB then re-execute the preceding branch. */ + n = 1; #if defined(TARGET_MIPS) - if ((env->hflags & MIPS_HFLAG_BMASK) != 0 && n > 1) { + if ((env->hflags & MIPS_HFLAG_BMASK) != 0 + && env->active_tc.PC != tb->pc) { env->active_tc.PC -= (env->hflags & MIPS_HFLAG_B16 ? 2 : 4); cpu->icount_decr.u16.low++; env->hflags &= ~MIPS_HFLAG_BMASK; + n = 2; } #elif defined(TARGET_SH4) if ((env->flags & ((DELAY_SLOT | DELAY_SLOT_CONDITIONAL))) != 0 - && n > 1) { + && env->pc != tb->pc) { env->pc -= 2; cpu->icount_decr.u16.low++; env->flags &= ~(DELAY_SLOT | DELAY_SLOT_CONDITIONAL); + n = 2; } #endif - /* This should never happen. */ - if (n > CF_COUNT_MASK) { - cpu_abort(cpu, "TB too big during recompile"); - } - /* Adjust the execution state of the next TB. */ + /* Generate a new TB executing the I/O insn. */ cpu->cflags_next_tb = curr_cflags() | CF_LAST_IO | n; if (tb->cflags & CF_NOCACHE) { -- 2.14.3