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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::1034; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1034.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1634056191653100001 Content-Type: text/plain; charset="utf-8" As per an ancient comment in mips_tr_translate_insn about the expectations of gdb, when restarting the insn in a delay slot we also re-execute the branch. Which means that we are expected to execute two insns in this case. This has been broken since 8b86d6d2580, where we forced max_insns to 1 while single-stepping. This resulted in an exit from the translator loop after the branch but before the delay slot is translated. Increase the max_insns to 2 for this case. In addition, bypass the end-of-page check, for when the branch itself ends the page. Signed-off-by: Richard Henderson Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- target/mips/tcg/translate.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c index 148afec9dc..f239f9ffc0 100644 --- a/target/mips/tcg/translate.c +++ b/target/mips/tcg/translate.c @@ -16016,6 +16016,16 @@ static void mips_tr_init_disas_context(DisasContex= tBase *dcbase, CPUState *cs) ctx->default_tcg_memop_mask =3D (ctx->insn_flags & (ISA_MIPS_R6 | INSN_LOONGSON3A)) ? MO_UNALN : MO_ALIGN; =20 + /* + * Execute a branch and its delay slot as a single instruction. + * This is what GDB expects and is consistent with what the + * hardware does (e.g. if a delay slot instruction faults, the + * reported PC is the PC of the branch). + */ + if (ctx->base.singlestep_enabled && (ctx->hflags & MIPS_HFLAG_BMASK)) { + ctx->base.max_insns =3D 2; + } + LOG_DISAS("\ntb %p idx %d hflags %04x\n", ctx->base.tb, ctx->mem_idx, ctx->hflags); } @@ -16085,17 +16095,14 @@ static void mips_tr_translate_insn(DisasContextBa= se *dcbase, CPUState *cs) if (ctx->base.is_jmp !=3D DISAS_NEXT) { return; } + /* - * Execute a branch and its delay slot as a single instruction. - * This is what GDB expects and is consistent with what the - * hardware does (e.g. if a delay slot instruction faults, the - * reported PC is the PC of the branch). + * End the TB on (most) page crossings. + * See mips_tr_init_disas_context about single-stepping a branch + * together with its delay slot. */ - if (ctx->base.singlestep_enabled && - (ctx->hflags & MIPS_HFLAG_BMASK) =3D=3D 0) { - ctx->base.is_jmp =3D DISAS_TOO_MANY; - } - if (ctx->base.pc_next - ctx->page_start >=3D TARGET_PAGE_SIZE) { + if (ctx->base.pc_next - ctx->page_start >=3D TARGET_PAGE_SIZE + && !ctx->base.singlestep_enabled) { ctx->base.is_jmp =3D DISAS_TOO_MANY; } } --=20 2.25.1