Re: [PATCH RFC 1/2] m68k: Add tracirqs

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Hi Michael,

On 23/10/2024 05:53, Michael Schmitz wrote:
Jean-Michel,

thanks for your patches!

Am 21.10.2024 um 22:44 schrieb Jean-Michel Hautbois:
The TRACE_IRQFLAGS_SUPPORT requires the architecture to call
trace_hardirqs_off() when interrupts are disabled and
trace_hardirqs_on() when they are enabled.
Add those calls to do_IRQ function.

You will also have to add these calls to the three sites in arch/m68k/ coldfire/head.S where interrupts are enabled or disabled.

Thanks for this ! I prepared a v2 with those calls added. I am wondering if my second patch is ok, I think it is not, could you please review it ? There may already be something related to the stack in the assembly part useful to implement arch_stack_walk() in a different way ?

Here:
ENTRY(system_call)
        SAVE_ALL_SYS
        move    #0x2000,%sr             /* enable intrs again */
        GET_CURRENT(%d2)

and here:
ret_from_exception:
        move    #0x2700,%sr             /* disable intrs */
        btst    #5,%sp@(PT_OFF_SR)      /* check if returning to kernel */         jeq     Luser_return            /* if so, skip resched, signals */

and here:
Lwork_to_do:
        movel   %a0@(TINFO_FLAGS),%d1   /* get thread_info->flags */
        move    #0x2000,%sr             /* enable intrs again */
        btst    #TIF_NEED_RESCHED,%d1
        jne     reschedule

There's one similar site in arch/m68k/kernel/head.S (ret_from_exception) where interrupts are enabled that would need a similar change, if you want to enable this for all m68k.

I won't be able to test it though ;-).
I see there are a few interrupts disabling in arch/m68k/include/asm/entry.h too ?


Registers %d0-%d5 and %a0-%a2 are saved on the stack at this point and can be clobbered if need be.

I don't know if they need to be clobbered...

Thanks,
JM


Cheers,

     Michael



Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@xxxxxxxxxx>
---
 arch/m68k/Kconfig      | 1 +
 arch/m68k/kernel/irq.c | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index cc26df907bfe3c8143a931d259eceabb16af7411..ab3375475721fa63418c40d4ba6ac76679ebc77d 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -39,6 +39,7 @@ config M68K
     select OLD_SIGSUSPEND3
     select UACCESS_MEMCPY if !MMU
     select ZONE_DMA
+    select TRACE_IRQFLAGS_SUPPORT

 config CPU_BIG_ENDIAN
     def_bool y
diff --git a/arch/m68k/kernel/irq.c b/arch/m68k/kernel/irq.c
index 9ab4f550342e5de11c528f55781432675ffd66bf..74cf60ebbc4bca51f3caa4046dbd2bdb02355711 100644
--- a/arch/m68k/kernel/irq.c
+++ b/arch/m68k/kernel/irq.c
@@ -21,9 +21,11 @@ asmlinkage void do_IRQ(int irq, struct pt_regs *regs)
 {
     struct pt_regs *oldregs = set_irq_regs(regs);

+    trace_hardirqs_off();
     irq_enter();
     generic_handle_irq(irq);
     irq_exit();
+    trace_hardirqs_on();

     set_irq_regs(oldregs);
 }






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