Re: [PATCH 2/4] target/arm: Move cortex-m related functions to new file v7m.c

[Auger Eric <eric.auger@redhat.com>]

Hi Thomas,

On 9/23/19 8:09 PM, Thomas Huth wrote:
> On 23/09/2019 16.31, Auger Eric wrote:
>> Hi Thomas,
>>
>> On 9/21/19 5:04 PM, Thomas Huth wrote:
>>> We are going to make CONFIG_ARM_V7M optional, so the related cortex-m
>>> CPUs should only be created if the switch is enabled. This can best
>>> be done if the code resides in a separate file, thus move the related
>>> functions to a new file v7m.c which only gets compiled if CONFIG_ARM_V7M
>>> is enabled.
>>>
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>> ---
>>>  target/arm/Makefile.objs |   1 +
>>>  target/arm/cpu.c         | 146 -----------------------------
>>>  target/arm/v7m.c         | 193 +++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 194 insertions(+), 146 deletions(-)
>>>  create mode 100644 target/arm/v7m.c
> [...]
>>> diff --git a/target/arm/v7m.c b/target/arm/v7m.c
>>> new file mode 100644
>>> index 0000000000..505043febe
>>> --- /dev/null
>>> +++ b/target/arm/v7m.c
>>> @@ -0,0 +1,193 @@
>>> +/*
>>> + * ARM v7m helpers.
>>> + *
>>> + * This code is licensed under the GNU GPL v2 or later.
>>> + *
>>> + * SPDX-License-Identifier: GPL-2.0-or-later
>>> + */
>>> +
>>> +#include "qemu/osdep.h"
>>> +#include "qemu/qemu-print.h"
>>> +#include "qemu-common.h"
>>> +#include "target/arm/idau.h"
>>> +#include "qemu/module.h"
>>> +#include "qapi/error.h"
>>> +#include "qapi/visitor.h"
>>> +#include "cpu.h"
>>> +#include "internals.h"
>>> +#include "exec/exec-all.h"
>>> +#include "hw/qdev-properties.h"
>>> +#if !defined(CONFIG_USER_ONLY)
>>> +#include "hw/loader.h"
>>> +#include "hw/boards.h"
>>> +#endif
>>> +#include "sysemu/sysemu.h"
>>> +#include "sysemu/tcg.h"
>>> +#include "sysemu/hw_accel.h"
>>> +#include "disas/capstone.h"
>>> +#include "fpu/softfloat.h"
>>
>> I guess some of those headers are not needed.
> 
> Yeah, I just copy-n-pasted from the source file ... I'll check what can
> be omitted (if this patch series has a chance at all...)
> 
>>> +
>>> +#if !defined(CONFIG_USER_ONLY) || !defined(TARGET_AARCH64)
>>> +
>>> +static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
>>> +{
>>> +    CPUClass *cc = CPU_GET_CLASS(cs);
>>> +    ARMCPU *cpu = ARM_CPU(cs);
>>> +    CPUARMState *env = &cpu->env;
>>> +    bool ret = false;
>>> +
>>> +    /*
>>> +     * 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
>>> +     * (which depends on state like BASEPRI, FAULTMASK and the
>>> +     * currently active exception).
>>> +     */
>>> +    if (interrupt_request & CPU_INTERRUPT_HARD
>>> +        && (armv7m_nvic_can_take_pending_exception(env->nvic))) {
>>
>> so what is the status wrt m_helper.c which stays unconditionally
>> compiled. m_helper functions seem to called from target/arm/translate.c
>> mostly. Have you abandoned the stub idea. It may be confusing to have 2
>> different helper files. At least a comment explaining where a new helper
>> shall go may be useful.
> 
> All the HELPER() functions should definitely stay in m_helper.c. They
> are required for linking. Or do you prefer a stub file instead? Then we
> could maybe make the whole m_helper.c conditional in the Makefile.objs
> instead.

I was simply referring to your previous approach:

Applying [Qemu-devel] [RFC PATCH 3/3] target/arm: Make m_helper.c
optional via CONFIG_ARM_V7M seems to fix the issue
https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg00333.html

It seems to work fine as it removes the call to armv7m_nvic.c functions
so no need to move the interrupt controller code?

Thanks

Eric

> 
> However, there's one thing I currently don't quite understand in this
> code (since I'm not an ARM guy, sorry) : There are references to "v8" in
> m_helper.c, too. Is that related to a separate CPU type, ie. should the
> v8 code also be available when CONFIG_ARM_V7M is disabled? Or can the
> code in m_helper.c be disabled completely if CONFIG_ARM_V7M is not set?
> 
>  Thomas
>