From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53031) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cxWk1-0000CK-FD for qemu-devel@nongnu.org; Mon, 10 Apr 2017 06:40:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cxWk0-0006BU-CN for qemu-devel@nongnu.org; Mon, 10 Apr 2017 06:40:13 -0400 From: Peter Maydell Date: Mon, 10 Apr 2017 11:39:53 +0100 Message-Id: <1491820793-5348-8-git-send-email-peter.maydell@linaro.org> In-Reply-To: <1491820793-5348-1-git-send-email-peter.maydell@linaro.org> References: <1491820793-5348-1-git-send-email-peter.maydell@linaro.org> Subject: [Qemu-devel] [PATCH 7/7] arm: Remove workarounds for old M-profile exception return implementation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Cc: patches@linaro.org, Richard Henderson Now that we've rewritten M-profile exception return so that the magic PC values are not visible to other parts of QEMU, we can delete the special casing of them elsewhere. Signed-off-by: Peter Maydell --- target/arm/cpu.c | 43 ++----------------------------------------- target/arm/translate.c | 8 -------- 2 files changed, 2 insertions(+), 49 deletions(-) diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 04b062c..b357aee 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -304,33 +304,6 @@ bool arm_cpu_exec_interrupt(CPUState *cs, int interrupt_request) } #if !defined(CONFIG_USER_ONLY) || !defined(TARGET_AARCH64) -static void arm_v7m_unassigned_access(CPUState *cpu, hwaddr addr, - bool is_write, bool is_exec, int opaque, - unsigned size) -{ - ARMCPU *arm = ARM_CPU(cpu); - CPUARMState *env = &arm->env; - - /* ARMv7-M interrupt return works by loading a magic value into the PC. - * On real hardware the load causes the return to occur. The qemu - * implementation performs the jump normally, then does the exception - * return by throwing a special exception when when the CPU tries to - * execute code at the magic address. - */ - if (env->v7m.exception != 0 && addr >= 0xfffffff0 && is_exec) { - cpu->exception_index = EXCP_EXCEPTION_EXIT; - cpu_loop_exit(cpu); - } - - /* In real hardware an attempt to access parts of the address space - * with nothing there will usually cause an external abort. - * However our QEMU board models are often missing device models where - * the guest can boot anyway with the default read-as-zero/writes-ignored - * behaviour that you get without a QEMU unassigned_access hook. - * So just return here to retain that default behaviour. - */ -} - static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request) { CPUClass *cc = CPU_GET_CLASS(cs); @@ -338,17 +311,7 @@ static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request) CPUARMState *env = &cpu->env; bool ret = false; - /* ARMv7-M interrupt return works by loading a magic value - * into the PC. On real hardware the load causes the - * return to occur. The qemu implementation performs the - * jump normally, then does the exception return when the - * CPU tries to execute code at the magic address. - * This will cause the magic PC value to be pushed to - * the stack if an interrupt occurred at the wrong time. - * We avoid this by disabling interrupts when - * pc contains a magic address. - * - * ARMv7-M interrupt masking works differently than -A or -R. + /* ARMv7-M interrupt masking works differently than -A or -R. * There is no FIQ/IRQ distinction. Instead of I and F bits * masking FIQ and IRQ interrupts, an exception is taken only * if it is higher priority than the current execution priority @@ -356,8 +319,7 @@ static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request) * currently active exception). */ if (interrupt_request & CPU_INTERRUPT_HARD - && (armv7m_nvic_can_take_pending_exception(env->nvic)) - && (env->regs[15] < 0xfffffff0)) { + && (armv7m_nvic_can_take_pending_exception(env->nvic))) { cs->exception_index = EXCP_IRQ; cc->do_interrupt(cs); ret = true; @@ -1091,7 +1053,6 @@ static void arm_v7m_class_init(ObjectClass *oc, void *data) cc->do_interrupt = arm_v7m_cpu_do_interrupt; #endif - cc->do_unassigned_access = arm_v7m_unassigned_access; cc->cpu_exec_interrupt = arm_v7m_cpu_exec_interrupt; } diff --git a/target/arm/translate.c b/target/arm/translate.c index 156ab46..c85bc6c 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -11914,14 +11914,6 @@ void gen_intermediate_code(CPUARMState *env, TranslationBlock *tb) dc->is_jmp = DISAS_EXC; break; } -#else - if (arm_dc_feature(dc, ARM_FEATURE_M)) { - /* Branches to the magic exception-return addresses should - * already have been caught via the arm_v7m_unassigned_access hook, - * and never get here. - */ - assert(dc->pc < 0xfffffff0); - } #endif if (unlikely(!QTAILQ_EMPTY(&cs->breakpoints))) { -- 2.7.4